Outbreak of Sternal Surgical Site Infections Due to Pseudomonas aeruginosa Traced to a Scrub Nurse with Onychomycosis

From 19 February 1999 through 31 October 1999, 16 (8.6%) of 185 patients who underwent median sternotomy developed infections with Pseudomonas aeruginosa. Seven patients had mediastinitis, 5 had deep sternal wound infection, 2 had superficial sternal wound infection, 1 had prosthetic valve endocarditis, and 1 had sepsis. Pulsed-field gel electrophoresis confirmed that all 13 isolates that were available for typing were the same strain. Cultures of hand specimens identified 1 nurse from whom the same strain of P. aeruginosa was repeatedly isolated; the nurse had been in contact with all 16 infected patients. Investigation revealed that the nurse had severe onycholysis and onychomycosis of the right thumbnail. Cultures of samples of this nail's subungual region and of multiple cosmetic products from the nurse's home yielded the identical P. aeruginosa strain. This outbreak of surgical site infections due to P. aeruginosa was caused by wound contamination from the thumbnail of this nurse, despite her appropriate use of latex surgical gloves.