Recent Epidemiological Changes in Group B Streptococcus Among Pregnant Korean Women

Abstract

Background Although group B Streptococcus (GBS) colonization rate among pregnant Korean women is lower than that among women from many Western countries, recent data show an upward trend. We investigated recent epidemiological changes in GBS among pregnant Korean women in terms of colonization rate, antimicrobial susceptibility, serotype, and resistance genotype. Methods Vaginal and anorectal swab specimens from 379 pregnant Korean women were cultured on Strep B Carrot Broth with GBS Detect (Hardy Diagnostics, USA), selective Todd-Hewitt broth (Becton Dickinson, USA), and Granada agar plate medium (Becton Dickinson). The antimicrobial susceptibility, serotypes, and macrolide-lincosamide-streptogramin B (MLS B ) resistance genes of the GBS isolates were tested. Results The GBS colonization rate among pregnant Korean women was 19.8% (75/379). Colonization rates using Strep B Carrot Broth with GBS Detect, selective Todd-Hewitt broth, and Granada agar plate medium cultures were 19.5%, 19.3%, and 15.0%, respectively. Six pregnant women were colonized by non-beta-hemolytic GBS and were detected only in Strep B Carrot Broth with GBS Detect. Resistance rates of GBS to clindamycin, erythromycin, and tetracycline were 16.0%, 28.0%, and 42.7%, respectively. The most common GBS serotypes were V (22.7%), VIII (20.0%), and III (20.0%). The frequency of MLS B resistance genes erm (B) and erm (TR) were 63.6% and 36.4%, respectively. Conclusions The GBS colonization rate among pregnant Korean women has risen to levels observed in Western countries. To accurately evaluate GBS epidemiology among pregnant Korean women, periodic studies in multiple centers, including primary clinics, are necessary.

A Retrospective National Study on Colonization Rate and Antimicrobial Susceptibility of Streptococcus agalactiae in Pregnant Korean Women, 2018–2020

“…The GBS colonization rates among pregnant Korean women ranged from 1.96%–19.8%, and the colonization rate varied depending on the culture medium used, the site of sample collection, and the number of participants. 6 7 16 The US Centers for Disease Control and Prevention (CDC) recommends the use of Todd Hewitt Broth with gentamicin and nalidixic acid (or Lim Broth) to maximize the likelihood of recovering group B streptococci upon plating on sheep blood agar. 17 Swabbing both the lower vagina and rectum (through the anal sphincter) increases the culture yield substantially compared with that obtained by sampling the cervix or the vagina without swabbing the rectum.…”

“…In the past, the GBS colonization rate in pregnant Korean women was known to be lower than that in pregnant women from Western countries; however, its prevalence has been increasing recently. 6 7 According to a single medical institution’s longitudinal studies, the colonization rates of GBS in pregnant Korean women were 3.9% in 1993, 8 5.9% in 1995, 9 11.5% in 2008–2009, 10 and 19.8% in 2017–2019. 7 Moreover, an abundance of serotype III and V GBS isolates with multi-drug resistance to clindamycin, erythromycin, and tetracycline has been rapidly increasing in Korea, thus narrowing the choice of therapeutic agents available against infections caused by these serotypes.…”

“… 6 7 According to a single medical institution’s longitudinal studies, the colonization rates of GBS in pregnant Korean women were 3.9% in 1993, 8 5.9% in 1995, 9 11.5% in 2008–2009, 10 and 19.8% in 2017–2019. 7 Moreover, an abundance of serotype III and V GBS isolates with multi-drug resistance to clindamycin, erythromycin, and tetracycline has been rapidly increasing in Korea, thus narrowing the choice of therapeutic agents available against infections caused by these serotypes. 7 11 12 However, there has been no nationwide survey on the colonization rate of GBS in pregnant Korean women or antimicrobial susceptibility testing of GBS isolated from pregnant Korean women.…”

“… 7 Moreover, an abundance of serotype III and V GBS isolates with multi-drug resistance to clindamycin, erythromycin, and tetracycline has been rapidly increasing in Korea, thus narrowing the choice of therapeutic agents available against infections caused by these serotypes. 7 11 12 However, there has been no nationwide survey on the colonization rate of GBS in pregnant Korean women or antimicrobial susceptibility testing of GBS isolated from pregnant Korean women. Therefore, this study retrospectively analyzed the regional colonization rate and antimicrobial susceptibility results of GBS in pregnant Korean women using data obtained from national network hospitals of Seoul Clinical Laboratories.…”

False-positive detection of Group B Streptococcus (GBS) in chromogenic media due to presence of Enterococcus faecalis in High Vaginal Swabs

“…This method is shown to have a sensitivity and specificity comparable or even better than the standard Lim broth enrichment followed by blood agar cultures (Block et al, 2008, Church et al, 2008. Using the Carrot Broth method, many studies have shown the prevalence of GBS in vaginal swabs in the range of 5 to 19.8% in pregnant women (Choi et al, 2021, Church et al, 2008, Xie et al, 2016. In India, the prevalence of GBS is highly variable depending on the population studied or the methods used.…”