Penicillin Failures?!

To the Editor.—

I share the concern of Kaplan and Johnson¹ that current formulations of benzathine penicillin G may not be up to the standards of the Wyeth product I originally investigated in the early 1950s. I do not, however, share their concerns about the reported low rate of “microbiological cure” of group A streptococcal (GAS) pharyngitis in the cohorts they studied. Their concerns are based on data obtained from the studies of the primary prevention of rheumatic fever by penicillin therapy in military epidemics. In those studies, the “bacteriologic cure” rate exceeded 90% in the selected cases of exudative pharyngitis caused by highly encapsulated, M protein-rich rheumatogenic strains.² Subsequent studies of sporadic streptococcal pharyngitis in schoolchildren, however, revealed not only a high frequency of persistent group A streptococcal throat carriage but, compared with the virulent infections causing rheumatic fever, far lower virulence properties of the strains producing mild sporadic pharyngitis associated with only modest immunologic responses.^3,4

In the absence of clinical relapse, therefore, expert committees do not advise reculturing the throat following the recommended treatment of nonepidemic GAS pharyngitis. Persistent convalescent carriage of such attenuated strains has not been associated with significant sequelae or with a significant secondary attack rate in contacts. Careful studies of infectivity of streptococci isolated during acute pharyngitis compared with those isolated during convalescence have clearly shown the latter’s diminished virulence.^5,6

If the rate of “failure of microbiologic cure” of sporadic GAS pharyngitis by treatment with either oral penicillin or intramuscular injection of benzathine penicillin G is as high as 35% to 37% in the infections reported by Kaplan and Johnson, why has rheumatic fever completely disappeared in these cohorts? Doesn’t that alone confirm that higher bacteriologic cure rates of these attenuated infections are unnecessary where …