Nontyphoidal Salmonella infection in children: relation to bacteremia, age, and infecting serotype

Background: Salmonella gastroenteritis, usually self- limited, can result in bacteremia and focal disease. This study was undertaken to determine the role of age and infecting Salmonella serotype on the risk of bacteremia in children. Methods: This was a review of medical records of children with positive nontyphoidal Salmonella cultures seen in an urban setting at the Children's Hospital of Michigan in Detroit between July 1993 and December 2007. Results: Isolates recovered from 633 patients, representing 50 serotypes, included 594 positive stool cultures and 72 (11.4% of all patients) positive blood cultures. Salmonella serotype Typhimurium was the most common serotype, accounting for 29.4% (186/633) of isolates, of which only 3 (1.6%) were recovered from blood. The most common serotype recovered from blood was serotype Heidelberg (40/120 of patients with Heidelberg serotype) accounting for 55.5% (40/72) of positive blood cultures. The patients' age range was 2 weeks to 20 years, with a median of 7 months (interquartile range, IQR=4-23 months). Bacteremic patients (n=72) had a median age of 6.5 months (IQR=4-11 months) and were comparable in age to non-bacteremic patients (n=266), who had a median age of 5.5 months (IQR=3-11 months) (p=0.24). The odds ratio (OR) for bacteremia in patients infected with serotype Typhimurium was 0.21 and in patients with serotype Heidelberg was 4.0. Patients with serotype Heidelberg infection in the age groups<3 months, 3-6 months, 6-12 months, and>12 months had an OR for bacteremia of 9.2, 2.5, 3.2, and 6.0, respectively. Conclusion: In our patient population, children with Salmonella serotype Heidelberg infection are at higher risk of bacteremia than children infected with other Salmonella serotypes. The risk is highest during the first 3 months of life.