Staphylococcus aureus Nasal Colonization in Patients with Cirrhosis: Prospective Assessment of Association with Infection

Objective: To determine if Staphylococcus aureus colonization of the anterior nares was a risk factor for S aureus infection in patients with cirrhosis and to determine the predictors of S aureus infection in colonized patients. Design: Prospective cohort study. Patients: 84 consecutive patients with cirrhosis admitted to the liver transplant unit of a university-affiliated Veterans' Affairs Medical Center. Results: Overall, 39 (46%) of the 84 patients were nasal carriers of S aureus, of which 24 (29%) were methicillin-resistant Staphylococcus aureus (MRSA) and 15 (18%) were methicillin-sensitive Staphylococcus aureus (MSSA). Only MRSA, but never MSSA, carriage was acquired in the hospital; all 15 of the MSSA versus 14 (58%) of the 24 MRSA carriers were nasal carriers on first (admission) culture (P=.001). Of the 10 (42%) of 24 MRSA carriers who were not colonized on admission, 3 became MRSA carriers within 1 month, and 7 acquired MRSA carriage more than a month later. Higher Child-Pugh score was independently associated with MRSA carriage (odds ratio [OR], 1.54; 95% confidence interval [$CI_{95}$], 1.1-2.3). S aureus nasal carriers (9 [23%] of 39) were significantly more likely to develop S aureus infections than noncarriers (2 [4%] of 45; P=.02). Central venous catheter use was associated independently with S aureus infections in the carriers (OR, 4.1; $CI_{95}$, 2.8- 6.1). Mortality was significantly higher in carriers who developed S aureus infections as compared to those who did not (57% vs 13%; P=.022) ; S aureus infection was an independent predictor of mortality in the carriers (OR, 8.7; $CI_{95}$, 1.2-63.8). Conclusions: Colonization of the anterior nares was a significant predictor of S aureus infection in patients with cirrhosis.