Clinical features and analysis of the duration of colonisation during an outbreak of Salmonella braenderup gastroenteritis

During an outbreak of acute Salmonella braenderup gastroenteritis we perfor med a standardised interview encompassing questions on clinical symptoms in 156 (127 adults and 29 children) of 215 identified patients. Sequential st ool cultures were obtained for up to five months in these 156 cases. We res tricted the analysis to the 122 patients with at least 3 or more available cultures. They were treated with a fluoroquinolone, trimethoprim-sulfametho xazole, or not treated with antibiotics, according to the decision of the p ractitioners. For this reason, a randomised double blind study was not poss ible. Minimum inhibitory concentrations (MIC) of the prescribed drugs were measured for representative isolates before and after treatment. The most frequent symptoms were diarrhoea (98%) and abdominal pain (96%). V omiting occurred in 43% of cases. Children were more severely ill. Seven we eks after acute gastroenteritis, stool cultures were still positive for sal monella in 71% of the 22 children and 30% of the 100 adults examined (p <0. 002). This rate decreased progressively in both groups to 5 and 3% respecti vely at 20 weeks (n.s.). Among adults, no significant difference in enteric carriage over time could be demonstrated between untreated patients and th ose treated with either a fluoro quinolone or trimethoprim-sulfame-thoxazol e. MIC for salmonella isolates remained unchanged after treatment. In a cohort of patients infected with a single strain of salmonella, fluoro quinolone therapy of acute gastroenteritis failed to influence the duration of enteric carriage, despite continuing susceptibility of the strain. In children, the rate of clearance of Salmonella braenderup from stool was statistically lower until the tenth week after the acute disease, but there was no further difference after 5 months.