Epidemiologic and molecular characterization of an outbreak of Candida parapsilosis bloodstream infections in a community hospital

Abstract

Candida parapsilosis is an important cause of bloodstream infections in the health care setting. We investigated a large C. parapsilosis outbreak occurring in a community hospital and conducted a case-control study to determine the risk factors for infection. We identified 22 cases of bloodstream infection with C. parapsilosis: 15 confirmed and 7 possible. The factors associated with an increased risk of infection included hospitalization in the intensive care unit (adjusted odds ratio, 16.4; 95% confidence interval, 1.8 to 148.1) and receipt of total parenteral nutrition (adjusted odds ratio, 9.2; 95% confidence interval, 0.9 to 98.1). Samples for surveillance cultures were obtained from health care worker hands, central venous catheter insertion sites, and medical devices. Twenty-six percent of the health care workers surveyed demonstrated hand colonization with C. parapsilosis, and one hand isolate was highly related to all case-patient isolates by tests with the DNA probe Cp3-13. Outbreak strain isolates also demonstrated reduced susceptibilities to fluconazole and voriconazole. This largest known reported outbreak of C. parapsilosis bloodstream infections in adults resulted from an interplay of host, environment, and pathogen factors. Recommendations for control measures focused on improving hand hygiene compliance.

FIG. 1.

Distribution of confirmed and probable C. parapsilosis infections by month of isolation, hospital A, Mississippi, 2001.

FIG. 2.

Cluster analysis results by Southern blotting with the Cp3-13 probe and testing for susceptibilities to fluconazole (FLU), voriconazole (VORI), and itraconazole (ITRA), hospital A, Mississippi, 2001. ID, type of isolate; H, hand; NOB, bloodstream or CVC tip isolates from patients after the outbreak period; OB, bloodstream or CVC tip isolates from case patients during the outbreak; OB*, noninvasive isolates from case patients during the outbreak; Other, isolates from patients unrelated to the outbreak.