Carriage of Staphylococcus aureus and of gram-negative bacilli resistant to third-generation cephalosporins in cirrhotic patients: a prospective assessment of hospital-acquired infections.

OBJECTIVE: To study the relation between Staphylococcus aureus nasal and stool colonization, stool carriage of gram-negative bacilli resistant to third-generation cephalosporins (CephR), and subsequent infections during hospitalization. DESIGN: Prospective study. PATIENTS: 551 cirrhotic patients with 589 consecutive hospital stays. All patients were screened within 48 hours of admission; 589 nasal swabs, 417 stool specimens, and 589 urine samples were analyzed. RESULTS: Carriage rates were 18.8% for methicillin-sensitive S aureus (MSSA), 16.3% for methicillin-resistant S aureus (MRSA), and 13.7% for CephR. We observed 87 episodes of spontaneous bacterial peritonitis, 63 cases of bacteremia, and 167 urinary tract infections occurred. Only 1 case of bacteremia and 4 urinary tract infections due to CephR occurred in patients carrying the same organism in their stools. The risk of MRSA ascitic fluid infections, bacteremia, and urinary tract infections was 3.1% versus 1% (not significant), 8.3% versus 0.8% (P<.001), and 11.4% versus 0.6% (P<.001) in carriers and noncarriers, respectively. Pulsed-field gel electrophoresis (PFGE) of isolates from 16 patients infected by MSSA (3 cases) and MRSA (13 cases) demonstrated that the colonizing strains matched the invasive strains in the 3 MSSA cases and in 8 of 13 MRSA cases. CONCLUSION: Carriage of CephR strains is not associated with subsequent infection by these organisms in hospitalized cirrhotic patients. In contrast, MRSA carriage was an important risk factor for MRSA bacteremia and urinary tract infection.