Candida parapsilosis bloodstream infection in pediatric oncology patients: Results of an epidemiologic investigation

OBJECTIVE: To investigate an outbreak of Candida parapsilosis bloodstream infections (BSIs) involving three patients admitted to a pediatric oncology unit between April and June 2002. METHODS: After the third case was documented, cultures were performed of the hands of all medical and paramedical staff members in the pediatric oncology unit and of environmental surfaces in the rooms occupied by the three patients. Electrophoretic karyotypuig with pulsed-field gel electrophoresis and arbitrarily primed polymerase chain reaction were used to assess the genetic relatedness among C. parapsilosis isolates. RESULTS: The three cases of C. parapsilosis BSI were diagnosed based on blood cultures performed during a 38-day period. Evidence of prior C. parapsilosis colonization of the gastrointestinal tract was present in only the first case. Each patient had an indwelling central venous catheter (CVC), which was promptly removed, and semiquantitative catheter tip cultures also revealed C. parapsilosis. None of the 30 environmental cultures performed was positive for C. parapsilosis, but the fungus was isolated from the hands of 6 of the 20 nurses tested. Both molecular typing methods revealed identical DNA fingerprinting patterns for all 13 patient isolates (7 from blood, 3 from CVC tips, and 3 from the gastrointestinal tract) and for 5 of the 6 recovered from the nurses' hands. CONCLUSIONS: These findings suggest the possibility of cross-infection with a single C. parapsilosis strain that was transmitted (probably during CVC dressing changes) by nurses whose hands were colonized with it. The role of previous gastrointestinal colonization in the first case cannot be excluded (Infect Control Hosp Epidemiol 2004;25:641-645).