Despite its excellent efficacy in the test tube, penicillin frequently does not work and fail to eradicate Group A beta-hemolytic streptococci (GABHS) from patients with acute and relapsing pharyngo-tonsillitis (PT) is cause for concern. Over the past 50 years, the rate of penicillin failure has consistently increased from about 7% in 1950 to almost 40% in 2000.
Various explanations exist for the failure of penicillin to eradicate GABHS PT (see page). One possibility is the poor penetration of penicillin into the tonsillar tissues as well as into the epithelial cells. Other explanations relate to the bacterial interactions between GABHS and other members of the pharyngo-tonsillar bacterial flora. For example, it is hypothesized that beta-lactamase secreted by beta-lactamase-producing bacteria (BLPB), which colonize the pharynx and tonsils, may “shield” GABHS from penicillins. Another possibility is the coaggregation between Moraxella catarrhalis and GABHS, which can facilitate colonization by GABHS. Normal bacterial flora can interfere with the growth of GABHS, and the absence of such competitive bacteria makes it easier for GABHS to colonize and invade the pharyngo-tonsillar area.
Beta-lactamase producing organisms "protecting" penicillin susceptible bacteria from penicillin
Therapeutic strategies that allow overcoming the above mechanisms are available and are based on extensive clinical research. This website describes the research and therapeutic option for patients who fail penicillin therapy.
Streptococcal tonsillitis
