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Author ORCID Identifier(s)

0009-0003-4323-0180

Abstract

Objectives High-contact public surfaces, such as bus seatbacks, mall escalator belts, and theater armrests, may act as reservoirs of opportunistic and antimicrobial-resistant microorganisms, posing a significant but underreported risk to community health. In urban environments like Coimbatore, Tamil Nadu, surface-level microbial surveillance remains poorly characterized. This study aimed to assess the magnitude, composition, and density of microbial contaminants on commonly touched surfaces across transit and commercial hubs.

Methods A total of 30 surface swab samples were collected from five public locations, including intra-city TNSTC buses, inter-state SETC coaches, Brookfields Mall escalator handrails, multiplex theaters and local bus seat-grips. Standardized 25 cm2 areas were swabbed using sterile, saline-moistened swabs and cultured on Nutrient Agar, MacConkey Agar, and Sabouraud Dextrose Agar. Colonies were incubated at 37°C for 24–48 hours. Isolates were identified by Gram staining, colony morphology, and biochemical assays. Antimicrobial susceptibility testing was performed using the Kirby–Bauer disc diffusion method (following Clinical and Laboratory Standards Institute 2021 guidelines.

Results Out of 30 surface samples, 28 (93.3%) were culture-positive, yielding 48 distinct microbial isolates. Gram-negative organisms accounted for 54.2% of isolates, including Escherichia coli (16.7%), Pseudomonas aeruginosa (14.6%), and Klebsiella pneumoniae (12.5%), while Gram-positive bacteria included Staphylococcus aureus (20.8%) and coagulase-negative staphylo-cocci (10.4%). Fungal species such as Aspergillus niger and Candida albicans were also detected. The highest bioburden was observed on fabric seatbacks in SETC coaches (6.7 × 104 CFU/cm2), exceeding values commonly reported in global literature. Multidrug resistance was noted in P. aeruginosa and S. aureus, particularly to ceftazidime, gentamicin, and cotrimoxazole.

Conclusion This study highlights the significant microbial load and presence of potential pathogens on high-touch public surfacesin Coimbatore. Findings suggest a plausible risk for fomite-mediated transmission, especially in enclosed environments like buses and theaters. The detection of multidrug-resistant strains supports the urgent need for improved surface sanitation protocols, public awareness on hand hygiene, and routine environmental surveillance programs that include antimicrobial resistance profiling.

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