Microbiological Spectrum, Antimicrobial Resistance Profiles, and Nugent Score Correlates in High Vaginal Swab Specimens: A Six-Year Retrospective Surveillance Study from a Tertiary Care Hospital in North India

Abstract

Background: Vaginal infections are a leading cause of gynaecological morbidity and adverse reproductive outcomes globally. Rising antimicrobial resistance among vaginal pathogens, combined with the loss of Lactobacillus-dominant flora as quantified by Nugent scoring, poses significant diagnostic and therapeutic challenges. Comprehensive long-term data integrating microbiological culture, antimicrobial susceptibility testing (AST), and Nugent scoring from Indian tertiary care settings are lacking. Methods: We conducted a six-year retrospective observational study (January 2020 – December 2025) in the Department of Microbiology, Pt. B.D. Sharma PGIMS, Rohtak. All 5,209 high vaginal swab (HVS) samples processed during this period were included. Organisms were identified by standard microbiological techniques and AST was performed by Kirby-Bauer disc diffusion per CLSI guidelines. Nugent scoring of Gram-stained smears was performed routinely. Results: Of 5,209 samples, 1,000 (19.2%) yielded significant growth. Escherichia coli was the most frequent isolate (48%), followed by Klebsiella pneumoniae (28%), Acinetobacter baumannii (6%), Pseudomonas aeruginosa (6%), coagulase-negative staphylococci (CONS) (4%), Candida tropicalis (2%), Proteus mirabilis (2%), Enterococcus faecium (2%), and Stenotrophomonas maltophilia (2%). Resistance rates to third-generation cephalosporins and fluoroquinolones exceeded 80% in E. coli, and 100% in K. pneumoniae, consistent with widespread ESBL production. Carbapenem resistance was 21–25% in E. coli and 57–64% in K. pneumoniae. Colistin retained 100% activity against all Gram-negative isolates. Nugent scoring revealed BV-range scores (7–10) in 20.3% of all 5,209 samples. Culture positivity rose significantly with Nugent score category: 3.6% (normal, 0–3), 34.4% (intermediate, 4–6), and 56.9% (BV, 7–10; χ²=692.4; p<0.001). E. coli and K. pneumoniae together comprised 88% of isolates in the BV score group. Conclusions: MDR Gram-negative bacilli, especially ESBL-producing E. coli and carbapenem-resistant K. pneumoniae, dominate vaginal infections in this tertiary care setting. Colistin remains the only uniformly active last-resort agent against XDR Gram-negative isolates. Nugent scoring is a powerful, low-cost predictor of pathogenic culture yield and should be routinely incorporated into the HVS laboratory workup. Institution-specific antibiograms and antimicrobial stewardship programmes are urgently required.