Dispersal of methicillin-resistant Staphylococcus epidermidis by staff in an operating suite for thoracic and cardiovascular surgery: relation to skin carriage and clothing.

Methicillin-resistant Staphylococcus epidermidis (MRSE) is a common cause of deep sternal infections. The aim of the present investigation was to evaluate staff in an operating suite for thoracic and cardiovascular surgery as a possible source of MRSE and the possibility of reducing the amount of MRSE shed into the air by wearing tightly woven scrub suits. A second aim was to compare the results of dispersal obtained in a test chamber with those from an operating room. We studied carriage of MRSE in the nose and on different skin sites and made an experimental study of dispersal of MRSE during exercise in a test chamber and during operations, using two different types of scrub suits. Dispersal of MRSE [defined as > 1% of the total count of colony forming units (CFU) shed into the air] occurred in 25% of women and 43% of men. Nasal carriage was found among 28% in women and 33% in men. Among five skin-sampling sites, carriage of MRSE was most frequent on the cheek (50%) and in the axilla (24%) and least frequent in the perineum (5%). Dispersal of MRSE was however more strongly associated with carriage in the perineum (P = 0.097) than on the cheek (P = 0.5) and in the axilla (P = 0.21). With regard to shedding of bacteria into the air, there was a significant difference in favour of the tightly woven clothes regarding total counts of CFU both in the test chamber (P = 0.02) and the operating theatre (P = 0.002). Regarding MRSE, no such difference was found. We found there were too many dispersers of MRSE among operating department staff to exclude them from work. Although tightly woven scrub suits significantly reduced the amount of bacteria shed into the air, the amount of MRSE was not significantly reduced. Full-scale experiments in operating rooms are not needed when evaluating the protective capacity of different scrub suits as results from a test chamber give conclusive information.