Prevalence of Erythromycin and Clindamycin Resistance in Streptococcus agalactiae Isolated from Pregnant Women in Iran: A Systematic Review and Meta-Analysis

Background and purpose: Group B Streptococcus (GBS), or Streptococcus agalactiae, is a major cause of invasive diseases such as meningitis and septicemia in newborns, as well as various diseases in pregnant women and non-pregnant adults with underlying conditions. This bacterium colonizes the vagina and rectum in 10% to 30% of pregnant women. GBS colonization in pregnant women increases the risk of preterm delivery and transmission of the bacteria to the baby during childbirth. Penicillin is the first-line antibiotic for treating GBS infections, while macrolides (e.g., erythromycin), lincosamides (e.g., clindamycin), and streptogramins have been recommended as alternative treatments. However, the prevalence of antibiotic resistance is rising and could lead to significant clinical challenges. Therefore, this study aimed to investigate the prevalence of resistance to erythromycin and clindamycin, as well as the associated resistance genes, in GBS strains isolated from pregnant women in Iran. Materials and methods: This meta-analysis examines studies focused on resistance to erythromycin and clindamycin in GBS strains isolated from pregnant women. A comprehensive search was conducted across databases, including PubMed, Scopus, Web of Science, SID (Scientific Information Database), and Google Scholar, using keywords such as Streptococcus agalactiae, Group B Streptococcus, antibiotic resistance, erythromycin, clindamycin, MLSB (macrolide, lincosamide, and streptogramin B) resistance, and related terms. Inclusion criteria included sufficient sample size, control of confounding factors, inclusion of the relevant antibiotics, and availability of full-text articles. Data were analyzed using Comprehensive Meta-Analysis software (Biostat V2.2). Heterogeneity between studies was assessed using the I2 index, and a random-effects model was applied due to heterogeneity in the results. Results: The initial database search identified 241 studies. After removing 41 duplicates, 201 studies were considered for meta-analysis. After reviewing the titles and abstracts, 158 studies were excluded for not meeting the research criteria, leaving 16 studies for final analysis. This meta-analysis investigated the prevalence of resistance to erythromycin and clindamycin, resistance phenotypes, and the genes encoding antibiotic resistance in GBS isolates from pregnant women. All studies included were cross-sectional. The pooled resistance rates for erythromycin and clindamycin were 27.9% (CI95%: 16-43.9) and 28.4% (CI95%: 17-43.5), respectively. Continuous and inducible resistance phenotypes were observed in 17.5% (CI95%: 6.2-40.4) and 10.9% (CI95%: 4.7-23.2) of the isolates. The M and L phenotypes were found in 8.1% (CI95%: 3.9-16) and 4.8% (CI95%: 2.7-8.4) of the isolates, respectively. The prevalence of resistance genes, including ermTR, ermB, and mefA, was 34% (CI95%: 27.4-41.4), 24.5% (CI95%: 3-77.1), and 6.7% (CI95%: 3.9-11.4), respectively. Conclusion: The study shows an increasing trend of erythromycin and clindamycin resistance in GBS isolates from pregnant women in Iran. Therefore, antibiotic susceptibility testing should be performed before prescribing these antibiotics to prevent the development and spread of resistant strains.