Decrease in Staphylococcus aureus colonization and hospital-acquired infection in a medical intensive care unit after institution of an active surveillance and decolonization program

Abstract

Objective: To evaluate the effects of an active surveillance program for Staphylococcus aureus linked to a decolonization protocol on the incidence of healthcare-associated infection and new nasal colonization due to S. aureus.

Design: Retrospective quasi-experimental study.

Setting: An 18-bed medical intensive care unit at a tertiary care center in Cleveland, Ohio.

Methods: From January 1, 2006, through December 31, 2007, all patients in the medical intensive care unit were screened for S. aureus nasal carriage at admission and weekly thereafter. During the preintervention period, January 1 through September 30, 2006, only surveillance occurred. During the intervention period, January 1 through December 31, 2007, S. aureus carriers received mupirocin intranasally. Beginning in February 2007, carriers also received chlorhexidine gluconate baths.

Results: During the preintervention period, 604 (73.7%) of 819 patients were screened for S. aureus nasal carriage, yielding 248 prevalent carriers (30.3%). During the intervention period, 752 (78.3%) of 960 patients were screened, yielding 276 carriers (28.8%). The incidence of S. aureus carriage decreased from 25 cases in 3,982 patient-days (6.28 cases per 1,000 patient-days) before intervention to 18 cases in 5,415 patient-days (3.32 cases per 1,000 patient-days) (P=.04; relative risk [RR], 0.53 [95% confidence interval {CI}, 0.28-0.97]) and from 9.57 to 4.77 cases per 1,000 at-risk patient-days (P=.02; RR, 0.50 [95% CI, 0.27-0.91]). The incidence of S. aureus hospital-acquired bloodstream infection during the 2 periods was 2.01 and 1.11 cases per 1,000 patient-days, respectively (P=.28). The incidence of S. aureus ventilator-associated pneumonia decreased from 1.51 to 0.18 cases per 1,000 patient-days (P=.03; RR, 0.12 [95% CI, 0.01-0.83]). The total incidence of S. aureus hospital-acquired infection decreased from 3.52 to 1.29 cases per 1,000 patient-days (P=.03; RR, 0.37 [95% CI, 0.14-0.90]).

Conclusions: Active surveillance for S. aureus nasal carriage combined with decolonization was associated with a decreased incidence of S. aureus colonization and hospital-acquired infection.