Penicillin failure in the treatment of group A streptococcal pharyngo-tonsillitis: Causes and solutions

Abstract

Despite its in vitro efficacy, the increased inability of penicillin to eradicate Group A beta-hemolytic streptococci (GABHS) from patients with acute and relapsing pharyngo-tonsillitis (PT) is of great concern. This review describes the causes of penicillin failure in eradicating GABHS PT. These include the presence of beta-lactamase producing bacteria (BLPB) that protect GABHS from penicillins; the absence of bacteria that interfere with the growth of GABHS; co-aggregation between GABHS and Moraxella catarrhalis; and the poor penetration of penicillin into the tonsillar tissues and the tonsillo-pharyngeal cells which allows intracellular GABHS and Staphylococcus aureus to survive. The inadequate intracellular penetration of penicillns can allow intracellular GABHS and S. aureus to persist. In the treatment of acute tonsillitis, the use of cephalosporins can overcome these interactions by eradicating aerobic BLPB (including M. catarrhalis), while preserving the potentially interfering organisms and eliminating GABHS. In treatment of recurrent and chronic PT the administration of clindamycin, or amoxicillin-clavulanic acid can eradicate both aerobic and anaerobic BLPB as well as GABHS. The superior intracellular penetration of cephalosporins and clindamycin enhances their efficacy against intracellular GABHS and S. aureus.