The first symposium developed jointly by the American College of Cardiology and the Brazilian Society of Cardiology, provided an overview of infectious diseases of the heart. The session featured an important review of viral and parasitic infections of the heart and the role of infection in myocarditis, pericarditis, and coronary artery disease CAD.

In her presentation, Dr. Maria de Lourdes Higuchi, MD, PhD, The Heart Institute, Sao Paulo, Brazil focused on Chlamydia pneumonia (CP) and Mycoplasma pneumoniae (MP), 2 microorganisms that have been implicated in bacterial infection and inflammatory conditions of the heart and pericardium. MP requires cholesterol for survival, and because vulnerable atheromas are rich in cholesterol, they may provide a favorable environment for MP growth. Studies have confirmed that MP is found primarily in the lipid core of ruptured thrombosed plaques. In addition, mycoplasma may increase the virulence of other infectious agents; for example, Dr. Higuchi noted that research has demonstrated a symbiotic relationship between Mycoplasma hominis and Trichomonas vaginalis [Dessi et al. Infect Immun 2005]. “Species interaction forms more stable and productive colonies,” she said. The result is more resistant chronic infections.

In CAD, coinfection with MP and CP may represent an important contributor to plaque inflammation, instability, and rupture, because greater amounts of MP and CP have been strongly correlated with histologic signs of increased plaque vulnerability. In other studies, CAD or myocardial infarction (MI) has been found to be more prevalent among individuals who are seropositive for both MP and CP, and elevated levels of serum MP and CP antibodies have been found in association with acute MI.

Dr. Higuchi also noted that small amounts of MP and CP have been found in some vessels without atherosclerotic plaque, suggesting that another factor may contribute to the proliferation of these microorganisms. Her research has shown that vulnerable plaques also contain archaea, the most primitive microorganisms [Clinics 2006]. The powerful antioxidative enzymes of archaea may enable them to enhance the survival of aerobic microorganisms such as MP and CP and to participate in the pathogenesis of plaque vulnerability, said Dr. Higuchi. She added that effective treatment will require targeting the fundamental pathways that maintain the symbiotic state of the microorganisms.