Porphyromonas gingivalis, a gram-negative, nonspore-forming, heterodiploid, anaerobic, black-pigmented bacterium, is widely considered to be an important etiological agent of periodontal disease...

Porphyromonas gingivalis, a gram-negative, nonspore-forming, heterodiploid, anaerobic, black-pigmented bacterium, is widely considered to be an important etiological agent of periodontal disease because of its strong correlation with active disease process and abscess formation in animal infection models. Therapy for severe periodontal disease usually involves scraping to remove dental plaque and debridement (surgical removal of affected tissue and abscesses) in combination with a 2-week regimen of anaerobe-specific metronidazole and/or a 3- to 5- week regimen of tetracycline. A mouse abscess model of infection has been developed for P. gingivalis in which the bacteria are injected into the skin of the animal and allowed to form an abscess over the course of a week. The lesion site where the abscess is forming can be surgically removed, plated on blood agar plates, and incubated in an anaerobic chamber to grow colonies after about 5 days of incubation. There is an emerging paradigm shift in our current understanding of the causes of coronary heart disease from a purely hereditary and nutritional causation to a possible infectious etiology. This shift comes from recent epidemiological studies that have demonstrated a correlation between periodontal disease and coronary heart disease. There is a recent report that P. gingivalis can invade oral epithelial tissues during severe disease and exacerbate the inflammatory responses. Inflammatory responses have been linked to atherosclerosis (plaque formation in arteries) that could lead to heart disease. In support of this, another recent report found that P. gingivalis could also invade human primary coronary artery endothelial cells in tissue culture. Considering all of the above information, which of Koch’s postulates, if any, have been satisfied so far for P. gingivalis involvement in heart disease? Be sure to state your rationale. Provide at least four different modern molecular experiments that could be performed to help satisfy Koch’s postulates for P. gingivalis involvement in heart disease.