WHY HAVE GROUP-A STREPTOCOCCI REMAINED SUSCEPTIBLE TO PENICILLIN - REPORT ON A SYMPOSIUM

In spite of 50 years of extensive use of penicillin, group A streptoco cci remain exquisitely susceptible to this antibiotic. This observatio n that continuing susceptibility has occurred despite the development of resistance to other antimicrobial agents prompted a day-long meetin g at Rockefeller University (New York) in October 1996, Among the most likely explanations for this remarkable state of continued susceptibi lity to penicillin are that beta-lactamase may not be expressed or may be toxic to the organism and/or that low-affinity penicillin-binding proteins either are not expressed or render organisms nonviable, Other potential explanations are that circumstances favorable for the devel opment of resistance have not yet occurred and/or that there are ineff icient mechanisms for or barriers to genetic transfer. Recommended fut ure actions include (1) additional laboratory investigations of gene t ransfer, penicillin-binding proteins, virulence factors, and homeologo us recombination and mismatch repair; (2) increased surveillance for t he development of penicillin resistance; (3) application of bioinforma tics to analyze streptococcal genome sequences; and (4) development of vaccines and novel antimicrobial agents. Thus far the susceptibility of group A streptococci to penicillin has not been a major clinical or epidemiological problem. A similar observation, however, could have b een made decades ago about Streptococcus pneumoniae. It is therefore v ital for the scientific community to closely examine why penicillin ha s remained uniformly highly active against group A streptococci in ord er to maintain this desirable state.