Contaminated feeding bottles: the source of an outbreak of Pseudomonas aeruginosa infections in a neonatal intensive care unit.

Background: Outbreaks of Pseudomonas aeruginosa have been reported in relationship with contamination of staff fingernails, hands, water baths, hand lotions and others. To our knowledge, contamination of milk and feeding bottles as a source of an outbreak of P aeruginosa infections has not been reported. The incidence of P aeruginosa infection/colonization in our neonatal intensive care unit increased from 1.9 per 1000 patient-days in August 2004 to 8.8 per 1000 patient-days in September 2004.

Methods: Samples were collected including hand and body lotions, water from the incubator humidifying system, the health care worker hands, and the feeding bottle preparation room. Strains were epidemiologically characterized by pulsed-field gel electrophoresis of SpeI-digested genomic DNA. P aeruginosa was isolated from a total of 30 neonates during the period September 2004 to December 2004.

Results: All cultures (139) of hand and body lotions, water from the incubator humidifying system, and hands of health care personnel were negative. Nine out of 48 samples collected from the feeding bottle preparation room were positive for P aeruginosa (6 samples of in-house prepared milk and 3 samples of water from dishwashers). Pulsed-field gel electrophoresis with SpeI showed that the strains isolated from neonates and from environmental samples were identical. Discontinuation of in-house preparation of feeding bottles and incorporation of unidose milk bottles stopped the outbreak.

Conclusion: The preparation and solution of milk from multidose powder preparation may be a source of P aeruginosa infections in a neonatal intensive care unit. The use of manufactured, nonmanipulated, unidose feeding bottles should be considered more adequate.