Combined seropositivity for H-pylori and C-pneumoniae is associated with age, obesity and social factors

Background Manifestations of cardiovascular disease (CVD) have been associa ted with chronic infection by Helicobacter pylori and Chlamydia pneumoniae both in cross-sectional and in prospective follow-up cohort studies. This a ssociation may be partly due to an increase in metabolic risk factors for C VD, secondary to low-grade inflammation caused by infections. Objective To investigate for subjects classified according to serology titr es for infection with C. pneumoniae and H. pylori associations between sero positivity and the degree of obesity and fasting insulin levels, as well as social factors. Methods Using methods based on those in earlier investigations of hypertens ive patients in the Dalby primary-health-care district, southern Sweden, we investigated frozen samples from serum of 310 middle-aged treated hyperten sives and 288 age-matched and sex-matched normotensive controls from a defi ned population. The baseline examination included the measurement of weight , height and blood pressure as a mean of two office readings with the subje ct supine. The body mass index (BMI) was calculated as kg/m(2). Pasting blo od samples were drawn for measurements of levels of serum lipids, blood glu cose, plasma insulin and serum lipids, including total cholesterol and trig lycerides. The serology titres for H. pylori were determined by an enzyme-l inked immunosorbent assay. The titres for C. pneumoniae were determined by a micro-immunofluorescence method. Self-reported factors concerning social and lifestyle backgrounds were recorded. Results The group (n = 245) of subjects with combined positive serology for H. pylori and C. pneumoniae differed from the group without any positive s erology (n = 57) in age (61.6 versus 57.4 years, P < 0.05) and BMI (27.3 ve rsus 25.8 kg/m2, P < 0.05). The seropositive group also differed in terms o f fasting levels of insulin (12.7 versus 11.6 pmol/l, P < 0.05), but this d ifference did not remain significant after adjustment for age and BMI. We d etected no intergroup difference in blood pressure and levels of glucose an d lipids. Members of the group with combined seropositivity reported having a lower social-class position (educational level) than that of members of the seronegative group. Conclusion Subjects with combined positive serology for H. pylori and C. pn eumoniae are characterized by greater age, lower social class and higher BM I, as well as higher fasting levels of insulin than those of seronegative s ubjects. Obesity might be a marker not only for lower social class but also for greater than normal susceptibility to such infections.