Failure to eradicate streptococci and beta-lactamase producing bacteria

Background: The presence of beta-lactamase-producing bacteria is associated with the failure of penicillins to eradicate Group A beta-hemolytic streptococci in patients with pharyngo-tonsillitis. This study correlated the rate of recovery of beta-lactamase-producing bacteria from healthy children with the rate of amoxicillin failure to eradicate Group A streptococci from children with acute Group A streptococcal pharyngo-tonsillitis.

Patients and Methods: A total of 228 children with Group A streptococcal pharyngo-tonsillitis, treated with amoxicillin for 10 days, and 663 healthy children were evaluated in a single year. Pharyngo-tonsillar cultures were obtained from all well children and from those with pharyngo-tonsillitis before treatment and on the 12th day.

Results: Amoxicillin failed to eradicate Group A streptococci from 48 of the 228 treated children (21%). Amoxicillin failure rate varied from month to month; it was high between October and May (22–32%), with the exception of April (11%); and low between June and September (8% to 12%). Beta-lactamase-producing bacteria were recovered from 226 of 663 (34%) well children. The rate of recovery of beta-lactamase-producing bacteria varied; it was also high between October and May (40–52%), with exception of April (23%), and the lowest between June and September (10–12%). Prior to their treatment, beta-lactamase-producing bacteria were recovered from 26 of the 48 (54%) children who eventually failed amoxicillin therapy, and from 28 of the 180 (16%) who did not fail (p < 0.001).

Conclusions: A correlation was noted between the rate of recovery of beta-lactamase-producing bacteria in healthy children and the rate of amoxicillin failure to eradicate Group A streptococci. A high failure rate of penicillins in eradication of Group A streptococci in pharyngo-tonsillitis can serve as sensitive indicator for a high prevalence rate of beta-lactamase-producing bacteria in the community.