Biological risk in the operating room: microbiological monitoring of the environment and analysis of the associated variables

The authors present an environmental microbiological monitoring programme carried out over a period of 15 months in 16 operating theatres performing specific types of surgery. The levels of microbial contamination of the air and of four of the most representative surfaces of the clean area were determined at 3 different times for each theatre, both before and during surgery. For the air assessment, the results obtained with three different samplers, Sed-3 Unit, SAS and RCS, were compared. The results were on the whole acceptable, but some poor conditions were detected during the theatres in use, especially in general surgery theatres; in some of these the floors showed levels of contamination consistently exceeding the reference limits. As the monitoring programme proceeded, the microbiological quality of the air and of the surfaces in the theatres notably improved. The three air samplers showed different conditions expressed with units of measure not always readily comparable. For active samplers, the bacterial load determined by RCS, although less variable, were always higher (even 2-3 fold) than those obtained with the SAS. Passive sampling takes longer but determines the real risk of infection for the patients; contemporary determination of the fall-out and the CFU/m3 helps to identify the occupational risks. Since the limit values established by the ISPESL guidelines for the operating theatres have been defined only for active samplers, there is urgent need for more exhaustive national guidelines to define similar values also for passive sampling. The Authors conclude stressing the importance of promoting continuing information-education programmes to heighten the awareness of all those involved in operating theatre activities.