An outbreak of Candida parapsilosis prosthetic valve endocarditis

Candida parapsilosis, an important nosocomial pathogen and the most common species of Candida found on the hands of health care workers, is a rare cause of prosthetic valve endocarditis (PVE). From March through June 1994, four cases of C. parapsilosis PVE were diagnosed at a 400-bed community hospital. The mean time to presentation after valve replacement surgery was 148 days (range, 20 to 345). Three of the four patients died of complications of PVE. Multiple environmental cultures were performed, and only one was positive for C. parapsilosis. Cultures from the bypass pump, cell saver, cardioplegia solution, and subsequent valves were all negative. All valve replacements were performed by the same operating room team. Interviews with the surgeon and physician assistant, the only personnel involved in all cases, revealed that their hypoallergenic gloves were subject to frequent tears during valve replacement procedures, often requiring several glove changes per procedure. Hand cultures of personnel were obtained, and cultures from 20 individuals (26%) were positive for C. parapsilosis. Hand cultures of the surgeon and physician assistant obtained 8 months after the last case had surgery were negative for yeasts. Molecular typing of the 3 available case isolates, 14 epidemiologically unrelated patient isolates, 1 environmental isolate, and 20 hand isolates was performed by electrophoretic karyotyping and restriction endonuclease analysis of genomic DNA using restriction enzymes BssHII and EagI followed by pulsed field gel electrophoresis. The three case isolates were identical by restriction endonuclease analysis of genomic DNA, and two of the three shared the same electrophoretic karyotyping profile. The remaining patient, environmental, and hand isolates represented 29 different DNA types and were distinctly different from the case isolates. All of the isolates tested were susceptible to amphotericin B, 5FC, fluconazole, and itraconazole. The circumstantial evidence suggests the probability of glove tears during valve replacement surgery and subsequent transmission of C. parapsilosis to patients.