P15 Bacteriological profile and antimicrobial resistance trends in chronic suppurative otitis media (CSOM) in India: comprehensive review (1961–2026)

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Abstract Background Chronic suppurative otitis media (CSOM), characterized by persistent middle ear suppuration through tympanic membrane perforation for ≥2 weeks, remains a major public health challenge in India with prevalence ranging from 1.4% to 14.7%, classifying India as a WHO high-prevalence zone. The earliest CSOM study from Uttar Pradesh in 1961 reported 14.7% prevalence among schoolchildren. This 65-year review analyses how CSOM pathogens and their resistance patterns have evolved across India's regions. Methods Review studies from Karnataka, Bhopal, Agartala, Bhopal, Panipat, Rajasthan, West Bengal, and other centres revealed that early studies used manual culture and Kirby-Bauer disc diffusion (CLSI M100). Recent studies incorporated VITEK-2/MicroScan automated systems for identification and AST (6-12h), MALDI-TOF MS for rapid proteomic speciation (<30 min), and Etest strips for precise MIC determination of anaerobes. Data were analysed by geographic region, pathogen predominance, resistance evolution, demographic patterns, and diagnostic methodology. Results Across Indian studies, Pseudomonas aeruginosa (19.9–67.5%) and Staphylococcus aureus (11.3–51.9%) consistently emerged as the predominant pathogens across all geographic regions and time periods, while anaerobic bacteria like Bacteroides fragilis and Finegoldia magna, along with fungi including Aspergillus species and Candida species were identified. Demographic analysis revealed male predominance with male-to-female ratios from 1.3:1 to 1.6:1, bilateral ear involvement in 22.5%, and peak disease among individuals aged 11-30 years. Antimicrobial resistance patterns showed dramatic escalation over time, with P. aeruginosa ciprofloxacin resistance increasing from 20% in the early 2000s to 78.9% in recent studies, alongside gentamicin resistance rates of 26–64%, although this pathogen maintained greater than 90% susceptibility to colistin, polymyxin B, carbapenems, and piperacillin/tazobactam. S. aureus exhibited methicillin-susceptible strains predominating over MRSA in 9 out of 10 studies, with vancomycin and linezolid retaining greater than 90% activity while demonstrating 78.9% ciprofloxacin resistance. Conclusions Diagnostic methodology evolution has profoundly impacted CSOM microbiology interpretation. Early studies (1961–1990s) using conventional methods yielded broad genus-level reporting prone to misidentification (Pseudomonas spp. versus Stenotrophomonas); post-2010s VITEK-2/MicroScan/MALDI-TOF revolution revealed colistin MIC creep (0.5→2 mg/L), MRSA clonal types (ST22), biofilm persistence, enhanced fungal/anaerobe recovery which was previously missed, enabling 25–40% improved therapeutic outcomes through rapid de-escalation from empirical fluoroquinolone failures. Modern systems facilitate resistance gene correlation (blaVIM, NDM, mecA) guiding precision stewardship. Conclusions The persistent predominance of P. aeruginosa and S. aureus over 65 years highlights enduring socioeconomic challenges driving CSOM in India. The escalating multidrug resistance crisis necessitates immediate development of region-specific antibiograms to guide empirical therapy—prioritizing colistin and carbapenem-based topical formulations for gram-negative pathogens alongside vancomycin or linezolid for S. aureus. The automated diagnostic revolution (MALDI-TOF MS/VITEK-2/MicroScan) has transformed CSOM precision. Future priorities include whole-genome sequencing for carbapenemase tracking, biofilm profiling, and pan-regional surveillance to combat hearing loss and resistance.

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