Beta-lactamase producing anaerobic bacteria in the oropharynx and their clinical relevance.

The mechanisms of resistance to beta-lactam antibiotics in anaerobic bacteria are production of beta-lactamases, alteration of penicillin-binding proteins and blocked penetration of beta-lactam agents through the outer membranes. The most important factor in beta-lactam resistance is production of beta-lactamase. Beta-lactamases have been found in oropharyngeal strains of bacteroides and fusobacteria isolated from orofacial infections, peritonsillitis and recurrent tonsillitis. Clinical failures with penicillin therapy of these infections are reported in an increasing frequency and other antimicrobial agents such as clindamycin and metronidazole should be considered in the treatment of these failures.