Assessment of airborne bacterial and fungal communities in different wards of educational hospitals: A case study in Urmia, Iran

Bioaerosols consist of aerosols which are biologically originated and can be present ubiquitously in different environments, including the indoor air of hospitals. The objective of this study was to survey the bioaerosol type and density in various environments of four governmental educational hospitals in Urmia, Iran, namely the intensive care unit (ICU), operating room, the internal medicine room, the infectious diseases room, the infectious diseases corridor, and ambient air.

Sampling was performed during summer and winter of 2019 at four different day-times using passive (sedimentation plate) and active methods (an Andersen one-stage viable impactor and Quick Take-30 sampling instrument) and by counting plates containing a bacterial and fungus-selective medium.

The results revealed that the highest microbial bioaerosol load was related to the infectious diseases corridor (100 and 150 CFU/m3 for total bacterial and fungal load, respectively). The highest bacterial and fungal density was observed in the afternoon at 17-18; and the concentration of bioaerosols was higher in summer than winter. A comparison of indoor and outdoor bacterial loads showed that the indoor bacterial concentration mean (49.1±23.8 CFU/m3) was higher than the outdoor value (47.1±21.5 CFU/m3), and the indoor levels of fungal contamination (83.3±31.9 CFU/m3) were significantly lower than outdoor values (182.5±48.0 CFU/m3). The predominantly isolated bacteria were Staphylococcus (95%) spp, and the main isolated fungi belong to the genera Aspergillus (50%) and Penicillium (32%).

The results of this study can be useful in developing indoor air microbial quality guidelines in hospitals, which has not been done so far.