Airborne microbial load and antimicrobial resistance profiles in two Egyptian hospitals

Background: Hospital-acquired infections (HAIs) are caused by microorganisms that might be multidrug-resistant (MDR) and can be airborne. This study aimed to assess the hospital air microbial loads, their associated risk factors, and detect MDR airborne pathogens. Methods: Between June 2022 and May 2023, a cross-sectional study was carried out in two hospitals in Cairo. Using passive air sampling, 288 settle plate samples were taken from operating rooms (ORs), intensive care units (ICUs), and admission (AD) areas. The isolated microorganisms were counted and identified, and their antibiotic susceptibility was determined. The association between microbial loads, air parameters, and other factors was determined. Results: The AD areas in both hospitals had the highest mean microbial load. The most common bacteria were Staphylococcus aureus (n = 49/196, 25%) and Klebsiella pneumoniae (n = 18/196, 9.2%). MDR bacteria represented 51.5% of all bacterial isolates. The predominant fungal genus was Aspergillus spp. (n= 55, 30.05%). Multivariate analyses found that significant factors affecting microbial loads were crowding index (OR = 21.73, p = 0.003), the lack of mechanical ventilation (OR = 6.10, p = 0.012), the presence of damp materials (OR = 0.21, p = 0.015), bed-making activities (OR = 0.17, p = 0.040) as well as the presence of waste materials (OR = 4.54, p = 0.011). Conclusion: S. aureus and K. pneumoniae were the commonest airborne pathogens. Crowding index, lack of mechanical ventilation, presence of damp materials, bed-making activities, and the presence of waste materials were all associated with high air microbial loads.