From imaging to infection: contrast dye contaminated with Klebsiella pneumoniae as a source of nosocomial infections

INTRODUCTION: Klebsiella pneumoniae rapidly disseminates in clinical environments and is frequently responsible for hospital outbreaks. The present study highlights an under-recognised and concerning nosocomial transmission route involving intravenous contrast dye, after a cluster of seven patients became acutely ill after undergoing contrast-enhanced computed tomography (CT).

METHODS: All applied consumables, administration sets and the environment of the CT scanner were sampled and cultured. Whole-genome sequencing and phylogenetic analyses were performed on outbreak isolates, with a hypervirulent strain and a quality-control strain serving as references.

RESULTS: Microbiological analysis of the residual contrast dye vials and associated administration set identified contamination with K. pneumoniae. Whole-genome sequencing confirmed a genetic link between these strains and the K. pneumoniae strain isolated from the patient's blood culture. Molecular characterization suggested that the detected strain represented a contaminant rather than a nosocomial outbreak clone belonging to ST45 with K62 serotype.

CONCLUSION: The exact source of contamination remains unknown, as contamination in the pharmaceutical supply chain or hospital practices cannot be excluded. However, storing the opened contrast dye bottle at body temperature for 8 h before administration undoubtedly contributed to an increase in the bacterial load. This incident underscores the potential risk associated with storing an opened contrast dye bottle at body temperature - a common practice in the radiology department.