NASAL CARRIAGE OF STAPHYLOCOCCUS-AUREUS AND CROSS-CONTAMINATION IN A SURGICAL INTENSIVE-CARE UNIT - EFFICACY OF MUPIROCIN OINTMENT

A six month prospective study was carried out in a surgical intensive care unit (SICU) of a university hospital to assess the incidence and routes of exogenous colonization by Staphylococcus aureus. A total of 157 patients were included in the study. One thousand one hundred and eleven specimens (nasal, surgical wound swabs, tracheal secretions obt ained on admission and once a week thereafter, and all clinical specim ens) were collected over a four month period from patients without nas al decontamination (A). They were compared with 729 specimens collecte d over a two month period from patients treated with nasal mupirocin o intment (B). All S. aureus strains were typed by restriction fragment length polymorphism (RFLP) pulsed-field gel electrophoresis after SmaI macrorestriction. The nasal colonization rates on admission were 25.5 and 32.7% in groups A and B, respectively. Thirty-one untreated patie nts (31.3%) and three patients (5.1%) treated with nasal ointment, acq uired the nasal S. aureus in the SICU (P=0.00027). Nasal carriers were more frequently colonized in the bronchopulmonary tract (Bp) and surg ical wound (Sw) (62%) than patients who were not nasal carriers (14%) (P<0.00001). The patterns were identical for nasal, Bp and Sw strains from the same patient. RFLP analysis characterized seven epidemic stra ins of methicillin-resistant S. aureus (MRSA) which colonized 60% of g roup A and 9% of group B patients (P<0.00001). The bronchopulmonary tr act infection rate was reduced in group 13 (P=0.032). In conclusion, i n an SICU, nasal carriage of S. aureus appeared to be the source of en dogenous and cross-colonization. The use of nasal mupirocin ointment r educed the incidence of Bp and Sw colonization, as well as the MRSA in fection rate.