Betsy L. Williams

Comparative Study of Deoxyribonucleic Acid Homology and Physiological Characteristics of Strains of Peptococcus saccharolyticus

Polynucleotide sequence relationships among strains of Peptococcus saccharolyticus were assessed by analysis of deoxyribonucleic acid-deoxyribonucleic acid homo and heteroduplexes with endonuclease S1. The results showed that P. saccharolyticus strains isolated from different subjects form a very tight group, with deoxyribonucleic acid homology levels ranging between 93 and 100%. Physiological tests of 23 strains included 30 different substrates. Results were remarkably uniform. All 23 strains grew better anaerobically with added H2 and CO2 than aerobically. However, colony size was greater on blood agar but not Trypticase soy (BBL Microbiology Systems, Cockeysville, Md.)-yeast extract agar with an atmosphere of 4% O2 with added H2 and CO2 than with anaerobic incubation. The data suggest that these strains are sufficiently closely related to justify their inclusion in a single discrete species, but their appropriate generic classification remains to be resolved.

Antigenic Analysis of Actinomyces Species

Patients with chronic periodontal inflammation frequently have a predominance of Actinomyces species in their lesions. For example, of the first four patients in a study by Williams et al. (8), three patients had a predominance of Actinomyces species at the subgingival sites. When the patients, all with six to eight mm pockets, were compared with age matched controls, the Actinomyces viscosus-naeslundii group of organisms were statistically more prominent than in the controls. Although we now realize that the current activity of periodontal destruction of tissues in these patients was not well characterized and that six to eight mm pockets do not necessarily mean active periodontal disease, nevertheless, Actinomyces were possible agents of inflammatory periodontal disease. In addition, Loesche (6) has shown that cessation of oral hygiene measures promptly results in gingivitis associated with an increase in numbers of Actinomyces in dental plaque.