Antibiotics may prevent heart attacks

BMJ 1999; 318 doi: (Published 13 February 1999) Cite this as: BMJ 1999;318:417
  1. Janice Hopkins Tanne
  1. New York

    Infections, particularly Chlamydia pneumoniae, have been suggested as causes or contributing factors in atherosclerosis and heart attacks. Now indirect evidence shows that antibiotics, taken to treat common infections, may protect against first time myocardial infarction (JAMA 1999:281;427-31).

    Patients who had taken tetracyclines were at significantly lower risk of having a heart attack than those who had not, according to retrospective analysis of data from 350general practices in the United Kingdom's General Practice Research Database, which includes about three million patients.

    The study, by the Boston Collaborative Drug Surveillance Program at Boston University in Lexington, Massachusetts, identified patients in the database who had a first heart attack between 1January 1992and 31October 1997.Patients were excluded who were older than 75or who had risk factors such as a history of ischaemic heart disease.

    Each patient was matched with controls from the same practice, also excluding those with risk factors. The study identified 3315patients with heart attacks and these were matched with 13139 controls.

    Some heart attack patients and some control patients had received antibiotics. However, more patients who had not had a heart attack had received antibiotics, compared with those who had had one.

    This finding suggested that taking antibiotics somehow protected against heart attacks.

    Compared with patients who received no antibiotics, those who received tetracyclines had an odds ratio of 0.7(confidence interval 0.55to 0.90) and those who had received quinlones had an odds ratio of 0.45(0.21to 0.95). Those who received macrolides (mainly erythromycin which is not very effective against C pneumoniae), sulphonamides, penicillins, or cephalosporins were not “protected” against a heart attack.

    The authors concluded that their findings indirectly support the hypothesis that certain chronic bacterial infections may have a role in the aetiology of ischaemic heart disease and that use of tetracyclines or quinolones might alter the course of such chronic infections and thereby reduce the risk of heart attack.

    Not so fast to the prescription pad, argued Dr Aaron Folsom of the School of Public Health at the University of Minnesota in Minneapolis (JAMA 1999:281;461-462). While C pneumoniae and Helicobacter pylori as well as herpes virus, cytomegalovirus, and periodontal infections may contribute to atherosclerosis, the mechanism is unclear. He pointed out that caution in antibiotic prescribing is needed to prevent development of drug resistant bacteria.

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