Quantification of periodontal pathogens in vascular, blood and subgingival samples from patients with peripheral arterial disease or abdominal aortic aneurysms

Background: The aim of this investigation was to quantify periodontal pathogens (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Campylobacter rectus and Tannerella forsythia) in vascular, blood and subgingival samples. As secondary objective, two molecular bacterial identification methods [nested-polimerase chain reaction (PCR) and quantitative PCR (qPCR)] were compared.

Methods: Seventy consecutive patients provided a vascular lesion, a blood sample, and 36 subgingival samples. Bacterial deoxyribonucleic acid (DNA) was extracted and qPCR was used to determine the prevalence and amounts of the target pathogens in each sample. Nested-PCR was only performed in the samples from vascular lesions. Periodontal examination was performed in 42 patients. U-Mann-Whitney or Chi-squared tests were used to compare microbiological results according to periodontal diagnosis.

Results: All targeted periodontal pathogens (A. actinomycetemcomitans, P. gingivalis, T. forsythia or C. rectus) were detected in subgingival samples with a prevalence rate of 72.2%, 47.2%, 74.3% and 82.9%, respectively. In 7.1% and 11.4% of vascular and blood samples, bacterial DNA was detected. One patient was positive for A. actinomycetemcomitans in the three types of samples. No differences were found in the levels of targeted bacteria when comparing periodontitis and non-periodontitis patients. Prevalence rates obtained with nested PCR were significantly higher than those obtained by qPCR.

Conclusions: The presence of of A. actinomycetemcomitans was demonstrated in vascular, blood and subgingival samples in one out of 36 patients. These results, although with a very low frequency, may support the hypothesis of a translocation of periodontal pathogens from subgingival microbiota to the blood stream and then to atheromatous plaques in carotid or other peripheral arteries. Nested-PCR is not an adequate method for identifying DNA of periodontal pathogens in low quantities, due to the high number of false negative results.