Estimation of microbial air contamination by settle plate method : are we within acceptable limit

Microbiological quality of air can be considered as a mirror of hygienic conditions of any place, especially operating theatres. Nowadays the evaluation of the level of air microbial contamination in places at risk is considered to be a basic step towards prevention. The objective of this study was to determine the bacterial load and antibiotic susceptibility pattern of various isolates in operating room’s indoor air. The index of microbial air contamination was based on the count of the microbial fallout on to Petri dishes left open to the air according to the 1/1/1 scheme (for 1 h, 1m from the floor, at least 1m away from walls or any obstacle). A total of 86 samples taken repeatedly from ten different operation theatres were processed and the isolates were Staphylococcus aureus, Coagulase negative Staphylococcus, Micrococcus spp and Bacillus spp. Total bacterial load from all the OTs were within acceptable standard limits. Not even a single strain of MRSA was detected. Thus, air quality of an operation theatre area is an important issue which cannot be neglected, especially in reference to the hospital acquired infections. Recording the susceptibility pattern of the isolates to commonly used antibiotics in the area not only helps to select appropriate antibiotics for empirical therapy but also helps to design suitable hospital infection prevention protocols in an effort to minimize the incidence of costly surgical site infections.