Azithromycin therapy in patients with chronic Chlamydia pneumoniae infection and coronary heart disease: immediate and long-term effects on inflammation, coagulation, and lipid status in a double-blind, placebo-controlled study

Abstract

Background: An association between Chlamydia pneumoniae (Cp) infection and coronary heart disease (CHD) has already been reported. We investigated the relationship between Cp infection and other risk factors in CHD patients, as well as the effects of azithromycin treatment. Methods: We studied 38 patients with Cp infection (Cp-pos) and 15 without (Cp-neg). Cp-pos patients had, both at inclusion and 2 years prior to inclusion, elevated Cp-specific IgA-antibodies, with or without the presence of pharyngeal Cp by polymerase chain reaction (PCR) detection. Blood was analyzed for Cp-antibodies, interleukin-6, interleukin-1 receptor antagonist (IL-1ra), CRP, orosomucoid, fibrinogen, leukocytes, PAI-1, tPA, von Willebrand factor (vWf), platelet count and aggregation, and lipids. Cp-pos patients were randomized to placebo or oral azithromycin, 500 mg on day 1 and then 250 mg/day for 4 days, with repeated therapy after 3 weeks. Blood was taken immediately, as well as 3 months and 2 years after therapy. Results: CRP and IL-1ra levels were higher in Cp-pos than in Cp-neg patients: median, interquartile range 8.5 (3.0–20) vs. 2.0 (1.0–3.8) mg/l, and 316 (165–404) vs. 178 (118–195) ng/l, p=0.0006 and p=0.002, and platelet aggregation was lower: 4.8 (2.9–6.4) vs. 8.1 (4.7–11.4) Ω, p<0.05. tPA levels increased in azithromycin-treated patients between entry and 3-month follow-up: mean±S.D. 3.7±4.2 vs. 1.0±2.1 μg/l, p<0.05. Other variables did not differ. Conclusions: Cp infection was associated with increased inflammatory activity and lower platelet aggregability, suggesting that inflammation may be of greater pathophysiological importance than platelet activity in these patients. Although an effect on Cp infection was not shown, azithromycin may have a positive effect on fibrinolysis, as increased levels of tPA were observed in the treatment group.