Airborne bacteria in veterinary surgical theatres in South Africa

The bioaerosol composition of the theatre environment plays a determining role in the development of surgical site infections (SSIs). It has been demonstrated that the concentration of viable airborne bacteria is influenced by the level of room occupancy, utilisation of surgical attire and importantly, proper ventilation systems, which are often lacking in the average veterinary facility. The aim of this study was to evaluate the airborne bacterial load encountered in non-environmentally controlled small animal veterinary theatres during routine surgical sterilisations, and to correlate these findings with the managerial practices at the facility. Four veterinary facilities with differing throughputs and managerial practices were recruited into the study. Blood agar settle plates, open from first incision to last suture, were used to quantify organisms that could settle in an incision. The 45 plates yielded 487 bacterial isolates (53 species). The Micrococcus (28.8%) and Staphylococcus (16.8%) genera were predominant. Of the isolates 61.8% were classified as human/small animal commensals and 37.2% belonged to species previously implicated in small animal SSIs. Specific trends were additionally evident in the bioaerosol loads. High room occupancy, lack of surgical attire and exposure to the outside environment were associated with higher bacterial counts. Accumulation from consecutive procedures was identified and linked to total occupancy time of the room. Current mitigation measures were not ideal to minimise the SSI risk. Routine, frequent and thorough cleaning in combination with surgical attire utilisation is recommended to reduce the bioburden for patient benefit.