Evolving trends in multiple-antibiotic-resistant bacteria in liver transplant recipients: a longitudinal study of antimicrobial susceptibility patterns

Abstract

The incidence, sources, impact on outcome, and temporal trends in multiple-antibiotic-resistant bacteria in liver transplant recipients over the last decade (from 1990 through 1999) were assessed. Of 165 consecutive patients who underwent transplantation, 31% (51 of 165 patients) had at least 1 infection caused by multiple-antibiotic-resistant bacteria. Overall, 69% (66 of 96 infections) of all bacterial infections were multiple-antibiotic resistant. Ninety-one percent (45 of 49 isolates) of the Staphylococcus aureus isolates, 50% (6 of 12 isolates) of the enterococci, and 54% of the gram-negative bacteria (47%; 7 of 15 Pseudomonas aeruginosa, and 60%; 12 of 20 Enterobacteriaceae) were multiple-antibiotic resistant. A significant trend toward an increase in infections caused by multiple-antibiotic-resistant bacteria (P =.003), largely caused by an increase in gram-positive infections, was documented through the decade. There was a significant increase in infections caused by methicillin-resistant S aureus (P =.0001) and vancomycin-resistant enterococci (P =.04) over time. The proportion of gram-negative isolates that were multiple-antibiotic resistant (P =.447) did not increase significantly over time. However, a strikingly high frequency of resistance to piperacillin or ceftazidime suggests that extended-spectrum beta-lactamase production in our Enterobacteriaceae may have been more prevalent than realized. Mortality at 1 year was significantly greater in patients with multiple-antibiotic resistant bacteria compared with all other patients (P =.001). These longitudinal trends have implications not only for guiding therapeutic practices, but ultimately for devising strategies to curtail multiple-antibiotic resistance in liver transplant recipients.