Specific bacteria that may have a key role in vascular pathogenesis, specifically atherosclerosis have been identified by scientists.
Using tissue specimens from the Department of Surgery and the Herbert Irving Comprehensive Cancer Center at Columbia University College of Dental Medicine, Dr. Emil Kozarov and his team isolated plaques from a 78-year-old man who had previously suffered a heart attack.
In the study, researchers describe processing the tissue using cell cultures and genomic analysis to look for the presence of culturable bacteria. In addition, they looked at five pairs of diseased and healthy arterial tissue.
The use of cell cultures aided in the isolation of the bacillus Enterobacter hormaechei from the patient's tissue. Implicated in bloodstream infections and other life-threatening conditions, the isolated bacteria were resistant to multiple antibiotics.
Surprisingly, using quantitative methods, this microbe was further identified in very high numbers in the patient but not in healthy arterial tissues.
One specific avenue of infection the researchers studied involved bacteria getting access to the circulatory system via internalization in white blood cells (phagocytes) designed to ingest harmful foreign particles.
The model that Kozarov's team was able to demonstrate showed an intermediate step where Enterobacter hormaechei is internalized by the phagocytic cells, but a step wherein bacteria are able to avoid immediate death in phagocytes.
Once in circulation, Kozarov said, bacteria using this 'Trojan horse' approach can persist in the organism for extended periods of time while traveling to and colonizing distant sites.
This can lead to multitude of problems for the patients and for the clinicians: failure of antibiotic treatment, vascular tissue colonization and initiation of an inflammatory process, or atherosclerosis, which ultimately can lead to heart attack or stroke.
"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," said Kozarov.
The findings are published in the latest Journal of Atherosclerosis and Thrombosis.