Cross-infection due to imipenem-resistant Bacteroides fragilis associated with a totally implantable venous port

Four patients in an oncology ward developed Bacteroides fragilis bacteremia over a 12-day period. Cross-infection between two of them, due to an imipenem-resistant strain, was demonstrated by epidemiological investigation and genotypic typing methods (arbitrarily primed PCR fingerprinting and nucleotide sequencing of the cfiA genes and upstream IS1186/IS1168 elements).