Chronic Salmonella bacteriuria with intermittent bacteremia treated with low doses of amoxicillin or ampicillin.

Amoxicillin and ampicillin were compared at a dose of 250 mg twice daily for 4 weeks to treat Salmonella typhi or Salmonella paratyphi A chronic bacteriuria with intermittent bacteremia. Eleven patients received amoxicillin, and 15 received ampicillin. Concentrations of the two drugs were measured in the urine and serum on treatment days 1, 2, and 7. The urine levels of both antibiotics were maximal 2 h after administration, and minimal levels were 80-fold higher than the S. typhi minimal inhibitory concentration and 20-fold higher than the S. paratyphi A minimal inhibitory concentration. The serum level of amoxicillin was below the minimal inhibitory concentration of S. paratyphi A 6 h after administration on each of the testing days. The serum antibiotic levels of the two drugs showed no cumulative effect at day 2 or day 7. Of the 11 patients treated with amoxicillin, 1 had positive urine cultures during treatment, and 1 treated with ampicillin continued to be symptomatic.. Recurrence of bacteriuria occurred in three of seven patients with persistent bladder calcification. None of the 26 patients in this study had positive blood culture during or after treatment. Amoxicillin and ampicillin at a dose of 250 mg twice daily were equally successful in treating chronic salmonelluria.