Outbreak of bloodstream infections caused by fluconazole-resistant Candida parapsilosis in a neonatal intensive care unit

Candida parapsilosis is the most common causative agent of invasive candidiasis in neonates, particularly in intensive care units. Resistance to azole antifungals, including fluconazole, complicates treatment and control of nosocomial spread. Aim of the study was to identify the probable causes of the outbreak and factors contributing to the subsequent spread of C. parapsilosis in a neonatal intensive care unit. Material and methods. An epidemiological investigation of the outbreak of fungal infection caused by C. parapsilosis was conducted at a children’s hospital in St. Petersburg from April to June 2015. Data from 21 patients were analyzed. Descriptive and analytical epidemiological methods, microbiological examination of blood, central venous catheters (CVCs), and the hospital environment, as well as antifungal susceptibility testing, were used. A cohort study with calculation of relative risks (RR) and 95% confidence intervals was conducted to identify the probable transmission factor. Results . Among 21 patients, 3 cases of catheterassociated bloodstream infection, 6 cases of candidemia, and 12 cases of CVC colonization were identified. The use of a 20% glucose solution was the most probable transmission factor at the beginning of the outbreak (RR 8.0–10.5; p < 0.05), followed by contact transmission of C. parapsilosis . The isolates were resistant to fluconazole. Neonates with a birth weight less than 1500 g represented the main risk group. Outbreak control was achieved by CVC replacement, switching antifungal therapy to micafungin, cohort isolation, and changing the hand antiseptic. Discussion . Contamination of infusion solutions, biofilm formation on CVCs, and transmission via healthcare workers’ hands are important factors in the emergence and spread of the outbreak of fungal infection caused by C. parapsilosis . The ability of C. parapsilosis to form biofilms and its resistance to azoles may contribute to prolonged circulation in intensive care units. Conclusions. The epidemiological investigation indicates a probable role of a common transmission factor at the beginning of the infection outbreak, followed by contact transmission of C. parapsilosis . Outbreak control required a combination of infection control measures and adjustment of antifungal therapy.