Prevalence of group B streptococcal colonization in the healthy non-pregnant population: a systematic review and meta-analysis

BACKGROUND

Colonization and transmission precede invasive group B streptococcal (GBS) disease. Data on GBS colonization prevalence, detection methods and risk factors for carriage are relevant for vaccine development and to understand GBS pathogenesis.

OBJECTIVES

To evaluate GBS colonization prevalence after the first week of life in the healthy non-pregnant population.

DATA SOURCES

Pubmed/Medline, Embase, Latin American and Caribbean Health Sciences Literature, World Health Organization Library Information System, and Scopus. Search performed 12 January 2021 with search terms related to 'GBS' and 'colonization, epidemiology, prevalence or screening' without restrictions.

STUDY ELIGIBILITY CRITERIA

All studies that reported prevalence of GBS colonization (any site) in the healthy population.

PARTICIPANTS

All individuals (>6 days of age), with no indication of pregnancy, invasive disease or severe underlying immunological co-morbidities.

METHODS

Logit transformation and a random effects model (DerSimonian and Laird) were used to pool colonization estimates. Subgroup analysis and meta-regression on a priori determined subgroups were performed.

RESULTS

We included 98 studies with 43 112 participants. Our search identified 9309 studies of which 8831 were excluded based on title and abstract and 380 after reading the full text. Colonization rates varied considerably between studies (I² = 97%), which could be partly explained by differences in culture methods (R² = 27%), culture sites (R² = 24%), continent (R² = 10%) and participant's age (R² = 6%). Higher prevalence was found with selective culture methods (19%, 95% CI 16%-23% versus non-selective methods 8%, 95% CI 6%-9%; p < 0.0001). Colonization rates were highest in rectum (19%, 95% CI 15%-24%), vagina (14%, 95% CI 12%-17%) and urethra (9%, 95% CI 5%-18%). In participants with negative rectal cultures, 7% (95% CI 5%-9%) had GBS cultured from another niche. Colonization prevalence was lower in children (6 months to 16 years; 3%, 95% CI 2%-5%) compared with adults (16%, 95% CI 14%-20%; p < 0.0001). Using selective culture methods in adults resulted in a prevalence of 26% (95% CI 19%-33%) rectal, 21% (95% CI 17%-25%) vaginal and 9% (95% CI 6%-14%) urethral colonization.

CONCLUSION

The rectum is the most common body site colonized by GBS. The best approach to screen for any GBS colonization is to screen multiple body sites using selective culture methods.

Biofilm formation by ST17 and ST19 strains of Streptococcus agalactiae

Bacterial biofilms are an important virulence factor with a vital role in evasion from the host immune system, colonization and infection. The aim of the present study was to evaluate in vitro the effects of three environmental factors (H⁺, glucose and human plasma) in biofilm formation, by carrier and invasive Streptococcus agalactiae strains of ST17 and ST19 sequence types, including DNase producers and non-producers. Bacteria ability to assemble biofilms was classified based on crystal violet assay. Biofilm formation was also monitored by scanning electron microscopy. Depending on the growth medium used, each bacterial isolate could fit in different biofilm production categories. Our data showed that optimal conditions for S. agalactiae biofilm assembly were reached after 48 h incubation at pH 7.6 in the presence of glucose and inactivated human plasma. In the presence of inactivated human plasma, the biofilm biomass of ST19 strains experienced a higher increase than ST17 strains. The composition of the extracellular polymeric matrix of the three strongest biofilm producers (all from ST17) was accessed by enzymatic digestion of mature biofilms and proteins were shown to be the predominant component. The detailed identification of the extracellular protein components should contribute to the development of new therapeutic strategies to fight S. agalactiae infections.

Increasing Resistance and Changes in Distribution of Serotypes of Streptococcus agalactiae in Poland

Streptococcus agalactiae is responsible for serious infections in newborn babies, pregnant women, and other patients. The aim of this study was to evaluate antimicrobial susceptibility, serotype distribution, and virulence determinants of the S. agalactiae isolates derived from clinical specimens considering the global increase of both antibiotic resistance and virulence. A total of 165 isolates were identified and serotyped by PCR techniques. Antimicrobial susceptibility was assessed by disk diffusion method, gradient diffusion method and VITEK^® System. Virulence associated genes were investigated by PCR; ability to form biofilm was assessed using a microtiter plate assay. The highest observed MIC value for penicillin G was 0.12 µg/mL, seen in 8.5% of isolates. Resistance to erythromycin and clindamycin were found in 30.38% and 24.8% of the strains, respectively. The serotype III (32.73%), V (25.45%), and Ia (18.18%) were found as the most frequently represented. Previously unidentified strains in Poland, belonging to serotypes VI (three strains) and VII (one strain) were recognized. The presence of genes encoding various virulence factors as well as diverse ability to form biofilm were found. In conclusion, macrolide-resistance and decreased susceptibility to penicillin G were revealed signifying the increasing resistance among group B streptococci. Moreover, the presence of genes encoding various virulence factors and the ability to form biofilm were confirmed indicating their role in the pathomechanisms of the evaluated GBS infections.

Determination of surface proteins profile, capsular genotyping, and antibiotic susceptibility patterns of Group B Streptococcus isolated from urinary tract infection of Iranian patients

Objectives

Group B Streptococcus (GBS) is an important opportunistic bacteria that causes a wide range of infections including neonatal sepsis, meningitis, pneumonia, soft tissue and urinary tract infections (UTI). The aim of this study was to evaluate the antimicrobial susceptibility patterns, surface proteins and capsular types of GBS isolates.

Results

100 of UTI isolates were confirmed as GBS. Antimicrobial susceptibility pattern showed that 95% of GBS isolates were resistant to tetracycline, followed by erythromycin (52%), clindamycin (47%), levofloxacin (9%) and penicillin, cefepime, cefotaxime, and ceftriaxone each with (8%), and vancomycin 1%. Common capsular types were III, Ib, V, II, Ia and IV respectively and the distribution of surface protein genes was as follows: rib (40%), alpha-c (22%), alp2/3 (18%) and epsilon (15%), and alp4 gene was not detected in the isolates. Our findings showed the relationship between capsular types with Alpha-like proteins, as well as reduced sensitivity to antibiotics, so the performance of antibiotic surveillance programs is recommended.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4428-4) contains supplementary material, which is available to authorized users.

Capsular Type, Sequence Type and Microbial Resistance Factors Impact on DNase Activity of Streptococcus agalactiae Strains from Human and Bovine Origin

Extracellular deoxyribonucleases (DNases) contribute to the spread of pathogenic bacteria through the evasion from host innate immunity. Our main objective was to evaluate the production of extracellular DNases by human and bovine Streptococcus agalactiae clinical strains and perform a correlation of genetic lineages and DNase activity with capsular type, genetic determinants, clinical origin (colonization and infection), and host (human or bovine). DNase activity was evaluated by qualitative and quantitative assays for a collection of 406 human (n = 285) and bovine (n = 121) strains. All (121/121) bovine were isolated from mastitis and revealed to be DNase (+), indicating a putative pathogenic role in this clinical scenario. From the human S. agalactiae strains, 86% (245/285) showed DNase activity, among which all strains belonging to capsular types, namely, Ia, Ib, III-2, and IV. All CC17 strains (n = 58) and 56/96 (58.3%) of the CC19 displayed DNase activity. DNase (-) strains belonged to the CC19 group. However, the subcharacterization of CC19 S. agalactiae strains through multiple-locus variable number tandem repeat analysis (MLVA), antibiotic resistance, mobile elements, and surface proteins did not provide any distinction among DNase producers and non-producers. The production of DNases by all human CC17 strains, about two-fifths of human CC19, and all bovine strains, suggest an important contribution of DNases to hypervirulence.

Molecular epidemiology of invasive and non-invasive group B Streptococcus circulating in Serbia

Streptococcus agalactiae (group B Streptococcus, GBS) remains the leading cause of invasive diseases in neonates and an important cause of infections in the elderly. The aim of this study was to access the prevalence of GBS genito-rectal colonisation of pregnant women and to evaluate the genetic characteristics of invasive and non-invasive GBS isolates recovered throughout Serbia. A total of 432 GBS isolates were tested for antimicrobial susceptibility, capsular polysaccharide (CPS) types and the presence of the hvgA gene. One hundred one randomly selected isolates were further characterized by clustered regularly interspaced short palindromic repeats (CRISPRs) analysis and/or multilocus sequence typing (MLST). The prevalence of GBS colonization in pregnant women was 15%. Overall, six capsular types (Ia, Ib, II to V) were identified, the most common being III (32.2%) and V (25.2%). The hiper-virulent clone type III/ST17 was present in 43.1% and 6.3% (p < 0.05) of paediatric and adults isolates, respectively. Comparative sequence analysis of the CRISPR1 spacers content indicated that a few clones comprised the vast majority of the tested GBS isolates. Thus, it was estimated that dominant clones recovered from infants were CPS III/ST17 in late-onset infections (19/23; 82.6%), and Ia/ST23 in early-onset disease (44.4%). Conversely, genotype CPS V/ST1 was the most prevalent in adults (4/9; 25.4%). All isolates were susceptible to penicillin. Macrolide resistance (23.1%) was strongly associated with the ermB gene and constitutive resistance to clindamycin (63.9%). The majority of strains was resistant to tetracycline (86.6%), mostly mediated by the tetM gene (87.7%). GBS isolates of CPS V/ST1 and CPS III/ST23 were significantly associated with macrolide and tetracycline resistance, respectively. In conclusion, hyper-virulent CPS III/ST17 and V/ST1 were recognized as dominant GBS clones in this study.

Incidence and serotype characterisation of Streptococcus agalactiae in a Portuguese hospital

AIMS

Streptococcus agalactiae, commonly known as group B Streptococcus (GBS), has been recognised as a worldwide causative pathogenic agent of neonatal sepsis, meningitis and pneumonia. To better understand the behaviour of S. agalactiae in pregnant women from a hospital from the North of Portugal, retrospective analyses were performed to describe epidemiological, clinical and microbiological characteristics of the isolates obtained.

METHODS

Based on laboratorial records and the hospital's patient files, a 6-year retrospective study was performed to analyse S. agalactiae isolates from screened pregnant women between 35 and 37 weeks of gestation and hospitalised neonates from pregnant women between 24 and 41 weeks of gestation admitted in Hospital Pedro Hispano. Serotype characterisation was also performed in 67 GBS strains.

RESULTS

In 6692 pregnant women between 35 and 37 weeks of gestation screened between 2011 and 2016, a total of 1377 S. agalactiae isolates (21%) were found. A high percentage (40%) of unknown colonisation status among hospitalised neonates from pregnant women between 24 and 41 weeks of gestations was also found. The incidence of neonatal sepsis was 8.7 (95% CI 7.0 to 10.8) cases per 1000 live births. Regarding serotype characterisation, serotype III (22.4%) was the most frequent, followed by serotype Ia (19.4%) and serotypes Ib and V (both with 17.9%).

CONCLUSION

High epidemiological values of GBS colonisation and incidence were found in this study. In Portugal studies on the epidemiology and behaviour of S. agalactiae remain limited, reinforcing the importance and need for S. agalactiae screening across the country.

Genetic and pathogenic difference between Streptococcus agalactiae serotype Ia fish and human isolates

Background

Streptococcus agalactiae (GBS) is a common pathogen to infect newborn, woman, the elderly, and immuno-compromised human and fish. 37 fish isolates and 554 human isolates of the GBS in 2007–2012 were investigated in serotypes, antibiotic susceptibility, genetic difference and pathogenicity to tilapia.

Results

PCR serotyping determined serotype Ia for all fish GBS isolates and only in 3.2 % (3–4.2 %) human isolates. For fish isolates, all consisted a plasmid less than 6 kb and belonged to ST7 type, which includes mainly pulsotypes I and Ia, with a difference in a deletion at the largest DNA fragment. These fish isolates were susceptible to all antimicrobials tested in 2007 and increased in non-susceptibility to penicillin, and resistance to clindamycin and ceftriaxone in 2011. Differing in pulsotype and lacking plasmid from fish isolates, human serotype Ia isolates were separated into eight pulsotypes II–IX. Main clone ST23 included pulsotypes II and IIa (50 %) and ST483 consisted of pulsotype III. Human serotype Ia isolates were all susceptible to ceftriaxone and penicillin and few were resistant to erythromycin, azithromycin, clindamycin, levofloxacin and moxifloxacine with the resistant rate of 20 % or less. Using tilapia to analyze the pathogenesis, fish isolates could cause more severe symptoms, including hemorrhage of the pectoral fin, hemorrhage of the gill, and viscous black and common scites, and mortality (>95 % for pulsotype I) than the human isolates (<30 %); however, the fish pulostype Ia isolate 912 with deletion caused less symptoms and the lowest mortality (<50 %) than pulsotype I isolates.

Conclusion

Genetic, pathogenic, and antimicrobial differences demonstrate diverse origin of human and fish serotype Ia isolates. The pulsotype Ia of fish serotype Ia isolates may be used as vaccine strains to prevent the GBS infection in fish.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0794-4) contains supplementary material, which is available to authorized users.

Molecular characterization and antimicrobial susceptibility of hemolytic Streptococcus agalactiae from post-menopausal women

PURPOSE

Streptococcus agalactiae (Group B streptococcus, GBS) is increasingly recognized as a pathogen in adult populations, including the elderly. Appropriate treatment involves antibiotics. An alternative to this strategy would be the administration of a polysaccharide vaccine therefore the capsular serotypes and molecular characterization of circulating strains needs to be known. Few studies have been conducted in this population.

METHODS

One hundred and seven GBS isolates collected from vagino-rectal swabs from 600 post-menopausal women were analysed for their capsular type, antimicrobial resistance and genetic relatedness (multilocus sequence typing, MLST).

RESULTS

The colonization rate was 17.8%. Capsular type III was predominant (34.6%), followed by type V (22.4%). The most frequent sequence type (ST) was 19 (23.3%), followed by 23 (18.7%), 1 (16.8%) and 17 (12.1%). Isolates were assembled into three phylogenetic groups from ST-19, ST-23 and ST-17 founders. All isolates were susceptible to penicillin, whereas resistance to erythromycin and clindamycin was recorded in 23.4% and 20.6% of isolates, respectively.

CONCLUSIONS

In our setting, the GBS colonization rate in postmenopausal women is similar to that reported in others populations studied. The population structure of these isolates is highly diverse and contains different STs. These data can contribute to the future development of a polysaccharide vaccine for preventing GBS infection in older adults.

[Serotypes and antibiotic resistance patterns in beta-hemolytic Streptococcus agalactiae isolates in colonized mothers and newborns with invasive disease]

INTRODUCTION

Current preventive measures against neonatal disease caused by Streptococcus agalactiae (GBS) are prenatal screening and intrapartum antibiotic prophylaxis with appropriate antimicrobials. An alternative to this strategy would be the administration of a polysaccharide vaccine as the distribution of capsular serotypes of circulating strains needs to be known.

METHODS

A study was made of 188 strains from pregnant women carrying GBS and 24 newborns with neonatal disease. Susceptibility testing was performed with penicillin, erythromycin and clindamycin following CLSI standards, and capsular serotype was determined by two methods: latex agglutination and PCR.

RESULTS

Of the 188 strains of S.agalactiae from the pregnant women, there was 80.8% agreement in the results between the two techniques. Resistant to erythromycin and clindamycin was found in 16.5% and 10.1%, respectively. For neonatal strains, 95.8% of the results obtained by the two techniques were identical. The rates of resistance to erythromycin and clindamycin were 8.3% and 4.1%, respectively. In both groups, most frequently isolated serotype was iii, and the most related to antimicrobial resistance serotype was v.

CONCLUSION

Epidemiological studies are necessary to continue surveillance of serotypes causing invasive disease and its antibiotic sensitivity patterns using sensitive and specific methods.

Macrolide- and tetracycline-resistance determinants of colonizing group B streptococcus in women in Egypt

Group B streptococcus (GBS) is a commensal bacterium of the human gastrointestinal and genital tracts. It is a leading cause of neonatal sepsis and meningitis, and has also been recognized as an important pathogen in pregnant women and the elderly. We investigated mechanisms of macrolide and tetracycline resistance in GBS colonizing women in Egypt. A total of 100 isolates were screened using standard antibiotic susceptibility tests. A multiplex PCR assay was used to detect macrolide- and tetracycline-resistance determinants. All isolates were uniformly susceptible to penicillin G, ampicillin, cefotaxime, vancomycin and levofloxacin. The resistance rates to erythromycin, clindamycin, azithromycin, tetracycline and chloramphenicol were 17, 14, 16, 98 and 1 %, respectively. Among the erythromycin-resistant isolates, 82.4 % had constitutive macrolide-lincosamide-streptogramin B (cMLSB) resistance, 5.9 % had inducible MLSB (iMLSB) resistance and 11.8 % had M phenotype resistance. Among the cMLSB phenotypes, 64.3 % of isolates harboured the ermB gene and 35.7 % of isolates harboured none of the investigated macrolide-resistance genes. The single strain expressing the iMLSB phenotype possessed the ermA gene. Of the two strains with the M phenotype, only one possessed the mefA/E gene. Conversely, seven macrolide-sensitive strains (MIC <0.03 µg ml(-1)) were ermB positive and one macrolide-sensitive strain (MIC <0.03 µg ml(-1)) harboured mefA/E. Tetracycline resistance was predominantly due to tetM, which was detected alone (83.7 %) or in association with tetL (12.2 %), tetK (1 %) or tetO (1 %). One strain carried tetM associated with both tetL and tetK, and another strain carried tetO alone. The tetO strains were positive for the mefA/E gene, and the tetL and tetK carrier strains harboured the ermB gene. Susceptible strains harbouring but not expressing an antibiotic-resistance gene should be regarded as potentially resistant. These results emphasize the need to monitor the epidemiology of GBS antibiotic resistance in Egypt.

Epidemiological surveillance of colonising group B Streptococcus epidemiology in the Lisbon and Tagus Valley regions, Portugal (2005 to 2012): emergence of a new epidemic type IV/clonal complex 17 clone

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In vitro activity of solithromycin against erythromycin-resistant Streptococcus agalactiae

The in vitro antibacterial activity of solithromycin (CEM-101) against macrolide-resistant isolates (n=62) of Streptococcus agalactiae (group B streptococcus [GBS]) was determined. Phenotypic characterization of macrolide-resistant strains was performed by double-disc diffusion testing. A multiplex PCR was used to identify the erm(B), erm(TR), and mef(A/E) genes, capsular genotypes, and alpha-like (Alp) protein genes from the GBS strains. Determination of MIC was carried out using the microdilution broth method. The Etest method was used for penicillin, azithromycin, clarithromycin, and erythromycin. Solithromycin had a MIC50 of ≤0.008 μg/ml and a MIC90 of 0.015 μg/ml against macrolide-susceptible S. agalactiae. These MICs were lower than those displayed by penicillin (MIC50 of 0.032 μg/ml and MIC90 of 0.047 μg/ml), the antibiotic agent of choice for prophylaxis and treatment of GBS infections. Against macrolide-resistant S. agalactiae, solithromycin had a MIC50 of 0.03 μg/ml and a MIC90 of 0.125 μg/ml. Against erm(B) strains, solithromycin had a MIC50 of 0.03 μg/ml and a MIC90 of 0.06 μg/ml, while against mef(A) strains, it had a MIC50 of 0.03 μg/ml and a MIC90 of 0.125 μg/ml. Most erythromycin-resistant GBS strains were of serotype V (64.5%) and associated significantly with alp2-3. Moreover, a statistically significant association was observed between the constitutive macrolide-lincosamide-streptogramin B resistance (cMLSB) phenotype and the erm(B) gene-carrying strains, the alp2-3 gene and the M phenotype, and the mef(A/E) gene and epsilon. Overall, our results show that solithromycin had lower or similar MICs than penicillin and potent activity against macrolide-resistant strains independent of their genotype or phenotype, representing a valid therapeutic alternative where β-lactams cannot be used.

Antimicrobial resistance and molecular epidemiology of streptococci from bovine mastitis

Streptococcus agalactiae (Group B Streptococcus, GBS), Streptococcus dysgalactiae subsp. dysgalactiae (Group C Streptococcus, GCS) and Streptococcus uberis are relevant mastitis pathogens, a highly prevalent and costly disease in dairy industry due to antibiotherapy and loss in milk production. The aims of this study were the evaluation of antimicrobial drug resistance patterns, particularly important for streptococcal mastitis control and the identification of strain molecular features. Antimicrobial resistance was assessed by disk diffusion against amoxicillin-clavulanic acid, cefazolin, cefoperazone, pirlimycin-PRL, rifaximin, streptomycin, chloramphenicol, erythromycin-ERY, gentamicin, tetracycline-TET and vancomycin. Genotypic relationships were identified using pulsed-field gel electrophoresis (PFGE), macrolide and/or tetracycline resistance gene profiling, GBS capsular typing, GBS virulence gene profiling and GBS and S. uberis multi locus sequence typing (MLST). The majority of the isolates were susceptible to all drugs except to aminoglycoside, macrolide, lincosamide and tetracycline. Close to half of the TET resistant isolates have tetO and tetK and almost all ERY-PRL resistant isolates have ermB. A high degree of intra-species polymorphism was found for GCS. The GBS belonged to ST-2, -554, -61, -23 lineages and five new molecular serotypes and human GBS insertion sequences in the cpsE gene were found. Also, GBS of serotype V with scpB and lmb seem to be related with GBS isolates of human origin (same ST-2 and similar PFGE). Overall our results suggested that different therapeutic programs may have been implemented in the different farms and that in most cases clones were herd-specific.

Phenotypes, genotypes, serotypes and molecular epidemiology of erythromycin-resistant Streptococcus agalactiae in Italy

The purpose of this investigation was to analyse Streptococcus agalactiae (group B Streptococcus, GBS) isolates collected in Italy from vaginal and urine samples in respect to their clonality, distribution of virulence factors and antimicrobial resistance determinants. Three hundred and eighty-eight GBS were recovered from clinical samples. They were analysed for antibiotic resistance profiling. Erythromycin-resistant strains were further characterised by multilocus sequence typing (MLST), serotyping and the detection of alp genes of the alpha-like protein (Alp) family. GBS isolates represented 40 different sequence types (STs), grouped in five clonal complexes (CCs) and belonged to seven serotypes. Most serotype V strains (81%) possessed alp2-3; serotype Ia carried mainly epsilon, while the serotype III mainly rib. All isolates were susceptible to penicillin, whereas resistance to erythromycin was detected in 15% of isolates. Most erythromycin-resistant GBS strains were of serotype V (56.8%) and belonged to the CC-1 group (50%). Macrolide resistance phenotypes were the cMLS(B) (46.5%) and the M phenotypes (46.5%) due to the presence of ermB and mefA/E genes, respectively. These results provide data which establish a baseline for monitoring erythromycin resistance in this region and also provide an insight into the correlation among clonal types, serotypes, surface protein and resistance genes. The increased prevalence of strains that displayed the M phenotype strengthens the importance of the epidemiological surveillance of macrolide resistance in GBS, which may also represent an important reservoir of resistance genes for other species.

Group B streptococci causing neonatal infections in barcelona are a stable clonal population: 18-year surveillance

We analyzed 212 group B streptococci (GBS) from newborns with invasive infections in the area of Barcelona, Spain, between 1992 and 2009, with the aim of documenting changes in the prevalences of serotypes, antimicrobial resistance, and genetic lineages and evaluating their associations with either early-onset disease (EOD) or late-onset disease (LOD). Serotypes III (n = 118) and Ia (n = 47) together accounted for nearly 78% of the isolates. All isolates carried an alpha or alpha-like protein gene, and specific associations between genes and serotypes, such as serotype Ib and bca, serotype II and bca, serotype III and rib, and serotype V and alp3, reflected the presence of particular genetic lineages. Macrolide resistance (14.2%) was significantly associated with serotype V. Pulsed-field gel electrophoresis (PFGE) clustering was an excellent predictor of serotype and antibiotic resistance. The combination of PFGE and multilocus sequence typing revealed a large number of genetically distinct lineages. Still, specific lineages were dominant in our collection, particularly the serotype III/ST17/rib lineage, which had enhanced potential to cause LOD. Serotype Ia was concentrated in a single PFGE cluster composed of two genetic lineages: ST23/eps and ST24/bca. The ST24/bca sublineage of serotype Ia, which is found infrequently elsewhere, may be emerging as an important cause of neonatal invasive infections in the Mediterranean region. In spite of the introduction of prophylaxis, resulting in a pronounced decline in the frequency of EOD, the study revealed a remarkably stable clonal structure of GBS causing neonatal infections in Barcelona over a period of 18 years.

Molecular characterization of capsular polysaccharides and surface protein genes in relation to genetic similarity of group B streptococci isolated from Polish pregnant women

Serotyping, subtyping and genotyping are important tools for epidemiological studies of group B streptococci (GBS). We investigated the genotype distribution of 353 GBS isolates originating from vaginal or rectal carriage to identify capsular serotypes and subtypes based on the surface protein genes of the alpha-like protein (Alp) family. GBS were recovered from 30% of 1176 pregnant women during the period 2007-2009, with a predominance of capsular genotypes III (35%), Ia (20%), V (17%), II (15%), Ib (8%) and IV (5%). The most common Alp gene was epsilon (26%), followed by rib (22%), alp2 (21%), bca (17%) and alp3 (14%). Several protein genes were significantly associated (G(2)=249·635, P<0·0001) with particular serotypes: epsilon with Ia, Ib, IV; bca with Ib, II; rib with II, III; alp3 with V; alp2 with III. High genetic diversity within GBS strains was observed using DNA macrorestriction. Serotypes Ib, II and III demonstrated the greatest genetic heterogeneity and serotype V the lowest heterogeneity (relative frequency coefficient ≥0·03 vs. -0·46, respectively). Macrolide-resistant strains with serotype V and alp3 gene, showed higher uniformity in genetic profile. The distribution of serotypes and surface proteins of GBS strains are necessary data to inform the design and formulation of new GBS vaccines for use in Poland and other countries.

Molecular epidemiology of group B streptococcal meningitis in children beyond the neonatal period from Angola

Streptococcus agalactiae is a major pathogen of neonates and immunocompromised adults. Prior studies have demonstrated that, beyond the neonatal period, S. agalactiae rarely causes invasive infections in children. However, during 2004-2005, S. agalactiae was the causative agent of 60 meningitis episodes in children aged 3 months to 12 years from Angola. To identify and study the specific causative genetic lineages of S. agalactiae childhood meningitis, which lack characterization to date, we conducted an extensive molecular analysis of the recovered isolates (n = 21). This constitutes what we believe to be the first molecular study of the population structure of invasive S. agalactiae isolates from Africa. A low genetic diversity was observed among the isolates, where the majority belonged to clonal complex (CC) 17 presenting the capsular subtype III-2 (86 % of cases) and marked by the intron group II GBSi1, which has previously been observed to be associated with neonatal hosts. The predominance of single-locus variants of sequence type (ST) 17 suggested the local diversification of this hypervirulent clone, which displayed novel alleles of the fbsB and sip virulence genes. The absence of the scpB-lmb region in two S. agalactiae isolates with the Ia/ST23 genotype is more typical of cattle than human isolates. Globally, these data provide novel information about the enhanced invasiveness of the CC17 genetic lineage in older children and suggest the local diversification of this clone, which may be related to the future emergence of a novel epidemic clone in Angola.