Detection of Aggregatibacter actinomycetemcomitans leukotoxin and fimbria‑associated protein gene genotypes among periodontitis patients and healthy controls: A case–control study

Abstract

Background: Aggregatibacter actinomycetemcomitans has been reported in higher proportions
in subgingival microbiota of individuals with aggressive periodontitis (AgP) compared with those
with chronic periodontitis (ChP) and healthy controls. The major virulence factors are the ones
that help in colonization and evasion of host’s defenses. Hence, this study was aimed to assess the
prevalence of A. actinomycetemcomitans 16S rRNA and its virulent genotypes (leukotoxin [lktA] and
fimbria‑associated protein [fap]).
Materials and Methods: In this case– control study We performed periodontal examination
and measured probing depth and clinical attachment level (CAL). Subgingival plaque samples from
200 (ChP: n = 128 and AgP: n = 72) periodontitis patients and 200 healthy controls were screened
for the presence of A. actinomycetemcomitans 16S rRNA, lktA, and fap genotypes by polymerase
chain reaction. The prevalence of genotypes between periodontitis patients and healthy controls
was compared with Pearson’s Chi‑square test. P < 0.05 was considered statistically significant.
Results: Mean pocket probing depth and CAL were high as compared to the healthy controls. The
prevalence of A. actinomycetemcomitans in ChP (n = 128), AgP (n = 72), and healthy individuals (n = 200)
was 32.0%, 61.1%, and 2.5%, respectively. A. actinomycetemcomitans lktA genotype prevalence was
71.8% among periodontitis patients, while A. actinomycetemcomitans fap genotype showed 31.8%
prevalence. The prevalence of these genotypes was insignificant in healthy controls.
Conclusion: The high odds ratio for A. actinomycetemcomitans prevalence suggests its strong link
to periodontitis. Detection of A. actinomycetemcomitans lktA + genotype may be a useful marker
for AgP as its prevalence was found to be high in AgP.
Key Words: Aggregatibacter actinomycetemcomitans, aggressive periodontitis, chronic
periodontitis, polymerase chain