Jens Boman

Chlamydia pneumoniae antigens, nucleic acids, or intact organisms have been detected in human atheroma. However, the presence of antibody does not predict subsequent cardiovascular (CV) events. We performed a systematic review to determine whether the detection of C. pneumoniae DNA in peripheral blood mononuclear cells (PBMC) was associated with CV disease. We sought studies of C. pneumoniae DNA detection in PBMC by polymerase chain reaction (PCR) among patients with CV disease or other clinical conditions. We pooled studies in which CV patients were compared with non-diseased controls. We analyzed differences between studies by meta-regression, to determine which epidemiological and technical characteristics were associated with higher prevalence. Eighteen relevant studies were identified. In nine CV studies with control subjects, the prevalence of circulating C. pneumoniae DNA was 252 of 1763 (14.3%) CV patients and 74 of 874 (8.5%) controls, for a pooled odds ratio of 2.03 (95% CI: 1.34, 3.08, P < 0.001). Prevalence was not adjusted for CV risk factors. Current smoking status, season, and age were associated with C. pneumoniae DNA detection. High prevalence (>40%) was found in patients with cardiac, vascular, chronic respiratory, or renal disease, and in blood donors. Substantial differences between studies were identified in methods of sampling, extraction, and PCR targets. C. pneumoniae DNA detection was associated with CV disease in unadjusted case-control studies. However, adjustment for potentially confounding measures such as smoking or season, and standardization of laboratory methods, are needed to confirm this association.

Several recently published studies suggest that Chlamydia pneumoniae may represent a risk factor for atherosclerosis or its complications. In order to establish whether C. pneumoniae is causally linked to atherosclerotic diseases, clinical intervention trials may be needed. However, to identify eligible subjects with a persistent C. pneumoniae infection and to monitor the effect of antibiotic therapy, there is a need for a reliable diagnostic marker. Blood-based polymerase chain reaction assays may be of value for identifying patients persistently infected with C. pneumoniae and for assessing the microbiologic efficacy of antichlamydial therapy in clinical intervention trials.

Nested polymerase chain reaction (nPCR) demonstrated the presence of Chlamydia pneumoniae-specific DNA in peripheral blood mononuclear cells (PBMC).

Infection as a possible underlying cause of atherosclerosis has aroused increasing interest in recent years, Chlamydia pneumoniae being one of the organisms upon which attention has been focused. Newly published results of antibiotic treatment of vascular disease not only appear to provide further support for the infection hypothesis, but also suggest a quite different approach to the treatment of atheromatous cardiovascular disease. However, confirmatory clinical trials will be needed before antibiotic treatment can be considered in such cases.

Two commercially available monoclonal antibodies for cell culture confirmation of Chlamydia trachomatis were compared in two prospective studies and one large retrospective study. In total, more than 33,000 genital specimens were cultured in parallel and stained with both antibodies, one of which was directed against the major outer membrane protein (MOMP) and one of which was directed against the lipopolysaccharide (LPS). We found the anti-LPS-based assay to be more sensitive and as specific as the anti-MOMP-based assay for C. trachomatis cell culture confirmation of genital specimens.

To investigate the association between the onset of polymyalgia rheumatica (PMR) and prior or persistent infection with Chlamydia pneumoniae or cytomegalovirus (CMV) (both known to infect the vessel wall) enteroviruses (EV) or respiratory syncytial virus (RSV). Serum samples were collected from 48 patients with newly-diagnosed PMR and from 22 controls of the same age. The presence of IgG, IgA and IgM antibodies to C. pneumoniae, IgG and IgM antibodies to CMV and EV, and complement fixing antibodies to RSV were analysed. Clinical symptoms of infection preceding PMR symptoms were associated with the presence of synovitis at the first visit. There were no significant differences in the seroprevalence rates of antibodies to C. pneumoniae, CMV, EV or RSV between PMR patients and controls. IgM antibodies to EV were found in two patients and IgM antibodies to CMV in another two patients. Serological evidence of an association between newly-diagnosed PMR and prior or chronic infection with C. pneumoniae was not found. IgM antibodies to EV in two patients, consistent with ongoing or recent infection, suggest that EV could represent one of perhaps several microbes which are able to trigger PMR.