A comparative study of Micrococcus pyogenes var. aureus in saliva of penicillin-treated and nontreated individuals

Abstract

In the evaluation of different culture media, the presence of Micrococcus pyogenes var. aureus was noted in 40 to 52.8 per cent of saliva samples cultured on a high-salt-content selective medium. In contrast, duplicate samples cultured on routine blood agar media accounted for only 10 to 17 per cent of positive cultures. Micrococcus pyogenes var. aureus strains were isolated from saliva of 67.3 per cent of penicillin-treated patients and from 45.5 per cent of nontreated controls. These organisms were isolated from both nasal swabs and saliva samples, obtained simultaneously, in 60 per cent of the penicillin-treated series and in 30 per cent of the nontreated controls. In incidences where only the nasal swab or saliva sample was positive for Micrococcus pyogenes var. aureus, cultures from nasal swabs were positive more than twice as often as were saliva samples. Of Micrococcus pyogenes var. aureus strains isolated from saliva of penicillin-treated patients 52.9 per cent were highly resistant and 26.5 per cent were moderately resistant to penicillin. In contrast, only 6.4 per cent of strains from controls were highly resistant and 23 per cent were moderately resistant to penicillin. In spite of the presence of a high percentage of penicillin-resistant strains, the relative numbers of these organisms in saliva did not exceed 0.16 per cent of the total aerobic cultivable flora in any of the fifty-five patients on continued penicillin therapy.