To identify the cause of mass mortality of adult Macrobrachium rosenbergii in a farm in Gaoyou City,Jiangsu Province,China,a dominant strain named DKQ-1 was isolated from the hepatopancreas of dying M.rosenbergii and ...To identify the cause of mass mortality of adult Macrobrachium rosenbergii in a farm in Gaoyou City,Jiangsu Province,China,a dominant strain named DKQ-1 was isolated from the hepatopancreas of dying M.rosenbergii and identified as Aeromonas dhakensis by purification culture,biochemical characterization,and 16S rRNA and gyrB gene sequence analysis.The results of the challenge test revealed that the strain was highly pathogenic and the 50%lethal dose(LD_(50))in 72 h to M.rosenbergii was 1.54×10^(5)CFU/mL.The amplification results of virulence genes show that strain DKQ-1 carried 9 virulence genes,including ascV,aexT,aer,act,lip,ompAI,gcaT,acg,and exu,supporting the strong virulence of strain DKQ-1 to M.rosenbergii.Histopathological observation of the hepatopancreas,gills,and intestines indicated that DKQ-1 injection into M.rosenbergii could cause serious tissue damage,which further supported the strong virulence of this strain.In addition,a drug susceptibility test revealed that strain DKQ-1 was sensitive to 16 kinds of antibiotics,resistant to 9 kinds of antibiotics,and had intermediate resistance to spectinomycin and kanamycin.This study is the first report of A.dhakensis isolated from M.rosenbergii and provided a reference for the pathogen identification of bacterial diseases in M.rosenbergii,and for the prevention and treatment caused by A.dhakensis.展开更多
[Objectives]To study the effects of microplastics on antibiotic resistance genes and virulence genes of Vibrio alginolyticus,so as to provide a certain reference for controlling marine pollution,curbing the spread of ...[Objectives]To study the effects of microplastics on antibiotic resistance genes and virulence genes of Vibrio alginolyticus,so as to provide a certain reference for controlling marine pollution,curbing the spread of environmental antibiotic resistance genes and virulence genes,formulating environmental policies,and maintaining food safety.[Methods]After adding V.alginolyticus into the artificial seawater,they were divided into three groups,namely blank control group(BLK),polyvinyl chloride microplastic group(PVC group)and polyvinyl alcohol microplastic group(PVA group).Aerated culture experiments were carried out,and the effects of microplastics on the expression of resistance genes and virulence genes of V.alginolyticus were studied by PCR and qPCR methods.[Results]The presence of microplastics significantly changed the resistance gene structure of V.alginolyticus.Compared with the control group,the cfxA and cfr resistance genes were detected in the microplastic group.However,only PVC group detected blaZ resistance gene,and only PVA group did not detect aaC resistance gene.In addition,compared with the control group,the expressions of virulence genes in the microplastic group were all down-regulated(P<0.01).[Conclusions]This study provides some reference for curbing the spread of environmental antibiotic resistance genes and virulence genes,formulating environmental policies,and maintaining food safety,but the specific mechanisms of drug resistance and virulence need further research.展开更多
Helicobacter pylori(H.pylori)is one of the most important human pathogens,infecting approximately half of the global population.Despite its high prevalence,only a subset of H.pylori infected individuals develop seriou...Helicobacter pylori(H.pylori)is one of the most important human pathogens,infecting approximately half of the global population.Despite its high prevalence,only a subset of H.pylori infected individuals develop serious gastroduodenal pathology.The pathogenesis of H.pylori infection and disease outcome is thus thought to be mediated by an intricate interplay between host,environmental and bacterial virulence factors.H.pylori has adapted to the harsh milieu of the human stomach through possession of various virulence genes that enable survival of the bacteria in the acidic environment,movement towards the gastric epithelium,and attachment to gastric epithelial cells.These virulence factors enable successful colonization of the gastric mucosa and sustain persistent H.pylori infection,causing chronic inflammation and tissue damage,which may eventually lead to the development of peptic ulcers and gastric cancer.Numerous studies have focused on the prevalence and role of putative H.pylori virulence genes in disease pathogenesis.While several virulence factors with various functions have been identified,disease associations appear to be less evident,especially among different study populations.This review presents key findings on the most important H.pylori virulence genes,including several bacterial adhesins and toxins,in children and adults,and focuses on their prevalence,clinical significance and potential relationships.展开更多
Objective This study aimed to evaluate the genetic diversity,virulence,and antimicrobial resistance of Aeromonas isolates from clinical patients,tap water systems,and food.Methods Ninety Aeromonas isolates were obtain...Objective This study aimed to evaluate the genetic diversity,virulence,and antimicrobial resistance of Aeromonas isolates from clinical patients,tap water systems,and food.Methods Ninety Aeromonas isolates were obtained from Ma’anshan,Anhui province,China,and subjected to multi-locus sequence typing(MLST)with six housekeeping genes.Their taxonomy was investigated using concatenated gyr B-cpn60 sequences,while their resistance to 12 antibiotics was evaluated.Ten putative virulence factors and several resistance genes were identified by PCR and sequencing.Results The 90 Aeromonas isolates were divided into 84 sequence types,80 of which were novel,indicating high genetic diversity.The Aeromonas isolates were classified into eight different species.PCR assays identified virulence genes in the isolates,with the enterotoxin and hemolysin genes act,aer A,alt,and ast found in 47(52.2%),13(14.4%),22(24.4%),and 12(13.3%)of the isolates,respectively.The majority of the isolates(≥90%)were susceptible to aztreonam,imipenem,cefepime,chloramphenicol,gentamicin,tetracycline,and ciprofloxacin.However,several resistance genes were detected in the isolates,as well as a new mcr-3 variant.Conclusions Sequence type,virulence properties,and antibiotic resistance vary in Aeromonas isolates from clinical patients,tap water systems,and food.展开更多
The Chinese giant salamander(Andrias davidianus) is the largest living amphibian in the world. Aeromonas hydrophila strain L602 was isolated from A. davidianus. The 16S rDNA gene of this isolate was amplified using PC...The Chinese giant salamander(Andrias davidianus) is the largest living amphibian in the world. Aeromonas hydrophila strain L602 was isolated from A. davidianus. The 16S rDNA gene of this isolate was amplified using PCR,and the phylogenetic tree was constructed by the neighbor-joining method. Four virulence genes(aerA,aha1,hly and alt) of A. hydrophila were amplified by PCR and drug resistances were tested using Kirby-Bauer disk diffusion method. The results showed that the length of this 16S rDNA sequence was 1453 bp,which showed 99% homology with A. hydrophila. The GenBank accession number was JX155398. Phylogenetic analysis indicated it grouped together with A. hydrophila. Four virulence genes were all detected,indicating that strain L602 was highly virulent. This stain was resistant to four antibiotics(vibramycin,furazolidone,ampicillin and erythromycin),while it was insensitive to streptomycin. Furthermore,this strain was susceptible to six antibiotics(sulfafurazole,ciprofloxacin,penbritin,norfloxacin,florfenicol and enrofloxacin). This study will help to validate the classification and virulence of pathogenic bacteria in amphibians.展开更多
Bovine Respiratory Disease (BRD) causes a severe form of pneumonia in all age of cattle. This study was designed to investigate the distribution of capsular types, serotypes, and virulence-associated genes of the majo...Bovine Respiratory Disease (BRD) causes a severe form of pneumonia in all age of cattle. This study was designed to investigate the distribution of capsular types, serotypes, and virulence-associated genes of the major bacterial pathogens from BRD outbreak samples in Ethiopia. In this study 166 samples were collected from clinically sick (<i>n</i> = 107) and pneumonic lung tissue (<i>n</i> = 59). Laboratory assay confirmed isolation of <i>M. haemolytica</i> 37 (22.29%), <i>P. multocida</i> 25 (15.06%), <i>B. trehalosi</i> 12 (7.23%), and <i>H. somni</i> 15 (9.04%). PCR assay of <i>P. multocida</i> capsular typing revealed 21 (84.0%) cap A (<i>hyaD-hyaC</i>) and 4 (16.0%) cap D (<i>dcbF</i>) strains. <i>M. haemolytica</i> serotypes belonged to A: 1, A: 2, and A: 6 from 26 (70.27%), 4 (10.81%), and 7 (18.92%) isolates, respectively. <i>P. multocida</i> biotyping showed isolation of A: 1, A: 2, and A: 3 from 3 (14.29%), 2 (9.52%), and 16 (76.19%) isolates, respectively. <i>M. haemolytica</i> harbored more than 60% <i>ssa</i> gene, and 90.91% <i>sodA</i> while <i>FbpA</i>, <i>TbpA</i>, and <i>lktC</i> genes were found in all isolates. Likewise, all <i>P. multocida</i> exhibited <i>toxA</i>, <i>FbpA</i>, <i>TbpA</i>, and <i>pmSLP</i> genes. The current finding showed that <i>M. haemolytica</i> serotype A: 1 is frequently associated with BRD followed by <i>P. multocida</i> biotype A: 3. These two isolates harbored diverse virulence-associated genes and presented the pathogenic potential of the current isolates. Thus, investigation of pathogenic strains of BRD, virulence genes distribution, and molecular epidemiology of the disease from wider areas of the country are essential. Hence, continuous outbreak surveillance and molecular approaches are indispensable in designing efficient prevention strategies.展开更多
Objective:To investigate the frequency of exoU and exoY genes in patients with Pseudomonas aeruginosa infection.Methods:In this study,100 clinical isolates of Pseudomonas aeruginosa were collected from patients hospit...Objective:To investigate the frequency of exoU and exoY genes in patients with Pseudomonas aeruginosa infection.Methods:In this study,100 clinical isolates of Pseudomonas aeruginosa were collected from patients hospitalized in educational-therapeutic hospitals and were identified using standard microbiological tests.Then,the antibiotic resistance pattern of the isolates was determined by the disk agar diffusion method.The bacterial DNAs were extracted by the alkaline lysis method.Finally,the presence of exoU and exoY genes was evaluated by the PCR test.Results:In this study,47%,72%,29%,39%,40%,and 44%of the isolates were non-susceptible to piperacillin,aztreonam,ceftazidime,imipenem,tobramycin,and ciprofloxacin,respectively.In addition,95%and 93%of the clinical isolates carried the exoU and exoY genes.Blood and fecal isolates had both virulence genes,while only one wound isolate had neither genes.Meanwhile,all urinary isolates contained the exoY gene and only one isolate lacked the exoU gene.Also,88 isolates simultaneously had both exoU and exoY genes.Conclusions:High prevalence of exoU and exoY genes in this region indicates a significant role of typeⅢsecretion system in pathogenesis of Pseudomonas aeruginosa.The typeⅢsecretion system may be a suitable target to reduce the pathogenicity of this bacterium.展开更多
The objectives of this study were to investigate antimicrobial resistance of Streptococcus uberis and Streptococcus parauberis isolated from cows with bovine clinical mastitis in China and to examine the distribution ...The objectives of this study were to investigate antimicrobial resistance of Streptococcus uberis and Streptococcus parauberis isolated from cows with bovine clinical mastitis in China and to examine the distribution of resistance-and virulence-related gene patterns.Antimicrobial susceptibility was determined by the E-test.Genes encoding antimicrobial resistance and invasiveness factors were examined by PCR.A total of 27 strains were obtained from 326 mastitis milk samples.Streptococcus parauberis isolates(n=11)showed high resistance to erythromycin(90.9%),followed by tetracycline(45.5%),chloramphenicol(36.4%)and clindamycin(27.3%).Streptococcus uberis isolates(n=16)were highly resistant to tetracycline(81.3%)and clindamycin(62.5%).Both species were susceptible to ampicillin.The most prevalent resistance gene in S.uberis was tetM(80.0%),followed by blaZ(62.5%)and ermB(62.5%).However,tetM,blaZ,and ermB genes were only found in 27.3,45.5,and 27.3%,respectively,of S.parauberis.In addition,all of the isolates carried at least one selected virulence-related gene.The most prevalent virulence-associated gene pattern in the current study was sua+pauA/skc+gapC+hasC detected in 22.2%of the strains.One S.uberis strain carried 7 virulence-associated genes and belonged to the sua+pauA/skc+gapC+cfu+hasA+hasB+hasC pattern.More than 59.3%of analysed strains carried 4 to 7 virulence-related genes.Our findings demonstrated that S.parauberis and S.uberis isolated from clinical bovine mastitis cases in China exhibited diverse molecular ecology,and that the strains were highly resistant to antibiotics commonly used in the dairy cow industry.The data obtained in the current study contribute to a better understanding of the pathogenesis of bacteria in mastitis caused by these pathogens,and the findings are relevant to the development of multivalent vaccines and targeted prevention procedures.展开更多
Nine strains of Aeromonas hydrophila isolated from diseased fish or soft-shelled tortoise were tested for the presence of three virulence genes including the genes encoding aerolysin,hemolysin,and extracellular serine...Nine strains of Aeromonas hydrophila isolated from diseased fish or soft-shelled tortoise were tested for the presence of three virulence genes including the genes encoding aerolysin,hemolysin,and extracellular serine protease(i.e.,aerA,hlyA,and ahpA,respectively).These genes were investigated using polymerase chain reaction(PCR)with specific primers for each gene.And the pathogenicities to Carrassius auratus ibebio of these strains were also assayed.PCR results demonstrated that the distribution patterns of aerA,hlyA,and ahpA were different in these strains.6/9 of A.hydrophila strains were aerA positive,8/9 of strains hlyA positive,7/9 of strains ahpA positive,respective-ly.However,the assay for pathogenesis showed that two strains(A.hydrophila XS91-4-1 and C2)were strong virulent,two strains(A.hydrophila ST78-3-3 and 58-20-9)avirulent and the rest middle virulent was to the fish.In conclusion,there are significant correlation between the distribution pattern of the three virulence genes and the patho-genicity to Carrassius auratus ibebio.All strong virulent A.hydrophila strains were aerA+hlyA+ahpA+genotype,and all aerA+hlyA+ahpA+strains were virulent.Strains with the genotype of aerA−hlyA−ahpA+have middle pathogenicity.In the present study,we found for the first time that all A.hydrophila isolated from the ahpA positive were virulent to Carrassius auratus ibebio.Additionally,there was a positive correlation between the virulence of A.hydrophila and the presence of aerA and ahpA.展开更多
In this work, we evaluated biofilm formation of Vancomycin Resistant of E. faecalis and E. faecium (VRE) in different culture media and adhesion substrate, as well as cellular hydrophobicity and presence of virulence ...In this work, we evaluated biofilm formation of Vancomycin Resistant of E. faecalis and E. faecium (VRE) in different culture media and adhesion substrate, as well as cellular hydrophobicity and presence of virulence genes. For this, 35 isolates were collected from a public hospital in Recife, Pernambuco, Brazil and identified by the Matrix-Assisted Laser Desorption Ionization - Time-of-flight - Mass Spectrometry (MALDI-TOF-MS) technique. Biofilm formation was analyzed by the Crystal Violet (CV) method and fluorescence microscopy, cellular hydrophobicity by hydrocarbon interaction and the presence of gelE, esp and asa1 genes by Polymerase Chain Reaction (PCR). 12 isolates were identified as E. faecalis and 23 as E. faecium. Most were obtained in Coronary Units (40.0%) and Intensive Care Unit (31.4%). E. faecium isolates were more resistant to the antibiotics tested than E. faecalis;however, E. faecalis stood out as a biofilm producer. Regarding the presence and gene frequency, it was observed that gelE (54.3%) and esp (54.3%) were the most prevalent, followed by asa1 (22.9%). When comparing the gene frequency, it was observed that gelE and esp were predominant (48.6% for both species), while asa1 was more frequent in E. faecalis (20.0%). The data presented here are worrying, because they reveal the virulence potential of isolates VRE, which contributes to the dissemination and persistence of these pathogens in the hospital environment.展开更多
BACKGROUND:The virulent factors of Escherichia coli(E.coli) play an important role in the process of pathopoiesis.The study aimed to compare drug-resistant genes and virulence genes between extended spectrum β-lactam...BACKGROUND:The virulent factors of Escherichia coli(E.coli) play an important role in the process of pathopoiesis.The study aimed to compare drug-resistant genes and virulence genes between extended spectrum β-lactamases(ESBLs)-producing E.coli and non-ESBLs-producing E.coli to provide a reference for physicians in management of hospital infection.METHODS:From October 2010 to August 2011,96 drug-resistant strains of E.coli isolated were collected from the specimens in Qingdao Municipal Hospital,Qingdao,China.These bacteria strains were divided into a ESBLs-producing group and a non-ESBLs-producing group.Drug sensitivity tests were performed using the Kirby-Bauer(K-B) method.Disinfectant gene,qacEA1-sull and 8 virulence genes(CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1) were tested by polymerase chain reaction(PCR).RESULTS:Among the 96 E.coli isolates,the ESBLs-producing E.coli comprised 46(47.9%)strains and the non-ESBLs-producing E.coli consisted of 50(52.1%) strains.The detection rates of multiple drug-resistant strain,qacEA1-sull,CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1 in 46ESBLs-producing E.coli isolates were 89.1%,76.1%,6.5%,69.6%,69.6%,89.1%,10.9%,26.1%,8.7%,and 19.6%,respectively.In the non-ESBLs-producing E.coli strains,the positive rates of multiple drug-resistant strain,qacEA1-sull,CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1 were 62.0%,80.0%,16.0%,28.0%,64.0%,38.0%,6.0%,34.0%,10.0%,and 24.0%,respectively.The difference in the detection rates of multiple drug-resistant strain,hlyA and VT1 between the ESBLs-producing E.coli strains and the non-ESBLs-producing E.coli strains was statistically significant(P<0.05).CONCLUSION:The positive rate of multiple drug-resistant strains is higher in the ESBLsproducing strains than in the non-ESBLs-producing strains.The expression of some virulence genes hlyA and VT1 varies between the ESBLs-producing strains and the non-ESBLs-producing strains.Increased awareness of clinicians and enhanced testing by laboratories are required to reduce treatment failures and prevent the spread of multiple drug-resistant strains.展开更多
Objective This study was performed to compare the genetic diversity,virulence,and antimicrobial resistance of Aeromonas strains isolated from patients and healthy individuals.Methods A total of 38 clinical strains and...Objective This study was performed to compare the genetic diversity,virulence,and antimicrobial resistance of Aeromonas strains isolated from patients and healthy individuals.Methods A total of 38 clinical strains and 19 strains from healthy individuals were isolated from the samples collected in Ma’anshan City,Anhui Province.Their taxonomy was investigated using concatenated gyrB-cpn60 sequences,and their resistance to 12 antibiotics was evaluated.The pathogenicity of these strains was examined through beta-hemolysis,protease activity,and virulence gene assays.Results The 57 Aeromonas strains were divided into 55 sequence types.Of these types,21 were novel,suggesting that their genetic diversity was high.These Aeromonas isolates could be divided into 7 species,and the positive rates of beta-hemolysis and protease activity were 49.1%and 73.7%,respectively.The detection rate of clinical patients in terms of beta-hemolysis and protease activity was higher than that of healthy individuals.Among the four most common Aeromonas strains,A.dhakensis had the highest detection rate of virulence genes.The multidrug resistance rate of the clinical isolates was much higher than that of the strains isolated from healthy individuals.Conclusions The taxonomy,virulence properties,and antibiotic resistance of Aeromonas isolates from patients differ from those of the isolates from healthy individuals.展开更多
Objective Aeromonas has recently been recognized as an emerging human pathogen.Aeromonasassociated diarrhea is a phenomenon occurring worldwide.This study was designed to determine the prevalence,genetic diversity,ant...Objective Aeromonas has recently been recognized as an emerging human pathogen.Aeromonasassociated diarrhea is a phenomenon occurring worldwide.This study was designed to determine the prevalence,genetic diversity,antibiotic resistance,and pathogenicity of Aeromonas strains isolated from food products in Shanghai.Methods Aeromonas isolates(n=79)collected from food samples were analyzed using concatenated gyrB-cpn60 sequencing.The antibiotic resistance of these isolates was determined using antimicrobial susceptibility testing.Pathogenicity was assessed usingβ-hemolytic,extracellular protease,virulence gene detection,C.elegans liquid toxicity(LT),and cytotoxicity assays.Results Eight different species were identified among the 79 isolates.The most prevalent Aeromonas species were A.veronii[62(78.5%)],A.caviae[6(7.6%)],A.dhakensis[3(3.8%)],and A.salmonicida[3(3.8%)].The Aeromonas isolates were divided into 73 sequence types(STs),of which 65 were novel.The isolates were hemolytic(45.6%)and protease-positive(81.0%).The most prevalent virulence genes were act(73.4%),fla(69.6%),aexT(36.7%),and ascV(30.4%).The results of C.elegans LT and cytotoxicity assays revealed that A.dhakensis and A.hydrophila were more virulent than A.veronii,A.caviae,and A.bivalvium.Antibiotic resistance genes[tetE,blaTEM,tetA,qnrS,aac(6)-Ib,mcr-1,and mcr-3]were detected in the isolates.The multidrug-resistance rate of the Aeromonas isolates was 11.4%,and 93.7%of the Aeromonas isolates were resistant to cefazolin.Conclusion The taxonomy,antibiotic resistance,and pathogenicity of different Aeromonas species varied.The Aeromonas isolates A.dhakensis and A.hydrophila were highly pathogenic,indicating that food-derived Aeromonas isolates are potential risks for public health and food safety.The monitoring of food quality and safety will result in better prevention and treatment strategies to control diarrhea illnesses in China.展开更多
Uropathogenic Escherichia coli is the common pathogen to cause urinary tract infections (UTIs) and have become multidrug-resistant (MDR) extended-spectrum β-lactamase (ESBL) producers. The differences in the antimicr...Uropathogenic Escherichia coli is the common pathogen to cause urinary tract infections (UTIs) and have become multidrug-resistant (MDR) extended-spectrum β-lactamase (ESBL) producers. The differences in the antimicrobial susceptibility, 5 bla genes, 12 virulence genes of 87 clinical ESBL-producing E. coli isolates and genomic variations and sequence types of 18 recurrent and repeated isolates from 9 patients were investigated. The 87 MDR-ESBL isolates collected mainly from indwelling urinary catheters (IUCs) and UTIs were highly resistant to fluoroquinolones, with over 50% of the isolates being resistant to cefepime and piperacillin/tazobactam and a few being resistant to carbapenem. These isolates carried at least two of the five bla genes examined, with the highest prevalence (87.4%) found for bla<sub>CTX-M</sub> (bla<sub>CTX-M3-like</sub> and bla<sub>CTX-M14-like</sub>), followed by bla<sub>CMY-2</sub> (80.5%) and bla<sub>SHV</sub> (56.3%). The predominant virulence genes were the fimbriae gene fimH and the toxin genes cnf1 and hlyA in blood isolates and the capsule gene kpsMTII in UTI and blood isolates. Over 80% of the isolates carried yersiniabactin and aerobactin of siderophores. In 18 isolates, the fluoroquinolone-resistant ST131 isolate of pulsotypes I and II with bla<sub>CTX-M-15</sub> was clonally disseminated in the hospital. The genomic plasticity of these ST131 occurred mainly through the conjugative plasmids with differences in replicon types A/C, I1, FIA, FIB and Y, size and number. In conclusion, MDR ESBL-producing E. coli isolates differed in virulence genes of UPEC and antibiotic resistance associated with the sources. Plasmid acquisition and chromosomal variations increase the spread of fluoroquinolone-resistant UPEC ST131 worldwide.展开更多
and pili genes are also investigated.Methods:This multicentre,prospective,observational study is conducted in seven major tertiary hospitals in Malaysia among non-pregnant adults.Simultaneously,a retrospective study i...and pili genes are also investigated.Methods:This multicentre,prospective,observational study is conducted in seven major tertiary hospitals in Malaysia among non-pregnant adults.Simultaneously,a retrospective study is conducted in the selected hospitals with similar approaches.GBS isolates are subjected to phenotyping,serotyping by multiplex PCR,antimicrobial susceptibility testing and PCR-detection of GBS virulence and pilus genes.Seven housekeeping genes are amplified and sequenced for multi-locus sequence typing.Discussion:Findings from the study may contribute to the management of clinical practice to diagnose and prevent GBS related diseases in a timely manner.Prudent use of antibiotics is encouraged by monitoring antimicrobial resistance.展开更多
Objective: To investigate some pathogenic characters of Salmonella enterica strains isolated from poultry.Methods: Twenty-three genetically distinct Salmonella enterica strains, of different serovars and pulsotype, we...Objective: To investigate some pathogenic characters of Salmonella enterica strains isolated from poultry.Methods: Twenty-three genetically distinct Salmonella enterica strains, of different serovars and pulsotype, were examined for virulence traits. Resistance to gastric acid environment was estimated by measuring the percentage of survived bacterial cells after exposure for 2 h to a synthetic gastric juice. Strains were analyzed with PCR for the presence of the following virulence genes: mgtC and rhu M located on SPI-3, sopB and pipB located on SPI-5, Salmonella virulence plasmid(spv)R(spvR), spvB and spvC located on Salmonella plasmid virulence and sodCI, sopE, and gipA located on prophage.Finally, resistance to 21 antibiotics was tested with Kirby–Bauer method.Results: A percentage of 82.60% of strains were resistant to gastric environment after induction and 60.87% of the strains exhibited constitutive resistance too. Nineteen different virulence profiles were detected. The phage related genes sodCI and sopE and the plasmid mediated operon spvR, spvB and spvC(spvRBC) were detected in 82.60%,47.82% and 52.17% of strains, respectively. Typhimurium and Enteritidis strains showed the highest number of virulence genes. Twenty-one different antibiotic resistance profiles were obtained and two isolates(Typhimurium and Enteritidis) resulted sensible to all the tested molecules. The ampicillin, streptomycin, sulfonamide and tetracycline resistance profile was detected in seven isolates(30.43%).Conclusion: Our results show that paratyphoid Salmonella strains with several characters of pathogenicity, that may be cause of severe pathology in animals and humans, are circulating among poultry.展开更多
Human health is threatened by foodborne illness and Staphylococcus aureus is a common foodborne pathogenic bacteria.It can cause food poisoning when we are infected,therefore,it is necessary to detect pathogenic bacte...Human health is threatened by foodborne illness and Staphylococcus aureus is a common foodborne pathogenic bacteria.It can cause food poisoning when we are infected,therefore,it is necessary to detect pathogenic bacteria.The virulence genes and detection methods of S.aureus are summarized from literatures.Traditional detection methods are simple but need bacteria enrichment and to prolong detection time.Immunological technology has high specificity,but false positive results are easy to occur in its detection.In recent years,molecular biology methods have developed rapidly,and various PCR techniques have been applied to detect foodborne pathogens.Real-time fluorescent quantitative PCR is more effective than ordinary PCR,while price is expensive when use it,the scope of use is limited.LAMP is a flexible detection method,biosensor and flow cytometry are fast but the cost of detection is high and the price is relatively expensive.展开更多
To characterize extended-spectrum beta-lactamase (ESBL) and extra-intestinal pathogenic Escherichia coli (ExPEC) associated virulence genes in E. coli isolates from chickens and humans in Trinidad and Tobago. This cro...To characterize extended-spectrum beta-lactamase (ESBL) and extra-intestinal pathogenic Escherichia coli (ExPEC) associated virulence genes in E. coli isolates from chickens and humans in Trinidad and Tobago. This cross sectional study was conducted over a three-month period. A total of 471 E. coli isolates;160 from humans treated at a regional tertiary hospital and 311 from chicken caecal samples from “pluck shops” in Trinidad & Tobago were identified using both conventional and molecular microbiological methods. Phenotypic confirmation of ESBL producing E. coli isolates from humans was by Microscan system (Siemens, USA) while the double disk diffusion method was used for the chicken isolates. Polymerase chain reaction (PCR) analysis was used to determine the ESBL and ExPEC-associated virulence genes in representative human isolates and all chicken isolates. From the 311 chicken E. coli isolates, 49.2% (153/311) produced ESBL, while 56.3% (90/160) from humans were ESBL positive. All human and chicken ESBL isolates were 100% susceptible to carbapenems and aminoglycosides antimicrobials. PCR detected 21.1% bla<sub>CTX-M</sub>, 13.3% bla<sub>TEM</sub> and 7.8% bla<sub>SHV</sub> genes among E coli isolates from humans compared to 0.6% bla<sub>CTX-M</sub> and 48.6% bla<sub>TEM</sub> genes in chickens. PCR analysis revealed diverse virulence profiles among the isolates. There was a high occurrence rate of ExPEC-asso- ciated virulence genes in E. coli isolates from both humans and chickens. However, the CTX-M-1 genes were most predominant in humans while TEM occurred in chic- ken isolates. The diverse ESBL and virulence associated gene profiles encountered in E. coli isolates from humans and chickens on the surface depicts no similarity or relationships despite occurrence in both cohort groups. Therefore E. coli strains from chickens and humans require further investigation to determine their clonal relatedness or transmission in the country.展开更多
Escherichia coli has become one of the most important causes of calf diarrhea.The aim of this study is to determine the patterns of antimicrobial resistance of E.coli isolates from six cattle farms and to identify pro...Escherichia coli has become one of the most important causes of calf diarrhea.The aim of this study is to determine the patterns of antimicrobial resistance of E.coli isolates from six cattle farms and to identify prominent resistance genes and virulence genes among the strains isolated from the diarrhea of calves.Antimicrobial susceptibility tests were performed using the disk diffusion method,and PCR was used to detect resistance and virulence genes.The prevalence of multidrug resistant(MDR)E.coli was 77.8%in dairy cattle and 63.6%in beef cattle.There were high resistance rates to penicillin(100%,100%)and ampicillin(96.3%,86.4%)in E.coli from dairy cattle and beef cattle.Interestingly,resistance rate to antimicrobials and distribution of resistance genes in£coli isolated from dairy cattle were higher than those in beef cattle.Further analysis showed that the most prevalent resistance genes were blojm and oodAl in dairy cattle and beef cattle,respectively.Moreover,seven diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,F41,K99 and STa)were present in the isolates from dairy cattle,with a prevalence ranging from 3.7%to 22.22%.Six diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,hylA and F41)were identified in the isolates from beef cattle,with a prevalence ranging from 2.27%to 63.64%.Our results provide important evidence for better exploring their interaction mechanism.Further studies are also needed to understand the origin and transmission route of£coli in cattle to reduce its prevalence.展开更多
The aiiA gene from Bacillus thuringiensis was cloned into the Pseudomonas/E. coli shuttle vector and transformed into Pseudomonas aeruginosa strain PAO1. Western blotting showed that the AiiA protein was expressed in ...The aiiA gene from Bacillus thuringiensis was cloned into the Pseudomonas/E. coli shuttle vector and transformed into Pseudomonas aeruginosa strain PAO1. Western blotting showed that the AiiA protein was expressed in PAO1. After induction by IPTG for 6 h and 18 h, expression of the aiiA gene in PAO1 completely degraded the quorum sensing autoinducers N-acylhomoserine lactones (AHLs): N-oxododecanoyl-L-homoserine lactone (OdDHL) and N-butyryl-L-homoserine lactone (BHL). The re- duced amount of AHLs in PAO1 was also correlated with decreased expression and production of several virulence factors such as elastase and pyocyanin. AiiA expression also influenced bacterial swarming motility. Most importantly, our studies indicated that aiiA played significant roles in P. aeruginosa biofilm formation and dispersion, as observed by the differences of the biofilm formation on liquid and solid surfaces, and biofilm structures under a scanning electron microscope.展开更多
基金Supported by the Earmarked Fund for the China Agriculture Research System(No.CARS-48)the Key Scientific and Technological Grant of Zhejiang for Breeding New Agricultural Varieties(No.2021 C 02069-4-3)the Major Research&Development Program(modern agriculture)of Jiangsu Province(No.BE 2019352)。
文摘To identify the cause of mass mortality of adult Macrobrachium rosenbergii in a farm in Gaoyou City,Jiangsu Province,China,a dominant strain named DKQ-1 was isolated from the hepatopancreas of dying M.rosenbergii and identified as Aeromonas dhakensis by purification culture,biochemical characterization,and 16S rRNA and gyrB gene sequence analysis.The results of the challenge test revealed that the strain was highly pathogenic and the 50%lethal dose(LD_(50))in 72 h to M.rosenbergii was 1.54×10^(5)CFU/mL.The amplification results of virulence genes show that strain DKQ-1 carried 9 virulence genes,including ascV,aexT,aer,act,lip,ompAI,gcaT,acg,and exu,supporting the strong virulence of strain DKQ-1 to M.rosenbergii.Histopathological observation of the hepatopancreas,gills,and intestines indicated that DKQ-1 injection into M.rosenbergii could cause serious tissue damage,which further supported the strong virulence of this strain.In addition,a drug susceptibility test revealed that strain DKQ-1 was sensitive to 16 kinds of antibiotics,resistant to 9 kinds of antibiotics,and had intermediate resistance to spectinomycin and kanamycin.This study is the first report of A.dhakensis isolated from M.rosenbergii and provided a reference for the pathogen identification of bacterial diseases in M.rosenbergii,and for the prevention and treatment caused by A.dhakensis.
基金Supported by Outstanding Graduate Entering Laboratory Project of College of Fisheries,Guangdong Ocean UniversitySpecial Fund for Science and Technology Innovation Strategy of Guangdong Province(Undergraduate Science and Technology Innovation Cultivation)(pdjh2021b0239)+3 种基金National Natural Science Foundation of China(32073015)Natural Science Foundation of Guangdong Province(2021A1515011078)Undergraduate Innovation and Entrepreneurship Training Program of Guangdong Ocean University(CXXL2022005)Undergraduate Innovation Team of Guangdong Ocean University(CCTD201802).
文摘[Objectives]To study the effects of microplastics on antibiotic resistance genes and virulence genes of Vibrio alginolyticus,so as to provide a certain reference for controlling marine pollution,curbing the spread of environmental antibiotic resistance genes and virulence genes,formulating environmental policies,and maintaining food safety.[Methods]After adding V.alginolyticus into the artificial seawater,they were divided into three groups,namely blank control group(BLK),polyvinyl chloride microplastic group(PVC group)and polyvinyl alcohol microplastic group(PVA group).Aerated culture experiments were carried out,and the effects of microplastics on the expression of resistance genes and virulence genes of V.alginolyticus were studied by PCR and qPCR methods.[Results]The presence of microplastics significantly changed the resistance gene structure of V.alginolyticus.Compared with the control group,the cfxA and cfr resistance genes were detected in the microplastic group.However,only PVC group detected blaZ resistance gene,and only PVA group did not detect aaC resistance gene.In addition,compared with the control group,the expressions of virulence genes in the microplastic group were all down-regulated(P<0.01).[Conclusions]This study provides some reference for curbing the spread of environmental antibiotic resistance genes and virulence genes,formulating environmental policies,and maintaining food safety,but the specific mechanisms of drug resistance and virulence need further research.
文摘Helicobacter pylori(H.pylori)is one of the most important human pathogens,infecting approximately half of the global population.Despite its high prevalence,only a subset of H.pylori infected individuals develop serious gastroduodenal pathology.The pathogenesis of H.pylori infection and disease outcome is thus thought to be mediated by an intricate interplay between host,environmental and bacterial virulence factors.H.pylori has adapted to the harsh milieu of the human stomach through possession of various virulence genes that enable survival of the bacteria in the acidic environment,movement towards the gastric epithelium,and attachment to gastric epithelial cells.These virulence factors enable successful colonization of the gastric mucosa and sustain persistent H.pylori infection,causing chronic inflammation and tissue damage,which may eventually lead to the development of peptic ulcers and gastric cancer.Numerous studies have focused on the prevalence and role of putative H.pylori virulence genes in disease pathogenesis.While several virulence factors with various functions have been identified,disease associations appear to be less evident,especially among different study populations.This review presents key findings on the most important H.pylori virulence genes,including several bacterial adhesins and toxins,in children and adults,and focuses on their prevalence,clinical significance and potential relationships.
基金supported by the National Natural Science Foundation of China grant numbers NSFC 81861138053 and NSFC 31761133004。
文摘Objective This study aimed to evaluate the genetic diversity,virulence,and antimicrobial resistance of Aeromonas isolates from clinical patients,tap water systems,and food.Methods Ninety Aeromonas isolates were obtained from Ma’anshan,Anhui province,China,and subjected to multi-locus sequence typing(MLST)with six housekeeping genes.Their taxonomy was investigated using concatenated gyr B-cpn60 sequences,while their resistance to 12 antibiotics was evaluated.Ten putative virulence factors and several resistance genes were identified by PCR and sequencing.Results The 90 Aeromonas isolates were divided into 84 sequence types,80 of which were novel,indicating high genetic diversity.The Aeromonas isolates were classified into eight different species.PCR assays identified virulence genes in the isolates,with the enterotoxin and hemolysin genes act,aer A,alt,and ast found in 47(52.2%),13(14.4%),22(24.4%),and 12(13.3%)of the isolates,respectively.The majority of the isolates(≥90%)were susceptible to aztreonam,imipenem,cefepime,chloramphenicol,gentamicin,tetracycline,and ciprofloxacin.However,several resistance genes were detected in the isolates,as well as a new mcr-3 variant.Conclusions Sequence type,virulence properties,and antibiotic resistance vary in Aeromonas isolates from clinical patients,tap water systems,and food.
基金supported by the Research Grant from the Science and Technology Department of Sichuan, China (2011JY0095)the Construction Project of Southwest University for Nationalities (2011XWD-S071007)
文摘The Chinese giant salamander(Andrias davidianus) is the largest living amphibian in the world. Aeromonas hydrophila strain L602 was isolated from A. davidianus. The 16S rDNA gene of this isolate was amplified using PCR,and the phylogenetic tree was constructed by the neighbor-joining method. Four virulence genes(aerA,aha1,hly and alt) of A. hydrophila were amplified by PCR and drug resistances were tested using Kirby-Bauer disk diffusion method. The results showed that the length of this 16S rDNA sequence was 1453 bp,which showed 99% homology with A. hydrophila. The GenBank accession number was JX155398. Phylogenetic analysis indicated it grouped together with A. hydrophila. Four virulence genes were all detected,indicating that strain L602 was highly virulent. This stain was resistant to four antibiotics(vibramycin,furazolidone,ampicillin and erythromycin),while it was insensitive to streptomycin. Furthermore,this strain was susceptible to six antibiotics(sulfafurazole,ciprofloxacin,penbritin,norfloxacin,florfenicol and enrofloxacin). This study will help to validate the classification and virulence of pathogenic bacteria in amphibians.
文摘Bovine Respiratory Disease (BRD) causes a severe form of pneumonia in all age of cattle. This study was designed to investigate the distribution of capsular types, serotypes, and virulence-associated genes of the major bacterial pathogens from BRD outbreak samples in Ethiopia. In this study 166 samples were collected from clinically sick (<i>n</i> = 107) and pneumonic lung tissue (<i>n</i> = 59). Laboratory assay confirmed isolation of <i>M. haemolytica</i> 37 (22.29%), <i>P. multocida</i> 25 (15.06%), <i>B. trehalosi</i> 12 (7.23%), and <i>H. somni</i> 15 (9.04%). PCR assay of <i>P. multocida</i> capsular typing revealed 21 (84.0%) cap A (<i>hyaD-hyaC</i>) and 4 (16.0%) cap D (<i>dcbF</i>) strains. <i>M. haemolytica</i> serotypes belonged to A: 1, A: 2, and A: 6 from 26 (70.27%), 4 (10.81%), and 7 (18.92%) isolates, respectively. <i>P. multocida</i> biotyping showed isolation of A: 1, A: 2, and A: 3 from 3 (14.29%), 2 (9.52%), and 16 (76.19%) isolates, respectively. <i>M. haemolytica</i> harbored more than 60% <i>ssa</i> gene, and 90.91% <i>sodA</i> while <i>FbpA</i>, <i>TbpA</i>, and <i>lktC</i> genes were found in all isolates. Likewise, all <i>P. multocida</i> exhibited <i>toxA</i>, <i>FbpA</i>, <i>TbpA</i>, and <i>pmSLP</i> genes. The current finding showed that <i>M. haemolytica</i> serotype A: 1 is frequently associated with BRD followed by <i>P. multocida</i> biotype A: 3. These two isolates harbored diverse virulence-associated genes and presented the pathogenic potential of the current isolates. Thus, investigation of pathogenic strains of BRD, virulence genes distribution, and molecular epidemiology of the disease from wider areas of the country are essential. Hence, continuous outbreak surveillance and molecular approaches are indispensable in designing efficient prevention strategies.
文摘Objective:To investigate the frequency of exoU and exoY genes in patients with Pseudomonas aeruginosa infection.Methods:In this study,100 clinical isolates of Pseudomonas aeruginosa were collected from patients hospitalized in educational-therapeutic hospitals and were identified using standard microbiological tests.Then,the antibiotic resistance pattern of the isolates was determined by the disk agar diffusion method.The bacterial DNAs were extracted by the alkaline lysis method.Finally,the presence of exoU and exoY genes was evaluated by the PCR test.Results:In this study,47%,72%,29%,39%,40%,and 44%of the isolates were non-susceptible to piperacillin,aztreonam,ceftazidime,imipenem,tobramycin,and ciprofloxacin,respectively.In addition,95%and 93%of the clinical isolates carried the exoU and exoY genes.Blood and fecal isolates had both virulence genes,while only one wound isolate had neither genes.Meanwhile,all urinary isolates contained the exoY gene and only one isolate lacked the exoU gene.Also,88 isolates simultaneously had both exoU and exoY genes.Conclusions:High prevalence of exoU and exoY genes in this region indicates a significant role of typeⅢsecretion system in pathogenesis of Pseudomonas aeruginosa.The typeⅢsecretion system may be a suitable target to reduce the pathogenicity of this bacterium.
基金This study was supported by the National Key Research and Development Project of China(2017YFD0502200)the National Natural Science Foundation of China(31802232)the International Science and Technology Cooperation Project of Gansu Province,China(17YF1WA169).
文摘The objectives of this study were to investigate antimicrobial resistance of Streptococcus uberis and Streptococcus parauberis isolated from cows with bovine clinical mastitis in China and to examine the distribution of resistance-and virulence-related gene patterns.Antimicrobial susceptibility was determined by the E-test.Genes encoding antimicrobial resistance and invasiveness factors were examined by PCR.A total of 27 strains were obtained from 326 mastitis milk samples.Streptococcus parauberis isolates(n=11)showed high resistance to erythromycin(90.9%),followed by tetracycline(45.5%),chloramphenicol(36.4%)and clindamycin(27.3%).Streptococcus uberis isolates(n=16)were highly resistant to tetracycline(81.3%)and clindamycin(62.5%).Both species were susceptible to ampicillin.The most prevalent resistance gene in S.uberis was tetM(80.0%),followed by blaZ(62.5%)and ermB(62.5%).However,tetM,blaZ,and ermB genes were only found in 27.3,45.5,and 27.3%,respectively,of S.parauberis.In addition,all of the isolates carried at least one selected virulence-related gene.The most prevalent virulence-associated gene pattern in the current study was sua+pauA/skc+gapC+hasC detected in 22.2%of the strains.One S.uberis strain carried 7 virulence-associated genes and belonged to the sua+pauA/skc+gapC+cfu+hasA+hasB+hasC pattern.More than 59.3%of analysed strains carried 4 to 7 virulence-related genes.Our findings demonstrated that S.parauberis and S.uberis isolated from clinical bovine mastitis cases in China exhibited diverse molecular ecology,and that the strains were highly resistant to antibiotics commonly used in the dairy cow industry.The data obtained in the current study contribute to a better understanding of the pathogenesis of bacteria in mastitis caused by these pathogens,and the findings are relevant to the development of multivalent vaccines and targeted prevention procedures.
基金This work was supported by the Science Innovation Project of Institute of Hydrobiology,Chinese Academy of Sciences(No.220317).
文摘Nine strains of Aeromonas hydrophila isolated from diseased fish or soft-shelled tortoise were tested for the presence of three virulence genes including the genes encoding aerolysin,hemolysin,and extracellular serine protease(i.e.,aerA,hlyA,and ahpA,respectively).These genes were investigated using polymerase chain reaction(PCR)with specific primers for each gene.And the pathogenicities to Carrassius auratus ibebio of these strains were also assayed.PCR results demonstrated that the distribution patterns of aerA,hlyA,and ahpA were different in these strains.6/9 of A.hydrophila strains were aerA positive,8/9 of strains hlyA positive,7/9 of strains ahpA positive,respective-ly.However,the assay for pathogenesis showed that two strains(A.hydrophila XS91-4-1 and C2)were strong virulent,two strains(A.hydrophila ST78-3-3 and 58-20-9)avirulent and the rest middle virulent was to the fish.In conclusion,there are significant correlation between the distribution pattern of the three virulence genes and the patho-genicity to Carrassius auratus ibebio.All strong virulent A.hydrophila strains were aerA+hlyA+ahpA+genotype,and all aerA+hlyA+ahpA+strains were virulent.Strains with the genotype of aerA−hlyA−ahpA+have middle pathogenicity.In the present study,we found for the first time that all A.hydrophila isolated from the ahpA positive were virulent to Carrassius auratus ibebio.Additionally,there was a positive correlation between the virulence of A.hydrophila and the presence of aerA and ahpA.
文摘In this work, we evaluated biofilm formation of Vancomycin Resistant of E. faecalis and E. faecium (VRE) in different culture media and adhesion substrate, as well as cellular hydrophobicity and presence of virulence genes. For this, 35 isolates were collected from a public hospital in Recife, Pernambuco, Brazil and identified by the Matrix-Assisted Laser Desorption Ionization - Time-of-flight - Mass Spectrometry (MALDI-TOF-MS) technique. Biofilm formation was analyzed by the Crystal Violet (CV) method and fluorescence microscopy, cellular hydrophobicity by hydrocarbon interaction and the presence of gelE, esp and asa1 genes by Polymerase Chain Reaction (PCR). 12 isolates were identified as E. faecalis and 23 as E. faecium. Most were obtained in Coronary Units (40.0%) and Intensive Care Unit (31.4%). E. faecium isolates were more resistant to the antibiotics tested than E. faecalis;however, E. faecalis stood out as a biofilm producer. Regarding the presence and gene frequency, it was observed that gelE (54.3%) and esp (54.3%) were the most prevalent, followed by asa1 (22.9%). When comparing the gene frequency, it was observed that gelE and esp were predominant (48.6% for both species), while asa1 was more frequent in E. faecalis (20.0%). The data presented here are worrying, because they reveal the virulence potential of isolates VRE, which contributes to the dissemination and persistence of these pathogens in the hospital environment.
文摘BACKGROUND:The virulent factors of Escherichia coli(E.coli) play an important role in the process of pathopoiesis.The study aimed to compare drug-resistant genes and virulence genes between extended spectrum β-lactamases(ESBLs)-producing E.coli and non-ESBLs-producing E.coli to provide a reference for physicians in management of hospital infection.METHODS:From October 2010 to August 2011,96 drug-resistant strains of E.coli isolated were collected from the specimens in Qingdao Municipal Hospital,Qingdao,China.These bacteria strains were divided into a ESBLs-producing group and a non-ESBLs-producing group.Drug sensitivity tests were performed using the Kirby-Bauer(K-B) method.Disinfectant gene,qacEA1-sull and 8 virulence genes(CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1) were tested by polymerase chain reaction(PCR).RESULTS:Among the 96 E.coli isolates,the ESBLs-producing E.coli comprised 46(47.9%)strains and the non-ESBLs-producing E.coli consisted of 50(52.1%) strains.The detection rates of multiple drug-resistant strain,qacEA1-sull,CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1 in 46ESBLs-producing E.coli isolates were 89.1%,76.1%,6.5%,69.6%,69.6%,89.1%,10.9%,26.1%,8.7%,and 19.6%,respectively.In the non-ESBLs-producing E.coli strains,the positive rates of multiple drug-resistant strain,qacEA1-sull,CNF2,hlyA,eaeA,VT1,est,bfpA,elt,and CNF1 were 62.0%,80.0%,16.0%,28.0%,64.0%,38.0%,6.0%,34.0%,10.0%,and 24.0%,respectively.The difference in the detection rates of multiple drug-resistant strain,hlyA and VT1 between the ESBLs-producing E.coli strains and the non-ESBLs-producing E.coli strains was statistically significant(P<0.05).CONCLUSION:The positive rate of multiple drug-resistant strains is higher in the ESBLsproducing strains than in the non-ESBLs-producing strains.The expression of some virulence genes hlyA and VT1 varies between the ESBLs-producing strains and the non-ESBLs-producing strains.Increased awareness of clinicians and enhanced testing by laboratories are required to reduce treatment failures and prevent the spread of multiple drug-resistant strains.
基金supported by Major Project of the thirteenth Five Year Special for infectious diseases of China[2018ZX10101002]。
文摘Objective This study was performed to compare the genetic diversity,virulence,and antimicrobial resistance of Aeromonas strains isolated from patients and healthy individuals.Methods A total of 38 clinical strains and 19 strains from healthy individuals were isolated from the samples collected in Ma’anshan City,Anhui Province.Their taxonomy was investigated using concatenated gyrB-cpn60 sequences,and their resistance to 12 antibiotics was evaluated.The pathogenicity of these strains was examined through beta-hemolysis,protease activity,and virulence gene assays.Results The 57 Aeromonas strains were divided into 55 sequence types.Of these types,21 were novel,suggesting that their genetic diversity was high.These Aeromonas isolates could be divided into 7 species,and the positive rates of beta-hemolysis and protease activity were 49.1%and 73.7%,respectively.The detection rate of clinical patients in terms of beta-hemolysis and protease activity was higher than that of healthy individuals.Among the four most common Aeromonas strains,A.dhakensis had the highest detection rate of virulence genes.The multidrug resistance rate of the clinical isolates was much higher than that of the strains isolated from healthy individuals.Conclusions The taxonomy,virulence properties,and antibiotic resistance of Aeromonas isolates from patients differ from those of the isolates from healthy individuals.
基金supported by the National Key Research and Development Program of China[grant number 2018YFC1603804]。
文摘Objective Aeromonas has recently been recognized as an emerging human pathogen.Aeromonasassociated diarrhea is a phenomenon occurring worldwide.This study was designed to determine the prevalence,genetic diversity,antibiotic resistance,and pathogenicity of Aeromonas strains isolated from food products in Shanghai.Methods Aeromonas isolates(n=79)collected from food samples were analyzed using concatenated gyrB-cpn60 sequencing.The antibiotic resistance of these isolates was determined using antimicrobial susceptibility testing.Pathogenicity was assessed usingβ-hemolytic,extracellular protease,virulence gene detection,C.elegans liquid toxicity(LT),and cytotoxicity assays.Results Eight different species were identified among the 79 isolates.The most prevalent Aeromonas species were A.veronii[62(78.5%)],A.caviae[6(7.6%)],A.dhakensis[3(3.8%)],and A.salmonicida[3(3.8%)].The Aeromonas isolates were divided into 73 sequence types(STs),of which 65 were novel.The isolates were hemolytic(45.6%)and protease-positive(81.0%).The most prevalent virulence genes were act(73.4%),fla(69.6%),aexT(36.7%),and ascV(30.4%).The results of C.elegans LT and cytotoxicity assays revealed that A.dhakensis and A.hydrophila were more virulent than A.veronii,A.caviae,and A.bivalvium.Antibiotic resistance genes[tetE,blaTEM,tetA,qnrS,aac(6)-Ib,mcr-1,and mcr-3]were detected in the isolates.The multidrug-resistance rate of the Aeromonas isolates was 11.4%,and 93.7%of the Aeromonas isolates were resistant to cefazolin.Conclusion The taxonomy,antibiotic resistance,and pathogenicity of different Aeromonas species varied.The Aeromonas isolates A.dhakensis and A.hydrophila were highly pathogenic,indicating that food-derived Aeromonas isolates are potential risks for public health and food safety.The monitoring of food quality and safety will result in better prevention and treatment strategies to control diarrhea illnesses in China.
文摘Uropathogenic Escherichia coli is the common pathogen to cause urinary tract infections (UTIs) and have become multidrug-resistant (MDR) extended-spectrum β-lactamase (ESBL) producers. The differences in the antimicrobial susceptibility, 5 bla genes, 12 virulence genes of 87 clinical ESBL-producing E. coli isolates and genomic variations and sequence types of 18 recurrent and repeated isolates from 9 patients were investigated. The 87 MDR-ESBL isolates collected mainly from indwelling urinary catheters (IUCs) and UTIs were highly resistant to fluoroquinolones, with over 50% of the isolates being resistant to cefepime and piperacillin/tazobactam and a few being resistant to carbapenem. These isolates carried at least two of the five bla genes examined, with the highest prevalence (87.4%) found for bla<sub>CTX-M</sub> (bla<sub>CTX-M3-like</sub> and bla<sub>CTX-M14-like</sub>), followed by bla<sub>CMY-2</sub> (80.5%) and bla<sub>SHV</sub> (56.3%). The predominant virulence genes were the fimbriae gene fimH and the toxin genes cnf1 and hlyA in blood isolates and the capsule gene kpsMTII in UTI and blood isolates. Over 80% of the isolates carried yersiniabactin and aerobactin of siderophores. In 18 isolates, the fluoroquinolone-resistant ST131 isolate of pulsotypes I and II with bla<sub>CTX-M-15</sub> was clonally disseminated in the hospital. The genomic plasticity of these ST131 occurred mainly through the conjugative plasmids with differences in replicon types A/C, I1, FIA, FIB and Y, size and number. In conclusion, MDR ESBL-producing E. coli isolates differed in virulence genes of UPEC and antibiotic resistance associated with the sources. Plasmid acquisition and chromosomal variations increase the spread of fluoroquinolone-resistant UPEC ST131 worldwide.
基金funded by the Ministry of Higher Education under Fundamental Research Grant Scheme(FRGS/1/2023/WAB04/UPM/01/4).
文摘and pili genes are also investigated.Methods:This multicentre,prospective,observational study is conducted in seven major tertiary hospitals in Malaysia among non-pregnant adults.Simultaneously,a retrospective study is conducted in the selected hospitals with similar approaches.GBS isolates are subjected to phenotyping,serotyping by multiplex PCR,antimicrobial susceptibility testing and PCR-detection of GBS virulence and pilus genes.Seven housekeeping genes are amplified and sequenced for multi-locus sequence typing.Discussion:Findings from the study may contribute to the management of clinical practice to diagnose and prevent GBS related diseases in a timely manner.Prudent use of antibiotics is encouraged by monitoring antimicrobial resistance.
文摘Objective: To investigate some pathogenic characters of Salmonella enterica strains isolated from poultry.Methods: Twenty-three genetically distinct Salmonella enterica strains, of different serovars and pulsotype, were examined for virulence traits. Resistance to gastric acid environment was estimated by measuring the percentage of survived bacterial cells after exposure for 2 h to a synthetic gastric juice. Strains were analyzed with PCR for the presence of the following virulence genes: mgtC and rhu M located on SPI-3, sopB and pipB located on SPI-5, Salmonella virulence plasmid(spv)R(spvR), spvB and spvC located on Salmonella plasmid virulence and sodCI, sopE, and gipA located on prophage.Finally, resistance to 21 antibiotics was tested with Kirby–Bauer method.Results: A percentage of 82.60% of strains were resistant to gastric environment after induction and 60.87% of the strains exhibited constitutive resistance too. Nineteen different virulence profiles were detected. The phage related genes sodCI and sopE and the plasmid mediated operon spvR, spvB and spvC(spvRBC) were detected in 82.60%,47.82% and 52.17% of strains, respectively. Typhimurium and Enteritidis strains showed the highest number of virulence genes. Twenty-one different antibiotic resistance profiles were obtained and two isolates(Typhimurium and Enteritidis) resulted sensible to all the tested molecules. The ampicillin, streptomycin, sulfonamide and tetracycline resistance profile was detected in seven isolates(30.43%).Conclusion: Our results show that paratyphoid Salmonella strains with several characters of pathogenicity, that may be cause of severe pathology in animals and humans, are circulating among poultry.
基金This work was supported by grant(2017YFC1601400)the Ministry of Science and Technology of the People’s Republic of China,Key Project in Science and Technology of Henan Province(182102410083).
文摘Human health is threatened by foodborne illness and Staphylococcus aureus is a common foodborne pathogenic bacteria.It can cause food poisoning when we are infected,therefore,it is necessary to detect pathogenic bacteria.The virulence genes and detection methods of S.aureus are summarized from literatures.Traditional detection methods are simple but need bacteria enrichment and to prolong detection time.Immunological technology has high specificity,but false positive results are easy to occur in its detection.In recent years,molecular biology methods have developed rapidly,and various PCR techniques have been applied to detect foodborne pathogens.Real-time fluorescent quantitative PCR is more effective than ordinary PCR,while price is expensive when use it,the scope of use is limited.LAMP is a flexible detection method,biosensor and flow cytometry are fast but the cost of detection is high and the price is relatively expensive.
文摘To characterize extended-spectrum beta-lactamase (ESBL) and extra-intestinal pathogenic Escherichia coli (ExPEC) associated virulence genes in E. coli isolates from chickens and humans in Trinidad and Tobago. This cross sectional study was conducted over a three-month period. A total of 471 E. coli isolates;160 from humans treated at a regional tertiary hospital and 311 from chicken caecal samples from “pluck shops” in Trinidad & Tobago were identified using both conventional and molecular microbiological methods. Phenotypic confirmation of ESBL producing E. coli isolates from humans was by Microscan system (Siemens, USA) while the double disk diffusion method was used for the chicken isolates. Polymerase chain reaction (PCR) analysis was used to determine the ESBL and ExPEC-associated virulence genes in representative human isolates and all chicken isolates. From the 311 chicken E. coli isolates, 49.2% (153/311) produced ESBL, while 56.3% (90/160) from humans were ESBL positive. All human and chicken ESBL isolates were 100% susceptible to carbapenems and aminoglycosides antimicrobials. PCR detected 21.1% bla<sub>CTX-M</sub>, 13.3% bla<sub>TEM</sub> and 7.8% bla<sub>SHV</sub> genes among E coli isolates from humans compared to 0.6% bla<sub>CTX-M</sub> and 48.6% bla<sub>TEM</sub> genes in chickens. PCR analysis revealed diverse virulence profiles among the isolates. There was a high occurrence rate of ExPEC-asso- ciated virulence genes in E. coli isolates from both humans and chickens. However, the CTX-M-1 genes were most predominant in humans while TEM occurred in chic- ken isolates. The diverse ESBL and virulence associated gene profiles encountered in E. coli isolates from humans and chickens on the surface depicts no similarity or relationships despite occurrence in both cohort groups. Therefore E. coli strains from chickens and humans require further investigation to determine their clonal relatedness or transmission in the country.
基金This study was supported by the National Science and Technology Ministry(2014BAD13B03-1)the project supported by the Heilongjiang Province Farms General Administration of China(HNK135-04-03)This work was supported by a grant from the Heilongjiang Bayi Agricultural University Support Program for San Heng San Zong(TDJH202002).
文摘Escherichia coli has become one of the most important causes of calf diarrhea.The aim of this study is to determine the patterns of antimicrobial resistance of E.coli isolates from six cattle farms and to identify prominent resistance genes and virulence genes among the strains isolated from the diarrhea of calves.Antimicrobial susceptibility tests were performed using the disk diffusion method,and PCR was used to detect resistance and virulence genes.The prevalence of multidrug resistant(MDR)E.coli was 77.8%in dairy cattle and 63.6%in beef cattle.There were high resistance rates to penicillin(100%,100%)and ampicillin(96.3%,86.4%)in E.coli from dairy cattle and beef cattle.Interestingly,resistance rate to antimicrobials and distribution of resistance genes in£coli isolated from dairy cattle were higher than those in beef cattle.Further analysis showed that the most prevalent resistance genes were blojm and oodAl in dairy cattle and beef cattle,respectively.Moreover,seven diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,F41,K99 and STa)were present in the isolates from dairy cattle,with a prevalence ranging from 3.7%to 22.22%.Six diarrheagenic virulence genes(irp2,fyuA,Stx1,eoeA,hylA and F41)were identified in the isolates from beef cattle,with a prevalence ranging from 2.27%to 63.64%.Our results provide important evidence for better exploring their interaction mechanism.Further studies are also needed to understand the origin and transmission route of£coli in cattle to reduce its prevalence.
基金the National Natural Science Foundation of China (Grant No. 30570020)Natural Science Foundation of Hubei Province of China (Grant No. 2004ABA120)
文摘The aiiA gene from Bacillus thuringiensis was cloned into the Pseudomonas/E. coli shuttle vector and transformed into Pseudomonas aeruginosa strain PAO1. Western blotting showed that the AiiA protein was expressed in PAO1. After induction by IPTG for 6 h and 18 h, expression of the aiiA gene in PAO1 completely degraded the quorum sensing autoinducers N-acylhomoserine lactones (AHLs): N-oxododecanoyl-L-homoserine lactone (OdDHL) and N-butyryl-L-homoserine lactone (BHL). The re- duced amount of AHLs in PAO1 was also correlated with decreased expression and production of several virulence factors such as elastase and pyocyanin. AiiA expression also influenced bacterial swarming motility. Most importantly, our studies indicated that aiiA played significant roles in P. aeruginosa biofilm formation and dispersion, as observed by the differences of the biofilm formation on liquid and solid surfaces, and biofilm structures under a scanning electron microscope.
