Pseudomonas aeruginosa, a well-known cause of infections acquired in newborn ICUs, usually resides in sinks and respiratory-therapy devices, and only rarely have outbreaks been linked to hands.

The authors tested 25 possible sources of the bacteria after nine infants were infected with Pseudomonas aeruginosa in August 1998. In addition, a total of 49 infants had shown evidence of Pseudomonas during 1997 and 1998.

The authors also tested the hands of healthcare workers who came in contact with any infants hospitalized in the ICU during that period.

• None of the environmental specimens were found to be contaminated with the bacteria.

• However, the hands of 10 out of the 165 healthcare workers tested were contaminated.

• One week later, only three of the 10 healthcare workers were still positive for the bacteria when retested.

Interestingly, the source of a majority of the infections in the infants was traced to a single healthcare worker, who carried the same strain of the bacteria as that infecting most of the infants. Researchers determined that being cared for by this healthcare worker increased the infants' chances of being infected by more than 41 times.

Based on these findings, the authors suggest that the hands of healthcare workers be tested early in any outbreak investigation. "Underlying conditions such as (outer ear infections or fungal nail infections) may be associated with persistent carriage of P. aeruginosa on the hands of healthcare workers and should be detected and eradicated," they conclude.

The New England Journal of Medicine September 7, 2000;343:695-700.