The importance of airborne bacterial contamination of wounds

An investigation was made into the sources of bacterial contamination of hip and knee joint replacement operations carried out in either a conventionally-ventilated or a laminar-flow operating room. It was demonstrated that the bacterial count in the air during the operations was 413/m3 in the conventionally-ventilated and 4/m3 in the laminar-flow room (a 97-fold reduction) and the average number of bacteria washed out after surgery was 105 and three, respectively (a 35-fold reduction); these facts suggest that 98 per cent of bacteria in the patients' wounds, after surgery in the conventionally-ventilated operating room, came directly or indirectly from the air. It was also ascertained that the minority of bacteria in the wound fell directly from the air (perhaps 30 per cent); the remainder presumably fell on to other surfaces and were transferred indirectly to the wound by other routes. Analysis of the relationship between the number of bacteria washed from the wound at the end of operation to both the number of bacteria in the air of the operating room and those on the patient's skin at the wound site, clearly showed that the most important and consistent route of contamination was airborne. However, on occasions when patients had exceptionally high skin carriage of bacteria, gross wound contamination occurred