β-Lactamase-producing anaerobic bacteria in recurrent tonsillitis

Clinical studies have emphasized the importance of anaerobic bacteria in recurrent tonsillitis. These bacteria are usually sensitive to penicillin. However, recent reports have demonstrated that penicillin-resistant Bacteroides strains can be isolated from inflamed tonsils. These strains are resistant to penicillin due to β-lactamase production and the strains may therefore be responsible for the failure of penicillin in the treatment of recurrent tonsillitis. Ten patients with recurrent tonsillitis were given 1 g tinidazole every 24 h for 7 days, 21 patients 0·15 g clindamycin every 6 h for 10 days and 19 patients 1 g phenoxymethylpenicillin every 12 h for 10 days. Tonsillar specimens were taken before and after antibiotic treatment. Tinidazole eliminated β-lactamase-producing Bacteroides strains in eight of nine patients. Five patients harboured β-lactamase-producing Staphylococcus aureus both before and after treatment. Clindamycin eradicated β-lactamase-producing Staph. aureus in nine of ten patients and Bacteroides strains in 10 of 14 patients. Penicillin failed to eliminate Staph. aureus in 11 patients. β-lactamase-producing Bacteroides strains were recovered in nine patients after therapy.