Microbial quality assessment of indoor air in a large hospital building during winter and spring seasons

Sensitivity of hospital building environment due to presence of potential sources of wide range of airborne microbes, make it a complex environment. Present study aimed to investigate seasonal (winter & spring) variation in airborne microbial levels as well as species on various locations (i.e. operation theatres (OT1 & OT2), wards (GMW & SW), out-patient department (OPD) and emergency services (ES)) of a large hospital building. Air samples were collected during peak hours, twice a week, covering one month of each season. Statistically significant variation (p > 0.05) in bacterial concentrations over two seasons was found only for OPD. However, fungal concentrations significantly varied (p < 0.05) over two seasons for all sites except for OT1 and OT2. Concentrations among most of sites were significantly different. Highest bacterial level was found in OPD (mean: 1649.7 CFU/m(3)) while lowest in the two OTs (mean: 221 CFU/m(3) for OT1 and 236 CFU/m(3) for OT2). Highest fungal level was found in GMW (mean: 193.4 CFU/m(3)) while lowest in the two OTs (mean: 41.1 CFU/m(3) for OT2 and 58 CFU/m(3) for OT1). Bacterial identification showed dominancy of gram positive cocci (89.8%) followed by gram positive rods (7.2%) and gram negative rods (3%). Identified bacterial strains belonged to genera staphylococcus, micrococcus, kocuria, aerococcus, kytococcus, bacillus and pseudomonas. The most abundant fungal genera included cladosporium (47%), aspergillus (17.1%), penicillium (7.1%), altemeria (6.2%), geotrichium (3.68%) and ulocladium (3.2%). Cleaning frequencies appeared to be important factor in maintaining low microbial load in air.