Abstract
PURPOSE: The aim of this cross-sectional study was to evaluate the environmental-human interface of antimicrobial resistance (AMR) by investigating drug-resistant bacteria in hospital air and the nasal microbiota of healthcare personnel across four tertiary care hospitals in Pakistan. MATERIAL AND METHODS: A total of 80 samples (40 aerosol samples and 40 nasal swabs) were collected and analyzed using culture-based microbiological identification. Antimicrobial susceptibility testing was performed using the Clinical & Laboratory Standards Institute-guided disc diffusion method, and polymerase chain reaction (PCR) was used to screen representative β-lactam-resistant isolates for key resistance genes, including blaZ, blaI, CTX-M, and SHV. RESULTS: Bacterial isolates were categorized into three ecological groups: environment-exclusive strains (eg, Escherichia coli detected only in aerosols and viridans streptococci detected only in nasal samples), co-existing strains prevalent in both niches (notably Staphylococcus aureus and Staphylococcus epidermidis), and strains showing marked differential prevalence between environments (eg, Serratia marcescens predominant in aerosols and Enterococcus spp. in nasal samples). A high proportion of isolates exhibited resistance to multiple antibiotic classes, consistent with multidrug-resistant (MDR) phenotypes, while resistance patterns suggestive of extensive drug resistance were observed in selected isolates. Molecular analysis confirmed the presence of clinically relevant β-lactamase genes, including blaZ/blaI in aerosol-derived S. aureus and CTX-M/SHV in nasal Klebsiella pneumoniae. CONCLUSION: These findings demonstrate that hospital air acts as not only a reservoir for environmental pathogens but also a potential conduit for microbial exchange with healthcare personnel. Therefore, integrated infection control strategies incorporating air quality management and personnel surveillance are essential. As the interpretation of the findings is limited by the cross-sectional design and reliance on culture-based methods, future studies should include longitudinal and molecular-based approaches.