beta-Hemolytic streptococci and other beta-hemolytic organisms in apical periodontitis and severe marginal periodontitis

Thirteen teeth with necrotic pulps and apical periodontitis and nine severe periodontal pockets were cultured for presence of beta-hemolytic streptoco cci and other beta-hemolytic organisms. Samples were dispersed and plated o n two non-selective and one selective growth media and incubated anaerobica lly and in 10% CO2 in air. A total of 59 beta-hemolytic colonies were purif ied and identified. Eight beta-hemolytic streptococcal isolates were obtain ed from three of the severe marginal periodontitis sites. All were identifi ed as belonging to the Streptococcus sanguis group. No beta-hemolytic strep tococci were detected in apical periodontitis samples. Twenty obligately an aerobic isolates were detected, all of which were known periodontal and end odontic pathogens. isolates from apical periodontitis sites were identified as Propionibacterium acnes, Actinomyces naeslundii, Actinomyces odontolyti cus and Peptostreptococcus micros, while severe marginal periodontal sites contained the same species with the addition of Actinomyces viscosus and Ac tinomyces meyeri. Of 19 staphylococci and micrococci, Staphylococcus: epide rmidis was the predominant isolate in both apical periodondtitis and severe marginal periodontitis sites. However, less commonly known organisms such as Staphylococcus cohnii and Micrococcus sp. were identified in severe marg inal periodontitis sites. The isolation of Bacillus sp. (12 isolates) in on e severe marginal periodontitis and two apical periodontitis subjects was e specially interesting, warranting consideration of this organism as a legit imate isolate and potential pathogen in oral disease.