Inflammation from Bacterial Infection May Underlie Formation of Atherosclerotic Plaques

Cardiovascular researchers have recovered bacteria from atherosclerotic plaque tissue, and they speculate that chronic infection with this organism may be at least partially responsible for inflammation in the artery that triggers plaque formation.

Investigators a Columbia University (New York, NY, USA) analyzed femoral atherosclerotic plaque and five pairs of diseased and healthy arterial tissue obtained from a 78-year old white male patient for the presence of culturable bacteria using cell cultures and genomic analysis.

They reported in the October 20, 2010, online edition of the Journal of Atherosclerosis and Thrombosis that they were able to isolate and then cultivate gram-negative aerobic bacilli from the plaque tissue. Ribosomal 16S DNA amplification and sequencing identified the isolates as Enterobacter hormaechei. The isolate was resistant to the antibiotics ampicillin, cefazolin, and erythromycin.

Enterobacter hormaechei, which is normally associated with pneumonia and sepsis, was found to be present in the diseased arterial tissue but not in the healthy regions.

"This is the first study providing direct evidence of Enterobacter spp. associated with atheromatous tissues,” said senior author Dr. Emil Kozarov, associate professor of oral biology at Columbia University. "The data suggest that chronic infection with bacteria may be an under-reported etiologic factor in vascular pathogenesis. Our findings warrant further studies of bacterial infections as a contributing factor to cardiovascular disease, and of the concept that "bacterial persistence” in phagocytic cells likely contributes to systemic dissemination.”

"In order to test the idea that bacteria are involved in vascular pathogenesis, we must be able not only to detect bacterial DNA, but first of all to isolate the bacterial strains from the vascular wall from the patient,” said Dr. Kozarov.

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