摘要：Background: In both residential and hospital indoor environments, humans can be exposed to airborne microorganisms. The hospital’s indoor air may contain a large number of disease-causing agents brought in by patients, staff, students, visitors, ventilation, or the outside. Hospitalized patients are at a higher risk of infection due to confined spaces, crowdedness, and poor infection prevention practices, which can accumulate and create favorable conditions for the growth and multiplication of microorganisms. Therefore, the aim of this study was to evaluate the indoor air bacterial load in Dilla University Hospital, Southern Ethiopia. Methods: An institutional-based cross-sectional study design was used to assess the bacterial load in the indoor air at Dilla University Hospital. To determine the bacterial load, a passive air sampling technique was used. The settle plate method was used to collect data, which involved exposing Petri-dishes filled with blood agar media to the indoor air of the sampled rooms for 60 minutes. Result: A total of 72 indoor air samples were collected once a week for 2 weeks at 14-day intervals from 18 rooms in 8 wards, and samples were collected twice a day in the morning and afternoon. The mean bacterial concentrations ranged from 450 to 1585.83 CFU/m 3 after 60 minutes of culture media exposure. The mean bacterial concentrations in the obstetrics, surgical, pediatric, gynecology, and medical wards exceeded WHO guidelines. A high indoor air bacterial load was found in 58 (80.6%) of the samples in this study. Gram-positive bacteria in the air were the most common 51 (71%) of the bacterial population measured in all indoor environments. Fungal growth was found in 65 (90.3%) of the samples. Temperatures (26.5°C-28.3°C) and relative humidity (61.1%-67.8%) in the rooms were both above WHO guidelines, creating favorable conditions for bacterial growth and multiplication. Conclusion: The majority of the wards at Dilla University Hospital had bacterial loads in the air that exceeded WHO guidelines. Overcrowding, high temperatures, inadequate ventilation, improper waste management, and a lack of traffic flow control mechanisms could all contribute to a high concentration of bacteria in the indoor air. To control the introduction of microorganisms by patients, students, caregivers, and visitors, it is critical to regularly monitor indoor air bacterial load and implement infection prevention and control measures.
