Hypervirulent emm59 Clone in Invasive Group A Streptococcus Outbreak, Southwestern United States.
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ABSTRACT:
SUBMITTER: Engelthaler DM
PROVIDER: S-EPMC4806960 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:We describe a hypervirulent clone of group B Streptococcus serotype III, subtype 4, sequence type 283, that caused invasive disease with a predilection for meningitis in Hong Kong during 1993-2012. The organism is associated with high mortality and increased summer prevalence and is linked to diseased fish from freshwater fish farms.
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Project description:We analyzed group B Streptococcus (GBS) neonatal invasive infections reported during 2007-2019 in France. The hypervirulent clonal complex (CC) 17 GBS was responsible for 66% (827/1,262) of cases. The role of CC17 GBS increased over time (p for trend = 0.0001), together with the emergence of a multidrug-resistant CC17 GBS sublineage.
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Project description:BACKGROUND:Although Streptococcus agalactiae is the leading causative agent of neonatal sepsis and meningitis, recently it is increasingly isolated from non-pregnant adults. The relation between its presence in the genitourinary tract and manifested clinical symptoms of STD patients remains an open question. In this study, a complex epidemiological investigation of GBS isolates from a venerology clinic was performed. METHODS:Ninety-six GBS isolates were serotyped and their genetic relatedness determined by PFGE. MLST was also performed for a subset of 20 isolates. The antibiotic susceptibility was tested with agar dilution. Surface proteins and the ST-17 hypervirulent clone was detected by PCR. RESULTS:The serotype prevalence was the following: V (29.2%), III (27.1%), Ia (22.9%), IV (10.4%), II (5.2%) and Ib (4.2%). A strong association was demonstrated between surface protein genes and serotypes. All isolates were fully susceptible to penicillin, but erythromycin and clindamycin resistance was high (41.7 and 35.4%, respectively), and 8 phenotypically macrolide sensitive isolates carried the ermB gene. 21.9% of all strains belonged to the hypervirulent ST17 clone, most being of serotype III and all were rib +. We found a few serotype IV isolates belonging to several STs and one serotype V/ST110 strain, containing a 44-bp deletion in the atr allele. CONCLUSIONS:The presence of silent ermB genes is of worry, as their expression upon macrolide exposure could lead to unforeseen therapeutic failure, while clindamycin is used for intrapartum antibiotic prophylaxis, in case of penicillin allergy. The other alarming result is the high prevalence of ST17 among these strains from STD patients, who could be sources of further infections. This is the first report from Hungary providing both serotyping and genotyping data of GBS isolates. These results could be helpful for vaccine production as the major vaccine candidates are capsular antigens or surface proteins.
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Project description:Clonal replacement is a major driver for changes in bacterial disease epidemiology. Recently, it has been proposed that episodic emergence of novel, hypervirulent clones of group A Streptococcus (GAS) results from acquisition of a 36-kb DNA region leading to increased expression of the cytotoxins Nga (NADase) and SLO (streptolysin O). We previously described a gene fusion event involving the gene encoding the GAS M protein (emm) and an adjacent M-like protein (enn) in the emm4 GAS population, a GAS emm type that lacks the hyaluronic acid capsule. Using whole-genome sequencing of a temporally and geographically diverse set of 1,126 isolates, we discovered that the North American emm4 GAS population has undergone clonal replacement with emergent GAS strains completely replacing historical isolates by 2017. Emergent emm4 GAS strains contained a handful of small genetic variations, including the emm-enn gene fusion, and showed a marked in vitro growth defect compared to historical strains. In contrast to other previously described GAS clonal replacement events, emergent emm4 GAS strains were not defined by acquisition of exogenous DNA and had no significant increase in transcript levels of nga and slo toxin genes via RNA sequencing and quantitative real-time PCR analysis relative to historic strains. Despite the in vitro growth differences, emergent emm4 GAS strains were hypervirulent in mice and ex vivo growth in human blood compared to historical strains. Thus, these data detail the emergence and dissemination of a hypervirulent acapsular GAS clone defined by small, endogenous genetic variation, thereby defining a novel model for GAS strain replacement. IMPORTANCE Severe invasive infections caused by group A Streptococcus (GAS) result in substantial morbidity and mortality in children and adults worldwide. Previously, GAS clonal strain replacement has been attributed to acquisition of exogenous DNA leading to novel virulence gene acquisition or increased virulence gene expression. Our study of type emm4 GAS identified emergence of a hypervirulent GAS clade defined by variation in endogenous DNA content and lacking augmented toxin gene expression relative to replaced strains. These findings expand our understanding of the molecular mechanisms underlying bacterial clonal emergence.
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Project description:BackgroundThe nosology of noninvasive pneumonia due to group B Streptococcus (GBS) is not well defined. This study compared clinical characteristics and outcomes of patients with invasive pneumonia and noninvasive pneumonia caused by GBS.MethodsWe conducted a retrospective cohort study among Veterans Affairs (VA) healthcare users between 2008 and 2017. Using data from electronic health records, we identified patients who had blood or respiratory cultures that grew GBS and had invasive pneumonia or noninvasive pneumonia. We analyzed patient and infection characteristics associated with all-cause mortality, including among the subset of patients with cultures that were monomicrobial for GBS.ResultsAmong 1791 patients with GBS pneumonia, 646 (36%) cases were invasive and 1145 (64%) were noninvasive. Among those, 535 and 424 cases of invasive and noninvasive pneumonia, respectively, had cultures that were monomicrobial for GBS. All-cause 30-day mortality among those with monomicrobial GBS pneumonia was 15% for both those with invasive and noninvasive disease, respectively. Increasing age, severity of illness, healthcare exposure in the previous 90 days, and polymicrobial infection with Staphylococcus aureus were independently associated with all-cause mortality at 30 days.ConclusionsIn this large cohort, even when considering cases for which GBS was the only pathogen recovered, >40% of GBS pneumonia cases were noninvasive. All-cause mortality was comparable for invasive and noninvasive pneumonia. These findings suggest that the burden of GBS pneumonia may be greater than previously recognized by surveillance of invasive GBS disease and may inform treatment and prevention efforts.
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Project description:Campylobacter jejuni clone SA is the major cause of sheep abortion and contributes significantly to foodborne illnesses in the United States. Clone SA is hypervirulent because of its distinct ability to produce systemic infection and its predominant role in clinical sheep abortion. Despite the importance of clone SA, little is known about its distribution and epidemiological features in cattle. Here we describe a prospective study on C. jejuni clone SA prevalence in 35 feedlots in 5 different states in the United States and a retrospective analysis of clone SA in C. jejuni isolates collected by National Animal Health Monitoring System (NAHMS) dairy studies in 2002, 2007, and 2014. In feedlot cattle feces, the overall prevalence of Campylobacter organisms was 72.2%, 82.1% of which were C. jejuni Clone SA accounted for 5.8% of the total C. jejuni isolates, but its prevalence varied by feedlot and state. Interestingly, starlings on the feedlots harbored C. jejuni in feces, including clone SA, suggesting that these birds may play a role in the transmission of Campylobacter In dairy cattle, the overall prevalence of clone SA was 7.2%, but a significant decrease in the prevalence was observed from 2002 to 2014. Whole-genome sequence analysis of the dairy clone SA isolates revealed that it was genetically stable over the years and most of the isolates carried the tetracycline resistance gene tet(O) in the chromosome. These findings indicate that clone SA is widely distributed in both beef and dairy cattle and provide new insights into the molecular epidemiology of clone SA in ruminants.IMPORTANCE C. jejuni clone SA is a major cause of small-ruminant abortion and an emerging threat to food safety because of its association with foodborne outbreaks. Cattle appear to serve as a major reservoir for this pathogenic organism, but there is a major gap in our knowledge about the epidemiology of clone SA in beef and dairy cattle. By taking advantage of surveillance studies conducted on a national scale, we found a wide but variable distribution of clone SA in feedlot cattle and dairy cows in the United States. Additionally, the work revealed important genomic features of clone SA isolates from cattle. These findings provide critically needed information for the development of preharvest interventions to control the transmission of this zoonotic pathogen. Control of C. jejuni clone SA will benefit both animal health and public health, as it is a zoonotic pathogen causing disease in both ruminants and humans.
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