Prevalence, antimicrobial resistance, and associated factors of bacterial vaginosis and aerobic vaginitis among women suspected of STIs in Bahir Dar, Ethiopia

Abstract Background Bacterial vaginosis (BV) and aerobic vaginitis (AV) are characterized by an imbalance of vaginal microbiome, becomes a serious public health crisis especially in low and middle income country. Objective To determine the Prevalence, Antimicrobial Resistance (AMR), and Associated Factors of Bacterial Vaginosis and Aerobic Vaginitis among Women Suspected of sexually transmitted infections (STIs) in Bahir Dar, Ethiopia. Materials and methods A facility-based cross-sectional study was conducted among 261 women suspected of STIs at selected health institutions in Bahir Dar City, northwest Ethiopia (February–May 2025). All eligible women were invited to minimize selection bias and ensure broad representation. Data was collected through structured interview, vaginal swab samples were collected and used for Gram stain methods to evaluate BV and AV scores according to the Nugent’s and Donder’s criteria, respectively. In situation of AV cases the aerobic bacterial pathogens and their antibiotic resistance were determined using the Kirby-Bauer disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Logistic regression was used to assess associations, with results reported as odds ratios (ORs) and 95% confidence intervals (CIs). Variables with a p -value less than 0.05 were considered statistically significant. Results The overall prevalence of bacterial vaginosis (BV) was 20.7% (54/261), while aerobic vaginitis (AV) was 17.2% (45/261), with a dual infection rate of 2.7% (7/261). Among 45 aerobic bacterial isolates, 25 (55.6%) were Gram-positive and 20 (44.4%) were Gram-negative. The most common species were Staphylococcus aureus (13/45, 28.9%) and Escherichia coli (12/45, 26.7%). Gram-positive species showed variable resistance, with 20% classified as MDR. All E. coli and K. pneumoniae isolates were MDR, while P. aeruginosa showed partial resistance; overall MDR prevalence was 49%. The most important factors significantly associated with BV were single marital status, occupation (commercial sex worker, housewife), vaginal pH > 4.5, Donders’ score (moderate to severe), and history of STI or abortion. For AV, key factors included occupation (housewife, commercial sex worker), vaginal burning sensation, vaginal pH > 4.5, positive BV status, and Nugent score indicating BV. Conclusion Bacterial vaginosis and aerobic vaginitis were prevalent among STI-suspected women in Bahir Dar, Ethiopia, with substantial multidrug resistance and significant associations with selected socio-demographic and clinical factors, underscoring the need for improved screening and resistance-guided management.