The scourge of coronary disease in diabetic patients: will antibiotics sweeten the pill?

Diabetes is a major and increasing public health problem and this is reflected in the growing proportion of diabetics presenting with coronary artery disease. In this issue, Erkens et al. present data that suggest a potential role for antibiotics in the prevention of coronary heart disease in diabetic patients. While the results are provocative, the authors readily admit that they should be regarded as hypothesis-generating rather than definitive. Although the hypothesis that chronic infection plays a role in the pathogenesis of coronary heart disease (CHD) is far from new, few studies have looked specifically at the diabetic population. The infectious agent for which the link with atherosclerosis is the strongest is Chlamydia pneumoniae, a Gram-negative obligatory intracellular bacterium, and we will only discuss this pathogen, which is also the focus of the paper by Erkens et al.. C. penmoniae is the second most prevalent bacterial cause of atypical pneumonia. It is also responsible for acute pharyngitis, sinusitis, and bronchitis. About half of the adult population have positive C. pneumoniae antibodies titres. There is no definitely reliable laboratory test, and some of these tests are technically demanding (e.g. microimmunofluorescence). More than 30 seroepidemiological studies have looked at the relationship between C. pneumoniae antibodies and CHD. In most of these studies, the odds ratio was at least two. In some of them, the odds ratio increased with increasing antibody titres. The results appear consistent from one study to another, thus the relation between C. pneumoniae and CHD may be real. But there may be biases: the populations differed, as did the design of the studies (case-control, prospective), the criteria for cases, the method of detection of antibodies, the cut-off for defining seropositivity, the degree of adjustment for potential confounders (e.g. smoking), publication bias favouring positive results; only very few studies were prospective. Recently, Danesh et al., in a metaanalysis of 15 prospective studies, found only a weak