RAPID CHARACTERIZATION OF PERIODONTAL BACTERIAL ISOLATES BY USING FLUOROGENIC SUBSTRATE TESTS

Eighty-nine species of subgingival bacteria, represented by 121 refere nce strains and 892 patient isolates, including gram-negative, gram-po sitive, aerobic, facultatively anaerobic, microaerophilic, and anaerob ic species, were characterized with a panel of fluorogenic, 4-methylum belliferyl-linked substrate tests. Identifications of all patient isol ates were confirmed by sodium dodecyl sulfate-polyacrylamide gel elect rophoresis (SDS-PAGE) of whole-cell proteins relative to reference str ains. Characteristic profiles of positive fluorogenic reactions differ entiated most of the species, including five Porphyromonas species, si x pigmenting and five nonpigmenting Prevotella species, Bacteroides fo rsythus, three Capnocytophaga species, six Actinomyces species, four P ropionibacterium species, and eight Streptococcus species. Two mannosi de isomers differentiated Actinomyces israelii and Actinomyces gerencs eriae. In addition to Porphyromonas gingivalis, B. forsythus, and Capn ocytophaga species, Fusobacterium alocis, Actinomyces odontolyticus, A ctinomyces meyeri, and Bifidobacterium dentium were all positive for s o-called trypsin-like activity. Fusobacterium nucleatum, Eikenella cor rodens, Actinobacillus actinomycetemcomitans, and Campylobacter specie s were nonreactive with the carbohydrate-based substrates tested. Fluo rogenic substrate tests provided a sensitive and simple method for bio chemical characterization that could presumptively identify to species level most subgingival isolates within 4 h. The method was ideal for rapidly obtaining presumptive identifications of isolates prior to con firming identifications by definitive methods, such as SDS-PAGE.