An outbreak of vancomycin-resistant Enterococcus faecium in liver transplant recipients

Vancomycin-resistant Enterococcus faecium (VREF) has become a significant nosocomial pathogen for immunosuppressed patients. During a 5-month period in 1993, 8 cases of invasive infection with VREF (7 with bacteremia) were identified in liver transplant recipients, half of whom were adults. Epidemiology and microbiology studies were designed to identify the source and to determine the risk factors for this infection. Overall mortality was 50% (3 adults and 1 child). Mortality in bacteremic patients was 57%. A case-control study showed that cases were more likely to have been treated with a third-generation cephalosporin or vancomycin and to have undergone more than four biliary tract procedures. Environmental surveillance cultures yielded only one VREF isolate from a rectal temperature probe, but this device was used in only 2 of the cases. Cultures from all surgery and radiology suites were negative. All VREF isolates were genotyped by contour-clamped homogenous electric field electrophoresis of chromosomal DNA restriction fragments. These studies showed that a single clone was responsible for the outbreak, although other clones could be detected in the hospital. After implementing strict contact isolation on the liver transplant unit, only 1 additional patient with VREF was identified during this outbreak. In conclusion, it was found that antibiotic use and biliary tract manipulation were risk factors for developing invasive infections with VREF after liver transplantation. Optimal treatment is still unclear but most likely includes a combination of two or more antibiotics. Prompt institution of infection control measures can preclude rapid spread of this nosocomial pathogen.