Genetic Diversity and Antimicrobial Drug Resistance of Serotype VI Group B Streptococcus, Canada.
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ABSTRACT:
SUBMITTER: Neemuchwala A
PROVIDER: S-EPMC6154151 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:We recently showed that 37/600 (6.2%) invasive infections with group B Streptococcus (GBS) in Toronto, Ontario, Canada, were caused by serotype IV strains. We report a relatively high level of genetic diversity in 37 invasive strains of this emerging GBS serotype. Multilocus sequence typing identified 6 sequence types (STs) that belonged to 3 clonal complexes. Most isolates were ST-459 (19/37, 51%) and ST-452 (11/37, 30%), but we also identified ST-291, ST-3, ST-196, and a novel ST-682. We detected further diversity by performing whole-genome single-nucleotide polymorphism analysis and found evidence of recombination events contributing to variation in some serotype IV GBS strains. We also evaluated antimicrobial drug resistance and found that ST-459 strains were resistant to clindamycin and erythromycin, whereas strains of other STs were, for the most part, susceptible to these antimicrobial drugs.
| S-EPMC4378482 | biostudies-literature
Project description:Using serotyping, multilocus sequence typing, and whole-genome sequencing (WGS) of selected strains, we studied the population structure of 102 group B Streptococcus (GBS) isolates prospectively sampled in 2014 from vaginal/rectal swabs of healthy pregnant women in metropolitan Toronto, Canada. We also determined the susceptibilities of each of the colonizing isolates to penicillin, erythromycin, clindamycin, tetracycline, and other antimicrobial agents. Overall, we observed a high rate of tetracycline resistance (89%) among colonizing GBS isolates. We found resistance to erythromycin in 36% of the strains, and 33% were constitutively or inducibly resistant to clindamycin. The most frequently identified serotypes were III (25%), Ia (23%), and V (19%). Serotype IV accounted for 6% of the colonizing isolates, a rate consistent with that observed among patients with invasive GBS infections in metropolitan Toronto. The majority of serotype IV isolates belonged to sequence type (ST)459, a tetracycline-, erythromycin-, and clindamycin-resistant ST first identified in Minnesota, which is considered to be the main driver of serotype IV GBS expansion in North America. WGS revealed that ST459 isolates from Canada are clonally related to colonizing and invasive ST459 organisms circulating in regions of the United States. We also used WGS to study recombination in selected colonizing strains from metropolitan Toronto, which revealed multiple episodes of capsular switching. Present and future circulating GBS organisms and their genetic diversity may influence GBS vaccine development.
| S-EPMC5277510 | biostudies-literature
Project description:Serotype M1 group A Streptococcus, the most common cause of invasive disease in many case series, generally have resisted extensive molecular subtyping by standard techniques (e.g., multilocus enzyme electrophoresis, pulsed-field gel electrophoresis). We used automated sequencing of the sic gene encoding streptococcal inhibitor of complement and of a region of the chromosome with direct repeat sequences to unambiguously differentiate 30 M1 isolates recovered from 28 patients in Texas with invasive disease episodes temporally clustered and thought to represent an outbreak. Sequencing of the emm gene was less useful for M1 strain differentiation, and restriction fragment length polymorphism analysis with IS1548 or IS1562 as Southern hybridization probes did not provide epidemiologically useful subtyping information. Sequence polymorphism in the direct repeat region of the chromosome and IS1548 profiling data support the hypothesis that M1 organisms have two main evolutionary lineages marked by the presence or absence of the speA2 allele encoding streptococcal pyrogenic exotoxin A2.
| S-EPMC2640708 | biostudies-other
Project description:Infections of Streptococcus pneumoniae in children can be prevented by vaccination; left untreated, they cause high morbidity and fatalities. This study aimed at determining the nasopharyngeal carrier rates, serotype distribution and antimicrobial resistance patterns of S. pneumoniae in healthy Palestinian children under age two prior to the full introduction of the pneumococcal 7-valent conjugate vaccine (PCV7), which was originally introduced into Palestine in a pilot trial in September, 2010. In a cross sectional study, nasopharyngeal specimens were collected from 397 healthy children from different Palestinian districts between the beginning of November 2012 to the end of January 2013. Samples were inoculated into blood agar and suspected colonies were examined by amplifying the pneumococcal-specific autolysin gene using a real-time PCR. Serotypes were identified by a PCR that incorporated different sets of specific primers. Antimicrobial susceptibility was measured by disk diffusion and MIC methods. The resulting carrier rate of Streptococcus pneumoniae was 55.7% (221/397). The main serotypes were PCV7 serotypes 19F (12.2%), 23F (9.0%), 6B (8.6%) and 14 (4%) and PCV13 serotypes 6A (13.6%) and 19A (4.1%). Notably, serotype 6A, not included in the pilot trial (PCV7) vaccine, was the most prevalent. Resistance to more than two drugs was observed for bacteria from 34.1% of the children (72/211) while 22.3% (47/211) carried bacteria were susceptible to all tested antibiotics. All the isolates were sensitive to cefotaxime and vancomycin. Any or all of these might impinge on the type and efficacy of the pneumococcal conjugate vaccines and antibiotics to be used for prevention and treatment of pneumococcal disease in the country.
| S-EPMC3858295 | biostudies-literature
Project description:BackgroundThe group B Streptococcus (GBS) is a human commensal bacterium, which is capable of causing several infectious diseases in infants, and people with chronic diseases. GBS has been the most common cause of infections in urinary tract of the elders, but relatively few studies reported the urine-isolated GBS and their antimicrobial susceptibilities. Hence, we decided to investigate GBS specially isolated from urine in Suzhou, China.Methods27 GBS samples were isolated from urine in Suzhou, China. The PCR and agarose gel electrophoresis were used to identify the serotype distribution. Susceptibility tests were based on MIC test and Kirby-Bauer test. Genome were sequenced via Illumina Hiseq platform and assembled by SPAdes. Genomes of five isolates were sequenced and submitted to NCBI genome database. The sequencing files in fastq format were submitted to NCBI SRA database.ResultsFive serotypes were identified. The resistant rates measured for tetracycline, erythromycin, clindamycin and fluoroquinolones were 74.1, 63.0, 44.4 and 48.1%, respectively. 18.5% of the isolates were nonsusceptible to nitrofurantoin. The resistance to tetracycline was mainly associated with the gene tetM. The erythromycin resistance was mainly associated with the genes ermB and mefE. The genes ermB and lnuB were the prevalent genes in cMLSB type. No known nitrofurantoin resistance gene was found in nitrofurantoin-nonsusceptible GBS.ConclusionsFive serotypes were identified in our study. High rates of GBS isolates were resistant to tetracycline, erythromycin, clindamycin and fluoroquinolones. The genes ermB and lnuB occupied high rates in cMLSB phenotype.
| S-EPMC6020191 | biostudies-literature
Project description:Streptococcus suis is an emerging zoonotic pathogen that causes septicemia, meningitis, arthritis, and pneumonia in swine and humans. The present study aimed to characterize the genetic diversity of S. suis serotype 2 isolated from pigs showing signs of illness in Brazil using pulsed-field gel electrophoresis (PFGE), single-enzyme amplified fragment length polymorphism (SE-AFLP), and profiling of virulence-associated markers. A total of 110 isolates were studied, 62.7% of which were isolated from the central nervous system and 19.1% from the respiratory tract. Eight genotypes were obtained from the combination of virulence genes, with 43.6% and 5.5% frequencies for the mrp (+) /epf (+) /sly (+) and mrp (-) /epf (-) /sly (-) genotypes, respectively. The presence of isolates with epf gene variation with higher molecular weight also appears to be a characteristic of Brazilian S. suis serotype 2. The PFGE and SE-AFLP were able to type all isolates and, although they presented a slight tendency to cluster according to state and year of isolation, it was also evident the grouping of different herds in the same PFGE subtype and the existence of isolates originated from the same herd classified into distinct subtypes. No further correlation between the isolation sites and mrp/epf/sly genotypes was observed.
| S-EPMC4836036 | biostudies-literature
Project description:For the first time, we used multilocus sequence typing (MLST) to understand how Romanian group B streptococcus (GBS) strains fit into the global GBS population structure. Colonising isolates recovered from adult human females were tested for antibiotic resistance, were molecularly serotyped based on the capsular polysaccharide synthesis (cps) gene cluster and further characterised using a set of molecular markers (surface protein genes, pilus-encoded islands and mobile genetic elements inserted in the scpB-lmb intergenic region). Pulsed-field gel electrophoresis was used to complement the MLST clonal distribution pattern of selected strains. Among the 55 strains assigned to six cps types (Ia, Ib, II-V), 18 sequence types (STs) were identified by MLST. Five STs represented new entries to the MLST database. The prevalent STs were ST-1, ST-17, ST-19 and ST-28. Twenty molecular marker profiles were identified. The most common profiles (rib+GBSi1+PI-1, rib+GBSi1+PI-1, PI-2b and alp2/3+PI-1, PI-2a) were associated with the cps III/ST-17 and cps V/ST-1 strains. A cluster of fluoroquinolone-resistant strains was detected among the cps V/ST-19 members; these strains shared alp1 and IS1548 and carried PI-1, PI-2a or both. Our results support the usefulness of implementing an integrated genotyping system at the reference laboratory level to obtain the reliable data required to make comparisons between countries.
| S-EPMC4015262 | biostudies-literature
Project description:Group B Streptococcus (GBS) is an important pathogen of neonates, pregnant women, and immunocompromised individuals. GBS isolates associated with human infection produce one of nine antigenically distinct capsular polysaccharides which are thought to play a key role in virulence. A comparison of GBS polysaccharide structures of all nine known GBS serotypes together with the predicted amino acid sequences of the proteins that direct their synthesis suggests that the evolution of serotype-specific capsular polysaccharides has proceeded through en bloc replacement of individual glycosyltransferase genes with DNA sequences that encode enzymes with new linkage specificities. We found striking heterogeneity in amino acid sequences of synthetic enzymes with very similar functions, an observation that supports horizontal gene transfer rather than stepwise mutagenesis as a mechanism for capsule variation. Eight of the nine serotypes appear to be closely related both structurally and genetically, whereas serotype VIII is more distantly related. This similarity in polysaccharide structure strongly suggests that the evolutionary pressure toward antigenic variation exerted by acquired immunity is counterbalanced by a survival advantage conferred by conserved structural motifs of the GBS polysaccharides.
| S-EPMC1087335 | biostudies-literature
Project description:Strains of serotype 2 Streptococcus suis are responsible for swine and human infections. Different serotype 2 genetic backgrounds have been defined using multilocus sequence typing (MLST). However, little is known about the genetic diversity within each MLST sequence type (ST). Here, we used whole-genome sequencing to test the hypothesis that S. suis serotype 2 strains of the ST25 lineage are genetically heterogeneous. We evaluated 51 serotype 2 ST25 S. suis strains isolated from diseased pigs and humans in Canada, the United States of America, and Thailand. Whole-genome sequencing revealed numerous large-scale rearrangements in the ST25 genome, compared to the genomes of ST1 and ST28 S. suis strains, which result, among other changes, in disruption of a pilus island locus. We report that recombination and lateral gene transfer contribute to ST25 genetic diversity. Phylogenetic analysis identified two main and distinct Thai and North American clades grouping most strains investigated. These clades also possessed distinct patterns of antimicrobial resistance genes, which correlated with acquisition of different integrative and conjugative elements (ICEs). Some of these ICEs were found to be integrated at a recombination hot spot, previously identified as the site of integration of the 89K pathogenicity island in serotype 2 ST7 S. suis strains. Our results highlight the limitations of MLST for phylogenetic analysis of S. suis, and the importance of lateral gene transfer and recombination as drivers of diversity in this swine pathogen and zoonotic agent.
| S-EPMC4783015 | biostudies-literature
Project description:BackgroundTo summarize information about invasive pneumococcal disease (IPD) among children in mainland China.MethodsSixteen eligible studies were included in this systematic review and the random effect model was used to estimate the pool prevalence of IPD.ResultsThe most predominant serotypes circulating in children were 19F (27.7, 95% confidence interval (95% CI): 17.7-37.6%), 19A (21.2%, 16.4-26.1%), 14 (16.5%, 12.8-20.1%), 6B (8.6%, 5.2-10.8%) and 23F (7.3%, 5.2-9.5%). The serotype coverage of the available pneumococcal conjugate vaccines PCV7, PCV10, and PCV13 was 60.8% (52.5-69.4%), 65.1% (57.7-72.4%), and 90.0% (87.1-92.8%), respectively. The pooled antibiotic resistance rates of Streptococcus pneumoniae revealed a resistance to penicillin prevalence rate of 32.0% (12.1-51.9%). Approximately 94.4% (90.7-98.1%) and 92.3% (87.4-97.3%) of isolates were resistant to erythromycin and clindamycin. eBURST analysis revealed great diversity among isolates, with 102 sequence types (STs) for 365 isolates. The major predominant clonal complexes (CCs) were CC271 (43.6%, 159/365), CC876 (13.4%, 49/365), CC81 (5.2%, 19/365), and CC90 (4.1%, 15/365). Long-term and regional surveillance of S. pneumoniae is necessary.ConclusionsBased on our pooled results showing that PCV13 coverage of the reported serotypes was 90% and that most serotypes contributed to the distribution of antibiotic-resistant isolates, implementation of PCV13 into the Chinese Expanded Program on Immunizations (EPI) would achieve health benefits in Chinese children.
| S-EPMC6844036 | biostudies-literature