Microbial Contamination on Used Surgical Masks among Hospital Personnel and Microbial Air Quality in their Working Wards: A Hospital in Bangkok.

OBJECTIVE To assess the relationship of bacterial and fungal contamination on used surgical masks worn by the hospital personnel and microbial air quality in their working wards. METHODS This is a cross-sectional study of 230 used surgical masks collected from 214 hospital personnel, and 215 indoor air samples collected from their working wards to culture for bacterial and fungal counts. This study was carried out at the hospital in Bangkok. Group or genus of isolated bacteria and fungi were preliminarily identified by Gram's stain and lacto-phenol cotton blue. Data were analyzed using paired t-test and Pearson's correlation coefficient at the significant level of p<0.050. RESULTS Means and standard deviation of bacterial and fungal contamination on inside area of the used masks were 47 ± 56 and 15 ± 9 cfu/ml/piece, and on outside area were 166 ± 199 and 34 ± 18 cfu/ml/piece, respectively, p<0.001. The bacterial and fungal contamination on used masks from hospital personnel working in the male and female medical wards and out-patient department, as well as the bacterial and fungal counts of the indoor air sample collected from the same area were relatively higher than the other wards. The predominant isolated bacteria and fungi contaminated on inside and outside areas of the used masks and air samples were similar (Staphylococcus spp. and Aspergillus spp.; respectively). For its relationship, results found that bacterial and fungal counts in air samples showed significantly positive correlation with the bacterial contamination load on outside area of the used masks, r=0.16, p=0.018 and r=0.21, p=0.003, respectively. CONCLUSION High bacterial contamination on outside area of the used masks was demonstrated, and it showed a significant correlation with microbial air quality of working wards.