Serotype distribution and antibiotic susceptibility of group B streptococci in pregnant women

Molecular Epidemiology of Group B Streptococcus Colonization in Egyptian Women

(1) Background: Streptococcus agalactiae or Group B Streptococcus (GBS) causes severe neonatal infections with a high burden of disease, especially in Africa. Maternal vaginal colonization and perinatal transmissions represent the common mode of acquiring the infection. Development of an effective maternal vaccine against GBS relies on molecular surveillance of the maternal GBS population to better understand the global distribution of GBS clones and serotypes. (2) Methods: Here, we present genomic data from a collection of colonizing GBS strains from Ismailia, Egypt that were sequenced and characterized within the global JUNO project. (3) Results: A large proportion of serotype VI, ST14 strains was discovered, a serotype which is rarely found in strain collections from the US and Europe and typically not included in the current vaccine formulations. (4) Conclusions: The molecular epidemiology of these strains clearly points to the African origin with the detection of several sequence types (STs) that have only been observed in Africa. Our data underline the importance of continuous molecular surveillance of the GBS population for future vaccine implementations.

Molecular typing and prevalence of antibiotic resistance and virulence genes in Streptococcus agalactiae isolated from Chinese dairy cows with clinical mastitis

Bovine mastitis is a common disease occurring in dairy farms and can be caused by more than 150 species of pathogenic bacteria. One of the most common causative organisms is Streptococcus agalactiae, which is also potentially harmful to humans and aquatic animals. At present, research on S. agalactiae in China is mostly concentrated in the northern region, with limited research in the southeastern and southwestern regions. In this study, a total of 313 clinical mastitis samples from large-scale dairy farms in five regions of Sichuan were collected for isolation of S. agalactiae. The epidemiological distribution of S. agalactiae was inferred by serotyping isolates with multiplex polymerase chain reaction. Susceptibility testing and drug resistance genes were detected to guide the clinical use of antibiotics. Virulence genes were also detected to deduce the pathogenicity of S. agalactiae in Sichuan Province. One hundred and five strains of S. agalactiae (33.6%) were isolated according to phenotypic features, biochemical characteristics, and 16S rRNA sequencing. Serotype multiplex polymerase chain reaction analysis showed that all isolates were of type Ia. The isolates were up to 100% sensitive to aminoglycosides (kanamycin, gentamicin, neomycin, and tobramycin), and the resistance rate to β-lactams (penicillin, amoxicillin, ceftazidime, and piperacillin) was up to 98.1%. The TEM gene (β-lactam-resistant) was detected in all isolates, which was in accordance with a drug-resistant phenotype. Analysis of virulence genes showed that all isolates harbored the cfb, cylE, fbsA, fbsB, hylB, and α-enolase genes and none harbored bac or lmb. These data could aid in the prevention and control of mastitis and improve our understanding of epidemiological trends in dairy cows infected with S. agalactiae in Sichuan Province.

Dog/cat-origin quinolone-resistant Streptococcus agalactiae isolates with point mutations in quinolone resistance-determining regions: Relatedness with clonal complex 10

OBJECTIVE

We aimed to investigate dog/cat-origin quinolone-resistant Streptococcus agalactiae isolates with point mutations in quinolone resistance-determining regions (QRDRs) and to define the relatedness between quinolone-resistant isolates and their microbiological features of capsular genotype, sequence type (ST)/clonal complex (CC), and antimicrobial resistance (AMR) gene.

METHODS

With dog/cat-origin 22 isolates, type strain, and human-origin 6 isolates, we performed antimicrobial susceptibility testing by agar plate dilution method using levofloxacin, ciprofloxacin, and moxifloxacin. We also determined amino acid sequences in QRDRs of gyrA/gyrB/parC/parE genes and their point mutations. We conducted capsular genotyping, multilocus sequence typing, and AMR genotyping in our previous investigations. Correlations between quinolone-resistant population and their microbiological features were examined.

RESULTS

We found dog/cat-origin seven (31.8%) quinolone-resistant isolates harboring minimum inhibitory concentrations (MICs) of levofloxacin 16-32 μg/mL, ciprofloxacin 32 μg/mL, and moxifloxacin 2-4 μg/mL: human three isolates indicated MICs of levofloxacin 16-64 μg/mL, ciprofloxacin 32 μg/mL, and moxifloxacin 2-16 μg/mL. Point mutations Ser81Leu in gyrA and Ser79Phe/Ser79Tyr/Asp83Asn/Gly128Asp in parC were observed among these resistant isolates: mutations Leu495Ile/Val503Ile in parE was found among quinolone-nonresistant isolates. There was a significant correlation between dog/cat-origin quinolone-resistant population and ST10 (p = 0.023)/CC10 (p = 0.021).

CONCLUSION

To our best knowledge, this is the first report assessing dog/cat-origin quinolone-resistant S. agalactiae. Our observations could be applied in future, by veterinarians while treating dogs and cats with clinical symptoms/signs suggestive of streptococcal infections.

Biofilm production ability and associated characteristics of Streptococcus agalactiae isolates from companion animals and humans

OBJECTIVE

We evaluated biofilm production ability (BPA) of Streptococcus agalactiae isolates from companion animals/humans and clarified the relationship between BPA populations and other microbiological features.

METHODS

Companion animal-/human-origin isolates were collected with host information. We measured BPA using crystal violet staining, via virulence-associated gene profiling (hylB-pavA-pilB-spb1-srtC1-brpA), capsular genotyping, multilocus sequence typing, and antimicrobial resistance (AMR) phenotyping/genotyping. Significant difference in BPA of isolates from different hosts was assessed. We analyzed the association between BPA populations and the virulence genotypes, capsular genotypes, sequence types/clonal complexes, and AMR phenotypes/genotypes. Inhibitory effect of berberine on BPA was evaluated.

RESULTS

Five, twenty-six, and twenty-six isolates belonged to strong, moderate, and weak biofilm producers, whereas seventeen showed no biofilm production. We defined strong, moderate, or weak biofilm producers as the producer group (n = 57) to conduct a comparative analysis between the producer and non-producer populations. There was a significant correlation between the producer population and vaginal specimen. We found significant associations between the producer group and presence (57.9%) of pilB and between the non-producer population and presence (70.6%) of spb1. There was no association between the producer group and capsular genotypes, sequence types/clonal complexes, and AMR phenotypes/genotypes (except for a significant correlation between the producer group and AMR to minocycline). We confirmed inhibitory effect of berberine at sub-minimum inhibitory concentrations (MICs) against the type strain on BPA.

CONCLUSION

Our observations suggest that S. agalactiae harboring pilB is more capable of producing biofilms, with berberine inhibitory effect at sub-MICs on BPA.

Intracellular invasion ability of Streptococcus agalactiae among non-invasive isolates from human adults and companion animals in Japan

OBJECTIVE

This study evaluated the cell invasion ability (CIA) of Streptococcus agalactiae isolates from humans and companion animals and clarified the relationship between CIA populations and their microbiological features.

METHODS

Human-origin and companion animal-origin isolates were collected along with host information. We measured CIA using human-lineage colon cancer epithelium (Caco-2) and keratinocyte (HaCaT) cell lines, via virulence-associated gene profiling (bca-rib-bac-lmb-cylE-hylB-pavA-pilB-spb1-srtC1-brpA), capsular genotyping, multilocus sequence typing, and antimicrobial resistance (AMR) phenotyping/genotyping. Significant differences in data regarding CIA into epithelium and keratinocytes and those of isolates from different hosts were assessed. We analyzed the association of CIA populations with the virulence genotypes, capsular genotypes, sequence types/clonal complexes, and AMR phenotypes/genotypes.

RESULTS

A comparative analysis was performed between human (n = 15) and canine (n = 17) non-invasive isolates. There was a difference in CIA data between Caco-2 and HaCaT cells using human and animal isolates. For percent invasion ability into Caco-2 cells, we designated values ≥ 0.1 as high-frequency CIA and values < 0.1 as low-frequency CIA. Fourteen isolates harbored high-frequency and 18 isolates harbored low-frequency strains. There was no association between the high-frequency population and the virulence genotypes, capsular genotypes, sequence types/clonal complexes, and AMR phenotypes/genotypes.

CONCLUSION

This is the first report assessing the invasion ability of S. agalactiae into HaCaT and Caco-2 cells. Our observations suggest that S. agalactiae is more capable of entering Caco-2 rather than HaCaT.

Comparison between Invasive and Non-Invasive Streptococcus agalactiae Isolates from Human Adults, Based on Virulence Gene Profiles, Capsular Genotypes, Sequence Types, and Antimicrobial Resistance Patterns

This study assessed whether invasive group B Streptococcus (GBS) isolates were similar to non-invasive isolates from adult patients. Invasive and non-invasive GBS isolates were collected from three hospitals and two laboratory centers between January 2015 and October 2019. The isolates were identified by 16S rRNA amplicon sequencing and amplification of the GBS-specific dltS gene. The virulence gene profiles, capsular genotypes, sequence types (STs)/clonal complexes (CCs), and antimicrobial resistance (AMR) phenotypes/genotypes were determined for the 72 invasive and 50 non-invasive isolates that were comparatively analyzed. We observed a significantly decreased rate of rib detection in the invasive isolates compared to that in the non-invasive isolates (77.8% vs. 92.0%, P < 0.05). Additionally, we found significant differences in the prevalence of CC1 (23.6% vs. 46.0%, P < 0.05) and CC26 (12.5% vs. 2.0%, P < 0.05) between invasive and non-invasive populations. However, there were no significant differences in the comparative data of the virulence gene profiles, capsular genotypes, other STs/CCs, and AMR phenotypes/genotypes between the two populations. These findings suggest that both invasive and non-invasive isolates share similar features in terms of virulence gene profile, capsular genotype, ST/CC, and AMR genotype/phenotype (except for the rates of rib detection and CC1/CC26 prevalence).

Group B Streptococcal Colonization, Molecular Characteristics, and Epidemiology

Streptococcus agalactiae or group B streptococcus (GBS) is a leading cause of serious neonatal infections. GBS is an opportunistic commensal constituting a part of the intestinal and vaginal physiologic flora and maternal colonization is the principal route of GBS transmission. GBS is a pathobiont that converts from the asymptomatic mucosal carriage state to a major bacterial pathogen causing severe invasive infections. At present, as many as 10 serotypes (Ia, Ib, and II–IX) are recognized. The aim of the current review is to shed new light on the latest epidemiological data and clonal distribution of GBS in addition to discussing the most important colonization determinants at a molecular level. The distribution and predominance of certain serotypes is susceptible to variations and can change over time. With the availability of multilocus sequence typing scheme (MLST) data, it became clear that GBS strains of certain clonal complexes possess a higher potential to cause invasive disease, while other harbor mainly colonizing strains. Colonization and persistence in different host niches is dependent on the adherence capacity of GBS to host cells and tissues. Bacterial biofilms represent well-known virulence factors with a vital role in persistence and chronic infections. In addition, GBS colonization, persistence, translocation, and invasion of host barriers are largely dependent on their adherence abilities to host cells and extracellular matrix proteins (ECM). Major adhesins mediating GBS interaction with host cells include the fibrinogen-binding proteins (Fbs), the laminin-binding protein (Lmb), the group B streptococcal C5a peptidase (ScpB), the streptococcal fibronectin binding protein A (SfbA), the GBS immunogenic bacterial adhesin (BibA), and the hypervirulent adhesin (HvgA). These adhesins facilitate persistent and intimate contacts between the bacterial cell and the host, while global virulence regulators play a major role in the transition to invasive infections. This review combines for first time epidemiological data with data on adherence and colonization for GBS. Investigating the epidemiology along with understanding the determinants of mucosal colonization and the development of invasive disease at a molecular level is therefore important for the development of strategies to prevent invasive GBS disease worldwide.

Identification of a proteomic biomarker associated with invasive ST1, serotype VI Group B Streptococcus by MALDI-TOF MS

BACKGROUND

Group B Streptococcus (GBS) is an important invasive pathogen in neonates, pregnant women and the elderly. Serotype VI GBS, which has been rarely reported globally, has emerged as a significant pathogen in Asia. However, traditional serologic latex agglutination (LA) methods may fail to type isolates that lack of or low expression of CPS.

METHODS

A total of 104 GBS strains were analyzed by MALDI-TOF MS. Multiplex PCR and multilocus sequence typing (MLST) were also performed to confirm their strains. The protein markers were purified with gel electrophoresis and LC-column, followed by identification with nanoLC-MS/MS analysis.

RESULTS

Protein peak of 6251-Da was appeared in most (20/24, 92%) serotypes VI (94% ST-1 or single locus variant of ST-1), and protein peak of 6891-Da was appeared in most serotypes III (15/18, 83%) and Ib (19/23, 83%) strains. The protein peak of 6251-Da and 6891-Da were identified as CsbD family protein and UPF0337 protein gbs0600, respectively.

CONCLUSIONS

The protein peak of 6251 Da may play a role of emergence of ST-1 clone, serotype VI GBS in central Taiwan and could be useful in rapid identifying invasive serotype VI from III isolates, which is hardly achieved by LA.

Clonal dissemination of invasive and colonizing clonal complex 1 of serotype VI group B Streptococcus in central Taiwan

BACKGROUND/PURPOSE

The aim of this study was to investigate clinical presentation, serotype distribution and genetic correlation of group B streptococcus (GBS) diseases. Since serotype VI prevalence far exceeded that reported in prior studies, genetic relationship of isolates was further analyzed.

METHODS

GBS isolates obtaining from patients with invasive diseases and pregnant women with colonization between June 2007 and December 2010 were analyzed. All isolates were tested for serotypes by multiplex PCR assay and pulsed-field gel electrophoresis (PFGE). Serotype VI isolates were further analyzed by multilocus sequence typing (MLST).

RESULTS

A total of 134 GBS isolates were recovered from blood of 126 patients with invasive disease (94.0%) and anogenital swabs of 8 pregnant women (6.0%). Most common serotype was Ib (21.6%), followed by V (20.1%), VI (18.7%), III (15.7%), II (11.9 %), Ia (11.2%), and IX (0.7%). Serotype VI was also the leading type in infants with early onset disease (EOD; 3/8, 37.5%) and colonizing pregnant women (3/8, 37.5%). PFGE distinguished 33 pulsotypes, reflecting genetic diversity among GBS isolates. Among 25 serotype VI isolates tested, 14 were ST-1, seven were ST-679, three were ST-678, one was ST-681, and distributed into four PFGE pulsotypes. ST-678, ST-679, and ST-681 were novel sequence types; ST-678 and ST-679 are single-locus variants of ST-1 that belongs to clonal complex (CC) 1.

CONCLUSION

CC1 dissemination of serotype VI GBS thus emerges as an important invasive pathogen in infants and nonpregnant adults in central Taiwan. Serotype prevalence of GBS must be continuously monitored geographically to guide prevention strategy of GBS vaccines.

Antimicrobial susceptibility profiles, serotype distribution and virulence determinants among invasive, non-invasive and colonizing Streptococcus agalactiae (group B streptococcus) from Malaysian patients

A total of 103 group B streptococci (GBS) including 22 invasive, 21 non-invasive, and 60 colonizing isolates were collected in a Malaysian hospital (June 2010–October 2011). Isolates were characterized by conventional and molecular serotyping and analyzed for scpB, lmb, hylB, cylE, bac, bca and rib gene content. Antimicrobial susceptibility to penicillins, macrolides, lincosamides, quinolones and tetracyclines was determined using disk diffusion and the MICs for penicillin were determined by E-test. Molecular serotyping for all eight serotypes (Ia, Ib, II–VII) was in full accordance with conventional serotyping. Overall, taking CS and MS together, serotype VI was the most common capsular type (22.3 %) followed by VII (21.4 %), III (20.4 %), Ia (17.5 %), V (9.7 %), II (7.7 %) and IV (1 %). Susceptibility to beta-lactam antimicrobials was prevalent (100 %). Resistance rates for erythromycin, clindamycin and tetracycline were 23.3 %, 17.5 % and 71.8 %, respectively. PCR-virulence gene screening showed the presence of cylE, lmb, scpB and hylB in almost all the isolates while rib, bca, and bac genes were found in 29.1 %, 14.6 % and 9.7 % of the isolates. Certain genes were significantly associated with specific serotypes, namely, rib with serotypes Ia, II, III and VI; bca and bac with serotypes II and III. Furthermore, serotype Ia was significantly more common among patients with invasive infections (p < 0.01) and serotype VI isolates were significantly more common among carriers (p < 0.05). In summary, serotype distribution correlates with virulence gene content will be useful in epidemiological studies and design of vaccines.

Serotype and surface protein gene distribution of colonizing group B streptococcus in women in Egypt

Group B streptococcus (GBS) is a leading cause of neonatal sepsis and meningitis. We determined the distribution of serotypes and surface protein encoding genes of GBS strains from pregnant and non-pregnant women in Egypt. Vaginal swabs from 364 women were screened by culture and 100 (27·4%) yielded GBS. Serotype V was the most predominant (33%), followed by serotypes II (17%), III (15%), Ia (14%), VI (12%), Ib (8%) and IV (1%). The most common surface protein genes were epsilon (27%), alp3 (26%), bca (18%), rib (16%) and alp2 (10%). Two isolates were negative for surface protein genes. The distribution of serotypes and surface proteins was similar to reports from other parts of the world but the relatively high frequency of serotype VI was a notable feature of the strains from women in Egypt.

Group B streptococcal bacteremia in a major teaching hospital in Malaysia: a case series of eighteen patients

BACKGROUND

Group B Streptococcus (GBS) is a leading cause of infections such as meningitis and septicemia in neonates and pregnant women; however the significance of invasive GBS disease has not been clearly defined in non-pregnant adults.

METHODS

We reviewed the hospital records of 18 cases with GBS bacteremia who attended the Universiti Kebangsaan Malaysia Medical Centre from June 2010 to October 2011. We analyzed the clinical findings of both bacteremic adults and neonates and compared them to previous studies of GBS bacteremia. Serotyping was done by latex agglutination test using 10 distinct antisera (Ia, Ib, and II-IX).

RESULTS

During the period of 1 year and 4 months, there were 18 patients with GBS bacteremia. Five cases occurred in neonates, one in a parturient woman, and 12 in other adults. All neonates with bacteremia were males and two of them were premature. Septicemia was the most common clinical presentation in neonates. They were treated with intravenous (IV) penicillin G and gentamicin. The adults included nine men (69%) and four women (31%). Their mean age was 60 years and all patients had more than two underlying conditions. The most common clinical syndrome was pneumonia (n=6, 46.5%). The others were peritonitis (n=3, 23.1%), primary bacteremia (n=2, 15.5%), septic arthritis (n=2, 15.5%), skin and soft tissue infection (n=1, 7.7%), meningitis (n=1, 8%), urinary tract infection (n=1, 8%), and intravascular device infection (n=1, 7.7%). Cardiovascular diseases (n=7, 53.8%) were the most common underlying conditions, and diabetes mellitus (n=5, 38.5%) was second. The other co-morbid conditions were hyperlipidemia (n=3, 23.1%), renal disease (n=3, 23.1%), liver disease and/or alcohol abuse (n=3, 23.1%), autoimmune disease or immunosuppressive condition (n=2, 15.5%), malignancy (n=2, 15.5%), respiratory disease (n=1, 8%), and postpartum condition (n=1, 8%), as well as miscellaneous conditions including intravenous drug abuse, HIV infection, and trauma (n=2, 15.5%). Polymicrobial bacteremia was found in five (45.4%) cases and Staphylococcus aureus was the most common concurrent bacterial isolate. Of the 18 GBS isolates in both adults and neonates, serotype Ia was predominant (38.9%), followed by VI (27.8%), V (11.1%), and III (5.5%); the remaining 16.7% were non-typeable.

CONCLUSIONS

GBS bacteremia is a significant problem and is associated with serious underlying disease, which may result in a high rate of mortality, not only in neonates and pregnant women, but also in non-pregnant adults.

Group B streptococcus serotype prevalence in reproductive-age women at a tertiary care military medical center relative to global serotype distribution

Background

Group B Streptococcus (GBS) serotype (Ia, Ib, II-IX) correlates with pathogen virulence and clinical prognosis. Epidemiological studies of seroprevalence are an important metric for determining the proportion of serotypes in a given population. The purpose of this study was to evaluate the prevalence of individual GBS serotypes at Madigan Healthcare System (Madigan), the largest military tertiary healthcare facility in the Pacific Northwestern United States, and to compare seroprevalences with international locations.

Methods

To determine serotype distribution at Madigan, we obtained GBS isolates from standard-of-care anogenital swabs from 207 women of indeterminate gravidity between ages 18-40 during a five month interval. Serotype was determined using a recently described molecular method of polymerase chain reaction by capsular polysaccharide synthesis (cps) genes associated with pathogen virulence.

Results

Serotypes Ia, III, and V were the most prevalent (28%, 27%, and 17%, respectively). A systematic review of global GBS seroprevalence, meta-analysis, and statistical comparison revealed strikingly similar serodistibution at Madigan relative to civilian-sector populations in Canada and the United States. Serotype Ia was the only serotype consistently higher in North American populations relative to other geographic regions (p < 0.005). The number of non-typeable isolates was significantly lower in the study (p < 0.005).

Conclusion

This study establishes PCR-based serotyping as a viable strategy for GBS epidemiological surveillance. Our results suggest that GBS seroprevalence remains stable in North America over the past two decades.