Nosocomial outbreak of Blastoschizomyces capitatus associated with contaminated milk in a haematological unit

SummaryIn July 2002, Blastoschizomyces capitatus was isolated from four neutropenic patients in a haematology unit. Two patients died due to disseminated infection while the other two had oropharyngeal colonisation. Nosocomial acquisition of the fungus was suspected and epidemiological and environmental studies were undertaken. To determine the potential source for the acquisition of the fungus, epidemiological relationships between the patients were investigated. We performed surveillance cultures on all patients and took environmental cultures of air, inanimate surfaces, food samples, blood products and chemotherapy drugs. No direct contact transmission between patients was found and B. capitatus was isolated only in vacuum flasks used for breakfast milk distribution. All isolates were compared by four independent molecular typing methods: pulsed-field gel electrophoresis, genomic DNA restriction endonuclease analysis, randomly amplified polymorphic DNA, and polymerase chain reaction fingerprinting using a single primer specific for one minisatellite or two microsatellite DNAs. Milk vacuum flasks and clinical strains were genetically indistinguishable by all typing techniques. Milk vacuum flasks were withdrawn from all hospital units and no further B. capitatus infection was detected. Our findings suggest that clonal dissemination of a single strain of B. capitatus from vacuum flasks used for milk distribution was responsible for this nosocomial outbreak in the haematological unit.