Abstract
The epidemiology, treatment, and prevention of group A streptococcal pharyngitis and its sequela of rheumatic fever have been extensively studied. Estimates of the incidence of streptococcal pharyngitis in the United States have ranged from 400,000 to 7 million cases annually. Case rates are highest in the winter and spring months, and children between the ages of five and fifteen years are most susceptible to infection (1,2). The nonsuppurative sequela of streptococcal pharyngitis, rheumatic fever, although less frequently observed, is of greater medical concern. Rheumatic fever follows infection in one to three percent of untreated cases, but more than half of these individuals develop rheumatic heart disease. | Several antibiotic regimens have been shown to be safe and effective for the treatment of streptococcal infections and the prevention of the sequela (3,4). However, there has been little impact on the incidence of either the infection or the sequela due to (a) failure to detect streptococcal infections and identify the individuals at risk of developing the nonsuppurative sequela, and (b) failure of correctly diagnosed patients to receive appropriate antibiotic therapy (5). Therefore, it is apparent that additional methods for the diagnosis and control of streptococcal infections are needed. Several new approaches to control are currently being investigated. The first concerns an immunologic approach to control. Streptococcal vaccines have been developed but their safety and long-term efficacy have not yet been determined (6). The second approach concerns bacterial interference. Recent investigations have demonstrated that certain constituents of the normal throat flora are capable of inhibiting the growth of group A streptococci in vitro (7). The presence of these inhibitory organisms in the throats of children was later shown to be associated with resistance to acquisition of group A streptococci (8). From these studies, it has been hypothesized that these organisms may play a role in resistance to streptococcal infections, and that this phenomenon might be exploited to increase resistance to streptococcal infections. | The purpose of the current investigation was to evaluate various epidemiological factors which may influence the. presence of organisms in the normal throat flora that are antagonistic to group A streptococci in vitro. Throat cultures were obtained from a population of individuals for one calendar year. These cultures were examined quantitatively and qualitatively for the presence of organisms inhibitory in vitro to the growth of group A streptococci. The influence of age, sex, race, and month at time of culture on the results was determined by statistical analyses.