Distribution of <i>fimA</i> genotypes of <i>Porphyromonas gingivalis</i> in subjects with various periodontal conditions

Abstract

<jats:p>Fimbria encoded by the gene <jats:italic>fimA</jats:italic> is considered one of the main factors in the colonization of the oral cavity by <jats:italic>Porphyromonas gingivalis</jats:italic>. Allelic variation in <jats:italic>fimA</jats:italic> led to the classification of strains of <jats:italic>P. gingivalis</jats:italic> into six genotypes. The occurrence of <jats:italic>P. gingivalis</jats:italic> was determined by polymerase chain reaction using 16S rRNA primers in 302 subgingival samples obtained from 102 Brazilian subjects exhibiting different periodontal conditions. Distribution of <jats:italic>fimA</jats:italic> genotypes was assessed in 146 <jats:italic>P. gingivalis</jats:italic> positive samples by polymerase chain reaction using primers pairs homologous to the different <jats:italic>fimA</jats:italic> genes. <jats:italic>P. gingivalis</jats:italic> was detected in 51 of 57 (89.4%) patients with periodontal attachment loss, in six of 20 gingivitis patients (30.0%) and in two of 25 (8.0%) subjects with a healthy periodontium. Variant type II was the only type detected in 53 sites (39.3%), distributed among 19 periodontitis patients (37.3%) and in one patient with no periodontal destruction. Type Ib was the second most prevalent genotype in periodontitis patients (19.6%). Genotype V was not detected in the studied population. Type IV was the most commonly type found among gingivitis patients, either alone or in combination with other genotypes. Multiple genotypes were detected in nine sites (6.1%). A <jats:italic>fimA</jats:italic> genotype was not identified in 26 sites (17.8%) of 146 sites positive for <jats:italic>P. gingivalis,</jats:italic> suggesting that other alleles of <jats:italic>fimA</jats:italic> not yet sequenced may be prevalent in this population. These data demonstrated that <jats:italic>P. gingivalis</jats:italic> type II strains followed by type Ib are more prevalent in periodontitis patients from a multiracial population in Brazil, suggesting an increased pathogenic potential of these types.</jats:p>

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