Background:Bio-aerosols are a potential hazard in hospitals and are mostly produced by hospital staff, patients and visitors. Bio-aerosols are solid or liquid particles pending in the air and they consist of aerosols accompanying micro-organisms or organic compounds of micro-organisms such as endotoxin, metabolite, toxin and other parts of organism. Those are a potential hazard in hospitals and are mostly produced by hospital staff, patients and visitors.Objectives:This study aimed to determine the types and amount of bacterial contamination in operating rooms and emergency department of an educational hospital in Zahedan, South-East of Iran.Materials and Methods:In this study, 72 samples were collected from three operating rooms and three rooms in the emergency department of an educational hospital during 2012. On the first day of every month, a sample was taken from each room during the morning shift; active sampling was done on plates consisting of blood agar and brain-heart infusion agar (BHI) for 10 minutes in the axis of a one-story Anderson impactor (flow rate 28.1 litter per minutes) and SIBATA air pump SIP 32-L and samples were then placed in a 35°C Incubator. Bacterial colonies were counted; warm coloring and differential tests were done and the data were analyzed using Mann-Whitney U and Kruskal-Wallis tests.Results:Seventeen types of bacteria were detected including Staphylococcus, Micrococcus, Viridians, Pneumococcus, Escherichia coli, Streptococcus, Bacillus cereus, B. subtilis, Klebsiella, Pseudomonas, Diphtheroid, Citrobacter and Enterobacter. Quantitative bacterial results showed that the number of observed bacteria in the emergency department with an average of 103.88 ± 33.84 cfu/m³ was more than that of the surgery rooms with an average of 63.32 ± 32.94 cfu/m³. Furthermore, the highest average number of all counted colonies (106 ± 28.45 cfu/m³) was determined in autumn. In all samples, S. aureus and Micrococcus were the most detected bacteria.Conclusions:The World Health Organization (WHO) has suggested relatively relaxed limits of 100 cfu/m3 for bacteria and 50 cfu/m3 for fungi in the hospital air. Therefore, quantitative and qualitative outcomes of this study demonstrate that contamination level and bacterial variety in surgery rooms and emergency departments is high and effective measures must be taken to control the possible health risks.

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