Seasonal and spatial variations of bioaerosols and antibiotic resistance bacteria in different wards of the hospital

Introduction: Transmission of bioaerosols through the air is known as an important route for a wide range of nosocomial infections. Therefore, in the present study, we aimed to evaluate the type and diversity of bioaerosols and antibiotic resistance of bacterial bioaerosols in the indoor environments of Sina educational and treatment hospital, Tabriz, Iran. 
Methods and materials: 150 samples of bacteria and fungi (75 fungi and 75 bacteria) bioaerosol samples were collected on petri dish containing Sabouraud dextrose agar from February to March and June to July 2020 in three periods of daytime (morning, noon and evening) according to National Institute for Occupational Safety and Health (NIOSH 0-800) standard. After sampling, fungal and bacterial samples were incubated and the disk diffusion agar method (Kirby-Bauer) was used for assessing the antibiotic resistance. 
Results: The concentration of bioaerosols varied significantly in different wards. In addition, the concentration of bioaerosols in winter was observed to be higher than in summer. The highest and lowest airborne fungal concentrations were found in burns operating room and men's infectious ward (49 CFU/m3) and children's burns ward (28 CFU/m3), respectively. The predominantly isolated bacteria were Streptococcus spp. (38%) and Staphylococcus spp. (37%). Also, the main isolated fungi belonged to the genera Aspergillus (75.9%) and Penicillium (22.5%). The highest rates of antibiotic resistance were observed for colistin (100%) in Gram-negative and penicillin (84.2%) in Gram-positive. 
Conclusion: Timely and regular disinfection of hospital wards can affect the density of bioaerosols. Owing to the prevalence of COVID-19 epidemic in the world, the staff and patients often were wearing masks, gloves and special clothing as well as using disinfectants to prevent coronavirus infection in wards during the summer sampling.