BACKGROUND: The microbiologic feature of aggressive periodontitis (AgP) in 
Chinese patients has not yet been determined. This study aims to investigate the 
prevalence of eight periodontal microorganisms and the distribution of the 
Porphyromonas gingivalis fimA genotype in a cohort of Chinese patients with AgP.
METHODS: Saliva and pooled subgingival plaque samples were collected from 81 
patients with AgP (25 with incisor-first molar type and 56 with generalized type 
[GAgP]) and 34 periodontally healthy controls. Eight periodontal microorganisms, 
including Aggregatibacter actinomycetemcomitans, P. gingivalis, Tannerella 
forsythia, Treponema denticola, Campylobacter rectus, Prevotella intermedia, 
Prevotella nigrescens, and Fusobacterium nucleatum were detected in these 
samples by the polymerase chain reaction (PCR). In addition, the distribution of 
fimA genotypes was assessed in P. gingivalis-positive individuals by PCR.
RESULTS: The prevalence of P. gingivalis, T. forsythia, T. denticola, C. rectus, 
P. intermedia, F. nucleatum, and A. actinomycetemcomitans in patients with AgP 
was significantly higher than that in healthy controls. The prevalence of A. 
actinomycetemcomitans in patients with GAgP was relatively low (30.4%) compared 
with other pathogens. Results of logistic regression analysis showed that 
younger patients were more likely to harbor A. actinomycetemcomitans (odds ratio 
= 2.85). Type II was the most prevalent fimA genotype of P. gingivalis in 
patients with AgP.
CONCLUSIONS: P. gingivalis, T. forsythia, T. denticola, C. rectus, P. 
intermedia, and F. nucleatum were the predominant periodontal pathogens of 
patients with GAgP in China. Type II of fimA was the most prevalent genotype of 
P. gingivalis in patients with AgP. The prevalence of A. actinomycetemcomitans 
in patients with GAgP was relatively low.