Possible transmission of Candida albicans on an intensive care unit: genotype and temporal cluster analyses

Abstract

Background: Nosocomial transmission of Candida spp. has not been fully explored and previous studies have shown conflicting results.

Aim: To evaluate the possible nosocomial transmission of Candida spp. on an intensive care unit (ICU).

Methods: A prospective study was conducted for a period of 19 months, including all patients on our ICU with growth of Candida spp. from surveillance and directed cultures. Molecular typing with repetitive sequence-based polymerase chain reaction was used to define genotype relationships between the Candida albicans and Candida glabrata isolates. Candida isolates obtained from blood cultures taken from patients in our county outside the ICU were used as a reference. Temporal cluster analysis was performed to evaluate genotype distribution over time.

Findings: Seventy-seven patients with 78 ICU stays, representing 12% of all ICU stays, were found to harbour 180 isolates of Candida spp. Molecular typing revealed 27 C. albicans genotypes and 10 of C. glabrata. Possible clustering, indicated by overlapping stays of patients with indistinguishable candida genotypes, was observed on seven occasions with C. albicans and on two occasions with C. glabrata. Two C. albicans genotypes were found significantly more often in the ICU group compared with the reference group. Moreover, C. albicans genotypes isolated from more than one patient were significantly more often found in the ICU group. Temporal cluster analysis revealed a significantly increased number of pairs with indistinguishable genotypes at a 21-day interval, indicating clustering.

Conclusion: This study indicates possible transmission of C. albicans between ICU patients based on genotyping and temporal cluster analysis.

Keywords: Candida; Intensive care unit; Molecular typing; Nosocomial infections.