Background: Evaluation of the type and concentration of microorganisms in the air of a hospital can be an indicator of whether such environments are clean or not, and also to be considered as a source of nosocomial infections. The aim of this study was to identify the type and concentration of Bio-aerosols associated with nosocomial infections in different wards of selected AJA hospitals in Tehran.
Materials and methods: In a cross-sectional and descriptive- analytical study 120 bacterial and 120 fungal samples were collected from the operation rooms, Intensive Care Units (ICUs) and Infectious diseases wards of two studied hospitals (A and B). A passive indoor environment sampling was carried out within 120 days, once every six days.
Results: The average concentration of bacteria in the air of A and B hospitals were 84 and 212 CFU/m³, respectively. Also, the Average concentration of fungal species of A and B hospitals were was 80 and 85 CFU/m³, respectively. The dominant fungal species of these hospitals were Cladosporium (25%) and Aspergillus niger (28%), respectively. Also, Staphylococcus epidermidis was determined as the dominant bacterial species in both hospitals. Significant linear correlation existed between population density and concentration of bio-aerosols.
Conclusion: According to the results of this study, bacterial and fungal bio-aerosol concentrations in the studied hospitals were higher than the existing standards and it indicates the low efficiency of the ventilation system in these hospitals.