Beta-hemolytic streptococci in advanced periodontitis.

The distribution of serotypes of beta-hemolytic streptococci was examined in 718 periodontitis patients. Subgingival samples were obtained with paper points from the 3 deepest lesions in each patient, transported in VMGA III, plated onto brucella agar with 5% sheep blood and incubated anaerobically for 7 days. Serotyping and speciation were performed with Meritec-Strep Beta-Hemolytic Streptococcus Grouping Set and the Analytab 20S Streptococcus System. Beta-hemolytic streptococci were recovered from 33.7% of patients and averaged 10.5% of the total viable counts in culture-positive subjects. The organisms occurred with higher prevalence in patients 35 years or older than in younger patients. The predominant serotypes were F (62.9%), non-typeable (18.1%), B (6.9%), C (6.9%) and G (5.2%). 100% of beta-hemolytic streptococci were sensitive to penicillin, but less than 5% were sensitive to tetracycline, metronidazole or ciprofloxacin. Beta-hemolytic streptococci may contribute to inflammatory periodontal disease and may interfere with healing after therapy.