To describe a nosocomial outbreak of Salmonella serotype Saintpaul gastroenteritis and to explore risk factors for infection.

Case-control study.

A 208-bed, university-affiliated children's hospital.

Patients hospitalized at Children's Hospital and Regional Medical Center, Seattle, Washington, during February 2001 who had stool specimens obtained for culture at least 24 hours after admission. Case-patients (n = 11) were patients with an indistinguishable strain of Salmonella Saintpaul cultured from their stool. Control-patients (n = 41) were patients hospitalized for problems other than gastroenteritis whose stool cultures were negative for Salmonella.

Risk factors were evaluated using the chisquare test or Fisher's exact test. Continuous variables were compared using the Mann–Whitney U test. A multivariable analysis was performed using logistic regression. The predictor of interest was the receipt of enteral feeding formula mixed by the hospital.

Case-patients were more likely than control-patients to have received formula mixed by the hospital (OR, 4.2; 95% confidence interval, 1.04 to 17.16). Other variables evaluated were not significant predictors of Salmonella Saintpaul infection.

Formula mixed by the hospital appears to have been the source of this Salmonella outbreak. Strict sanitation measures must be ensured in formula preparation and delivery, and bacterial pathogens should be included in the differential diagnosis for nosocomial gastroenteritis.