beta-lactamase production and antimicrobial susceptibility of oral heterogeneous Fusobacterium nucleatum populations in young children

Oral Fusobacterium nucleatum populations from 20 young, healthy children we re examined for p-lactamase production. Ten children (50%) harbored, altoge ther, 25 beta-lactamase-positive F. nucleatum isolates that were identified as F. nucleatum subsp. polymorphum, F. nucleatum subsp. nucleatum, and F. nucleatum subsp. vincentii (J. L. Dzink, M. T. Sheenan, and S. S. Socransky , Int. J. Syst. Bacteriol. 40:74-78, 1990). In vitro susceptibility of thes e beta-lactamase-producing and 26 non-beta-lactamase-producing F. nucleatum isolates was tested with penicillin G, amoxicillin-clavulanic acid, tetrac ycline hydrochloride, metronidazole, trovafloxacin, and azithromycin. Excep t for penicillin G, the antimicrobials exhibited good activity against all F. nucleatum isolates.