We compared
nalidixic acid, 55 mg/kg/day, with
ampicillin, 100 mg/kg/day, both given orally for 5 days, in the treatment of children with
dysentery caused by
shigellosis. All patients entered into the study had illness of less than 72 hours' duration and no prior allopathic
drug therapy. Treatment was randomized and administered in double-blind fashion. Patients initially treated with
ampicillin who were infected with a Shigella strain resistant to
ampicillin were considered as a separate group (
ampicillin-R). All isolates were susceptible to
nalidixic acid. Similar percentages of patients treated with
nalidixic acid (26/32, 81%) and with
ampicillin (17/22, 77%) were clinically cured by the end of
therapy; the rate in
ampicillin-R (3/14, 21%) patients was significantly lower (p less than 0.001). Stool frequency in patients treated with
nalidixic acid was significantly less than for
ampicillin-treated or
ampicillin-R patients during the final 3 study days. All patients treated with
nalidixic acid and
ampicillin had Shigella eradicated from their stool by day 3, compared with 77% (10/13) of
ampicillin-R patients (p less than 0.05,
ampicillin-R vs
nalidixic acid or
ampicillin). We conclude that
nalidixic acid is an effective alternative to
ampicillin in the treatment of
shigellosis caused by
nalidixic acid-susceptible strains.