BETA-LACTAMASE-PRODUCING BACTERIA IN ADULT PERIODONTITIS

In 23 untreated adult periodontitis patients, the occurrence of beta-l actamase producing periodontal bacteria was determined, In addition to non-selective isolation media, selective isolation and growth of beta -lactamase positive subgingival bacterial species was carried out on b lood agar plates supplemented with amoxicillin and plates with amoxici llin + clavulanic acid. Porphyromonas gingivalis, Prevotella intermedi a, Actinobacillus actinomycetemcomitans, Peptostreptococcus micros, Fu sobacterium nucleatum, Bacteroides forsythus, and Campylobacter rectus isolates from the non-selective medium were tested for beta-lactamase activity by a nitrocefin disk method (DrySlide(R)) and by a laborator y chromogenic nitrocefin- based test. Isolates from the amoxicillin pl ates that were absent on the amoxicillin/clavulanic acid plates were i dentified and tested for beta-lactamase production. Based on the non-s elective plates, six of 23 P. intermedia isolates, 2 of 19 B. forsythu s isolates and 3 of 23 F. nucleatum isolates were beta-lactamase posit ive. The P-lactamase positive species Prevotella loescheii, Prevotella buccae, Prevotella buccalis and Actinomyces spp were recovered from t he selective amoxicillin plates. P-Lactamase positive subgingival spec ies were recovered from 17 of 23 patients (74%) but usually comprised low proportions of the subgingival microbiota (range < 0.01-15%). Comp arison of the DrySlide(R) test and the nitrocefin-based laboratory tes t revealed full agreement of test results. beta-Lactamase activity in whole subgingival plaque was detected in 12 patient samples (52%). It was concluded that beta-lactamase activity in subgingival bacteria in adult periodontitis is a common feature. However, since the majority o f the samples showed only low-level enzymatic activity, the clinical r elevance of this observation with regard to therapy with unprotected e nzyme-susceptible beta-lactams is uncertain, though failure on the oth er hand, is difficult to rule out when a mechanism of resistance is pr esent. The majority of beta-lactamase positive strains was found among species of the Prevotella genus.