An evaluation of penicillin prophylaxis during an outbreak of foodborne streptococcal pharyngitis.

Between August 16 and 21, 1974, an outbreak of beta-hemolytic group A M-9 T-9 streptococcal pharyngitis affected 49% of a randomly selected group of inmates at a jail in southern Florida. Food-specific attack rates incriminated improperly stored egg salad served at lunch on August 16 as the vehicle of transmission. By August 20, 290 symptomatic inmates had been placed on penicillin or erythromycin; on that day fewer than 5% of throat cultures from 400 allegedly non-penicillin-allergic largely asymptomatic inmates, cultured just before penicillin prophylaxis, were positive for the epidemic strain. At the time prophylaxis was given, secondary transmission had accounted for only 3% of cases. No non-suppurative sequelae were observed but 5% of inmates who received penicillin prophylaxis experienced an adverse reaction to the drug. Although widespread penicillin prophylaxis during outbreaks of group A beta-hemolytic streptococcal pharyngitis will likely prevent transmission of these organisms, prompt treatment of all symptomatic cases may be equally as effective in controlling adult institutional foodborne outbreaks of streptococcal pharyngitis and will likely minimize the number of adverse reactions to penicillin which may be seen.