Bacterial Signatures in Thrombus Aspirates of Myocardial Infarction

Study Questions:

Is bacterial DNA present in thrombus aspirates of patients with ST-segment elevation myocardial infarction (STEMI), and is there an association between bacteria findings and oral pathology in the same cohort?

Methods:

Thrombus aspirates and arterial blood from 101 patients with STEMI undergoing primary percutaneous coronary intervention (PCI) were analyzed with real-time quantitative polymerase chain reaction with specific primers and probes to detect bacterial DNA from several oral species and Chlamydia pneumoniae.

Results:

Total number of patients was 101, 76% were male, and mean age was 63.3 years. The median value for the total amount of bacterial DNA in thrombi was 16 times higher than that found in their blood samples. Bacterial DNA typical for endodontic infection, mainly oral viridans streptococci, was measured in 78.2% of thrombi, and periodontal pathogens were measured in 34.7%. Bacteria-like structures were detected by transmission electron microscopy in all nine thrombus samples analyzed; whole bacteria were detected in three of nine cases. Monocyte/macrophage markers for bacteria recognition (CD14) and inflammation (CD68) were detected in thrombi (eight of eight) by immunohistochemistry. Among the subgroup of 30 patients with MI examined by panoramic tomography, a significant association between the presence of periapical abscesses and oral viridans streptococci DNA–positive thrombi was found (odds ratio, 13.2; 95% confidence interval, 2.11–82.5; p = 0.004).

Conclusions:

Dental infection and oral bacteria, especially viridans streptococci, may be associated with the development of acute coronary thrombosis.

Perspective:

The findings add to the literature suggesting that oral flora is involved in the pathogenesis of atherosclerosis and the acute coronary syndromes. However, there have been many randomized clinical trials designed to assess the impact of antibiotic therapy on outcome after an acute coronary syndrome or PCI, each of which did not show a benefit. Most were designed to target Chlamydia pneumoniae, but would have been effective against streptococci. Among the arguments of lack of efficacy were that the course of treatment was too short. The finding of viridans streptococci in thrombus does not establish a causal relationship nor that the bacteria were anything more than oral flora circulating in healthy persons or associated with periodontal disease that lodged in the thrombus.

Clinical Topics: Acute Coronary Syndromes, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Stable Ischemic Heart Disease, Interventions and ACS, Interventions and Imaging

Keywords: Acute Coronary Syndrome, Anti-Bacterial Agents, Atherosclerosis, Chlamydophila pneumoniae, Coronary Thrombosis, DNA, Bacterial, Immunohistochemistry, Inflammation, Macrophages, Microscopy, Electron, Transmission, Monocytes, Myocardial Infarction, Pathology, Oral, Percutaneous Coronary Intervention, Periapical Abscess, Polymerase Chain Reaction, Primary Prevention, Thrombosis, Tomography, Viridans Streptococci


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