A cluster of Candida krusei infections in a haematological unit

BACKGROUND Candida krusei infections are associated with high mortality. In order to explore ways to prevent these infections, we investigated potential routes for nosocomial spread and possible clonality of C. krusei in a haematological unit which had experienced an unusually high incidence of cases. METHODS We searched for C. krusei contamination of the hospital environment and determined the level of colonization in patients and health care workers. We also analyzed the possible association between exposure to prophylactic antifungals or chemotherapeutic agents and occurrence of C. krusei. The C. krusei isolates found were genotyped by pulsed-field electrophoresis method in order to determine possible relatedness of the cases. RESULTS Twelve patients with invasive C. krusei infection and ten patients with potentially significant infection or mucosal colonization were documented within nine months. We were unable to identify any exogenic source of infection or colonization. Genetic analysis of the isolates showed little evidence of clonal transmission of C. krusei strains between the patients. Instead, each patient was colonized or infected by several different closely related genotypes. No association between medications and occurrence of C. krusei was found. CONCLUSION Little evidence of nosocomial spread of a single C. krusei clone was found. The outbreak may have been controlled by cessation of prophylactic antifungals and by intensifying infection control measures, e.g. hand hygiene and cohorting of the patients, although no clear association with these factors was demonstrated.