Microbial contamination associated with routine aseptic practice

We have studied the rate of fortuitous contamination associated with routine aseptic technique under operational conditions. Stainless steel strips, as simulators of surgical instruments, were contained in sterilized surgical packs and assayed by nursing personnel during surgical and other invasive procedures at three different hospitals. The rates of contamination observed for the 36 investigators ranged from 0% to 11·3%, with an overall rate of 2·7%. Assays conducted in a clean room environment, under conditions approaching industrial sterility standards, showed a contamination rate of 0·16%. We concluded that aseptic practices, as routinely performed without any noticeable breaks or transgressions, do not guarantee sterility. The concept of surgical sterility implies low level, but measurable, microbial contamination.