β‐lactamase producing bacteria in adult periodontitis

Abstract In 23 untreated adult periodontitis patients, the occurrence of β‐lactamase producing periodontal bacteria was determined. In addition to non‐selective isolation media, selective isolation and growth of β‐Mactamase positive subgingival bacterial species was carried out on blood agar plates supplemented with amoxicillin and plates with amoxicillin + clavulanic acid. Porphyromonas gingivalis, Prevolella intermedia, Actinobacillus actinomycetemcomilans, Peplostreploc‐occus micros, Fusobaclerium nucleatum, Bacleroides forsythus and Campylo‐bacter rectus isolates from the non‐selective medium were tested for β‐Mactamase activity by a nitrocefin disk method (DrySlide®) and by a laboratory chromo‐genic nitrocefin‐ based test. Isolates from the amoxicillin plates that were absent on the amoxicillin/clavulanic acid plates were identified and tested for β‐Mactamase production. Based on the non‐selective plates, six of 23 P. intermedia isolates, 2 of 19 B. forsythus isolates and 3 of 23 F. nucleatutm isolates were β‐Mactamase positive. The β‐Mactamase positive species Prevoleila loescheii, Prevotella buccae, Prevolella buccalis and Actinomvces spp were recovered from the selective amoxiciliin plates. β‐Lactamase positive subgingival species were recovered from 17 of 23 patients (74%) but usually comprised low proportions of the sub gingival microbiota (range < 0.01–15%). Comparison of the DrySlide® test and the nitrocefin‐based laboratory test revealed full agreement of test results. β‐lactamase activity in whole sub gingival plaque was detected in 12 patient samples (52%). It was concluded that β‐Mactamase activity in sub gingival bacteria in adult periodontitis is a common feature. However, since the majority of the samples showed only low‐level enzymatic activity, the clinical relevance of this observation with regard to therapy with unprotected enzyme‐susceptible β‐lactamase is uncertain, though failure on the other hand, is difficult to rule out when a mechanism of resistance is present. The majority of β‐Mactamase positive strains was found among species of the Prevotella genus.