Prevention of bacterial overgrowth.

Abstract

For years it has been recognized that one of the hazards of the use of antibiotics is gross alteration in the normal pattern of bacterial flora. Secondary to this is overgrowth with organisms not commonly found in significant proportions at the study site [1-4]. Such overgrowth may be followed by superinfection, a complication with a high mortality rate [4]. In an earlier report [5], we discussed the importance of interrelationships among bacterial species in maintaining the status quo of bacterial flora in the oropharynx. Data were presented which suggest that members of the viridans group of streptococci, the predominant strains of the oropharyngeal flora in most individuals, can inhibit the growth of enteric gram-negative bacilli, the organisms that commonly overgrow at this site following therapy with massive doses of penicillin. It was proposed that suppression (or elimination) of these streptococci by massive doses of antibiotics suppresses (or eliminates) their inhibitory action and permits multiplication of the previously inhibited (or newly introduced) bacilli. During parenteral therapy with large doses of penicillin, individuals carrying streptococci that were resistant to the levels attained in the pharynx * and that persisted, therefore, while the antibiotic was being given, did not demonstrate overgrowth [5]. In retrospect, such patients had recently received penicillin orally. Such exposure to the antibiotic is known to favor the selection of resistant