Bioaerosol sampling for airborne bacteria in a small animal veterinary teaching hospital

Airborne microorganisms within the hospital environment can potentially cause infection in susceptible patients. The objectives of this study were to identify, quantify, and determine the nosocomial potential of common airborne microorganisms present within a small animal teaching hospital.

Bioaerosol sampling was done initially in all 11 rooms and, subsequently, weekly samples were taken from selected rooms over a 9-week period. Samples were collected twice (morning and afternoon) at each site on each sampling day. The rooms were divided into two groups: Group 1, in which morning sampling was post-cleaning and afternoon sampling was during activity, and Group 2, in which morning sampling was pre-cleaning and afternoon sampling was post-cleaning. The total aerobic bacterial plate counts per m(3) and bacterial identification were done using standard microbiological methods.

A total of 14 bacterial genera were isolated with the most frequent being Micrococcus spp. followed by species of Corynebacterium, Bacillus, and Staphylococcus. There was a significant interaction between location and time for rooms in Group 1 (p=0.0028) but not in Group 2 (p>0.05). Microbial counts for rooms in Group 2 were significantly greater in the mornings than in the afternoon (p=0.0049). The microbial counts were also significantly different between some rooms (p=0.0333).

The detection of significantly higher airborne microbial loads in different rooms at different times of the day suggests that the probability of acquiring nosocomial infections is higher at these times and locations.