Prevalence and capsular type distribution of Streptococcus agalactiae isolated from pregnant women in Namibia and South Africa

Streptococcus agalactiae colonization is common among pregnant women with HIV infection and is neither predicted by hospital tier nor trimester in Mwanza, Tanzania

BACKGROUND

Streptococcus agalactiae, also known as Group B Streptococcus (GBS) is a member of the gastrointestinal tract and vaginal microbiota, and one of the commonest pathogens affecting pregnant women, neonates and infants. Its observed rate of colonization varies globally due to laboratory methods used, socio-cultural, epidemiological and clinical factors. This study therefore, aimed at determining the prevalence of GBS colonization and associated risk factors among HIV-infected and uninfected pregnant women in various health care facility tiers in Tanzania to guide priority screening and management.

METHODS

A cross-sectional analytical study was conducted from February to June 2021 from the antenatal clinics in the primary, secondary and tertiary health care levels in the northwestern part of Tanzania involving 872 pregnant women. Demographic, obstetric and other clinical data were collected using a pre-tested structured questionnaire. Two swabs (vaginal and rectal) were collected and cultured-on blood agar and CHROMagarTMStrepB agar, followed by antimicrobial susceptibility testing. A two-sample test of proportions was used to compare the GBS prevalence in various sub-groups, and logistic regression analysis was deployed to ascertain the association between predictor variables and GBS colonization.

RESULTS

The overall proportion of S. agalactiae colonization was 24.5% (214/872) [95% CI: 21.7 - 27.5%], and was significantly higher in the HIV infected group [63.1% (70/111)] than in the HIV-negative group [18.9% (144/761)]; OR (95% CI) = 7.33 (4.77-11.29, p-value < 0.001)]. Colonization was more prevalent in the rectal samples compared to vaginal samples [21.1% versus 8.83%, respectively; p-value < 0.001)] and S. agalactiae recovery was higher using CHROMagarTMStrepB agar compared to blood agar [24.4% versus 18.8%, respectively, p-value = 0.004]. There was no association between GBS colonization and health care facility levels or pregnancy trimesters. The S. agalactiae isolates were sensitive to ampicillin (100%), erythromycin (76.3%), clindamycin (84.4%) and vancomycin (98.1%).

CONCLUSIONS

Approximately a quarter of pregnant women are colonized by GBS in Mwanza, Tanzania; and colonization is remarkably higher among HIV-infected women. Ampicillin is recommended for prophylaxis and treatment of GBS. Introduction of routine GBS screening among all HIV-infected pregnant women using ultrasensitive CHROMagar™ Strep B agar is recommended, and molecular characterization of GBS isolates would be of interest to guide future vaccination strategies.

Group B streptococcal infections in pregnancy and early life

SUMMARYBacterial infections with Group B Streptococcus (GBS) are an important cause of adverse outcomes in pregnant individuals, neonates, and infants. GBS is a common commensal in the genitourinary and gastrointestinal tracts and can be detected in the vagina of approximately 20% of women globally. GBS can infect the fetus either during pregnancy or vaginal delivery resulting in preterm birth, stillbirth, or early-onset neonatal disease (EOD) in the first week of life. The mother can also become infected with GBS leading to postpartum endometritis, and rarely, maternal sepsis. An invasive GBS infection of the neonate may present after the first week of life (late-onset disease, LOD) through transmission from caregivers, breast milk, and other sources. Invasive GBS infections in neonates can result in sepsis, pneumonia, meningitis, neurodevelopmental impairment, death, and lifelong disability. A policy of routine screening for GBS rectovaginal colonization in well-resourced countries can trigger the administration of intrapartum antibiotic prophylaxis (IAP) when prenatal testing is positive, which drastically reduces rates of EOD. However, many countries do not routinely screen pregnant women for GBS colonization but may administer IAP in cases with a high risk of EOD. IAP does not reduce rates of LOD. A global vaccination campaign is needed to reduce the significant burden of invasive GBS disease that remains among infants and pregnant individuals. In this narrative review, we provide a comprehensive overview of the global impact of GBS colonization and infection, virulence factors and pathogenesis, and current and future prophylactics and therapeutics.

Stillbirths and Neonatal Deaths Caused by Group B Streptococcus in Africa and South Asia Identified Through Child Health and Mortality Prevention Surveillance (CHAMPS)

Background

Invasive Group B Streptococcus (GBS) is a common cause of early-onset neonatal sepsis and is also associated with stillbirth. This study aimed to determine the proportion of stillborn infants and infants who died between 0 and 90 days attributable to GBS using postmortem minimally invasive tissue sampling (MITS) in 7 low- and middle-income countries (LMICs) participating in Child Health and Mortality Prevention Surveillance (CHAMPS).

Methods

Deaths that occurred between December 2016 and December 2021 were investigated with MITS, including culture for bacteria of blood and cerebrospinal fluid (CSF), multipathogen polymerase chain reaction on blood, CSF, and lung tissue and histopathology of lung, liver, and brain. Data collection included clinical record review and verbal autopsy. Expert panels reviewed all information and assigned causes of death.

Results

We evaluated 2966 deaths, including stillborn infants (n = 1322), infants who died during first day of life (0 to <24 hours, n = 597), early neonatal deaths (END) (1 day to <7 days; END; n = 593), and deaths from 7 to 90 days (n = 454). Group B Streptococcus was determined to be in the causal pathway of death for 2.7% of infants (79 of 2, 966; range, 0.3% in Sierra Leone to 7.2% in South Africa), including 2.3% (31 of 1322) of stillbirths, 4.7% (28 of 597) 0 to <24 hours, 1.9% (11 of 593) END, and 2.0% (9 of 454) of deaths from 7 to 90 days of age. Among deaths attributed to GBS with birth weight data available, 61.9% (39 of 63) of decedents weighed <2500 grams at birth. Group B Streptococcus sepsis was the postmortem diagnosis for 100% (31 of 31) of stillbirths. For deaths <90 days, postmortem diagnoses included GBS sepsis (83.3%, 40 of 48), GBS meningitis (4.2%, 2 of 48), and GBS pneumonia (2.1%, 1 of 48).

Conclusions

Our study reveals significant heterogeneity in the contribution of invasive GBS disease to infant mortality across different countries, emphasizing the need for tailored prevention strategies. Moreover, our findings highlight the substantial impact of GBS on stillbirths, shedding light on a previously underestimated aspect in LMICs.

Distribution and Prevalence of Serotypes of Group B Streptococcus Isolated from Pregnant Women in 30 Countries: A Systematic Review

Objective

This review aimed to compile scientific data on the distribution and prevalence of group B Streptococcus (GBS) serotypes isolated from pregnant women across 30 countries from 2010 to 2019.

Methods

This was a systematic review that addresses the distribution and prevalence of GBS in pregnant women. The search included studies published between January 2010 and December 2019 in PubMed, Virtual Health Library (BVS), ScienceDirect, Scientific Electronic Library Online (SciELO), and LILACS databases. We also surveyed relevant articles published in English, Spanish, and Portuguese between February and April 2020. Original articles, communication, short report, theses, and dissertations were included. The prevalence of GBS colonization, method for capsular serotyping, antimicrobial resistance, distribution and prevalence of serotypes were extracted from each study.

Results

In all, 795 publications were identified. After applying the eligibility criteria, 48 articles were included for the final systematic analysis; most articles were from Asia and were published during the years 2014 to 2017. For the identification of serotypes, most studies used the polymerase chain reaction technique. There were records of all 10 GBS serotypes, namely, Ia, Ib, and II-IX, among the countries analyzed. GBS susceptibility and resistance to antibiotics were addressed in 37.5% of the publications analysed.

Conclusion

This review showed that GBS serotypes are distributed differently in the 30 analyzed countries, with serotypes Ia, Ib, and II to V being the most prevalent. Furthermore, our results highlighted the relationship of GBS with maternal colonization, implications for neonates, and antibiotic resistance.

Prevalence of Group B Streptococcus maternal colonization, serotype distribution, and antimicrobial resistance in Sub-Saharan Africa: A systematic review and meta-analysis

OBJECTIVE

Group B Streptococcus (GBS)-associated maternal, perinatal, and neonatal mortality and morbidity disproportionately affects Sub-Saharan Africa (SSA). This systematic review and meta-analysis aimed to address the estimated prevalence, antimicrobial susceptibility, and serotype distribution of GBS isolates in SSA.

METHODS

This study was done according to PRISMA guidelines. MEDLINE/PubMed, CINAHL (EBSCO), Embase, SCOPUS, Web of Sciences databases, and Google Scholar were used to retrieve both published and unpublished articles. STATA software version 17 was used for data analysis. Forest plots using the random-effect model were used to present the findings. Heterogeneity was assessed using Cochrane chi-square (I²) statistics, while the Egger intercept was used to assess publication bias.

RESULTS

Fifty-eight studies that fulfilled the eligibility criteria were included for meta-analysis. The pooled prevalence of maternal rectovaginal colonization and vertical transmission of GBS were 16.06, 95% CI [13.94, 18.30] and 43.31%, 95% CI [30.75, 56.32], respectively. The highest pooled proportion of antibiotic resistance to GBS was observed in gentamicin (45.58%, 95% CI [4.12%, 91.23]), followed by erythromycin, (25.11%, 95% CI [16.70, 34.49]). The lowest antibiotic resistance was observed in vancomycin (3.84%, 95% CI [0.48, 9.22]). Our findings indicate that serotypes Ia/Ib/II/ III/and V cover almost 88.6% of serotypes in SSA.

CONCLUSIONS

The estimated high prevalence and resistance to different antibiotic classes observed in GBS isolates from SSA suggests the need for implementation of effective intervention efforts.

Group B Streptococcal Colonization among Pregnant Women and Neonates in a Tertiary Care Hospital in South India

OBJECTIVES

To assess the prevalence of maternal and neonatal group B Streptococcal colonization, incidence of neonatal systemic illness, and antibiotic sensitivity of isolates.

METHODS

This prospective cohort study was conducted in a South Indian tertiary care hospital. Rectovaginal swabs from pregnant mothers at 36^0/7-37^6/7 wk gestation and throat and rectal swabs from their neonates at 48 h of age were collected. Presence of group B Streptococcus (GBS) was identified by broth enrichment step, and traditional microbiologic methods and antibiotic sensitivity of isolates was noted. All mothers received intrapartum antibiotic prophylaxis (IAP). Culture-positive sepsis, clinical sepsis, pneumonia, meningitis, and urinary tract infection were defined as neonatal systemic illness. Neonates of colonized mothers were followed at 3 mo for late-onset sepsis.

RESULTS

Of the 310 mothers, 40 were GBS colonized (prevalence: 12.9%; 95% CI 9.2%, 17.6%). None of the neonates were colonized. Maternal GBS colonization was significantly associated with premature rupture of membrane (RR - 2.93, 95% CI - 1.66-5.16) and neonatal systemic illness (RR - 2.78, 95% CI - 1.39-5.54). Positive correlation was noted between duration of IAP ≤ 4 h and neonatal illness and between maternal GBS colonization and Apgar at 1 min ≤ 4. Clindamycin resistance was noted in 20%. All neonates remained well at 3 mo follow-up.

CONCLUSION

High maternal colonization alerts the need for GBS screening in India. Clindamycin resistance among GBS isolates questions its effectiveness as alternative therapy in penicillin allergy.

Group B Streptococcal Colonization in African Countries: Prevalence, Capsular Serotypes, and Molecular Sequence Types

Streptococcus agalactiae or group B streptococcus (GBS) is a commensal of the gastrointestinal and genitourinary tracts of healthy women and an important cause of neonatal invasive infections worldwide. Transmission of bacteria to the newborn occurs at birth and can be prevented by intrapartum antibiotic prophylaxis. However, this not available in resource limited settings in Africa, which carries a particular high burden of disease. Serotype based vaccines are in development and present a suitable alternative to prevent neonatal infections. To be able to assess vaccine efficacy, knowledge and surveillance of GBS epidemiological data are required. This review summarizes investigations about the serotype distribution and the multi-locus sequence types (MLST) found in different African countries. While most serotypes and MLST data are comparable to findings from other continents, some specific differences exist. Serotype V is predominant among colonizing maternal strains in many different African countries. Serotypes that are rarely detected in western industrialized nations, such as serotypes VI, VII and IX, are prevalent in studies from Ghana and Egypt. Moreover, some specific MLST sequence types that seem to be more or less unique to Africa have been detected. However, overall, the data confirm that a hexavalent vaccine can provide broad coverage for the African continent and that a protein vaccine could represent a promising alternative.

Deep Learning Model for Pathogen Classification Using Feature Fusion and Data Augmentation

Background:

Bacterial pathogens are deadly for animals and humans. The ease of their dissemination, coupled with their high capacity for ailment and death in infected individuals, makes them a threat to society.

Objective:

Due to high similarity among genera and species of pathogens, it is sometimes difficult for microbiologists to differentiate between them. Their automatic classification using deep-learning models can help in reliable, and accurate outcomes.

Method:

Deep-learning models, namely; AlexNet, GoogleNet, ResNet101, and InceptionV3 are used with numerous variations including training model from scratch, fine-tuning without pre-trained weights, fine-tuning along with freezing weights of initial layers, fine-tuning along with adjusting weights of all layers and augmenting the dataset by random translation and reflection. Moreover, as the dataset is small, fine-tuning and data augmentation strategies are applied to avoid overfitting and produce a generalized model. A merged feature vector is produced using two best-performing models and accuracy is calculated by xgboost algorithm on the feature vector by applying cross-validation.

Results:

Fine-tuned models where augmentation is applied produces the best results. Out of these, two-best-performing deep models i.e. (ResNet101, and InceptionV3) selected for feature fusion, produced a similar validation accuracy of 95.83 with a loss of 0.0213 and 0.1066, and a testing accuracy of 97.92 and 93.75, respectively. The proposed model used xgboost to attained a classification accuracy of 98.17% by using 35-folds cross-validation.

Conclusion:

The automatic classification using these models can help experts in the correct identification of pathogens. Consequently, they can help in controlling epidemics and thereby minimizing the socio-economic impact on the community.

A current review of pathogenicity determinants of Streptococcus sp

The genus Streptococcus comprises important pathogens, many of them are part of the human or animal microbiota. Advances in molecular genetics, taxonomic approaches and phylogenomic studies have led to the establishment of at least 100 species that have a severe impact on human health and are responsible for substantial economic losses to agriculture. The infectivity of the pathogens is linked to cell-surface components and/or secreted virulence factors. Bacteria have evolved sophisticated and multifaceted adaptation strategies to the host environment, including biofilm formation, survival within professional phagocytes, escape the host immune response, amongst others. This review focuses on virulence mechanism and zoonotic potential of Streptococcus species from pyogenic (S. agalactiae, S. pyogenes) and mitis groups (S. pneumoniae).

Molecular epidemiology, antimicrobial activity, and virulence gene clustering of Streptococcus agalactiae isolated from dairy cattle with mastitis in China

Streptococcus agalactiae is a contagious pathogen that causes bovine mastitis worldwide, resulting in considerable economic losses. In this study, we isolated 42 S. agalactiae strains in 379 milk samples from cows with subclinical mastitis on 15 dairy farms in 12 Chinese provinces. Analysis based on capsular typing and multilocus sequence typing, combined with patterns of virulence gene scanning and antimicrobial resistance, identified the lineages and populations of the isolates. We grouped the 42 isolates into 7 sequence types belonging to 6 clonal complexes, mainly CC103 (31/42 isolates; 73.8%). We identified an ST-23 strain named Sa 129 for the first time on Chinese dairy farms-this strain is usually associated with human isolates. Capsular types Ia and II were predominant in capsular typing. The prevalence of virulence profile 1 (bibA, cfb, cspA, cylE, fbsA, fbsB, hylB, and pavA) was 64.3%, and represented the main trend in China. With respect to antimicrobial resistance, most isolates were susceptible to β-lactams, rifamycin, glycopeptides, and oxazolidone; resistance to several antimicrobial agents, including lincomycin, clindamycin, and doxycycline, varied in 4 different regions. Our research provides a profile for the molecular epidemiology, multilocus sequence typing, antimicrobial resistance, and virulence gene clustering of S. agalactiae, and may be beneficial for the clinical monitoring, prevention, and control of mastitis in dairy cattle.

Group B Streptococcus colonization rate and serotype distribution among pregnant women and their newborns at Adama Hospital Medical College, Ethiopia

Rectovaginal area of pregnant women can be colonized transiently with group B Streptococcus (GBS) without causing disease. The bacteria can be transmitted to the newborn before and during birth and cause early-onset neonatal disease. In this study, we aimed to determine the GBS colonization rate among pregnant women before delivery and their newborns and serotypes distribution of GBS. Two hundred-eighty pregnant women along with their newborns were screened for GBS colonization from June 2014 to October 2014 at Adama Hospital Medical College. Rectovaginal swabs from pregnant women before delivery and specimen from nasal area, external ear, umbilical cord and throat of newborns were collected and cultured. The serotyping of GBS was performed by using serotype-specific antisera. To collect sociodemographic and clinical data we employed a structured questionnaire. GBS colonization among pregnant women and their newborns were 13.2% 95% CI (8.9-17.5) and 7.4% 95% CI (4.6-10.6). Out of 37 GBS strains recovered from pregnant women, the prevalent serotypes were Ia 6(16.2%), Ib 8(21.6%), II 10(27%), III 3(8.1%), and V 8(21.6%). Out of 21 GBS strains recovered from newborns, prevalent serotypes were Ia 3(14.3%), Ib 6(28.6%), II 6(28.6%), III 4(19%), and V 1(4.8%). This study indicated the existence of primary risk factors for neonatal disease in Adama area. Serotype II was the common serotype detected in this study which is followed by serotype Ib, Ia, and V. As colonizing GBS serotypes could cause invasive disease among newborns, vaccine formulation which includes serotype II, Ia, V, Ib, and III can prevent of invasive disease caused by GBS in the study area.

Antibiotic Resistance and Molecular Epidemiological Characteristics of Streptococcus agalactiae Isolated from Pregnant Women in Guangzhou, South China

Streptococcus agalactiae colonization in pregnant women can cause postpartum intrauterine infections and life-threatening neonatal infections. To formulate strategies for the prevention and treatment of S. agalactiae infections, we performed a comprehensive analysis of antibiotic resistance and a molecular-based epidemiological investigation of S. agalactiae in this study. Seventy-two S. agalactiae strains, collected from pregnant women, were subjected to antibiotic susceptibility tests; then, the screened erythromycin and clindamycin nonsusceptible isolates were used for macrolides and clindamycin resistance genes detection, respectively. Detection of resistance genes, serotyping, and determination of virulence genes were performed by polymerase chain reaction. The clonal relationships among the colonized strains were evaluated by multilocus sequence typing. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) mass peak analysis was performed to discriminate the specific sequence types (STs). In our study, 69.4% and 47.2% of the strains were nonsusceptible to erythromycin and clindamycin, respectively; the multidrug resistance rate was 66.7%. All erythromycin nonsusceptible strains harbored resistance genes, whereas only 52.9% of the clindamycin nonsusceptible strains possessed the linB gene. Erythromycin resistance was mainly mediated by the ermB or mefA/E genes. Four serotypes were identified, and the most common serotype was serotype III (52.8%), followed by Ib (22.2%), Ia (18.0%), and II (4.2%). All the strains were divided into 18 STs that were assigned to nine clonal complexes. Most of the major STs were distributed into specific serotypes, including ST19/serotype III, ST17/serotype III, ST485/serotype Ia, ST862/serotype III, and ST651/serotype III. Analysis of virulence genes yielded seven clusters, of which bca-cfb-scpB-lmb (61.6%) was the predominant virulence gene cluster. Among all ST strains distributed in this region, only the ST17 strains had a mass peak at 7620 Da. The outcomes of this study are beneficial for the epidemiological comparison of colonized S. agalactiae in different regions and may be helpful for developing the strategies for the prevention of S. agalactiae infection in Guangzhou. Furthermore, our results show that MALDI-TOF MS can be used for the rapid identification of the ST17 strains.

Prevalence and capsular type distribution of group B Streptococcus isolated from vagina of pregnant women in Nghe An province, Vietnam

BACKGROUND AND OBJECTIVES

Identification of GBS serotypes provides helpful information for appropriate the development of suitable vaccines; however, no reports from Vietnam have been published. This study has been performed to find the prevalence and serotypes of group B Streptococcus isolated from vagina of pregnant women in Nghe An province, Vietnam.

MATERIALS AND METHODS

Vaginal swabs were collected from pregnant women at 35-37 weeks of gestation at the Nghe An Obstetrics and Pediatrics Hospital, Vietnam between May 2018 and July 2019. The swabs were cultured on 5% sheep blood agar for isolation of GBS. All isolates were identified using the Gram staining, CAMP test and specific PCR. GBS strains were serotyped using the multiplex PCR assays.

RESULTS

The prevalence of vaginal GBS colonization was 9.20% of 750 participants. Among the isolates, serotypes III (39.13%) and V (31.89%) were the most frequent, followed by serotypes Ia (11.59%), VI (11.59%), Ib (2.90%), II (1.45%) and VII (1.45%), respectively. Serotypes IV, VIII and IX were not found.

CONCLUSION

The prevalence of GBS in the Nghe An province of central Vietnam was similar to reports from other parts of the world. The predominat GBS serotypes (III, V, Ia and VI) were slightly different from those previously described from other regions around the world. The high frequency of serotype VI was a notable feature of the strains from pregnant women in Vietnam.

Genomic Insights Into the Distribution and Evolution of Group B Streptococcus

Streptococcus agalactiae, also known as Group B Streptococcus (GBS), is a bacteria with truly protean biology. It infects a variety of hosts, among which the most commonly studied are humans, cattle, and fish. GBS holds a singular position in the history of bacterial genomics, as it was the substrate used to describe one of the first major conceptual advances of comparative genomics, the idea of the pan-genome. In this review, I describe a brief history of GBS and the major contributions of genomics to understanding its genome plasticity and evolution as well as its molecular epidemiology, focusing on the three hosts mentioned above. I also discuss one of the major recent paradigm shifts in our understanding of GBS evolution and disease burden: foodborne GBS can cause invasive infections in humans.