Despite its in vitro efficacy, penicillin
often fails to eradicate Group A β-hemolytic streptococci (GABHS) from patients
with acute and relapsing pharyngo-tonsillitis (PT).
A review of the literature details the
causes of penicillin failure to eradicate GABHS PT and the therapeuticmodalities to reduce and overcome antimicrobial failure.
- The causes of penicillin failure in eradicating GABHS PT include:
- The presence of β-lactamase producing bacteria (BLPB) that "protect" GABHS from any penicillin
- The absence of bacteria that interfere with the growth of GABHS
- Co-aggregation between GABHS and Moraxella catarrhalis
- 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 penicillin can allow intracellular GABHS and S. aureus to persist.
In the treatment of acute tonsillitis,
the use of cephalosporin 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 cephalosporin and clindamycin also enhances their
efficacy against intracellular GABHS and S. aureus.
