Dog-eared NICU outbreak spread by workers' hands

Hand washing the culprit, not man's best friend

An outbreak of Malassezia pachydermatis (MP), a fungus rarely reported as a nosocomial pathogen, was linked to MP ear colonization in pet dogs owned by health care workers, a Centers for Disease Control and Prevention investigator reports.

While dogs may have been the reservoir for the pathogen, inadequate hand washing by health care workers was considered the primary cause of introduction and transmission within a neonatal intensive care unit (NICU), reported Huan Chang, MD, medical epidemiologist in the CDC hospital infections program.

"Fifty percent of healthy dogs are colonized, and approximately 80 percent of those with [ear infections] are caused by this organism," she told Hospital Infection Control. "But the key was really hand washing."

Reporting the case recently in Washington, DC, at the annual conference of the Society for Healthcare Epidemiology of America (SHEA), Chang said reinforced hand-washing practices in the unit were the key measure that interrupted transmission. The CDC investigation began when a cluster of patients were found to be infected or colonized with MP in an NICU at Dartmouth Hitchcock Medical Center in Hanover, NH. In all, 15 patients were identified with either MP infection or colonization, including eight patients with bloodstream infections and one with meningitis. Colonization was also found on the hands of one health care worker and in the ears of several dogs owned by health care workers, but Chang said a clear chain of transmission couldn't be established.

"A lot of the health care workers had contact with the patients, [and] we could not keep track," she told SHEA attendees. "There were a lot of respiratory therapists that went in and out, as well as the patients' parents. Most of these [contacts] are not documented on the charts. This was a retrospective study -- we really couldn't say it was this one health care worker."

The CDC concluded that MP was introduced to the NICU patients via the hands of health care workers who may have become colonized from pets at home. The pathogen then persisted in the NICU because of inadequate hand washing. No other cases occurred after control measures were implemented that included increased education of health care workers about nosocomial MP, reinforced hand-washing practices, and discharge of MP infected and colonized patients after appropriate treatment, she said. *