Prevalence of Peptostreptococcus micros morphotypes in patients with adult periodontitis

The prevalence of the smooth and rough colonial morphotypes of Peptostreptococcus micros was examined with culture technique in 123 patients with adult periodontitis (age 24–68 years). Of all subgingival samples, 91% contained the smooth morphotype of P. micros. The smooth morphotype constituted a mean percentage of the total anaerobic viable biota of 6.0%, with a range of 0.02–35.7%o. Of these samples, 49%> contained colonies of the rough morphotype as well, with a mean percentage of the total anaerobic viable biota of 2.3%> (range 0.01–16.2%i). None of the samples contained only the rough morphotype. The total percentage of P. micros varied from 0.02–35.71%> with a mean of 7.2%>. No correlation was found between the prevalence of both morphotypes of P. micros and the age of the subjects or with loss of attachment or pocket depth.