Introduction: Bacterial skin and soft tissue infections (SSTIs) are a cause of frequent inpatient and outpatient care visits whose causative agents are associated with a high antimicrobial resistance burden. For insig...Introduction: Bacterial skin and soft tissue infections (SSTIs) are a cause of frequent inpatient and outpatient care visits whose causative agents are associated with a high antimicrobial resistance burden. For insights on antimicrobial susceptibilities in a rural setting, we examined specimens from suspected SSTIs from two public health facilities in Kenya. We additionally assessed antibiotic use, appropriateness of empiric therapy and risk factors for SSTI. Methodology: Between 2021 and 2023, 265 patients at Kisii and Nyamira County Referral hospitals were enrolled. Wound swabs/aspirates were collected and processed following standard microbiological procedures. Identification and antimicrobial susceptibility were performed using the VITEK 2 Compact platform. Demographic, clinical, and microbiological data were analyzed with R Statistical software. Results: S. aureus was isolated in 16.2% (43/265) of patients with a methicillin resistance (MRSA) proportion of 14% (6/43). While 13/15 drugs elicited susceptibilities ranging from 84% - 100%, penicillin (16%) and trimethoprim-sulfamethoxazole [TMP-SXT] (23%) yielded the lowest susceptibilities. Escherichia coli (n = 33), Klebsiella pneumoniae (n = 8), Pseudomonas aeruginosa (n = 8), and Citrobacter species (n = 4) were the most commonly isolated gram-negative species. Gram-negative strains showed high susceptibilities to most of the tested drugs (71% - 100%) with the exception of ampicillin (18%), TMP-SXT (33%), and first and second generation cephalosporins. Conclusions: The low MRSA prevalence and generally high antibiotic susceptibilities for S. aureus and gram-negative bacteria present opportunities for antibiotic stewardship in the study setting. Diminished susceptibilities against penicillin/ampicillin and TMP-SXT accord with prevailing local data and add a layer of evidence for their cautious empiric use.展开更多
The incidence of gram-negative multidrug-resistant(MDR) bacterial pathogens is increasing in hospitals and particularly in the intensive care unit(ICU) setting. The clinical consequences of infections caused by MDR pa...The incidence of gram-negative multidrug-resistant(MDR) bacterial pathogens is increasing in hospitals and particularly in the intensive care unit(ICU) setting. The clinical consequences of infections caused by MDR pathogens remain controversial. The purpose of this review is to summarize the available data concerning the impact of these infections on mortality in ICU patients. Twenty-four studies, conducted exclusively in ICU patients, were identified through Pub Med search over the years 2000-2015. Bloodstream infection was the only infection examined in eight studies, respiratory infections in four and variable infections in others. Comparative data on the appropriateness of empirical antibiotic treatment were provided by only seven studies. In ten studies the presence of antimicrobial resistance was not associated with increased mortality; on the contrary, in other studies a significant impact of antibiotic resistance on mortality was found, though, sometimes, mediated by inappropriate antimicrobial treatment. Therefore, a direct association between infections due to gram-negative MDR bacteria and mortality in ICU patients cannot be confirmed. Sample size, presence of multiple confounders and other methodological issues may influence the results. These data support the need for further studies to elucidate the real impact of infections caused by resistant bacteria in ICU patients.展开更多
Over the past years, infectious disease has caused enormous economic loss in pig industry. Among the pathogens, gram negative bacteria not only cause inflammation, but also cause different diseases and make the pigs m...Over the past years, infectious disease has caused enormous economic loss in pig industry. Among the pathogens, gram negative bacteria not only cause inflammation, but also cause different diseases and make the pigs more susceptible to virus infection. Vaccination, medication and elimination of sick pigs are major strategies of controlling disease. Genetic methods, such as selection of disease resistance in the pig, have not been widely used. Recently, the completion of the porcine whole genome sequencing has provided powerful tools to identify the genome regions that harboring genes controlling disease or immunity. Immunogenornics, which combines DNA variations, transcriptorne, immune response, and QTL mapping data to illustrate the interactions between pathogen and host immune system, will be an effective genomics tool for identification of disease resistance genes in pigs. These genes will be potential targets for disease resistance in breeding programs. This paper reviewed the progress of disease resistance study in the pig focusing on Gram-negative bacilli. Major porcine Gram-negative bacilli and diseases, suggested candidate genes/pathways against porcine Gram-negative bacilli, and distributions of QTLs for immune capacity on pig chromosomes were summarized. Some tools for immunogenomics research were described. We conclude that integration of sequencing, whole genome associations, functional genomics studies, and immune response information is necessary to illustrate molecular mechanisms and key genes in disease resistance.展开更多
PCR and DNA sequencing were used to screen and characterize integrons and resistance genes in Gram-negative bacteria isolated from seafood products in Japan.A total of 215 Gram-negative bacteria were isolated from loc...PCR and DNA sequencing were used to screen and characterize integrons and resistance genes in Gram-negative bacteria isolated from seafood products in Japan.A total of 215 Gram-negative bacteria were isolated from local and imported seafood samples collected from retail markets in Hiroshima Prefecture.Class 1 integrons containing gene cassettes encoding resistance to trimethoprim展开更多
Humanity is facing an enormous and growing worldwide threat from the emergence of multi-drug-resistant(MDR)Gram-negative bacteria such as Escherichia coli,Klebsiella pneumoniae,and Acinetobacter baumannii.Polymyxin B ...Humanity is facing an enormous and growing worldwide threat from the emergence of multi-drug-resistant(MDR)Gram-negative bacteria such as Escherichia coli,Klebsiella pneumoniae,and Acinetobacter baumannii.Polymyxin B and E(colistin)constitute the last-line therapies for treating MDR Gram-negative bacteria.Polymyxin is a cationic antibacterial peptide that can destroy the outer membrane of Gram-negative bacteria.With the increasing clinical application of polymyxin,however,there have been many reports of the occurrence of polymyxin-resistant Gram-negative bacteria.This resistance is mainly mediated by the modification or complete loss of lipopolysaccharide(LPS).LPS is also a virulence factor of Gram-negative bacteria,and alterations of LPS may correlate with virulence.Although it is generally believed that the biological costs associated with drug resistance may enable benign susceptible bacteria to overcome resistant bacteria when antibiotic pressure is reduced,some studies have shown that polymyxin-resistant bacteria are associated with higher virulence and greater fitness compared with their susceptible counterparts.To predict the development of polymyxin resis-tance and evaluate interventions for its mitigation,it is important to understand the relative biological cost of polymyxin resistance compared with susceptibility.The impact of polymyxin resistance mecha-nisms on the virulence and fitness of these three Gram-negative bacteria are summarized in this review.展开更多
Background The prevalence of hospital-acquired infections caused by carbapenem-resistant gram-negative bacteria(CRGNB)is increasing worldwide.Several risk factors have been associated with such infections.The present ...Background The prevalence of hospital-acquired infections caused by carbapenem-resistant gram-negative bacteria(CRGNB)is increasing worldwide.Several risk factors have been associated with such infections.The present study aimed to identify risk factors and determine the mortality rates associated with CRGNB infections in intensive care units.Methods This retrospective case-control study was conducted at Erciyes University Hospital(Kayseri,Turkey)between January 2017 and December 2021.Demographic and laboratory data were obtained from the Infection Control Committee data and record system.Patients who had CRGNB infection 48–72 h after hospitalization were assigned to the case group,while those who were not infected with CRGNB during hospitalization formed the control group.Risk factors,comorbidity,demographic data,and mortality rates were compared between the two groups.Results Approximately 1449 patients(8.97%)were monitored during the active follow-up period;of those,1171 patients were included in this analysis.CRGNB infection developed in 14 patients(70.00%)who had CRGNB colonization at admission;in 162(78.26%)were colonized during hospitalization,whereas 515(54.56%)were not colonized.There was no significant difference in age,sex(male/female)or comorbidities.The total length of hospital stay was statistically significantly longer(P=0.001)in the case group(median:24[interquartile range:3–378]days)than the control group(median:16[interquartile range:3–135]days).The rates of colonization at admission(25.5%;vs.10.6%,P=0.001)and mortality(64.4%vs.45.8%,P=0.001)were also significantly higher in the cases than in the control group,respectively.In the univariate analysis,prolonged hospitalization,the time from intensive care unit admission to the development of infection,presence of CRGNB colonization at admission,transfer from other hospitals,previous antibiotic use,enteral nutrition,transfusion,hemodialysis,mechanical ventilation,tracheostomy,reintubation,central venous catheter,arterial catheterization,chest tube,total parenteral nutrition,nasogastric tube use,and bronchoscopy procedures were significantly associated with CRGNB infections(P<0.05).Multivariate analysis identified the total length of stay in the hospital(odds ratio[OR]=1.02;95%confidence interval[CI]:1.01 to 1.03;P=0.001),colonization(OR=2.19;95%CI:1.53 to 3.13;P=0.001),previous antibiotic use(OR=2.36;95%CI:1.53 to 3.62;P=0.001),intubation(OR=1.59;95%CI:1.14 to 2.20;P=0.006),tracheostomy(OR=1.42;95%CI:1.01 to 1.99;P=0.047),and central venous catheter use(OR=1.62;95%CI:1.20 to 2.19;P=0.002)as the most important risk factors for CRGNB infection.Conclusions Colonization,previous use of antibiotics,and invasive interventions were recognized as the most important risk factors for infections.Future research should focus on measures for the control of these parameters.展开更多
Methylation of 16S rRNA is an important mechanism of aminoglycoside resistance among gram-negative pathogens. In this report, 16S rRNA methylase genes were amplified using PCR among gram-negative bacillus isolates fro...Methylation of 16S rRNA is an important mechanism of aminoglycoside resistance among gram-negative pathogens. In this report, 16S rRNA methylase genes were amplified using PCR among gram-negative bacillus isolates from hospitals in the Changchun area of China and 16S rRNA methylase genotypes (armA, rmtB, rmtA, rmtC, rmtD, and npmA) were identified by direct sequencing. Fifty of the isolates (43.1%) harbored 16S rRNA methylase genes. The common 16S rRNA methylase genes were armA and rmtB (12.1% and 31.0%, respectively), whereas the rmtA, rmtC, rmtD, and npmA genes were absent from the sample. It suggests that the predominant 16S rRNA methylase genes among gramnegative bacilli in the Changchun area are armA and rmtB.展开更多
<b>Background:</b> The increasing resistance of bacteria to various antibiotics is a worldwide public health issue. Carbapenems that have elicited great hope in treating infections caused by multidrug-resi...<b>Background:</b> The increasing resistance of bacteria to various antibiotics is a worldwide public health issue. Carbapenems that have elicited great hope in treating infections caused by multidrug-resistant germs have seen their efficacy narrowed over time with the emergence of other novel resistance mechanisms, notably the production of Carbapenemases. <b>Methods:</b> A prospective cross-sectional study was conducted from May 2017 to May 2018 in Douala (Cameroon) to detect carbapenemase-producing Gram-negative bacilli. Isolated strains were identified using the Vitek2<sup>TM</sup> system. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method on agar plates with 20 selected commercially available antibiotic discs. The bacterial strains were tested for the production of three Carbapenemases (OXA-48, NDM, KPC), using an immuno-chromatographic technique, with the “RESIST-3 O.K.N. K-SeT” rapid detection kit. <b>Results:</b> During the study period, 1687 strains of Gram-negative bacilli were isolated in selected laboratories with a total of 200 multi-resistant strains identified (11.9%). Among the multi-resistant strains, <i>E. coli</i> was the species most represented in <i>Enterobacteriaceae</i> (27.5%) followed by <i>K. pneumoniae</i> (15.5%) and the non-fermenting Gram-negative bacilli were predominantly <i>P. aeruginosa</i> (20.5%). These strains mainly came from urine and pus, <i>i.e.</i> 41% and 32% respectively. Thirty-two (16%) strains produced one of the Carbapenemases with a higher frequency at the General Hospital (84%). NDM-type carbapenemase was the most frequently identified (8.5%), OXA-48 type 7.5%, and no KPC production was observed. Among the <i>Enterobacteriaceae</i> 22.9% produced Carbapenemases and only 5.1% of the non-fermenting bacilli produced these enzymes. The isolates strains were completely resistant to all antibiotics except Amikacin and Fosfomycin. The strains producing the NDM-type carbapenemase showed higher rates of resistance to almost all of the antibiotics tested. <b>Conclusion:</b> Multidrug-resistant strains are experiencing an increase in evolution. The apparition of strains producing Carbapenemases prominently, the NDM and OXA-48 favor this increase. The activities of antibiotics with high efficacies on these strains are low.展开更多
Antibiotic resistant bacteria pathogens remain the leading cause of shellfish borne diseases and a major health threat to humans worldwide. The objectives of this study were to isolate, identify, and determine the ant...Antibiotic resistant bacteria pathogens remain the leading cause of shellfish borne diseases and a major health threat to humans worldwide. The objectives of this study were to isolate, identify, and determine the antibiotic resistance patterns of Gram-negative bacteria from shellfish. We analyzed a total of 540 shellfish (117 clams, 88 oysters, and 136 periwinkles) samples collected from different vendors at Iko and Douglas Creeks in Akwa Ibom State, South-South Nigeria. Conventional cultural techniques, morphological, biochemical characteristics, and PCR amplification were used to identify the bacterial isolates. Antibiotic susceptibility tests (Kirby-Bauer disk diffusion method) and ESBL phenotype (disk) of the isolates were performed. One hundred and thirty-five (135) Gram-negative bacteria comprising 5 genera and 14 species were detected at a prevalence of: <i>Alcaligenes faecalis</i> <i><b>TRB</b></i>-7 38 (28.2%), <i>Pseudomonas oryzihabitans strain <b>KCB</i>005</b> 16 (11.9%), <i>Paenalcaligenes retgerii strain <b>B</i>5</b> 12 (8.9%) <i>Pseudomonas aeruginosa <b>JB</i>2</b> 10 (7.4%), <i>Providencia stuartii <b>DMC</i>-28b</b> 9 (6.7%), <i>Alcaligenes species <b>TLT</i>151</b> 8 (5.9%), <i>Pseudomonas aeruginosa <b>CIFRI DTSB</i>1</b> 7 (5.2%), <i>Paenalcaligenes species <b>UN</i>24</b> 7 (5.2%), <i>Alcaligenes faecalis <b>BT</i>10</b> 7 (5.2%), <i>Vibrio species strain <b>PrVy</i>108</b> 6 (4.4%), <i>Pseudomonas xiamenensis <b>C</i>10-2</b> 5 (3.7%), <i>Providencia vemicola <b>Bu</i>15_38</b> 4 (2.9%), <i>Pseudomonas anguillisceptica</i> <b>4029</b> 3 (2.2%), and <i>Pseudomonas aeruginosa <b>N</i>15-01092</b> 3 (2.2%). All tested isolates showed various degrees of resistance to the thirteen antimicrobials evaluated. High levels of resistance (100%) to cefepime and imipenem were expressed by all isolates except the <i>Providencia</i> species. For the EBSL indicators, all isolates apart from <i>Alcaligenes</i> species were resistant (100%) to ceftriaxone. All <i>Vibrio</i> species were susceptible to norfloxacin, nalidixic acid, and ceftazidime. The identification of antibiotic resistant Gram-negative bacteria (GNARB) from shellfish in this study highlights the risk of disseminated multi-drug resistance—a serious public health concern.展开更多
Tigecycline serves as a critical“final-resort”antibiotic for treating bacterial infections caused by multidrug-resistant bacteria for which treatment options are severely limited.The increasing prevalence of tigecyc...Tigecycline serves as a critical“final-resort”antibiotic for treating bacterial infections caused by multidrug-resistant bacteria for which treatment options are severely limited.The increasing prevalence of tigecycline resistance,particularly among Gram-negative bacteria,is a major concern.Various mechanisms have been iden-tified as contributors to tigecycline resistance,including upregulation of nonspecific Resistance Nodulation Divi-sion(RND)efflux pumps due to mutations in transcriptional regulators,enzymatic modification of tigecycline by monooxygenase enzymes,and mutations affecting tigecycline binding sites.This review aims to consolidate our understanding of tigecycline resistance mechanisms in Gram-negative bacteria and offer insights and perspectives for further drug development.展开更多
<b>Introduction:</b> Oral cancer is the third most prominent type of cancer in Bangladesh. During or after oral cancer treatment, immune-compromised cancer patients may be susceptible to an infection by mu...<b>Introduction:</b> Oral cancer is the third most prominent type of cancer in Bangladesh. During or after oral cancer treatment, immune-compromised cancer patients may be susceptible to an infection by multi-drug-resistant opportunistic microbes. This study aims to identify the prevalent microorganisms from the infected site of oral cancer patients and observe their antibiotic susceptibility pattern. <b>Materials and Methods:</b> Clinical samples were collected from the infected sites of oral cancer patients and healthy people. The swabs collected were placed on nutrient agar slant, then incubated for 24 hours at 37ºC. Bacteria from the slant were inoculated in several selective media (Mannitol Salt Agar Media, KF Streptococcus Agar media, Cetrimide Agar, Eosin Methylene Blue Agar). Several biochemical tests identified opportunistic microorganisms. Finally, the antibiotic susceptibility test was performed by the Kirby Bauer disc diffusion method. <b>Results:</b> The study found that 65.4% of microbes isolated from the patients’ oral cavities were Gram-negative bacteria, and 34.6% were Gram-positive bacteria. Among the patient group isolates (n = 55), the most prevalent organism was <i>Pseudomonas</i> spp. (30;54.54%). Others were <i>Klebsiella</i> spp. (27;49.09%), <i>Staphylococcus</i> spp. (24;43.63%), <i>E. coli</i> (14;25.45%), <i>Streptococcus</i> spp. (14;25.45%), <i>Proteus</i> spp. (12;21.8%) and <i>Enterococcus</i> spp. (6;10.90%). Both Gram-positive and Gram-negative microbes from the patient group have shown high resistance to the commonly used antibiotics. In the control group (n = 50), the most prevalent organism was <i>Staphylococcus</i> spp. (15;30%). Other organisms were <i>Streptococcus</i> spp. (6;12%), <i>Klebsiella</i> spp. (11;22%), <i>E. coli</i> (3;6%), <i>Streptococcus</i> spp. (14;25.45%), <i>Pseudomonas</i> spp. (8;16%). The microbes of the control group showed less resistance to the antibiotics and rather showed sensitivity to them. <b>Conclusion:</b> The study revealed a high prevalence of multi-drug-resistant opportunistic microbes on immune-compromised oral cancer patients compared to microbes isolated from healthy people’s oral cavity.展开更多
Objective:To detect and evaluate the various methods for metallo-β-lactamases(MBL) production in Pseudomonas aeruginosa(P.aeruginosa) and Acinetobacter species.Methods:A total of 109 P.aeruginosa and 85 Acinetobacter...Objective:To detect and evaluate the various methods for metallo-β-lactamases(MBL) production in Pseudomonas aeruginosa(P.aeruginosa) and Acinetobacter species.Methods:A total of 109 P.aeruginosa and 85 Acinetobacter species were screened for imipenem resistance by Kirby- Bauer disc diffusion methods.Detection of MBL production was(lone by imipenem-EDTA combined disc test,double disc synerygy test(DDST) and imipenem-EDTA MBL E test.Results: A total of 63(57.8%) strains of P.aeruginosa and 46(54.1%) strains of Acinetobacter spp.were found to be resistant to imipenem.Of the 63 imipenem resistant P.aeruginosa tested for MBL production.44(69.89;) were found to be positive and among 46 imipenem resistant Acinetobacter. 19(41.3%) were shown to be the MBL producers.Conclusions:Imipenem-EDTA combined disc test and MBL E test are equally effective for MBL detection in both P.aeruginosa and Acinetobacter spp.,but given the cost-constraints,combined disc can be used as a convenient screening method in the clinical microbiology laboratory.展开更多
Background and Aim: Multi drug resistant Non fermenting gram negative bacilli (NFGNB) have emerged as a major cause of health-care associated infections especially in immunocompromised hosts. The aim of the study was ...Background and Aim: Multi drug resistant Non fermenting gram negative bacilli (NFGNB) have emerged as a major cause of health-care associated infections especially in immunocompromised hosts. The aim of the study was to investigate the prevalence of NFGNB as a cause of health-care associated infections (HAI) in cancer patients and determine their resistance pattern. Patients and Methods: During the study period, 158 NFGNB isolates were collected. Microscan Walk Away 9 was used for identification and testing for the metallo-β-lactamases (MBLs) was done by Imipenem-EDTA combined disk synergy test (CDST-IPM). Results: NFGNB represented 29.0% of infections caused by gram negative organisms. Carbapenem resistance, the multi-drug resistant (MDR) phenotype, and MBL production were documented in 70%, 63%, and 59% of NFGNB isolates, respectively. MDR-NFGNB rates were significantly higher among hospitalized patients, medical department and those with longer duration of hospital stay (p = 0.034, 0.026, 0.019;respectively) than non MDR-NFGNB. Conclusion: A high level of carbapenem and multi-drug resistance were detected among the non-fermenter pathogens isolated from hospitalized cases and were more frequently encountered in high risk adult cancer patients requiring longer duration of hospitalization. The MDR-NFGNB are constituting important causes of health-care associated infections in cancer patients.展开更多
Gram-negative bacilli Pseudomonas aeruginosa is an important pathogen in hospitalized patients, contributing to their morbidity and mortality due to its multiple resistance mechanisms. Therefore, as therapeutic option...Gram-negative bacilli Pseudomonas aeruginosa is an important pathogen in hospitalized patients, contributing to their morbidity and mortality due to its multiple resistance mechanisms. Therefore, as therapeutic options become restricted, the search for new agents is a priority. Latterly an accelerated increase in frequency of multidrug-resistant clinical strains has severely limited the availability of therapeutic options. Several in vitro and in vitro studies evaluating the efficacy of different antimicrobials agents and development of vaccines against P. aeruginosa have been reported as novel approaches, such as inhibition of virulence factor expression or inhibition of their metabolic pathways.展开更多
文摘Introduction: Bacterial skin and soft tissue infections (SSTIs) are a cause of frequent inpatient and outpatient care visits whose causative agents are associated with a high antimicrobial resistance burden. For insights on antimicrobial susceptibilities in a rural setting, we examined specimens from suspected SSTIs from two public health facilities in Kenya. We additionally assessed antibiotic use, appropriateness of empiric therapy and risk factors for SSTI. Methodology: Between 2021 and 2023, 265 patients at Kisii and Nyamira County Referral hospitals were enrolled. Wound swabs/aspirates were collected and processed following standard microbiological procedures. Identification and antimicrobial susceptibility were performed using the VITEK 2 Compact platform. Demographic, clinical, and microbiological data were analyzed with R Statistical software. Results: S. aureus was isolated in 16.2% (43/265) of patients with a methicillin resistance (MRSA) proportion of 14% (6/43). While 13/15 drugs elicited susceptibilities ranging from 84% - 100%, penicillin (16%) and trimethoprim-sulfamethoxazole [TMP-SXT] (23%) yielded the lowest susceptibilities. Escherichia coli (n = 33), Klebsiella pneumoniae (n = 8), Pseudomonas aeruginosa (n = 8), and Citrobacter species (n = 4) were the most commonly isolated gram-negative species. Gram-negative strains showed high susceptibilities to most of the tested drugs (71% - 100%) with the exception of ampicillin (18%), TMP-SXT (33%), and first and second generation cephalosporins. Conclusions: The low MRSA prevalence and generally high antibiotic susceptibilities for S. aureus and gram-negative bacteria present opportunities for antibiotic stewardship in the study setting. Diminished susceptibilities against penicillin/ampicillin and TMP-SXT accord with prevailing local data and add a layer of evidence for their cautious empiric use.
文摘The incidence of gram-negative multidrug-resistant(MDR) bacterial pathogens is increasing in hospitals and particularly in the intensive care unit(ICU) setting. The clinical consequences of infections caused by MDR pathogens remain controversial. The purpose of this review is to summarize the available data concerning the impact of these infections on mortality in ICU patients. Twenty-four studies, conducted exclusively in ICU patients, were identified through Pub Med search over the years 2000-2015. Bloodstream infection was the only infection examined in eight studies, respiratory infections in four and variable infections in others. Comparative data on the appropriateness of empirical antibiotic treatment were provided by only seven studies. In ten studies the presence of antimicrobial resistance was not associated with increased mortality; on the contrary, in other studies a significant impact of antibiotic resistance on mortality was found, though, sometimes, mediated by inappropriate antimicrobial treatment. Therefore, a direct association between infections due to gram-negative MDR bacteria and mortality in ICU patients cannot be confirmed. Sample size, presence of multiple confounders and other methodological issues may influence the results. These data support the need for further studies to elucidate the real impact of infections caused by resistant bacteria in ICU patients.
基金supported by National Natural Science Foundation of China(30901021)863the Key Programs for Science and Technology Development of Hubei Province
文摘Over the past years, infectious disease has caused enormous economic loss in pig industry. Among the pathogens, gram negative bacteria not only cause inflammation, but also cause different diseases and make the pigs more susceptible to virus infection. Vaccination, medication and elimination of sick pigs are major strategies of controlling disease. Genetic methods, such as selection of disease resistance in the pig, have not been widely used. Recently, the completion of the porcine whole genome sequencing has provided powerful tools to identify the genome regions that harboring genes controlling disease or immunity. Immunogenornics, which combines DNA variations, transcriptorne, immune response, and QTL mapping data to illustrate the interactions between pathogen and host immune system, will be an effective genomics tool for identification of disease resistance genes in pigs. These genes will be potential targets for disease resistance in breeding programs. This paper reviewed the progress of disease resistance study in the pig focusing on Gram-negative bacilli. Major porcine Gram-negative bacilli and diseases, suggested candidate genes/pathways against porcine Gram-negative bacilli, and distributions of QTLs for immune capacity on pig chromosomes were summarized. Some tools for immunogenomics research were described. We conclude that integration of sequencing, whole genome associations, functional genomics studies, and immune response information is necessary to illustrate molecular mechanisms and key genes in disease resistance.
基金supported by a Grant-in-Aid for Scientific Research(No.25460532 and 26.04912)to Tadashi S.from the Ministry of Education,Culture,Sports,Science,and Technology of Japan
文摘PCR and DNA sequencing were used to screen and characterize integrons and resistance genes in Gram-negative bacteria isolated from seafood products in Japan.A total of 215 Gram-negative bacteria were isolated from local and imported seafood samples collected from retail markets in Hiroshima Prefecture.Class 1 integrons containing gene cassettes encoding resistance to trimethoprim
基金supported by the National Key Research and Development Program of China (2017YFC1600100 and2017YFC1200203)the National Natural Science Foundation of China (81702040)the National Science Foundation of Zhejiang Province,China (LY20H190002)
文摘Humanity is facing an enormous and growing worldwide threat from the emergence of multi-drug-resistant(MDR)Gram-negative bacteria such as Escherichia coli,Klebsiella pneumoniae,and Acinetobacter baumannii.Polymyxin B and E(colistin)constitute the last-line therapies for treating MDR Gram-negative bacteria.Polymyxin is a cationic antibacterial peptide that can destroy the outer membrane of Gram-negative bacteria.With the increasing clinical application of polymyxin,however,there have been many reports of the occurrence of polymyxin-resistant Gram-negative bacteria.This resistance is mainly mediated by the modification or complete loss of lipopolysaccharide(LPS).LPS is also a virulence factor of Gram-negative bacteria,and alterations of LPS may correlate with virulence.Although it is generally believed that the biological costs associated with drug resistance may enable benign susceptible bacteria to overcome resistant bacteria when antibiotic pressure is reduced,some studies have shown that polymyxin-resistant bacteria are associated with higher virulence and greater fitness compared with their susceptible counterparts.To predict the development of polymyxin resis-tance and evaluate interventions for its mitigation,it is important to understand the relative biological cost of polymyxin resistance compared with susceptibility.The impact of polymyxin resistance mecha-nisms on the virulence and fitness of these three Gram-negative bacteria are summarized in this review.
文摘Background The prevalence of hospital-acquired infections caused by carbapenem-resistant gram-negative bacteria(CRGNB)is increasing worldwide.Several risk factors have been associated with such infections.The present study aimed to identify risk factors and determine the mortality rates associated with CRGNB infections in intensive care units.Methods This retrospective case-control study was conducted at Erciyes University Hospital(Kayseri,Turkey)between January 2017 and December 2021.Demographic and laboratory data were obtained from the Infection Control Committee data and record system.Patients who had CRGNB infection 48–72 h after hospitalization were assigned to the case group,while those who were not infected with CRGNB during hospitalization formed the control group.Risk factors,comorbidity,demographic data,and mortality rates were compared between the two groups.Results Approximately 1449 patients(8.97%)were monitored during the active follow-up period;of those,1171 patients were included in this analysis.CRGNB infection developed in 14 patients(70.00%)who had CRGNB colonization at admission;in 162(78.26%)were colonized during hospitalization,whereas 515(54.56%)were not colonized.There was no significant difference in age,sex(male/female)or comorbidities.The total length of hospital stay was statistically significantly longer(P=0.001)in the case group(median:24[interquartile range:3–378]days)than the control group(median:16[interquartile range:3–135]days).The rates of colonization at admission(25.5%;vs.10.6%,P=0.001)and mortality(64.4%vs.45.8%,P=0.001)were also significantly higher in the cases than in the control group,respectively.In the univariate analysis,prolonged hospitalization,the time from intensive care unit admission to the development of infection,presence of CRGNB colonization at admission,transfer from other hospitals,previous antibiotic use,enteral nutrition,transfusion,hemodialysis,mechanical ventilation,tracheostomy,reintubation,central venous catheter,arterial catheterization,chest tube,total parenteral nutrition,nasogastric tube use,and bronchoscopy procedures were significantly associated with CRGNB infections(P<0.05).Multivariate analysis identified the total length of stay in the hospital(odds ratio[OR]=1.02;95%confidence interval[CI]:1.01 to 1.03;P=0.001),colonization(OR=2.19;95%CI:1.53 to 3.13;P=0.001),previous antibiotic use(OR=2.36;95%CI:1.53 to 3.62;P=0.001),intubation(OR=1.59;95%CI:1.14 to 2.20;P=0.006),tracheostomy(OR=1.42;95%CI:1.01 to 1.99;P=0.047),and central venous catheter use(OR=1.62;95%CI:1.20 to 2.19;P=0.002)as the most important risk factors for CRGNB infection.Conclusions Colonization,previous use of antibiotics,and invasive interventions were recognized as the most important risk factors for infections.Future research should focus on measures for the control of these parameters.
文摘Methylation of 16S rRNA is an important mechanism of aminoglycoside resistance among gram-negative pathogens. In this report, 16S rRNA methylase genes were amplified using PCR among gram-negative bacillus isolates from hospitals in the Changchun area of China and 16S rRNA methylase genotypes (armA, rmtB, rmtA, rmtC, rmtD, and npmA) were identified by direct sequencing. Fifty of the isolates (43.1%) harbored 16S rRNA methylase genes. The common 16S rRNA methylase genes were armA and rmtB (12.1% and 31.0%, respectively), whereas the rmtA, rmtC, rmtD, and npmA genes were absent from the sample. It suggests that the predominant 16S rRNA methylase genes among gramnegative bacilli in the Changchun area are armA and rmtB.
文摘<b>Background:</b> The increasing resistance of bacteria to various antibiotics is a worldwide public health issue. Carbapenems that have elicited great hope in treating infections caused by multidrug-resistant germs have seen their efficacy narrowed over time with the emergence of other novel resistance mechanisms, notably the production of Carbapenemases. <b>Methods:</b> A prospective cross-sectional study was conducted from May 2017 to May 2018 in Douala (Cameroon) to detect carbapenemase-producing Gram-negative bacilli. Isolated strains were identified using the Vitek2<sup>TM</sup> system. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method on agar plates with 20 selected commercially available antibiotic discs. The bacterial strains were tested for the production of three Carbapenemases (OXA-48, NDM, KPC), using an immuno-chromatographic technique, with the “RESIST-3 O.K.N. K-SeT” rapid detection kit. <b>Results:</b> During the study period, 1687 strains of Gram-negative bacilli were isolated in selected laboratories with a total of 200 multi-resistant strains identified (11.9%). Among the multi-resistant strains, <i>E. coli</i> was the species most represented in <i>Enterobacteriaceae</i> (27.5%) followed by <i>K. pneumoniae</i> (15.5%) and the non-fermenting Gram-negative bacilli were predominantly <i>P. aeruginosa</i> (20.5%). These strains mainly came from urine and pus, <i>i.e.</i> 41% and 32% respectively. Thirty-two (16%) strains produced one of the Carbapenemases with a higher frequency at the General Hospital (84%). NDM-type carbapenemase was the most frequently identified (8.5%), OXA-48 type 7.5%, and no KPC production was observed. Among the <i>Enterobacteriaceae</i> 22.9% produced Carbapenemases and only 5.1% of the non-fermenting bacilli produced these enzymes. The isolates strains were completely resistant to all antibiotics except Amikacin and Fosfomycin. The strains producing the NDM-type carbapenemase showed higher rates of resistance to almost all of the antibiotics tested. <b>Conclusion:</b> Multidrug-resistant strains are experiencing an increase in evolution. The apparition of strains producing Carbapenemases prominently, the NDM and OXA-48 favor this increase. The activities of antibiotics with high efficacies on these strains are low.
文摘Antibiotic resistant bacteria pathogens remain the leading cause of shellfish borne diseases and a major health threat to humans worldwide. The objectives of this study were to isolate, identify, and determine the antibiotic resistance patterns of Gram-negative bacteria from shellfish. We analyzed a total of 540 shellfish (117 clams, 88 oysters, and 136 periwinkles) samples collected from different vendors at Iko and Douglas Creeks in Akwa Ibom State, South-South Nigeria. Conventional cultural techniques, morphological, biochemical characteristics, and PCR amplification were used to identify the bacterial isolates. Antibiotic susceptibility tests (Kirby-Bauer disk diffusion method) and ESBL phenotype (disk) of the isolates were performed. One hundred and thirty-five (135) Gram-negative bacteria comprising 5 genera and 14 species were detected at a prevalence of: <i>Alcaligenes faecalis</i> <i><b>TRB</b></i>-7 38 (28.2%), <i>Pseudomonas oryzihabitans strain <b>KCB</i>005</b> 16 (11.9%), <i>Paenalcaligenes retgerii strain <b>B</i>5</b> 12 (8.9%) <i>Pseudomonas aeruginosa <b>JB</i>2</b> 10 (7.4%), <i>Providencia stuartii <b>DMC</i>-28b</b> 9 (6.7%), <i>Alcaligenes species <b>TLT</i>151</b> 8 (5.9%), <i>Pseudomonas aeruginosa <b>CIFRI DTSB</i>1</b> 7 (5.2%), <i>Paenalcaligenes species <b>UN</i>24</b> 7 (5.2%), <i>Alcaligenes faecalis <b>BT</i>10</b> 7 (5.2%), <i>Vibrio species strain <b>PrVy</i>108</b> 6 (4.4%), <i>Pseudomonas xiamenensis <b>C</i>10-2</b> 5 (3.7%), <i>Providencia vemicola <b>Bu</i>15_38</b> 4 (2.9%), <i>Pseudomonas anguillisceptica</i> <b>4029</b> 3 (2.2%), and <i>Pseudomonas aeruginosa <b>N</i>15-01092</b> 3 (2.2%). All tested isolates showed various degrees of resistance to the thirteen antimicrobials evaluated. High levels of resistance (100%) to cefepime and imipenem were expressed by all isolates except the <i>Providencia</i> species. For the EBSL indicators, all isolates apart from <i>Alcaligenes</i> species were resistant (100%) to ceftriaxone. All <i>Vibrio</i> species were susceptible to norfloxacin, nalidixic acid, and ceftazidime. The identification of antibiotic resistant Gram-negative bacteria (GNARB) from shellfish in this study highlights the risk of disseminated multi-drug resistance—a serious public health concern.
基金supported by the National Key Research and De-velopment Program of China[grant number 2022YFE0199800]Key R&D Program of Shandong Province[grant number 2020CXGC011305]+1 种基金Shandong Provincial Natural Science Foundation[grant number ZR2020MH308]the National Natural Science Foundation of China[grant number 82,271,658].
文摘Tigecycline serves as a critical“final-resort”antibiotic for treating bacterial infections caused by multidrug-resistant bacteria for which treatment options are severely limited.The increasing prevalence of tigecycline resistance,particularly among Gram-negative bacteria,is a major concern.Various mechanisms have been iden-tified as contributors to tigecycline resistance,including upregulation of nonspecific Resistance Nodulation Divi-sion(RND)efflux pumps due to mutations in transcriptional regulators,enzymatic modification of tigecycline by monooxygenase enzymes,and mutations affecting tigecycline binding sites.This review aims to consolidate our understanding of tigecycline resistance mechanisms in Gram-negative bacteria and offer insights and perspectives for further drug development.
文摘<b>Introduction:</b> Oral cancer is the third most prominent type of cancer in Bangladesh. During or after oral cancer treatment, immune-compromised cancer patients may be susceptible to an infection by multi-drug-resistant opportunistic microbes. This study aims to identify the prevalent microorganisms from the infected site of oral cancer patients and observe their antibiotic susceptibility pattern. <b>Materials and Methods:</b> Clinical samples were collected from the infected sites of oral cancer patients and healthy people. The swabs collected were placed on nutrient agar slant, then incubated for 24 hours at 37ºC. Bacteria from the slant were inoculated in several selective media (Mannitol Salt Agar Media, KF Streptococcus Agar media, Cetrimide Agar, Eosin Methylene Blue Agar). Several biochemical tests identified opportunistic microorganisms. Finally, the antibiotic susceptibility test was performed by the Kirby Bauer disc diffusion method. <b>Results:</b> The study found that 65.4% of microbes isolated from the patients’ oral cavities were Gram-negative bacteria, and 34.6% were Gram-positive bacteria. Among the patient group isolates (n = 55), the most prevalent organism was <i>Pseudomonas</i> spp. (30;54.54%). Others were <i>Klebsiella</i> spp. (27;49.09%), <i>Staphylococcus</i> spp. (24;43.63%), <i>E. coli</i> (14;25.45%), <i>Streptococcus</i> spp. (14;25.45%), <i>Proteus</i> spp. (12;21.8%) and <i>Enterococcus</i> spp. (6;10.90%). Both Gram-positive and Gram-negative microbes from the patient group have shown high resistance to the commonly used antibiotics. In the control group (n = 50), the most prevalent organism was <i>Staphylococcus</i> spp. (15;30%). Other organisms were <i>Streptococcus</i> spp. (6;12%), <i>Klebsiella</i> spp. (11;22%), <i>E. coli</i> (3;6%), <i>Streptococcus</i> spp. (14;25.45%), <i>Pseudomonas</i> spp. (8;16%). The microbes of the control group showed less resistance to the antibiotics and rather showed sensitivity to them. <b>Conclusion:</b> The study revealed a high prevalence of multi-drug-resistant opportunistic microbes on immune-compromised oral cancer patients compared to microbes isolated from healthy people’s oral cavity.
文摘Objective:To detect and evaluate the various methods for metallo-β-lactamases(MBL) production in Pseudomonas aeruginosa(P.aeruginosa) and Acinetobacter species.Methods:A total of 109 P.aeruginosa and 85 Acinetobacter species were screened for imipenem resistance by Kirby- Bauer disc diffusion methods.Detection of MBL production was(lone by imipenem-EDTA combined disc test,double disc synerygy test(DDST) and imipenem-EDTA MBL E test.Results: A total of 63(57.8%) strains of P.aeruginosa and 46(54.1%) strains of Acinetobacter spp.were found to be resistant to imipenem.Of the 63 imipenem resistant P.aeruginosa tested for MBL production.44(69.89;) were found to be positive and among 46 imipenem resistant Acinetobacter. 19(41.3%) were shown to be the MBL producers.Conclusions:Imipenem-EDTA combined disc test and MBL E test are equally effective for MBL detection in both P.aeruginosa and Acinetobacter spp.,but given the cost-constraints,combined disc can be used as a convenient screening method in the clinical microbiology laboratory.
文摘Background and Aim: Multi drug resistant Non fermenting gram negative bacilli (NFGNB) have emerged as a major cause of health-care associated infections especially in immunocompromised hosts. The aim of the study was to investigate the prevalence of NFGNB as a cause of health-care associated infections (HAI) in cancer patients and determine their resistance pattern. Patients and Methods: During the study period, 158 NFGNB isolates were collected. Microscan Walk Away 9 was used for identification and testing for the metallo-β-lactamases (MBLs) was done by Imipenem-EDTA combined disk synergy test (CDST-IPM). Results: NFGNB represented 29.0% of infections caused by gram negative organisms. Carbapenem resistance, the multi-drug resistant (MDR) phenotype, and MBL production were documented in 70%, 63%, and 59% of NFGNB isolates, respectively. MDR-NFGNB rates were significantly higher among hospitalized patients, medical department and those with longer duration of hospital stay (p = 0.034, 0.026, 0.019;respectively) than non MDR-NFGNB. Conclusion: A high level of carbapenem and multi-drug resistance were detected among the non-fermenter pathogens isolated from hospitalized cases and were more frequently encountered in high risk adult cancer patients requiring longer duration of hospitalization. The MDR-NFGNB are constituting important causes of health-care associated infections in cancer patients.
文摘Gram-negative bacilli Pseudomonas aeruginosa is an important pathogen in hospitalized patients, contributing to their morbidity and mortality due to its multiple resistance mechanisms. Therefore, as therapeutic options become restricted, the search for new agents is a priority. Latterly an accelerated increase in frequency of multidrug-resistant clinical strains has severely limited the availability of therapeutic options. Several in vitro and in vitro studies evaluating the efficacy of different antimicrobials agents and development of vaccines against P. aeruginosa have been reported as novel approaches, such as inhibition of virulence factor expression or inhibition of their metabolic pathways.
