Objective:To determine the distribution,phenotypic and genetic background of extended spectrumβ-lactamases(ESBL)-producing Klebsiella(K.)pneumoniae clinical isolates associated with K1 and K2 serotypes in two selecte...Objective:To determine the distribution,phenotypic and genetic background of extended spectrumβ-lactamases(ESBL)-producing Klebsiella(K.)pneumoniae clinical isolates associated with K1 and K2 serotypes in two selected hospitals in Malaysia.Methods:A total of 192 K.pneumoniae isolates were collected and subjected to antibiotic susceptibility,hypermucoviscosity test and multiplex PCR to detect the presence of K1-and K2-serotype associated genes.Multilocus sequence typing(MLST)was performed on ESBL-producing K.pneumoniae isolates presented with K1 and K2 serotypes,followed by phylogenetic analysis.Results:A total of 87 out of 192(45.3%)of the K.pneumoniae isolates collected were ESBL producers.However,only 8.3%(16/192)and 10.9%(21/192)of the total isolates were detected to carry K1-and K2-serotype associated genes,respectively.Statistical analysis showed that K1 and K2 capsular serotypes were not significantly associated with ESBL phenotype(P=0.196).However,they were significantly associated with hypervirulent,as demonstrated by the positive string test(P<0.001).MLST analysis revealed that ST23 as the predominant sequence type(ST)in the K1 serotype,while the ST in the K2 serotype is more diverse.Conclusions:Although the occurrence of ESBL-producing isolates among the hypervirulent strains was low,their coexistence warrants the need for continuous surveillance.MLST showed that these isolates were genetically heterogeneous.展开更多
Background: The main objective of this study is to describe the rate of the different serotypes of HPV in cervical cytologies and biopsies in three different periods: 2002-2006 (prior to the implementation of the vacc...Background: The main objective of this study is to describe the rate of the different serotypes of HPV in cervical cytologies and biopsies in three different periods: 2002-2006 (prior to the implementation of the vaccination programs in Spain), 2009-2011 (shortly after this implementation) and 2020 (almost 15 years after introduction of the vaccine) at a single hospital. Methods: This is an observational, descriptive, retrospective study based on the review of the results of the determination of the HPV serotype using the commercial kit (Genomica<sup>®</sup>;PharmaMar LTD) in cervical liquid-based cytologies and biopsies at a single large tertiary hospital, Hospital Clínico San Carlos, in Madrid, Spain. We have collected the data from three different time periods: 2002-2006;2009-2011, and 2020 to try to understand the potential changes associated with the use of the vaccine. Results: In these time periods we have reviewed the data from 1420 women. In the three periods the most frequent serotype was HPV 16, followed by HPV 18 or a combination of both. The most frequent low risk serotype was HPV 6 followed by the combination of HPV 6 and 11. It has been verified in our study that the prevalence of the category “others”, constituted by the three risk groups, has undergone a progressive increase, beginning with an infection rate of 65.43% in 2002-2006 to finally rise up to 90.92% in the year 2020. Conclusions: Our study reveals an increase in the number of infections by the HPV serotypes that are not included in the tetravalent vaccine.展开更多
Objective:To identify the circulating serotypes of human echovinis in Malaysia from 2002 in 2013.Methods:A toial of 31 retrospective samples from non-polio acute flacid paralysis,hand-food-and-mouth disease,viral meni...Objective:To identify the circulating serotypes of human echovinis in Malaysia from 2002 in 2013.Methods:A toial of 31 retrospective samples from non-polio acute flacid paralysis,hand-food-and-mouth disease,viral meningitis and enterovirus cases were subjected to amplification of partial VPI gene by RT-PCR.Results:Sequencing and phylogeneiic analysis of the partial sequences identified presence of human echovinis and human coxsackie viruses.It was found that echovinis 11 was the commonly circulating serotype followed by echovinis6.echovinis 7.echovinis 3.echovinis 9.echovinis 30 and echovinis I in decreasing order.Additionally two types of human coxsackie virus isolates were detected which were coxsackie A24 and B3.Condusions:From the findings,there is a possibility that echovinis 11 is the predominant serotype among Malaysian patients with echovinis infection.However,a larger sample size will yield a more confident result to support this evidence.____________________展开更多
BACKGROUND Hand,foot,and mouth disease(HFMD)has become one of the most common infectious diseases in China.Before 2016,the primary causal serotypes were enterovirus A71(EV-A71)and coxsackievirus A16(CV-A16).Following ...BACKGROUND Hand,foot,and mouth disease(HFMD)has become one of the most common infectious diseases in China.Before 2016,the primary causal serotypes were enterovirus A71(EV-A71)and coxsackievirus A16(CV-A16).Following the introduction of EV-A71 vaccines in China since 2016,the situation could change.CV-A6 has recently replaced EV-A71 and CV-A16 in some areas of China.However,the epidemiological characteristics of central China remain unknown.AIM To investigate the clinical symptoms and pathogen spectrum of HFMD in Shiyan City,central China,in recent years.METHODS The epidemiological,clinical,and laboratory data from HFMD cases reported to the Shiyan Center for Disease Control and Prevention between January 2016 and December 2020 were analyzed.196 throat swab specimens were collected from hospitalized HFMD patients between January 2018 and December 2020.To detect and genotype enteroviruses,real-time reverse transcription-polymerase chain reaction and sequencing of the 5'-untranslated region were used.In Shiyan,168 laboratory-confirmed HFMD cases were studied using a logistic regression model to determine the effect of predominant enterovirus serotypes.Based on the logistic regression model,the least absolute shrinkage and selection operator model was used to analyze the correlation between CV-A6 infection and various clinical characteristics in HFMD patients in Shiyan.RESULTS From 2016 to 2020,35840 HFMD cases were reported in Shiyan.The number of cases decreased by 48.4%from 2016 to 2017.Approximately 1.58-fold increases were found in 2018 and 2019 when compared to the previous year,respectively.In 2020,a decrease of about 85.5%was reported when compared to 2019.The most common serotypes shifted from EV-A71 and CV-A16(about 60%-80%in 2016 and 2018)to others(more than 80.0%in 2017,2019,and 2020).EV-A71 lost its dominance in 2017 in Shiyan.Among 196 confirmed HFMD cases,85.7%tested positive for enterovirus,with CV-A6 being the most common serotype(121/168,72.0%).The positive rates for CV-A16 and CVA10 were 4.8%and 3.0%,respectively.There was no EV-A71 discovered.Infection with CV-A6 was linked to fever,myocardial damage,increased creatine kinase MB isoenzyme,and lactate dehydrogenase levels.CONCLUSION CV-A6 was the most common enterovirus serotype in Shiyan City,replacing EV-A71 and CV-A16 as the HFMD pathogen.Developing vaccines against CV-A6 or multiple pathogens,as well as rising CV-A6 surveillance,will help prevent HFMD in central China.展开更多
Streptococcus suis is one of the major pathogens of swine streptococcosis. Among them, the strongest virulence and highest rate of clinical isolation serotype is S. suis serotype 2(SS2). Moreover, SS2 is also an impor...Streptococcus suis is one of the major pathogens of swine streptococcosis. Among them, the strongest virulence and highest rate of clinical isolation serotype is S. suis serotype 2(SS2). Moreover, SS2 is also an important zoonosis pathogen, which caused severe public health issues in China. It has been reported that SS2 has several virulence factors, including muramidase released protein, extracellular factors, capsule, fibronectin-binding protein, enolase, hemolysin, small RNA, biofilm, two-component regulatory systems, STK/STP, etc., whose functions involved in adhesion, anti-phagocytosis, inflammatory pathway activation, invasion, etc. Actually, SS2 has developed a variety of ways to escape from host immune system during evolution. In particularly, capsule could resist phagocytosis through inhibiting sphingosine dependent immune cell recognition, which plays an important role in escaping host inflammation response; moreover, superoxide dismutase encoding by sod A enables SS2 escaping reactive oxygen species(ROS) in host immune cells; besides, binding complement factor h with Fhb could suppress the activation of complement alternative pathway and bactericidal effect. And SS2 could also hinder the formation of neutrophil extracellular traps(NETs) to avoid trapping by swine neutrophils, while host immune globulin could be degraded by Ig A1 hydrolase and Ig M protease. In addition, SS2 could escape host immune defense with the help of multiple transcriptional factors and micro-RNA. So far, the pathogenesis of meningitis, arthritis caused by SS2 infection, is still unclear, and the virulence regulatory mechanism of phosphorylation, micro-RNA need to be further clarified. Importantly, the study of interaction mechanism of pathogen and host contribute to further demonstration the pathogenesis of SS2.展开更多
Objective: To ascertain the role of imported cases and serotypes on dengue outbreaks in Taiwan which have been sporadic yet highly volatile during the past two decades, exhibiting record-breaking magnitude in recent y...Objective: To ascertain the role of imported cases and serotypes on dengue outbreaks in Taiwan which have been sporadic yet highly volatile during the past two decades, exhibiting record-breaking magnitude in recent years. Methods: Confirmed case and serotype data from Taiwan Centers for Disease Control during 1998-2017 were fully examined, with fitting of weekly and daily case data of each city/county to a mathematical model to pinpoint the waves of cases and their locations. Moreover, we quantify the timing of turning point and transmission potential of each wave and determine its circulating serotype, to ascertain any pattern or connection between the variations in circulating serotypes and the magnitude/transmissibility of outbreak. Results: While the number of imported case increased steadily during past two decades, the yearly number of indigenous cases fluctuated wildly. Moreover, while yearly percentages of serotypes for imported cases remains steady, that of indigenous cases does not exhibit any clear pattern. There was at least one wave of reported cases somewhere in Taiwan every year from 1998 to 2015, except in 2016-2017. The effective reproduction number R for all waves in all locations ranged from 1.14 to 2.87, with the exception of two Tainan waves, in 2010(3.95) and 2015(6.84). Four major outbreaks of over 2000 cases reveal circulation of one dominant serotype. Conclusions: Correlation between imported cases and indigenous outbreak prove to be difficult to ascertain, even with the availability of serotype data. However, although there had been occasional co-circulation of serotypes in one location, and for some years with different serotypes circulating in different locations, all major outbreaks of over 2 000 cases during the past two decades are due to circulation of mainly a single serotype, perhaps indicating greater transmission potential with one dominating serotype.展开更多
Non-O157 STEC has been shown to have a diverse ecological distribution among food-animals. It has been associated with both outbreaks and individual cases of severe illness. This group of the organisms is now consider...Non-O157 STEC has been shown to have a diverse ecological distribution among food-animals. It has been associated with both outbreaks and individual cases of severe illness. This group of the organisms is now considered as a major contributor to human disease. The clinical description of the diseases caused by these organisms is reviewed. The host specificity of these pathogens is described and discussed. These organisms appear widespread among food animals like cattle and sheep, and can therefore affect a range of foods directly from the meat and excretions of these animals being used in farming practices. This article reviews the origins, diversity and pathogenesis of non-O157 STEC.展开更多
Rapid identification and characterization of Listeria monocytogenes are required for the food industry, epidemiological studies, and disease prevention and control. However, typing procedures are labor-intensive and t...Rapid identification and characterization of Listeria monocytogenes are required for the food industry, epidemiological studies, and disease prevention and control. However, typing procedures are labor-intensive and time-consuming, and they require technical expertise, a panel of sera and reference culture strains or sophisticated and expensive equipment. To improve upon traditional diagnostic methods for L. monocytogenes we developed and evaluated an efficient procedure for the specific identification of L. monocytogenes and the major pathogenic serotypes of the species based on loop-mediated isothermal amplification (LAMP). Four individual reactions were designed using primers targeting any L. monocytogenes serotypes (LAMP-AS) and the 1/2a (LAMP-1/2a), 1/2b (LAMP-1/2b), and 4b (LAMP-4b) serotypes. The procedure distinguished L. monocytogenes from closely genetically related species and the targeted serotypes. Cross-reactivity with a few rare serotypes isolated from food or clinical samples did not impair the usefulness of the procedure. Thus, our approach constitutes a fast, easy and low-cost alternative for L. monocytogenes diagnosis and serotyping and may be useful for surveillance and epidemiological investigation programs.展开更多
Introduction: In the North-Benin, there are three agents causing pediatric purulent meningitis outside the neonatal period. These are: Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b...Introduction: In the North-Benin, there are three agents causing pediatric purulent meningitis outside the neonatal period. These are: Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b. The aim of this research work was to investigate bacteria serotypes that caused childhood purulent meningitis in the pediatric unit of the Borgou à Regional University Teaching Hospital (CHUD-Borgou) located in Parakou (North-Benin). Patients and Methods: Through a prospective and descriptive study centered on children aged 0 to 5 years old suspected of meningitis and hospitalized, the cerebrospinal fluid (CSF) samples of those children were analyzed at the WHO reference laboratory in Banjul for serotyping by real time polymerase chain reaction (RT/PCR). Results: Among the 1396 children hospitalized during that period, 366 were suspected of meningitis and had benefitted from lumbar puncture. Among those 366 suspected cases, 51 cases of purulent meningitis were confirmed after CSF cytobacteriological and biochemical test at the CHUD-Borgou laboratory. Among 51 CSF samples in which purulent meningitis was confirmed, 44 were sent to Banjul. In addition, 310 CSF samples from non-confirmed cases of meningitis were also sent to Banjul. In the whole set of samples sent for real time PCR, 151 cases of Streptococcus pneumoniae (42.7%) were found, 5 cases of Neisseria meningitidis (1.4%) and 1 case of Haemophilus influenzae (0.3%) were also encountered. As regards Streptococcus pneumonia, the serotypes encountered were: 1, 3, 4, 5, 7F, 8, 9V, 9V/9A, 9N/9L, 14, 18C, 19A, 23F, 33F as well as non typed and non typable serotypes. As for Neisseria meningitidis, only serogroup A was found in it. For Haemophilus influenzae, only serotype b was identified. Conclusion: Four non vaccine serotypes (8, 9V/9A, 9N/9L and 33F), non typed and non typable serotypes which are not covered by 13-valent pneumococcal conjugate vaccine (PCV 13) were identified. This highlights the need to enhance surveillance of pediatric purulent meningitis and serotyping by RT/PCR of all CSF samples in order to adapt if necessary future new pneumococcal vaccines to circulating non vaccine serotypes.展开更多
An agglutination test based on colored silica nanoparticles(colored SiNps) was established to detect serotypes of Pseudomonas aeruginosa. Monodisperse colored SiNps were used as agglutination test carriers. The colore...An agglutination test based on colored silica nanoparticles(colored SiNps) was established to detect serotypes of Pseudomonas aeruginosa. Monodisperse colored SiNps were used as agglutination test carriers. The colored SiNps were prepared through reverse microemulsion with reactive dyes, sensitized with 11 kinds of mono-specific antibodies against P. aeruginosa, and denoted as IgG-colored SiNps. Eleven kinds of IgG-colored SiNps were individually mixed with P. aeruginosa on a glass slide.Different serotypes of P. aeruginosa could be identified by agglutination test with evident agglutination. The P. aeruginosa could be detected in a range from 3.6×10^5 to 3.6×10^12 cfu mL^–1. This new agglutination test was confirmed to be a specific,sensitive, fast, easy-to-perform, and cost-efficient tool for the routine diagnosis of P. aeruginosa.展开更多
The control and prevention of pasteurellosis in rabbits which makes the hosts unsuitable for experimental use raised the needs to improve and simplify the procedures of Enzyme-Linked Immunosorbent Assay (ELISA) for de...The control and prevention of pasteurellosis in rabbits which makes the hosts unsuitable for experimental use raised the needs to improve and simplify the procedures of Enzyme-Linked Immunosorbent Assay (ELISA) for detect of antibody against P.multocida. A comparison on the sensitivity and specificity of bacterial culture of antemortem and postmortem samples, complement fixation test and enzyme-linked immunosorbent assay of 11 apparently healthy adult rabbits was conducted. The incidence rates showed 45.45%,54.54% and 72.73% respectively. The sensitivity for the three methods were 0.63, 0.67,and 1.00,and specificity for them were 1.00, 0.67 and 1.00 respectively. Somatic serotypes of isolates of P.multocida from rabbits of three groups (rabbits of group 2 were with clinic signs, those of groups 1 and 3 were apparently healthy) revealed no remarkable differences,and the predominant types were type 3 and type 3, 4. This was somewhat different from the reports derived from other states. As the antigen of different serotype used in ELISA may have different sensitivity and specificity, which is affected also by different preparation method, a type non-specific antigen should be selected to meet such request. The trial of accomplishment of ELISA without positive and negative controls was presented for discussion.展开更多
Objective:To determine the antimicrobial susceptibility and serotypes of Neisseria(N.)meningitidis and Streptococcus(S.)pneumoniae in Sri Lankan patients.Methods:We retrospectively analyzed 11 blood culture specimens ...Objective:To determine the antimicrobial susceptibility and serotypes of Neisseria(N.)meningitidis and Streptococcus(S.)pneumoniae in Sri Lankan patients.Methods:We retrospectively analyzed 11 blood culture specimens from suspected patients with invasive meningococcal disease and 26 S.pneumoniae clinical isolates.We tested 6 antimicrobials against N.meningitidis and 12 antimicrobials against S.pneumoniae.Meningococcal serogroup was determined by realtime PCR and Quellung serotyping was used for pneumococcal analysis.Results:N.meningitidis serogroup B was the most common in this study.Intermediate-susceptibility to penicillin was seen in 75.0%(6/8)of strains.Susceptibility to ciprofloxacin,levofloxacin and cotrimoxazole was 62.5%(5/8),62.5%(5/8)and 87.5%(7/8),respectively.Excellent susceptibility was seen in cefotaxime and meropenem.In S.pneumoniae,the most common serotype was 19F in both invasive and non-invasive pneumococcal diseases.The majority of strains showed multidrug resistance.Penicillin non-susceptibility in non-meningeal strains were 13.6%and all meningeal strains were penicillin resistant.Erythromycin was highly resistant in both groups.Amoxicillin showed excellent susceptibility in non-invasive pneumococcal diseases strains.Linezolid,levofloxacin and vancomycin showed 100.0%susceptibility in all pneumococcal isolates.Conclusions:Implementation of vaccines should be considered,especially for children and high-risk populations.This may contribute to reducing pneumococcal and meningococcal invasive disease burden and help prevent emergence of antimicrobial resistant strains.展开更多
In order to diagnose the diseased pigs in a certain large pig farm in Binzhou City,Shandong Province,the dead piglets with joint swelling were subjected to necroscopy,and the pathogenic bacterium was isolated and iden...In order to diagnose the diseased pigs in a certain large pig farm in Binzhou City,Shandong Province,the dead piglets with joint swelling were subjected to necroscopy,and the pathogenic bacterium was isolated and identified. One Gram-positive Streptococcus was isolated. The strain was subjected to characteristic culture,microscopic examination and molecular biological identification,and resistance detection,animal regression experiment and mouse pathogenicity test were carried out. The results showed that the isolate was identified to be Streptococcus suis serotype 7,which was resistant to multiple drugs; and the pathogenicity test showed that the strain had high pathogenicity to pigs,resulting in neurosis on partial pigs,and the strain had no pathogenicity to Kunming and BALB/c mice but certain pathogenicity to CD1 mice.展开更多
Streptococcus agalactiae (GBS) is considered as the most important cause of invasive bacterial disease in infants. There are few current data from serotype IX of GBS worldwide. The present work has been done in order ...Streptococcus agalactiae (GBS) is considered as the most important cause of invasive bacterial disease in infants. There are few current data from serotype IX of GBS worldwide. The present work has been done in order to make a contribution to the knowledge of serotype IX through phenotypic and genotypic study of virulence and resistance. Of 200 strains tested, 5.5% were serotype IX and all were colonizing. In 63.6% of the strains the presence of the bac, bca and hylB genes was determined, and in 54.5% of lmb and rib. All strains were susceptible to Clindamycin and Erythromycin however five isolates showed the resistance genes: ermB, ermTR and/or mefA. The presence of serotype IX in Misiones, a province situated in the northeaster of Argentina, which limits with Paraguay and Brazil in South America, gives the region a particular situation. Currently, public health efforts are aimed at prevention and treatment, study of the virulence mechanisms, surveillance of resistance to antibiotics and the development of effective vaccines to prevent GBS infection.展开更多
Klebsiella pneumoniae liver abscess (KPLA) has been described as an invasive syndrome with extrahepatic complications. The majority of KPLA is caused by capsular serotype K1 and K2 isolates. We report a case of carbap...Klebsiella pneumoniae liver abscess (KPLA) has been described as an invasive syndrome with extrahepatic complications. The majority of KPLA is caused by capsular serotype K1 and K2 isolates. We report a case of carbapenem resistant Klebsiella pneumoniae liver abscess. The patient initially presented with infected right above-the-knee amputation and was later found with a large liver abscess. Initial antimicrobial susceptibility showed carbapenem resistant K. pneumoniae (CRKP). Further molecular workup revealed that the isolate was a less virulent non-K1/K2 serotype, and both rmpA and kfu genes were negative. The lack of outer membrane porins likely contributed to the carbapenem resistance. To our knowledge, this is a first reported case of carbapenem resistant, non-K1/K2 serotype K. pneumoniae liver abscess in the United States.展开更多
Streptococcus pneumoniae is a medically important pathogen capable of causing human infections of pneumonia, bacteremia, otitis media, and meningitis. Although there are vaccinations available, infections with S. pneu...Streptococcus pneumoniae is a medically important pathogen capable of causing human infections of pneumonia, bacteremia, otitis media, and meningitis. Although there are vaccinations available, infections with S. pneumoniae still remains a global problem. S. pneumoniae is a highly adaptable bacterial species with numerous serotypes based on capsular polysaccharides. The different serotypes vary in their ability to colonize and causing pathology. Here we compared the regulation of five different virulence factors from four common serotypes of S. pneumoniae that vary in their carriage, morbidity, and mortality rates in the human population using two different in vitro methods, broth and cell culture. We determine that there is variation of virulence factor gene regulation within a serotype using two different culture methods, and variation between the serotypes in the same culture condition. The regulation of genes appeared to have a correlation with the ability of the various serotypes to grow in broth culture, adhere to cultured lung cells, and invade the cultured lung cells, as serotypes that shared similar regulation of virulence factors tended to behave similarly in culture. Many studies with S. pneumoniae rely on the use of one selected serotype, but since there is a wide variation in the growth and regulatory mechanisms of these bacteria. As demonstrated here, future studies should utilize more strains in models before concluding mechanisms of pathobiology.展开更多
Background: Streptococcus pneumoniae (pneumococcus) is one of the most frequent causes of bacterial infection in children and is a leading cause of otitis, sinusitis, pneumonia, and meningitis worldwide. Nasopharyngea...Background: Streptococcus pneumoniae (pneumococcus) is one of the most frequent causes of bacterial infection in children and is a leading cause of otitis, sinusitis, pneumonia, and meningitis worldwide. Nasopharyngeal colonization is a risk factor for pneumococcal disease, a leading cause of complications and death in infants. HIV-infected persons are at high risk of invasive pneumococcal disease. Method: Nasopharyngeal swabs were collected from 296 HIV infected children below five years recruited from Gertrude’s Children hospital and Nazareth Hospital Nairobi, Kenya. The nasopharyngeal swabs were processed to isolate S. pneumoniae, which were serotyped and tested for drug susceptibility. Results: The carriage prevalence of S. pneumoniae in the study was 30.4% while the isolated serotypes were (in order of decreasing frequency): 35B, 19F, 3, 13, 15A, 11A, 16F, 7C and 23A. Most of the serotypes were resistant to the commonly used antibiotics but all were susceptible to vancomycin and chloramphenicol. Conclusion: Carriage prevalence of nasopharyngeal S. pneumonia in HIV infected children was lower than that of similar prevalence studies in children. Most of the S. pneumoniae isolates were however non pneumococcal vaccine isolates.展开更多
It is reckoned worldwide that verocytotoxigenic Escherichia coli (VTEC) serotypes are important food borne pathogens causing severe health problems in humans. A cross sectional epidemiological study was carried out to...It is reckoned worldwide that verocytotoxigenic Escherichia coli (VTEC) serotypes are important food borne pathogens causing severe health problems in humans. A cross sectional epidemiological study was carried out to determine the prevalence of VTEC serotypes (O157 and non O157) in both apparently healthy and diarrhoeic cattle in Abuja, FCT. A total of 718 faecal samples collected from abattoirs and cattle herds from Abuja, FCT representing 381 from apparently healthy and 337 from diarrhoeic cattle were analyzed. Primary isolation of typical E. coli was done using Eosin Methylene Blue (EMB) agar and performing biochemical tests. Samples were further analyzed using Cefixime, Tellurite-Sorbitol McConkey (CT-SMAC) agar to identify sorbitol and non sorbitol fermenting E. coli. Further characterization of both the sorbitol fermenting and non sorbitol fermenting E. coli was done using commercially procured latex agglutination test kits from Oxoid, United Kingdom. The prevalence of VTEC O157 in apparently healthy cattle was 1.84% and 2.96% for diarrhoeic cattle while the prevalence of non O157 VTEC was 3.67% and 7.12% for apparently healthy and diarrhoeic cattle respectively. There was no strong association (p > 0.05) between faecal consistency and infection with VTEC O157. A strong association (p < 0.05) however existed between faecal consistency and infection with non-O157 VTEC. Diarrhoeic cattle appear likely to be more affected. The implication of the study is that individuals in contact with cattle such as veterinarians, abattoir workers and cattle herdsmen are at risk of exposure to VTEC and proper hygienic control measures should be adopted.展开更多
Salmonella and E.coli possess different surface protein structures that can induce protective immune responses.Identification of these proteins capacitates development of diverse applications in prevention and diagnos...Salmonella and E.coli possess different surface protein structures that can induce protective immune responses.Identification of these proteins capacitates development of diverse applications in prevention and diagnosis that contribute to effectively control disease-causing enterobacteria pathogens such as Salmonella and E.coli.A simple procedure for obtaining protein complexes of Salmonella serotypes and E.coli is performed in this study.A sonication process with heat treatment of whole bacteria induced the release of protein complexes.Concentration of the protein extract was quantified using protein quantification Kits-Rapid,and protein complex profile was obtained by SDS-PAGE(Sodium dodecyl sulfate polyacrylamide gel electrophoresis)and silver staining.The concentrations of protein ranged from 29.45 to 45.35μg/mL in the Salmonella protein extracts,and from 25.35 to 36.72μg/mL in the E.coli protein extracts.Six major groups of proteins from E.coli(YfiO,NipB,OmpF,YfgL,Talc,YaeT)and four major groups of proteins from Salmonella(Flagellin,OmpA,Porin,SEF21)were preliminarily determined by a simple procedure of extraction based on the molecular weight.展开更多
Streptococcus suis serotype 2(S.suis 2)is a zoonotic pathogen that clinically causes severe swine and human infections(such as meningitis,endocarditis,and septicemia).In order to cause widespread diseases in different...Streptococcus suis serotype 2(S.suis 2)is a zoonotic pathogen that clinically causes severe swine and human infections(such as meningitis,endocarditis,and septicemia).In order to cause widespread diseases in different organs,S.suis 2 must colonize the host,break the blood barrier,and cause exaggerated inflammation.In the last few years,most studies have focused on a single virulence factor and its influences on the host.Membrane vesicles(MVs)can be actively secreted into the extracellular environment contributing to bacteria-host interactions.Gram-negative bacteria-derived outer membrane vesicles(OMVs)were recently shown to activate host Caspase-11-mediated non-canonical inflammasome pathway via deliverance of OMV-bound lipopolysaccharide(LPS),causing host cell pyroptosis.However,little is known about the effect of the MVs from S.suis 2(Gram-positive bacteria without LPS)on cell pyroptosis.Thus,we investigated the molecular mechanism by which S.suis 2 MVs participate in endothelial cell pyroptosis.In this study,we used proteomics,electron scanning microscopy,fluorescence microscope,Western blotting,and bioassays,to investigate the MVs secreted by S.suis 2.First,we demonstrated that S.suis 2 secreted MVs with an average diameter of 72.04 nm,and 200 proteins in MVs were identified.Then,we showed that MVs were transported to cells via mainly dynamin-dependent endocytosis.The S.suis 2 MVs activated NLRP3/Caspase-1/GSDMD canonical inflammasome signaling pathway,resulting in cell pyroptosis,but it did not activate the Caspase-4/-5 pathway.More importantly,endothelial cells produce large amounts of reactive oxygen species(ROS)and lost their mitochondrial membrane potential under induction by S.suis 2 MVs.The results in this study suggest for the first time that MVs from S.suis 2 were internalized by endothelial cells via mainly dynamin-dependent endocytosis and might promote NLRP3/Caspase-1/GSDMD pathway by mitochondrial damage,which produced mtDNA and ROS under induction,leading to the pyroptosis of endothelial cells.展开更多
基金supported by the Ministry of Higher Education under the Fundamental Research Grant Scheme(FRGS/1/2021/SKK0/UPM/02/8)the Universiti Putra Malaysia Research University Grant Scheme(GP/IPS/2021/9702000).
文摘Objective:To determine the distribution,phenotypic and genetic background of extended spectrumβ-lactamases(ESBL)-producing Klebsiella(K.)pneumoniae clinical isolates associated with K1 and K2 serotypes in two selected hospitals in Malaysia.Methods:A total of 192 K.pneumoniae isolates were collected and subjected to antibiotic susceptibility,hypermucoviscosity test and multiplex PCR to detect the presence of K1-and K2-serotype associated genes.Multilocus sequence typing(MLST)was performed on ESBL-producing K.pneumoniae isolates presented with K1 and K2 serotypes,followed by phylogenetic analysis.Results:A total of 87 out of 192(45.3%)of the K.pneumoniae isolates collected were ESBL producers.However,only 8.3%(16/192)and 10.9%(21/192)of the total isolates were detected to carry K1-and K2-serotype associated genes,respectively.Statistical analysis showed that K1 and K2 capsular serotypes were not significantly associated with ESBL phenotype(P=0.196).However,they were significantly associated with hypervirulent,as demonstrated by the positive string test(P<0.001).MLST analysis revealed that ST23 as the predominant sequence type(ST)in the K1 serotype,while the ST in the K2 serotype is more diverse.Conclusions:Although the occurrence of ESBL-producing isolates among the hypervirulent strains was low,their coexistence warrants the need for continuous surveillance.MLST showed that these isolates were genetically heterogeneous.
文摘Background: The main objective of this study is to describe the rate of the different serotypes of HPV in cervical cytologies and biopsies in three different periods: 2002-2006 (prior to the implementation of the vaccination programs in Spain), 2009-2011 (shortly after this implementation) and 2020 (almost 15 years after introduction of the vaccine) at a single hospital. Methods: This is an observational, descriptive, retrospective study based on the review of the results of the determination of the HPV serotype using the commercial kit (Genomica<sup>®</sup>;PharmaMar LTD) in cervical liquid-based cytologies and biopsies at a single large tertiary hospital, Hospital Clínico San Carlos, in Madrid, Spain. We have collected the data from three different time periods: 2002-2006;2009-2011, and 2020 to try to understand the potential changes associated with the use of the vaccine. Results: In these time periods we have reviewed the data from 1420 women. In the three periods the most frequent serotype was HPV 16, followed by HPV 18 or a combination of both. The most frequent low risk serotype was HPV 6 followed by the combination of HPV 6 and 11. It has been verified in our study that the prevalence of the category “others”, constituted by the three risk groups, has undergone a progressive increase, beginning with an infection rate of 65.43% in 2002-2006 to finally rise up to 90.92% in the year 2020. Conclusions: Our study reveals an increase in the number of infections by the HPV serotypes that are not included in the tetravalent vaccine.
基金supported by Institute for Medical Research Operational Grant(Vol:040300/OS27403)
文摘Objective:To identify the circulating serotypes of human echovinis in Malaysia from 2002 in 2013.Methods:A toial of 31 retrospective samples from non-polio acute flacid paralysis,hand-food-and-mouth disease,viral meningitis and enterovirus cases were subjected to amplification of partial VPI gene by RT-PCR.Results:Sequencing and phylogeneiic analysis of the partial sequences identified presence of human echovinis and human coxsackie viruses.It was found that echovinis 11 was the commonly circulating serotype followed by echovinis6.echovinis 7.echovinis 3.echovinis 9.echovinis 30 and echovinis I in decreasing order.Additionally two types of human coxsackie virus isolates were detected which were coxsackie A24 and B3.Condusions:From the findings,there is a possibility that echovinis 11 is the predominant serotype among Malaysian patients with echovinis infection.However,a larger sample size will yield a more confident result to support this evidence.____________________
基金Supported by the Hubei Province Health and Family Planning A Scientific Research Project,No.WJ2017M220the Wuhan Health Bureau Scientific Research Fund,No.WX19C11+2 种基金the Joint Precision Medical Research Fund From Taihe Hospital,No.2016JZ10the Shiyan COVID-19 Pilot Emergency Scientific Research Project,No.20Y19the Wuhan Children's Hospital Research Project,No.2017FE007.
文摘BACKGROUND Hand,foot,and mouth disease(HFMD)has become one of the most common infectious diseases in China.Before 2016,the primary causal serotypes were enterovirus A71(EV-A71)and coxsackievirus A16(CV-A16).Following the introduction of EV-A71 vaccines in China since 2016,the situation could change.CV-A6 has recently replaced EV-A71 and CV-A16 in some areas of China.However,the epidemiological characteristics of central China remain unknown.AIM To investigate the clinical symptoms and pathogen spectrum of HFMD in Shiyan City,central China,in recent years.METHODS The epidemiological,clinical,and laboratory data from HFMD cases reported to the Shiyan Center for Disease Control and Prevention between January 2016 and December 2020 were analyzed.196 throat swab specimens were collected from hospitalized HFMD patients between January 2018 and December 2020.To detect and genotype enteroviruses,real-time reverse transcription-polymerase chain reaction and sequencing of the 5'-untranslated region were used.In Shiyan,168 laboratory-confirmed HFMD cases were studied using a logistic regression model to determine the effect of predominant enterovirus serotypes.Based on the logistic regression model,the least absolute shrinkage and selection operator model was used to analyze the correlation between CV-A6 infection and various clinical characteristics in HFMD patients in Shiyan.RESULTS From 2016 to 2020,35840 HFMD cases were reported in Shiyan.The number of cases decreased by 48.4%from 2016 to 2017.Approximately 1.58-fold increases were found in 2018 and 2019 when compared to the previous year,respectively.In 2020,a decrease of about 85.5%was reported when compared to 2019.The most common serotypes shifted from EV-A71 and CV-A16(about 60%-80%in 2016 and 2018)to others(more than 80.0%in 2017,2019,and 2020).EV-A71 lost its dominance in 2017 in Shiyan.Among 196 confirmed HFMD cases,85.7%tested positive for enterovirus,with CV-A6 being the most common serotype(121/168,72.0%).The positive rates for CV-A16 and CVA10 were 4.8%and 3.0%,respectively.There was no EV-A71 discovered.Infection with CV-A6 was linked to fever,myocardial damage,increased creatine kinase MB isoenzyme,and lactate dehydrogenase levels.CONCLUSION CV-A6 was the most common enterovirus serotype in Shiyan City,replacing EV-A71 and CV-A16 as the HFMD pathogen.Developing vaccines against CV-A6 or multiple pathogens,as well as rising CV-A6 surveillance,will help prevent HFMD in central China.
基金supported by the National Key R&D Program of China (2017YFD0500203)the National Transgenic Major Program of China (2014ZX0800946B)+3 种基金the National NaturalScience Foundation of China (31672574)the Special Fund for Agro-scientific Research in the Public Interest, China (201403054)the Jiangsu Agricultural Science and Technology Innovation Fund, China ([CX (16) 1028])the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (PAPD)
文摘Streptococcus suis is one of the major pathogens of swine streptococcosis. Among them, the strongest virulence and highest rate of clinical isolation serotype is S. suis serotype 2(SS2). Moreover, SS2 is also an important zoonosis pathogen, which caused severe public health issues in China. It has been reported that SS2 has several virulence factors, including muramidase released protein, extracellular factors, capsule, fibronectin-binding protein, enolase, hemolysin, small RNA, biofilm, two-component regulatory systems, STK/STP, etc., whose functions involved in adhesion, anti-phagocytosis, inflammatory pathway activation, invasion, etc. Actually, SS2 has developed a variety of ways to escape from host immune system during evolution. In particularly, capsule could resist phagocytosis through inhibiting sphingosine dependent immune cell recognition, which plays an important role in escaping host inflammation response; moreover, superoxide dismutase encoding by sod A enables SS2 escaping reactive oxygen species(ROS) in host immune cells; besides, binding complement factor h with Fhb could suppress the activation of complement alternative pathway and bactericidal effect. And SS2 could also hinder the formation of neutrophil extracellular traps(NETs) to avoid trapping by swine neutrophils, while host immune globulin could be degraded by Ig A1 hydrolase and Ig M protease. In addition, SS2 could escape host immune defense with the help of multiple transcriptional factors and micro-RNA. So far, the pathogenesis of meningitis, arthritis caused by SS2 infection, is still unclear, and the virulence regulatory mechanism of phosphorylation, micro-RNA need to be further clarified. Importantly, the study of interaction mechanism of pathogen and host contribute to further demonstration the pathogenesis of SS2.
基金supported by funding from grants from Taiwan Ministry of Science and Technology(MOST 103-2314-B-039-010-MY3)China Medical UniversityTaiwan(CMU106-S-02)
文摘Objective: To ascertain the role of imported cases and serotypes on dengue outbreaks in Taiwan which have been sporadic yet highly volatile during the past two decades, exhibiting record-breaking magnitude in recent years. Methods: Confirmed case and serotype data from Taiwan Centers for Disease Control during 1998-2017 were fully examined, with fitting of weekly and daily case data of each city/county to a mathematical model to pinpoint the waves of cases and their locations. Moreover, we quantify the timing of turning point and transmission potential of each wave and determine its circulating serotype, to ascertain any pattern or connection between the variations in circulating serotypes and the magnitude/transmissibility of outbreak. Results: While the number of imported case increased steadily during past two decades, the yearly number of indigenous cases fluctuated wildly. Moreover, while yearly percentages of serotypes for imported cases remains steady, that of indigenous cases does not exhibit any clear pattern. There was at least one wave of reported cases somewhere in Taiwan every year from 1998 to 2015, except in 2016-2017. The effective reproduction number R for all waves in all locations ranged from 1.14 to 2.87, with the exception of two Tainan waves, in 2010(3.95) and 2015(6.84). Four major outbreaks of over 2000 cases reveal circulation of one dominant serotype. Conclusions: Correlation between imported cases and indigenous outbreak prove to be difficult to ascertain, even with the availability of serotype data. However, although there had been occasional co-circulation of serotypes in one location, and for some years with different serotypes circulating in different locations, all major outbreaks of over 2 000 cases during the past two decades are due to circulation of mainly a single serotype, perhaps indicating greater transmission potential with one dominating serotype.
文摘Non-O157 STEC has been shown to have a diverse ecological distribution among food-animals. It has been associated with both outbreaks and individual cases of severe illness. This group of the organisms is now considered as a major contributor to human disease. The clinical description of the diseases caused by these organisms is reviewed. The host specificity of these pathogens is described and discussed. These organisms appear widespread among food animals like cattle and sheep, and can therefore affect a range of foods directly from the meat and excretions of these animals being used in farming practices. This article reviews the origins, diversity and pathogenesis of non-O157 STEC.
文摘Rapid identification and characterization of Listeria monocytogenes are required for the food industry, epidemiological studies, and disease prevention and control. However, typing procedures are labor-intensive and time-consuming, and they require technical expertise, a panel of sera and reference culture strains or sophisticated and expensive equipment. To improve upon traditional diagnostic methods for L. monocytogenes we developed and evaluated an efficient procedure for the specific identification of L. monocytogenes and the major pathogenic serotypes of the species based on loop-mediated isothermal amplification (LAMP). Four individual reactions were designed using primers targeting any L. monocytogenes serotypes (LAMP-AS) and the 1/2a (LAMP-1/2a), 1/2b (LAMP-1/2b), and 4b (LAMP-4b) serotypes. The procedure distinguished L. monocytogenes from closely genetically related species and the targeted serotypes. Cross-reactivity with a few rare serotypes isolated from food or clinical samples did not impair the usefulness of the procedure. Thus, our approach constitutes a fast, easy and low-cost alternative for L. monocytogenes diagnosis and serotyping and may be useful for surveillance and epidemiological investigation programs.
文摘Introduction: In the North-Benin, there are three agents causing pediatric purulent meningitis outside the neonatal period. These are: Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b. The aim of this research work was to investigate bacteria serotypes that caused childhood purulent meningitis in the pediatric unit of the Borgou à Regional University Teaching Hospital (CHUD-Borgou) located in Parakou (North-Benin). Patients and Methods: Through a prospective and descriptive study centered on children aged 0 to 5 years old suspected of meningitis and hospitalized, the cerebrospinal fluid (CSF) samples of those children were analyzed at the WHO reference laboratory in Banjul for serotyping by real time polymerase chain reaction (RT/PCR). Results: Among the 1396 children hospitalized during that period, 366 were suspected of meningitis and had benefitted from lumbar puncture. Among those 366 suspected cases, 51 cases of purulent meningitis were confirmed after CSF cytobacteriological and biochemical test at the CHUD-Borgou laboratory. Among 51 CSF samples in which purulent meningitis was confirmed, 44 were sent to Banjul. In addition, 310 CSF samples from non-confirmed cases of meningitis were also sent to Banjul. In the whole set of samples sent for real time PCR, 151 cases of Streptococcus pneumoniae (42.7%) were found, 5 cases of Neisseria meningitidis (1.4%) and 1 case of Haemophilus influenzae (0.3%) were also encountered. As regards Streptococcus pneumonia, the serotypes encountered were: 1, 3, 4, 5, 7F, 8, 9V, 9V/9A, 9N/9L, 14, 18C, 19A, 23F, 33F as well as non typed and non typable serotypes. As for Neisseria meningitidis, only serogroup A was found in it. For Haemophilus influenzae, only serotype b was identified. Conclusion: Four non vaccine serotypes (8, 9V/9A, 9N/9L and 33F), non typed and non typable serotypes which are not covered by 13-valent pneumococcal conjugate vaccine (PCV 13) were identified. This highlights the need to enhance surveillance of pediatric purulent meningitis and serotyping by RT/PCR of all CSF samples in order to adapt if necessary future new pneumococcal vaccines to circulating non vaccine serotypes.
基金supported by the Open Project of the State Key Laboratory of Veterinary Etiological Biology, China (SKLVEB 2013 KFKT 0015)
文摘An agglutination test based on colored silica nanoparticles(colored SiNps) was established to detect serotypes of Pseudomonas aeruginosa. Monodisperse colored SiNps were used as agglutination test carriers. The colored SiNps were prepared through reverse microemulsion with reactive dyes, sensitized with 11 kinds of mono-specific antibodies against P. aeruginosa, and denoted as IgG-colored SiNps. Eleven kinds of IgG-colored SiNps were individually mixed with P. aeruginosa on a glass slide.Different serotypes of P. aeruginosa could be identified by agglutination test with evident agglutination. The P. aeruginosa could be detected in a range from 3.6×10^5 to 3.6×10^12 cfu mL^–1. This new agglutination test was confirmed to be a specific,sensitive, fast, easy-to-perform, and cost-efficient tool for the routine diagnosis of P. aeruginosa.
文摘The control and prevention of pasteurellosis in rabbits which makes the hosts unsuitable for experimental use raised the needs to improve and simplify the procedures of Enzyme-Linked Immunosorbent Assay (ELISA) for detect of antibody against P.multocida. A comparison on the sensitivity and specificity of bacterial culture of antemortem and postmortem samples, complement fixation test and enzyme-linked immunosorbent assay of 11 apparently healthy adult rabbits was conducted. The incidence rates showed 45.45%,54.54% and 72.73% respectively. The sensitivity for the three methods were 0.63, 0.67,and 1.00,and specificity for them were 1.00, 0.67 and 1.00 respectively. Somatic serotypes of isolates of P.multocida from rabbits of three groups (rabbits of group 2 were with clinic signs, those of groups 1 and 3 were apparently healthy) revealed no remarkable differences,and the predominant types were type 3 and type 3, 4. This was somewhat different from the reports derived from other states. As the antigen of different serotype used in ELISA may have different sensitivity and specificity, which is affected also by different preparation method, a type non-specific antigen should be selected to meet such request. The trial of accomplishment of ELISA without positive and negative controls was presented for discussion.
文摘Objective:To determine the antimicrobial susceptibility and serotypes of Neisseria(N.)meningitidis and Streptococcus(S.)pneumoniae in Sri Lankan patients.Methods:We retrospectively analyzed 11 blood culture specimens from suspected patients with invasive meningococcal disease and 26 S.pneumoniae clinical isolates.We tested 6 antimicrobials against N.meningitidis and 12 antimicrobials against S.pneumoniae.Meningococcal serogroup was determined by realtime PCR and Quellung serotyping was used for pneumococcal analysis.Results:N.meningitidis serogroup B was the most common in this study.Intermediate-susceptibility to penicillin was seen in 75.0%(6/8)of strains.Susceptibility to ciprofloxacin,levofloxacin and cotrimoxazole was 62.5%(5/8),62.5%(5/8)and 87.5%(7/8),respectively.Excellent susceptibility was seen in cefotaxime and meropenem.In S.pneumoniae,the most common serotype was 19F in both invasive and non-invasive pneumococcal diseases.The majority of strains showed multidrug resistance.Penicillin non-susceptibility in non-meningeal strains were 13.6%and all meningeal strains were penicillin resistant.Erythromycin was highly resistant in both groups.Amoxicillin showed excellent susceptibility in non-invasive pneumococcal diseases strains.Linezolid,levofloxacin and vancomycin showed 100.0%susceptibility in all pneumococcal isolates.Conclusions:Implementation of vaccines should be considered,especially for children and high-risk populations.This may contribute to reducing pneumococcal and meningococcal invasive disease burden and help prevent emergence of antimicrobial resistant strains.
基金Supported by Natural Science Foundation of Shandong Province(ZR2014CQ009)Binzhou Municipal Science and Technology Project(2013GG0304)
文摘In order to diagnose the diseased pigs in a certain large pig farm in Binzhou City,Shandong Province,the dead piglets with joint swelling were subjected to necroscopy,and the pathogenic bacterium was isolated and identified. One Gram-positive Streptococcus was isolated. The strain was subjected to characteristic culture,microscopic examination and molecular biological identification,and resistance detection,animal regression experiment and mouse pathogenicity test were carried out. The results showed that the isolate was identified to be Streptococcus suis serotype 7,which was resistant to multiple drugs; and the pathogenicity test showed that the strain had high pathogenicity to pigs,resulting in neurosis on partial pigs,and the strain had no pathogenicity to Kunming and BALB/c mice but certain pathogenicity to CD1 mice.
文摘Streptococcus agalactiae (GBS) is considered as the most important cause of invasive bacterial disease in infants. There are few current data from serotype IX of GBS worldwide. The present work has been done in order to make a contribution to the knowledge of serotype IX through phenotypic and genotypic study of virulence and resistance. Of 200 strains tested, 5.5% were serotype IX and all were colonizing. In 63.6% of the strains the presence of the bac, bca and hylB genes was determined, and in 54.5% of lmb and rib. All strains were susceptible to Clindamycin and Erythromycin however five isolates showed the resistance genes: ermB, ermTR and/or mefA. The presence of serotype IX in Misiones, a province situated in the northeaster of Argentina, which limits with Paraguay and Brazil in South America, gives the region a particular situation. Currently, public health efforts are aimed at prevention and treatment, study of the virulence mechanisms, surveillance of resistance to antibiotics and the development of effective vaccines to prevent GBS infection.
文摘Klebsiella pneumoniae liver abscess (KPLA) has been described as an invasive syndrome with extrahepatic complications. The majority of KPLA is caused by capsular serotype K1 and K2 isolates. We report a case of carbapenem resistant Klebsiella pneumoniae liver abscess. The patient initially presented with infected right above-the-knee amputation and was later found with a large liver abscess. Initial antimicrobial susceptibility showed carbapenem resistant K. pneumoniae (CRKP). Further molecular workup revealed that the isolate was a less virulent non-K1/K2 serotype, and both rmpA and kfu genes were negative. The lack of outer membrane porins likely contributed to the carbapenem resistance. To our knowledge, this is a first reported case of carbapenem resistant, non-K1/K2 serotype K. pneumoniae liver abscess in the United States.
文摘Streptococcus pneumoniae is a medically important pathogen capable of causing human infections of pneumonia, bacteremia, otitis media, and meningitis. Although there are vaccinations available, infections with S. pneumoniae still remains a global problem. S. pneumoniae is a highly adaptable bacterial species with numerous serotypes based on capsular polysaccharides. The different serotypes vary in their ability to colonize and causing pathology. Here we compared the regulation of five different virulence factors from four common serotypes of S. pneumoniae that vary in their carriage, morbidity, and mortality rates in the human population using two different in vitro methods, broth and cell culture. We determine that there is variation of virulence factor gene regulation within a serotype using two different culture methods, and variation between the serotypes in the same culture condition. The regulation of genes appeared to have a correlation with the ability of the various serotypes to grow in broth culture, adhere to cultured lung cells, and invade the cultured lung cells, as serotypes that shared similar regulation of virulence factors tended to behave similarly in culture. Many studies with S. pneumoniae rely on the use of one selected serotype, but since there is a wide variation in the growth and regulatory mechanisms of these bacteria. As demonstrated here, future studies should utilize more strains in models before concluding mechanisms of pathobiology.
文摘Background: Streptococcus pneumoniae (pneumococcus) is one of the most frequent causes of bacterial infection in children and is a leading cause of otitis, sinusitis, pneumonia, and meningitis worldwide. Nasopharyngeal colonization is a risk factor for pneumococcal disease, a leading cause of complications and death in infants. HIV-infected persons are at high risk of invasive pneumococcal disease. Method: Nasopharyngeal swabs were collected from 296 HIV infected children below five years recruited from Gertrude’s Children hospital and Nazareth Hospital Nairobi, Kenya. The nasopharyngeal swabs were processed to isolate S. pneumoniae, which were serotyped and tested for drug susceptibility. Results: The carriage prevalence of S. pneumoniae in the study was 30.4% while the isolated serotypes were (in order of decreasing frequency): 35B, 19F, 3, 13, 15A, 11A, 16F, 7C and 23A. Most of the serotypes were resistant to the commonly used antibiotics but all were susceptible to vancomycin and chloramphenicol. Conclusion: Carriage prevalence of nasopharyngeal S. pneumonia in HIV infected children was lower than that of similar prevalence studies in children. Most of the S. pneumoniae isolates were however non pneumococcal vaccine isolates.
文摘It is reckoned worldwide that verocytotoxigenic Escherichia coli (VTEC) serotypes are important food borne pathogens causing severe health problems in humans. A cross sectional epidemiological study was carried out to determine the prevalence of VTEC serotypes (O157 and non O157) in both apparently healthy and diarrhoeic cattle in Abuja, FCT. A total of 718 faecal samples collected from abattoirs and cattle herds from Abuja, FCT representing 381 from apparently healthy and 337 from diarrhoeic cattle were analyzed. Primary isolation of typical E. coli was done using Eosin Methylene Blue (EMB) agar and performing biochemical tests. Samples were further analyzed using Cefixime, Tellurite-Sorbitol McConkey (CT-SMAC) agar to identify sorbitol and non sorbitol fermenting E. coli. Further characterization of both the sorbitol fermenting and non sorbitol fermenting E. coli was done using commercially procured latex agglutination test kits from Oxoid, United Kingdom. The prevalence of VTEC O157 in apparently healthy cattle was 1.84% and 2.96% for diarrhoeic cattle while the prevalence of non O157 VTEC was 3.67% and 7.12% for apparently healthy and diarrhoeic cattle respectively. There was no strong association (p > 0.05) between faecal consistency and infection with VTEC O157. A strong association (p < 0.05) however existed between faecal consistency and infection with non-O157 VTEC. Diarrhoeic cattle appear likely to be more affected. The implication of the study is that individuals in contact with cattle such as veterinarians, abattoir workers and cattle herdsmen are at risk of exposure to VTEC and proper hygienic control measures should be adopted.
文摘Salmonella and E.coli possess different surface protein structures that can induce protective immune responses.Identification of these proteins capacitates development of diverse applications in prevention and diagnosis that contribute to effectively control disease-causing enterobacteria pathogens such as Salmonella and E.coli.A simple procedure for obtaining protein complexes of Salmonella serotypes and E.coli is performed in this study.A sonication process with heat treatment of whole bacteria induced the release of protein complexes.Concentration of the protein extract was quantified using protein quantification Kits-Rapid,and protein complex profile was obtained by SDS-PAGE(Sodium dodecyl sulfate polyacrylamide gel electrophoresis)and silver staining.The concentrations of protein ranged from 29.45 to 45.35μg/mL in the Salmonella protein extracts,and from 25.35 to 36.72μg/mL in the E.coli protein extracts.Six major groups of proteins from E.coli(YfiO,NipB,OmpF,YfgL,Talc,YaeT)and four major groups of proteins from Salmonella(Flagellin,OmpA,Porin,SEF21)were preliminarily determined by a simple procedure of extraction based on the molecular weight.
基金supported by the National Natural Science Foundation of China(U22A20520)the Innovation Team Project of Modern Agricultural Industrial Technology System of Guangdong Province,China(2023KJ119)the Natural Science Foundation Program of Guangdong Province,China(2023A1515012206)。
文摘Streptococcus suis serotype 2(S.suis 2)is a zoonotic pathogen that clinically causes severe swine and human infections(such as meningitis,endocarditis,and septicemia).In order to cause widespread diseases in different organs,S.suis 2 must colonize the host,break the blood barrier,and cause exaggerated inflammation.In the last few years,most studies have focused on a single virulence factor and its influences on the host.Membrane vesicles(MVs)can be actively secreted into the extracellular environment contributing to bacteria-host interactions.Gram-negative bacteria-derived outer membrane vesicles(OMVs)were recently shown to activate host Caspase-11-mediated non-canonical inflammasome pathway via deliverance of OMV-bound lipopolysaccharide(LPS),causing host cell pyroptosis.However,little is known about the effect of the MVs from S.suis 2(Gram-positive bacteria without LPS)on cell pyroptosis.Thus,we investigated the molecular mechanism by which S.suis 2 MVs participate in endothelial cell pyroptosis.In this study,we used proteomics,electron scanning microscopy,fluorescence microscope,Western blotting,and bioassays,to investigate the MVs secreted by S.suis 2.First,we demonstrated that S.suis 2 secreted MVs with an average diameter of 72.04 nm,and 200 proteins in MVs were identified.Then,we showed that MVs were transported to cells via mainly dynamin-dependent endocytosis.The S.suis 2 MVs activated NLRP3/Caspase-1/GSDMD canonical inflammasome signaling pathway,resulting in cell pyroptosis,but it did not activate the Caspase-4/-5 pathway.More importantly,endothelial cells produce large amounts of reactive oxygen species(ROS)and lost their mitochondrial membrane potential under induction by S.suis 2 MVs.The results in this study suggest for the first time that MVs from S.suis 2 were internalized by endothelial cells via mainly dynamin-dependent endocytosis and might promote NLRP3/Caspase-1/GSDMD pathway by mitochondrial damage,which produced mtDNA and ROS under induction,leading to the pyroptosis of endothelial cells.
