High rates of colonization and antimicrobial resistance of group B streptococcus highlight the need for vaccination even after implementation of guidelines for intrapartum antibiotic prophylaxis

Group B Streptococcus Detection Rate and Clindamycin Resistance Among Reproductive-Age Women in Korea During 2003-2022

BACKGROUND

Group B Streptococcus (GBS) is one of the leading causes of neonatal early-onset sepsis, resulting in high mortality and significant comorbidity. Intrapartum penicillin prophylaxis is recommended for pregnant women with GBS colonization to prevent vertical transmission. For pregnant women at high risk of anaphylaxis to penicillin, clindamycin is recommended only if the susceptibility of GBS isolates has been identified. We retrospectively examined the GBS detection rate and clindamycin resistance among Korean women of reproductive age over the last 20 years.

METHODS

Microbiologic studies using vaginal, vaginal-rectal or vaginal-perianal swabs from female patients 15-49 years of age during 2003-2022 were reviewed. Annual GBS detection rates and clindamycin resistance rates were calculated. The study period was divided into two periods (period 1, 2003-2015; period 2, 2016-2022) based on the introduction of universal culture-based GBS screening in our center in 2016. GBS detection rates and clindamycin resistance rates were compared between the periods using χ² tests.

RESULTS

A total of 14,571 women were tested 16,879 times and GBS was isolated in 1,054 tests (6.2%), with 423 clindamycin-resistant isolates (40.1%). The GBS detection rate increased from 3.4% (301/8,869) in period 1 to 9.4% (2,753/8,010) in period 2 (P < 0.001). Even during period 1, the GBS detection rate was higher in 2009-2015 compared to 2003-2008 (P < 0.001). Clindamycin resistance rates have remained at similar levels since 2009, which were 39.5% (199/301) in period 1 and 40.2% (303/753) in period 2 (P = 0.833).

CONCLUSION

This study demonstrated that GBS detection rates in Korean women of reproductive age significantly increased almost three times during the twenty years of the study period, with a persistently high clindamycin resistance rate of up to 40%.

Distributions of candidate vaccine Targets, virulence Factors, and resistance features of invasive group B Streptococcus using Whole-Genome Sequencing: A Multicenter, population-based surveillance study

BACKGROUND

Group B Streptococcus (GBS) is a leading cause of morbidity and mortality in young infants worldwide. This study aimed to investigate candidate GBS vaccine targets, virulence factors, and antimicrobial resistance determinants.

METHODS

We used whole-genome sequencing to characterize invasive GBS isolates from infants < 3 months of age obtained from a multicenter population-based study conducted from 2015 to 2021 in China.

RESULTS

Overall, seven serotypes were detected from 278 GBS isolates, four (Ia, Ib, III, V) of which accounted for 97.8 %. We detected 30 sequence types (including 10 novel types) that were grouped into six clonal complexes (CCs: CC1, CC10, CC17, CC19, CC23 and CC651); three novel ST groups in CC17 were detected, and the rate of CC17, considered a hyperinvasive neonatal clone complex, was attached to 40.6 % (113/278). A total of 98.9 % (275/278) of isolates harbored at least one alpha-like protein gene. All GBS isolates contained at least one of three pilus backbone determinants and the pilus types PI-2b and PI-1 + PI-2a accounted for 79.8 % of the isolates. The 112 serotype III/CC17 GBS isolates were all positive for hvgA. Most of the isolates (75.2 %) were positive for serine-rich repeat glycoprotein determinants (srr1or srr2). Almost all isolates possessed cfb (99.6 %), c1IE (100 %), lmb (95.3 %) or pavA (100 %) gene. Seventy-seven percent of isolates harboured more than three antimicrobial resistance genes with 28.4 % (79/278) gyrA quinoloneresistancedeterminants mutation, 83.8 % (233/278) carrying tet cluster genes and 77.3 % (215/278) carrying erm genes which mediated fluoroquinolone, tetracycline and clindamycin resistance, respectively."

CONCLUSIONS

The findings from this large whole-genome sequence of GBS isolates establish important baseline data required for further surveillance and evaluating the impact of future vaccine candidates.

Maternal medically diagnosed infection and antibiotic prescription during pregnancy and risk of childhood cancer: A population-based cohort study in Taiwan, 2004 to 2015

While associations between maternal infections during pregnancy and childhood leukemia in offspring have been extensively studied, the evidence for other types of childhood cancers is limited. Additionally, antibiotic exposure during pregnancy could potentially increase the risk of childhood cancers. Our study investigates associations between maternal infections and antibiotic prescriptions during pregnancy and the risk of childhood cancer in Taiwan. We conducted a population-based cohort study using the Taiwan Maternal and Child Health Database (TMCHD), linked with national health and cancer registries. The study included 2 267 186 mother-child pairs, and the median follow-up time was 7.96 years. Cox proportional hazard models were utilized to estimate effects. Maternal infections during pregnancy were associated with a moderate increase in the risk of childhood hepatoblastoma (adjusted hazard ratio [HR] = 1.34; 95% confidence interval [CI]: 0.90-1.98) and a weaker increase in the risk of childhood acute lymphoblastic leukemia (ALL) (adjusted HR = 1.15; 95% CI: 0.99-1.35). Antibiotic prescriptions during pregnancy were also associated with an elevated risk of childhood ALL (adjusted HR = 1.30; 95% CI: 1.04-1.63), particularly with tetracyclines (adjusted HR = 2.15; 95% CI: 1.34-3.45). Several specific antibiotics were also associated with an increased risk of hepatoblastoma and medulloblastoma. Children exposed in utero to antibiotic prescription or both infections and antibiotics during pregnancy were at higher risk of developing ALL. Our findings suggest that there are associations between maternal infections, antibiotic use during pregnancy and the risk of several childhood cancers in addition to ALL and highlight the importance of further research in this area.

Group B Streptococcus and the risk of perinatal morbidity and mortality following term labor

Streptococcus agalactiae (group B Streptococcus) colonizes the genital tract of approximately 20% of pregnant women. In the absence of intervention, approximately 1% of infants born to colonized mothers exhibit a clinical infection. This has led to implementation of screening and intervention in the form of intrapartum antibiotic prophylaxis in many countries, including the United States. However, screening has not been introduced in a substantial minority of other countries because of the absence of supportive level 1 evidence, the very large number needed to treat to prevent 1 case, and concerns about antimicrobial resistance. Optimal screening would involve rapid turnaround (to facilitate intrapartum testing) and report antibiotic sensitivity, but no such method exists. There is significant scope for a personalized medicine approach, targeting intrapartum antibiotic prophylaxis to cases at greatest risk, but the pathogen and host factors determining the risk of invasive disease are incompletely understood. Epidemiologic data have indicated the potential of prelabor invasion of the uterus by group B Streptococcus, and metagenomic analysis revealed the presence of group B Streptococcus in the placenta in approximately 5% of pregnant women at term before onset of labor and membrane rupture. However, the determinants and consequences of prelabor invasion of the uterus by group B Streptococcus remain to be established. The vast majority (98%) of invasive neonatal disease is caused by 6 serotypes, and hexavalent vaccines against these serotypes have completed phase 2 trials. However, an obstacle to phase 3 studies is conducting an adequately powered trial to demonstrate clinical effectiveness given that early-onset disease affects approximately 1 in 1000 births in the absence of vaccination.

Molecular Epidemiology of Group B Streptococcus Isolates from Pregnant Women with Premature Rupture of Membranes in Fuzhou, China

Objective

This study investigated the molecular epidemiology of Group B Streptococcus (GBS) in pregnant women with premature rupture of membranes (PROM) in Fuzhou region of China as a source of clinical reference.

Methods

GBS isolates were obtained from pregnant women with PROM. All isolates were genotyped, serotyped, and tested for drug-resistance and virulence genes using PCR and DNA sequencing. Antibiotic susceptibility testing was performed using the Vitek^® 2 automated system.

Results

Among the 140 GBS isolates, seventeen sequence types (STs) were identified, of which ST19 (20.0%) was the most prevalent, followed by ST862, ST10, and ST12. Three clonal complexes (CC19, CC10 and CC1) were identified. The predominant serotype was III (45.7%), followed by V (23.6%), Ib (18.6%), Ia (7.1%), and II (3.6%). The prevalence of multidrug resistance was 72.8% (102/140). All isolates were susceptible to penicillin G, ampicillin, quinupristin, linezolid, vancomycin, and tigecycline. The majority of isolates were resistant to erythromycin (70.0%), clindamycin (72.1%), and tetracycline (81.4%), and 28.6% of isolates were resistant to levofloxacin and moxifloxacin. Of the 98 erythromycin-resistant strains, mreA, ermB, mefA, mefE, ermA, and ermTR were detected in 100%, 70.4%, 49.0%, 22.4%, 13.3%, and 9.2%, respectively. No linB was detected among 101 clindamycin-resistant strains. Of the 114 tetracycline-resistant strains, tetM, tetK, tetL and tetO were detected in 52.6%, 61.4%, 7.9%, and 23.7%, respectively. Regarding virulence genes, all strains carried rib and hylB, followed by scpB (98.6%), and bca (80.7%), whereas only one strain carried bac.

Conclusion

ST19/III and ST862/III were the most prevalent GBS subtypes. Penicillin G remains a first-line antibiotic for intrapartum antibiotic prophylaxis and treatment of GBS infections. The prevalence of resistance to clindamycin, erythromycin, and tetracycline is high among GBS isolates in the Fuzhou region. ST862 and ST651 are emerging animal origin STs in human infections, and may become potential zoonotic threats.