But antibiotic treatment does nothing to stop atherosclerosis, as two major studies have just discovered. The first involved 4012 patients with stable coronary artery disease who were given either the antibiotic azithromycin or a placebo, and the second recruited 4162 patients with acute coronary syndrome who were given either the antibiotic gatifloxacin or placebo. In neither trial did the antibiotic group fare any better than those given a placebo (N Engl J Med, 2005; 352: 1637-45, 1646-54).