Antimicrobial Susceptibility Patterns of Vaginal Bacteria and Lactobacillus in Comparison Study

Abstract

Background: The vaginal microbiota, dominated by Lactobacillus species, plays a critical role in preventing infections by maintaining a low pH and inhibiting pathogens. However, antimicrobial therapies for vaginitis may inadvertently disrupt this protective flora. The study aimed to compare the antimicrobial susceptibility profiles of bacterial pathogens isolated from vaginal swabs with those of Lactobacillus strains from vaginal and extra-vaginal sources. 

Methods: Women with vaginal discharges attending Al-Kafeel Specialized Hospital in Kerbala from March 2023 to April 2024 were enrolled. High vaginal swabs were collected from vaginitis patients. Bacterial isolates were identified using standard culture techniques and the Vitek 2 system. Eight Lactobacillus isolates were obtained from fermented dairy products (n=4), healthy women (n=3), and a probiotic suppository (n=1). Antimicrobial susceptibility testing was performed on bacterial and Lactobacillus isolates using standard methods. A side-by-side comparison of their antimicrobial resistance patterns was conducted.

Results:  This study of 200 vaginal isolates revealed striking resistance disparities: while pathogenic Staphylococci exhibited >70% macrolide resistance (reaching 90% in Coagulase-negative Staphylococcus) and Streptococci showed 60-83.3% resistance, commensal Lactobacilli maintained 100% susceptibility to levofloxacin, vancomycin and tetracycline, though demonstrating complete resistance to cefoxitin (100%) and high-level aminoglycoside resistance (75-87.5%). Gram-negative pathogens displayed concerning carbapenem resistance (up to 66.7% in Klebsiella pneumoniae), contrasting sharply with Lactobacilli preserved susceptibility profile, highlighting the critical need for microbiome-conscious antibiotic selection in vaginal infections.

Conclusions: These findings highlight the potential collateral damage of antimicrobial therapy on vaginal Lactobacilli. Tailored antibiotic selection or probiotic adjuvants may be needed to preserve the vaginal microbiome while treating infections. 

Keywords: Vaginal microbiota, Antimicrobial susceptibility, Vaginitis, Dysbiosis