Serotype distribution and mother-to-baby transmission rate of Streptococcus agalactiae among expectant mothers in Kuwait

Maternal and neonatal group B streptococcus colonisation: A systematic review and the meta-analysis of matched-pair studies

AIM

To determine the prevalence of group B Streptococcus (GBS) carriage among parturient women and neonates, and the relative risk of vertical transmission, the relative risk of early and late-onset GBS and the pooled incidence of early-late-onset GBS infection.

METHODS

A systematic search of relevant cohort studies from three electronic databases to identify all relevant studies published up to 7 November 2022. The review was conducted in accordance with PRISMA guidelines. Estimates were pooled using random-effects meta-analyses.

RESULTS

A total of 54 articles with 355 787 matched pairs of parturient women and neonates from 30 countries were included in the analysis. The pooled prevalence of GBS colonisation was 17.1% among the pregnant women and 1.0% among neonates. The pooled prevalence of vertical transmission of GBS was 4.5% and the pooled relative risk of GBS colonisation of neonates born to mothers with GBS was 9.9.

CONCLUSION

We support the implementation of targeted intrapartum antibiotic prophylaxis for all women who are positive for GBS as well as women with risks factors for early onset GBS in their infants regardless of their GBS colonisation status.

Vertical Transmission, Risk Factors, and Antimicrobial Resistance Patterns of Group B Streptococcus among Mothers and Their Neonates in Southern Ethiopia

Background

Group B Streptococcus (GBS) contributes to maternal and neonatal morbidity and mortality by increasing intrauterine infection or vertical transmission at the time of birth. Despite many efforts to reduce the potential risk of vertical transmission, GBS remains the main cause of serious disease (neonatal sepsis, meningitis, and/or pneumonia) in vulnerable newborns during the first week of life. This study aimed to assess vertical transmission, risk factors, and antimicrobial resistance patterns of GBS among pregnant women and their neonates.

Methods

A facility-based cross-sectional study was conducted among mothers and their neonates from February to May 2021. A total of 201 pregnant women with their neonates participated in this study. A well-designed questionnaire was used to collect sociodemographic and clinical data. A vaginal swab from mother before delivery and neonatal nasal and ear canal swab samples were taken as soon as after delivery within 30 minutes. Vaginal swabs, neonatal ear canal, and nasal swabs were placed into Todd–Hewitt broth and incubated at 37°C for 18–24 hours at 35–37°C in 5% CO₂ conditions and then subcultured on 5% sheep blood agar for 18–48 hours. Presumptive identification of GBS was made by morphology, Gram stain, catalase, and hemolytic activity on sheep blood agar plates. CAMP and bacitracin susceptibility tests were used as confirmatory tests for GBS. Data were analyzed using SPSS version 21. P value ≤0.05 was considered statistically significant.

Results

Vertical transmission rates of GBS (mother to neonates) were 11.9%. The prevalence of GBS among pregnant women and newborns was 24/201 (11.9%) (95% CI = 7.5–16.9) and 11/201 (5.5%) (95% CI = 2.5–9.0), respectively. The history of prolonged rupture of membranes (AOR = 3.5, CI = 2.2–18.8) and urinary tract infection (AOR = 2.9, CI = 1.7–16.3) were associated factors for maternal GBS colonization. Gestational age of <37 weeks (p=0.008), low birth weight of <2.5 kg (p=0.001), and maternal history of vaginal discharge (p=0.048) were associated factors for neonatal GBS colonization. Low antibiotic resistance was observed for erythromycin 8.6%, clindamycin 5.7%, and chloramphenicol 2.9%.

Conclusion

In this study, high vertical transmission (mother to neonates) rate was observed. The prevalence of vaginal GBS colonization of women at delivery was 11.9% and significantly associated with the history of prolonged rupture of membranes and urinary tract infections. Gestational age of <37 weeks, low birth weight of <2.5 kg, and maternal history of vaginal discharge were associated with neonatal GBS colonization. Hence, there is a need for antenatal culture-based GBS screening, risk factor-based interventions, and regular follow-up of drug resistance patterns for proper treatment and management of GBS.

Diagnostic Accuracy of Loop-Mediated Isothermal Amplification Assay for Group B Streptococcus Detection in Recto-Vaginal Swab: Comparison with Polymerase Chain Reaction Test and Conventional Culture

A rapid method for obtaining group B streptococcus (GBS) screening results has been required in the obstetric field. We aimed to determine the diagnostic performance of the Loop-Mediated Isothermal Amplification (LAMP) assay is acceptable compared to the existing polymerase chain reaction (PCR) assay. The study involved 527 pregnant women aged 19 to 44 years. Rectovaginal swabs were collected between 35 and 37 weeks of gestation or prior to impending preterm births or term labor without GBS screening. We presented the diagnostic performance of the LAMP assay with a 95% confidence interval (CI) compared to the PCR and microbiological culture. In total, 115 (21.8%), 115 (21.8%) and 23 (4.4%) patients showed positive results using the LAMP, PCR assay and microbiological culture method, respectively. The LAMP assay showed 100% sensitivity (95% CI, 96.8–100.0), 100% specificity (95% CI, 99.1–100.0) and 100% diagnostic accuracy (95% CI, 99.3–100.0) with the reference being the PCR assay. Meanwhile, the LAMP assay showed 87.0% sensitivity (95% CI, 71.0–100.0), 81.2% specificity (95% CI, 77.6–84.7), and 81.4% diagnostic accuracy (95% CI, 78.0–84.8) with the microbiological culture as a reference. This study presented the LAMP assay as an acceptable method for GBS screening with a similar performance to the existing PCR method.

Proportion of Streptococcus agalactiae vertical transmission and associated risk factors among Ethiopian mother-newborn dyads, Northwest Ethiopia

Group B Streptococcus (GBS) vertical transmission causes fetal and neonatal colonization and diseases. However, there is scarcity of data in low-income countries including Ethiopia. We conducted a cross-sectional study on 98 GBS positive mothers, and their newborns to find proportion of vertical transmission. GBS was identified from swabs by using recommended methods and vertical transmission at birth was confirmed by the culture of body surface swabs of newborns within 30 minutes following birth. GBS positivity among swabbed specimens collected for other purposes was 160/1540 (10.4%); 98 were from 385 recto-vaginal swabs of pregnant women, and 62 were from 1,155 swabs of the 385 births. Of the 98 GBS positive cases, 62 newborns were GBS colonized with vertical transmission proportion of 63.3%(95% CI: 54.1–72.4%). We identified that the proportion of vertical transmission in this study was within the range of other many global studies, but higher than recently published data in Ethiopia. Maternal educational level, employment and lower ANC visit were significantly associated risk factors to GBS vertical transmission. Efforts need to be made to screen pregnant women during antenatal care and to provide IAP to GBS positive cases to reduce mother to newborn vertical transmission.

High prevalence of Group B Streptococcus colonization among pregnant women in Amman, Jordan

Background

Little is known of the burden of Group B Streptococcus (GBS) colonization among pregnant women in Jordan. We conducted a pilot study to determine the prevalence of GBS among pregnant women in Amman, Jordan, where GBS testing is not routine. We also explored GBS serotypes and the performance of a rapid GBS antigen diagnostic test.

Methods

We collected vaginal-rectal swabs from women who presented for labor and delivery at Al-Bashir Hospital. Three methods were used to identify GBS: Strep B Rapid Test (Creative Diagnostics), blood agar media (Remel) with confirmed with BBL Streptocard acid latex test (Becton Dickinson), and CHROMagar StrepB (Remel). Results were read by a senior microbiologist. We defined our gold standard for GBS-positive as a positive blood agar culture confirmed by latex agglutination and positive CHROMagar. PCR testing determined serotype information. Demographic and clinical data were also collected.

Results

In April and May 2015, 200 women were enrolled with a median age of 27 years (IQR: 23–32); 89.0% were Jordanian nationals and 71.9% completed secondary school. Median gestational age was 38 weeks (IQR: 37–40); most women reported prenatal care (median 9 visits; IQR: 8–12). Median parity was 2 births (IQR: 1–3). Pre-pregnancy median BMI was 24.1 (IQR: 21.5–28.0) and 14.5% reported an underlying medical condition. Obstetric complications included gestational hypertension (9.5%), gestational diabetes (6.0%), and UTI (53.5%), of which 84.5% reported treatment. Overall, 39 (19.5%) of women were GBS-positive on blood agar media and CHROMagar, while 67 (33.5%) were positive by rapid test (36% sensitivity, 67% specificity). Serotype information was available for 25 (64%) isolates: III (48%), Ia (24%), II (20%), and V (8%). No demographic or clinical differences were noted between GBS+ and GBS-negative women.

Conclusions

Nearly one in five women presenting for labor in Jordan was colonized with GBS, with serotype group III as the most common. The rapid GBS antigen diagnostic had low sensitivity and specificity. These results support expanded research in the region, including defining GBS resistance patterns, serotyping information, and risk factors. It also emphasizes the need for routine GBS testing and improved rapid GBS diagnostics for developing world settings.

Bacterial Load and Molecular Markers Associated With Early-onset Group B Streptococcus: A Systematic Review and Meta-analysis

BACKGROUND

The natural history of neonatal group B Streptococcus (GBS) is poorly understood. Little is known about the bacterial factors influencing the transmission of GBS from mother to neonate, or the development of invasive early-onset GBS disease (EOGBS) in colonized neonates. We reviewed whether bacterial load and molecular markers are associated with GBS vertical transmission and progression to EOGBS.

METHODS

We searched Medline, Embase, Cochrane and Web of Science from inception to October 10, 2016, for observational studies in English. We also hand-searched reference lists of relevant publications and experts cross-checked included studies. Two reviewers independently screened studies, extracted data and appraised the quality of included studies using the Quality in Prognosis Studies tool. We conducted random-effects meta-analyses where possible and narratively synthesized the evidence in text and tables.

RESULTS

Seventeen studies were included from 1107 records retrieved from electronic databases and publication references. Meta-analyses of 3 studies showed that neonates colonized by serotype III had a higher risk of developing EOGBS than serotype Ia (pooled risk ratio: 1.51, 95% confidence interval: 1.12-2.03) and serotype II (risk ratio: 1.95, 95% confidence interval: 1.10-3.45). Eleven studies showed that in heavily colonized mothers, 2-3 times more neonates were colonized, and in heavily colonized neonates, up to 15 times more neonates had EOGBS, compared with light colonization. Most evidence was published before 2000 and was at risk of bias.

CONCLUSIONS

Acknowledging the difficulty of natural history studies, well-controlled studies are needed to assess the predictive value of pathogen subtype and heavy load; they may be useful for better-targeted prevention.

Risk factors for neonatal group B streptococcus vertical transmission: a prospective cohort study of 1815 mother-baby pairs

BACKGROUND

The potential factors associated with group B streptococcus (GBS) vertical transmission have not been studied in detail.

STUDY DESIGN

A prospective cohort study was conducted to recruit 1815 mother-neonate pairs for GBS analysis. Pearson's chi-squared tests and generalized linear models were used to explore the risk factors for neonatal GBS colonization.

RESULTS

The rate of GBS vertical transmission was 14.1%. GBS colonization in all neonates was significantly associated with maternal GBS colonization, mode of delivery, episiotomy, number of prenatal vaginal exams, parity, and hypertension. For neonates born to GBS-positive mothers, GBS vertical transmission was associated with the mode of delivery, episiotomy, and sexually transmitted diseases. For neonates born to GBS-negative mothers, neonatal GBS colonization was associated with the number of prenatal vaginal exams, parity, and hypertension.

CONCLUSION

These findings suggest the need for prenatal GBS screening for pregnant women and intrapartum antimicrobial prophylaxis for GBS-colonized women.

Molecular characteristics of Streptococcus agalactiae in a mother-baby prospective cohort study: Implication for vaccine development and insights into vertical transmission

BACKGROUND

Streptococcus agalactiae (GBS) is a leading cause of neonatal sepsis and meningitis in many countries. This study aimed to determine the molecular characteristics of GBS colonized in mothers and their infants so as to provide implication for vaccine strategies and confirm vertical transmission.

METHODS

A prospective cohort study was conducted to recruit 1815 mother-neonate pairs. All GBS isolates from pregnant women and her infants were tested for serotypes, multilocus sequence types and virulence genes. The relationship between multiple molecular characteristics of GBS isolates was tested by the correspondence analysis, and the agreement between mother-neonate paired data in molecular characteristics was analyzed using Kappa tests.

RESULTS

The predominant serotypes were III, Ia and V, and the most prevalent sequence types (STs) were ST19, ST17, ST10, and ST12. All isolates carried at least one pilus island (PI). The most common combination of PIs was PI-2b alone, followed by PI-1+PI-2a and PI-2a alone, and the most prevalent alpha-like protein (alp) genes were rib, epsilon and alphaC. Moreover, a strong relationship was noted between STs, serotypes, alp genes and PIs, including ST17 associated with serotype-III/rib/PI-2b, ST19 with serotype-III/rib/PI-1+PI-2a, and ST485 with serotype-Ia/epsilon/PI-2b. The rate of GBS vertical transmission was 14.1%, and the kappa test revealed good agreement in multiple molecular characteristics among GBS-positive mother-neonate pairs. Notably, the switching of molecular characteristics was found during vertical transmission.

CONCLUSIONS

Our findings underscore the value of monitoring multiple molecular characteristics so as to provide implication for multivalent strategies and gain insights into GBS vertical transmission and vertical characteristic switching.

Group B Streptococcus Colonization among Saudi Women During Labor

Background:

The presence of group B streptococcus in the genital area during pregnancy and labor is associated with high neonatal morbidity and mortality. However, the exact prevalence of group B streptococcus among Saudi women has not yet been established.

Objective:

The aim of this study was to determine the prevalence of group B streptococcal colonization in Saudi pregnant women as a primary end-point and neonatal complications as a secondary end-point.

Materials and Methods:

A prospective, observational, cross-sectional study was conducted to estimate the prevalence of group B streptococcal colonization among Saudi women admitted in labor to the King Fahd Hospital of the University, Al-Khobar, Saudi Arabia. A total of 1371 maternal specimens (vaginal swabs, rectal swabs and midstream urine) were collected from 457 patients between October 2011 and September 2016. Neonatal specimens (urine, blood and cerebrospinal fluid) were collected if clinically indicated.

Results:

Of the 457 women enrolled in this study, 87 (19%) had positive cultures for group B streptococcus either in the vaginal or rectal swab or both. Group B streptococcus was also found to be the most commonly isolated organism. In total, there were five cases of neonatal sepsis, of which one early-onset neonatal sepsis was caused by group B streptococcus.

Conclusions:

This study found that the prevalence of group B streptococcal colonization is 19% among Saudi women admitted in labor to the King Fahd Hospital of the University.

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.

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.

Emergence of methicillin-resistant Staphylococcus aureus in the Maternity Hospital, Kuwait

OBJECTIVE

To establish the relatedness of methicillin-resistant Staphylococcus aureus (MRSA) isolates in the Maternity Hospital, Kuwait.

MATERIALS AND METHODS

A total of 22 MRSA were isolated from 20 neonates and 1 mother in the Special Care Unit, Maternity Hospital, Kuwait. They were characterized using antibiogram, pulsed-field gel electrophoresis (PFGE), SCCmec typing, spa typing and multi locus sequence typing (MLST), and were screened for genes encoding Panton Valentine leukocidin (PVL) and capsular polysaccharide types 5 and 8.

RESULTS

The isolates were resistant to cadmium acetate (n = 22 or 100%), trimethoprim (n = 13 or 59.1%), gentamicin (n = 7 or 31.8%), ciprofloxacin (n = 5 or 22.7%), erythromycin and clindamycin (n = 2 or 9.1%), tetracycline (n = 2 or 9.1%) and fusidic acid (n = 2 or 9.1%). Eight isolates contained genes for PVL while 15 and 6 carried genes for types 5 and 8 capsular polysaccharide, respectively. Molecular typing distinguished 12 clones. Ten of these clones consisted of 20 isolates belonging to ST60-SCCmec-IV-t3935 (5 isolates), ST6-SCCmec-IV-t6269 (4 isolates), ST194-SCCmec-IV-t6892 (3 isolates), ST1-SCCmec-V-t2962 (2 isolates) and 1 isolate each of ST77-SCCmec-IV-t339, ST935-SCCmec-V-t1084, ST1317-SCCmec-V-t1548, ST9-SCCmec-V-t5801, ST627-SCCmec-IV-t1340 and ST2148-SCCmec-IV-t2810.

CONCLUSION

The study demonstrated the emergence of MRSA including novel ST60 and ST194 clones at the Maternity Hospital in Kuwait.

Serotype distribution and invasive potential of group B streptococcus isolates causing disease in infants and colonizing maternal-newborn dyads

BACKGROUND

Serotype-specific polysaccharide based group B streptococcus (GBS) vaccines are being developed. An understanding of the serotype epidemiology associated with maternal colonization and invasive disease in infants is necessary to determine the potential coverage of serotype-specific GBS vaccines.

METHODS

Colonizing GBS isolates were identified by vaginal swabbing of mothers during active labor and from skin of their newborns post-delivery. Invasive GBS isolates from infants were identified through laboratory-based surveillance. GBS serotyping was done by latex agglutination. Serologically non-typeable isolates were typed by a serotype-specific PCR method. The invasive potential of GBS serotypes associated with sepsis within seven days of birth was evaluated in association to maternal colonizing serotypes.

RESULTS

GBS was identified in 289 (52.4%) newborns born to 551 women with GBS-vaginal colonization and from 113 (5.6%) newborns born to 2,010 mothers in whom GBS was not cultured from vaginal swabs. The serotype distribution among vaginal-colonizing isolates was as follows: III (37.3%), Ia (30.1%), and II (11.3%), V (10.2%), Ib (6.7%) and IV (3.7%). There were no significant differences in serotype distribution between vaginal and newborn colonizing isolates (P = 0.77). Serotype distribution of invasive GBS isolates were significantly different to that of colonizing isolates (P<0.0001). Serotype III was the most common invasive serotype in newborns less than 7 days (57.7%) and in infants 7 to 90 days of age (84.3%; P<0.001). Relative to serotype III, other serotypes showed reduced invasive potential: Ia (0.49; 95%CI 0.31-0.77), II (0.30; 95%CI 0.13-0.67) and V (0.38; 95%CI 0.17-0.83).

CONCLUSION

In South Africa, an anti-GBS vaccine including serotypes Ia, Ib and III has the potential of preventing 74.1%, 85.4% and 98.2% of GBS associated with maternal vaginal-colonization, invasive disease in neonates less than 7 days and invasive disease in infants between 7-90 days of age, respectively.

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.

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

Group B streptococcus (GBS) is a leading cause of neonatal sepsis and is usually acquired via the woman's birth canal. GBS serotypes isolated from 200 pregnant women were determined. Serotypes V (19%) and VI (17%) were the most frequent followed by serotypes III (12%), Ia (11.5%) and IV (10%); 17% of the strains were non-typable. All isolates were susceptible to penicillin, 96% to erythromycin and 97.5% to clindamycin. The emergence of new GBS serotypes has important implications for vaccine prevention strategies.

An overview of the natural history of early onset group B streptococcal disease in the UK

Clinicians need information on the risk of Early Onset Group B Streptococcal disease (EOGBS) for counselling pregnant women and to decide who would benefit most from antibiotic treatment during labour. We carried out a systematic review of the research literature and conducted meta-analyses to obtain estimates for the natural history of EOGBS that are representative of the UK population. The mean rate of colonisation for the UK was 14% and we found weak evidence that the prevalence is increasing over time. Maternal GBS colonisation was more likely in women who delivered preterm compared with at term. Just over one-third of babies born to colonised mothers become colonised with GBS at birth (36%), and 3% of colonised babies develop EOGBS bacteraemia. In the UK, EOGBS constitutes one-third of all early onset bacteraemia due to pathogens, in contrast to one-half in the USA.

Type IV neonatal early-onset group B streptococcal disease in a United States hospital

Group B streptococcus (GBS) serotypes causing neonatal disease vary by geographic region. Surveillance at the Brigham and Women's Hospital in Boston, Massachusetts, revealed a case of neonatal early-onset sepsis caused by type IV GBS. Neonatal type IV disease occurs in the Middle East but has not recently been described in U.S. infants.