Nontyphoidal Salmonella enteric infections and bacteremia

Antimicrobial treatment of nontyphoidal Salmonella gastroenteritis is usually advocated for infants younger than 3 months of age based on published data showing that infants in this age group are more prone to have bacteremia and develop extraintestinal focal infections. A review of nontyphoidal Salmonella isolates from our institution from January, 1981, through March, 1988, was undertaken to assess the role of age and specific serovar on the incidence of bacteremia. Two hundred twenty isolates were identified: one cerebrospinal fluid, 14 blood and 205 stool. The mean age of patients with bacteremia was 182 months, not significantly different from the mean age of 142 months for patients with stool isolates. Salmonella weltevreden was the most frequent isolate accounting for 23% of all isolates and all isolates of this organism were from stool cultures. Patients with S. weltevreden infections had mean and median ages of 50 and 2.5 months and were younger than patients with stool isolates from other serovars who had mean and median ages of 174 and 38 months. Infants younger than 3 or 6 months of age with positive stool cultures in whom blood cultures were obtained did not demonstrate a higher incidence of bacteremia than did older patients. We conclude that the incidence of bacteremia in patients with nontyphoidal Salmonella gastroenteritis is highly related to the invasiveness of the infecting specific Salmonella serovar.