Treatment of Salmonella gastroenteritis with ampicillin, amoxicillin, or placebo.

In a randomized, prospective, double-blind study infants and children with uncomplicated Salmonella gastroenteritis were treated with ampicillin (15 patients), amoxicillin (15 patients), or placebo (14 patients). The dosage of antibiotics was 100 mg/kg/day in four equally divided doses given for five days. There was no significant benefit from antibiotic therapy on the duration of diarrhea (means 8.8, 7.3, and 7.2 days, respectively) or on the duration of recovery of Salmonella from stool cultures (means 41.3, 37.0, and 20.9 days, respectively). Bacteriologic relapse was not observed in placebo-treated patients but eight patients given ampicillin (53%) and eight given amoxicillin (53%) had relapse (P = .003). Salmonella isolated in relapse were still susceptible in vitro to the antibiotics. Of the 16 patients with bacteriologic relapse six (38%) had concomitant recurrence of diarrhea. It is concluded that ampicillin or amoxicillin therapy provides no benefit to patients with uncomplicated Salmonella gastroenteritis and substantially increases the risk of bacteriologic and symptomatic relapse.