Ampicillin and Shigellosis

To the Editor. —In the October issue of theJournalwe reported a study of shigellosis in outpatients conducted in 1969 and 1970 demonstrating the bacteriological and clinical effectiveness of ampicillin.¹This work confirmed previously reported observations of effectiveness made in hospitalized children with severe shigellosis.²Since the outpatient manuscript was submitted for publication (in March, 1972) increasing numbers of ampicillin-resistant shigellae have been isolated in our area. In addition the incidence of infection due toShigella sonneiappears to be rising in our patients. Forty-three percent of 197 strains of shigellae isolated in 1971 from children on one of our pediatric services (Children's Medical Center) wereS sonnei. From Jan 1 through October of 1972, 53% of 105Shigellastrains wereS sonnei. In 1971 only 1% ofS sonneistrains were resistant to ampicillin in vitro but this has risen to 25% in the first ten