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The Pharmaceutical Journal
Cardiac patients benefit from antibiotic therapy regardless of infection status
Antibiotic treatment reduces adverse cardiac events in patients with acute coronary syndromes whether or not they are infected with Chlamydia pneumoniae or Helicobacter pylori, say researchers from the Mayday Hospital, Croydon, and St George's Hospital Medical School, London.
Infection with these organisms is associated with coronary heart disease and this prompted the researchers to conduct a study to find out if antibiotic treatment could reduce adverse cardiac events.
They found that patients treated with antibiotics were less likely to die or be readmitted to hospital with acute coronary syndrome than patients given placebo. However, the reduced risk was not related to the presence of the two bacteria.
"The beneficial effect of the antibiotics was independent of whether a person was infected with H pylori or C pneumoniae," said Dr Michael Mendall, consultant gastroenterologist at the Mayday Hospital.
"This implies these antibiotics are not [just] working against these organisms. The antibiotics may be acting against other organisms to reduce the overall infectious burden of the body or may have their own anti-inflammatory properties."
The researchers randomly assigned 325 patients who had been admitted to hospital following myocardial infarction (MI) or unstable angina to receive either amoxicillin, azithromycin (Zithromax), or placebo for one week. Patients treated with antibiotic therapy were also given omeprazole (Losec) and metronidazole. Blood tests were carried out to detect antibodies to H pylori and C pneumoniae before study treatment was started.
The researchers found that after 12 weeks, patients who received antibiotic therapy were 36 per cent less likely to be readmitted to hospital for unstable angina or for non-fatal MI, or to suffer a fatal MI, than those who received placebo (17.2 per cent versus 27.2 per cent, P=0.02). This reduction persisted during the one-year follow-up.
They also found that in unstable angina patients who received amoxicillin, C-reactive protein levels were reduced (P=0.03). However, there was only a trend towards reduction in those who had experienced an MI. Fibrinogen levels were reduced in all patients given antibiotic treatment but the reduction was not statistically significant.
Dr Mendall pointed out that azithromycin, but not amoxicillin, is known to have anti-inflammatory properties. "The failure to find a difference in effect between the two antibiotic regimens suggests that metronidazole or omeprazole may be the important component of the regimen," he added.
The study is published as a rapid access article on the Circulation website
Citation: The Pharmaceutical Journal URI: 20007553
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