Enhancement of growth of group A beta-hemolytic streptococci in mixed infections with aerobic and anaerobic bacteria.

OBJECTIVE

To evaluate the potential for mutual enhancement of growth of group A beta-hemolytic streptococci (GABHS), and 11 commonly associated aerobic and anaerobic microorganisms frequently isolated in tonsillar infections.

METHODS

Enhancement was assessed by measuring the relative increase in colony-forming units (CFU) of GABHS and each of the 11 microorganisms inducing a subcutaneous abscess in mice.

RESULTS

Of the 11 combinations of GABHS and aerobe or anaerobe, GABHS was enhanced in 10 cases and the other microorganism in 5, namely, Staphylococcus aureus, Haemophilus influenzae type b, Klebsiella pneumoniae, Prevotella melaninogenica and Bacteroides fragilis.

CONCLUSIONS

These findings confirm the mutual symbiotic enhancement of growth of GABHS in the presence of other aerobic and anaerobic bacteria.