Surveillance of bacterial colonization in operating rooms

Surgical site infections (SSIs) continue to occur at an unacceptably high rate, incurring direct costs of up to $10 billion per year in the United States and far more than that in total economic costs. There is a continued need to identify potential sources of microbial contamination that lead to surgical infections.

Using contact culture plates, we randomly took a total of 517 samples of various surfaces in 33 operating rooms (ORs) over a 6-mo period.

Flat surfaces treated with decontamination techniques (floors, anesthesia carts, operating tables, and other flat surfaces) grew small numbers of bacterial colonies, as did other surfaces that were decontaminated less often. Personal items, especially the tops of shoes and personal hats, had much higher contamination than the surfaces just described, which in the case of these two items averaged 50-60 CFU/20 cm(2). The outsides of face masks contained slightly more organisms than did floors, but the insides had almost 100 times more organisms, which was of concern because of high leakage rates at the mask-face interface.

The culture system used in our study can be used as a simplified and cost-effective method of identifying the comparative densities of organisms on different surfaces for surveillance of microbial contamination in the OR. To reduce bacterial contamination, shoe covers and disposable hair coverings should be worn at every operation in which there are substantial risks of SSI. Masks that reduce leakage at the mask-face interface should be worn and discarded after each operation.