Antibiotic treatment of Chlamydia pneumoniae after acute coronary syndrome

N Engl J Med. 2005 Apr 21;352(16):1646-54. doi: 10.1056/NEJMoa043528.


Background: Chlamydia pneumoniae has been found within atherosclerotic plaques, and elevated titers of antibody to this organism have been linked to a higher risk of coronary events. Pilot studies have suggested that antibiotic treatment may reduce the risk of cardiovascular events.

Methods: We enrolled 4162 patients who had been hospitalized for an acute coronary syndrome within the preceding 10 days and evaluated the efficacy of long-term treatment with gatifloxacin, a bactericidal antibiotic known to be effective against C. pneumoniae, in a double-blind, randomized, placebo-controlled trial. Subjects received 400 mg of gatifloxacin daily during an initial 2-week course of therapy that began 2 weeks after randomization, followed by a 10-day course every month for the duration of the trial (mean duration, 2 years), or placebo. The primary end point was a composite of death from all causes, myocardial infarction, documented unstable angina requiring rehospitalization, revascularization (performed at least 30 days after randomization), and stroke.

Results: A Kaplan-Meier analysis revealed that the rates of primary-end-point events at two years were 23.7 percent in the gatifloxacin group and 25.1 percent in the placebo group (hazard ratio, 0.95; 95 percent confidence interval, 0.84 to 1.08; P=0.41). No benefit was seen in any of the prespecified secondary end points or in any of the prespecified subgroups, including patients with elevated titers to C. pneumoniae or C-reactive protein.

Conclusions: Despite long-term treatment with a bactericidal antibiotic effective against C. pneumoniae, no reduction in the rate of cardiovascular events was observed.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Angina, Unstable / drug therapy*
  • Angina, Unstable / prevention & control
  • Anti-Bacterial Agents / adverse effects
  • Anti-Bacterial Agents / therapeutic use*
  • Cardiovascular Diseases / mortality
  • Cardiovascular Diseases / prevention & control*
  • Chlamydophila Infections / drug therapy*
  • Chlamydophila pneumoniae
  • Double-Blind Method
  • Female
  • Fluoroquinolones / adverse effects
  • Fluoroquinolones / therapeutic use*
  • Gatifloxacin
  • Humans
  • Male
  • Middle Aged
  • Myocardial Infarction / drug therapy*
  • Myocardial Infarction / prevention & control
  • Myocardial Revascularization
  • Proportional Hazards Models
  • Prospective Studies
  • Stroke / prevention & control


  • Anti-Bacterial Agents
  • Fluoroquinolones
  • Gatifloxacin