Hospital Air and Healthcare Personnel as Reservoirs of Drug-Resistant Bacteria in Tertiary Care Settings in Pakistan

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. Plain Language Summary: Why was this study done? The emergence of antibiotic-resistant bacteria is a serious and growing threat to global health. Hospitals cater to many people who are at high risk of infection, and healthcare workers are routinely exposed to antibiotic-resistant bacteria during their daily work. We tried to understand whether hospital air and healthcare staff themselves may contribute to the spread of antibiotic-resistant bacteria within hospital environments. What did the researchers do and find? We collected samples from hospital air and from the nose of 40 healthcare workers across four major hospitals in Pakistan. We identified the bacteria present and tested which antibiotics were still effective against them. We found that some bacteria, such as Staphylococcus aureus , were detected both in the air and among healthcare workers, suggesting possible movement between the environment and staff. Many of these bacteria showed resistance to multiple antibiotics, which can make infections harder to treat. We also identified specific genes that explain why these bacteria are resistant. What do these results mean? Our findings suggest that hospital air and healthcare workers are part of a connected system in which antibiotic-resistant bacteria can circulate. This highlights the importance of protecting both patients and healthcare staff. In addition to surface cleaning, hospitals may benefit from broader infection control strategies, such as improved air management and routine staff monitoring, to reduce the risk of transmission. Keywords: antimicrobial resistance, bacterial infection, molecular epidemiology, environmental health