Effect of penicillin or cefprozil therapy on tonsillar flora.

The effect on the tonsillar bacterial flora of antimicrobial therapy with penicillin or a second-generation cephalosporin (cefprozil) was studied. Sixty children scheduled for elective tonsillectomy because of recurrent group A beta-haemolytic streptococcal tonsillitis participated in a prospective randomized study that divided them into three groups. One group received no therapy, and the others were given either penicillin or cefprozil for 10 days prior to surgery. The core of the patients' tonsils was cultured for aerobic bacteria. Group A beta-haemolytic streptococci (GABHS) were isolated from 15/20 (75%) of untreated, 11/20 (55%) of penicillin, and 2/20 (10%) of the cefprozil group (P < 0.001). Thirty-two beta-lactamase-producing bacteria were recovered from 19/20 (95%) of untreated, 33 from 17/20 (85%) treated with penicillin and six from 4/20 (20%) treated with cefprozil (P < 0.01). Alpha-haemolytic streptococci (AHS) inhibiting GABHS were less often isolated from patients treated with penicillin. These data illustrate the ability of a second-generation cephalosporin to eradicate GABHs, as well as beta-lactamase-producing bacteria, while preserving AHS.