Comparison of Quantitative and Semiquantitative Enzyme-Linked Immunosorbent Assays for Immunoglobulin G against Chlamydophila pneumoniae to a Microimmunofluorescence Test for Use with Patients with Respiratory Tract Infections

Abstract

We previously reported a high degree of variation in the sensitivities of serodiagnostic kits for the detection of Chlamydophila pneumoniae in sera from healthy donors. Since a low predictive value of a test can impair its diagnostic value, we have extended our studies to samples from patients with pneumonia. We focused on the most promising enzyme-linked immunosorbent assays (ELISAs) (SeroCP and SeroCP Quant; Savyon) identified in our previous study and included a new ELISA (sELISA; Medac). The agreement between all ELISAs for immunoglobulin G (IgG) and a reference microimmunofluorescence (MIF) test for IgG (SeroFIA; Savyon) was >90% for a collective of 80 patients. The positive predictive values were all >93%. The negative predictive values ranged from 68 to 83%. False-negative results were obtained only for samples that had low titers in the MIF test. The correlation of the IgG antibody titers determined by the MIF and SeroCP Quant tests was high (r sp ‫؍‬ 0.9). Since the semiquantitative SeroCP and quantitative SeroCP Quant ELISAs achieved the highest sensitivities, they were evaluated further by using a second batch of sera from 50 patients with predominantly medium and low antibody titers in the MIF test and a control collection of sera from 80 children with negative MIF results. Again, the tests showed a high concordance with the MIF results (96%), and the antibody titers in the SeroCP Quant and MIF tests correlated well (r sp ‫؍‬ 0.8). The specificities determined with the negative sera were >99% for the SeroCP Quant test and 86% for the SeroCP test. These results show that ELISAs that are fast and objective deliver seroprevalence results, sensitivities, and specificities that are very similar to those of the MIF test.

Chronic Chlamydia pneumoniae infection in patients with symptomatic atherothrombosis

“…18,19 However, Hermann and colleagues reported that ELISAs that are fast and objective deliver seroprevalence results, sensitivities, and specificities that are very similar to those of the MIF test. 8 Our results corroborate other investigations that reported the presence of chlamydial structures and even viable C. pneumoniae in atherosclerotic plaques. Experimental proof, however, of an etiological role of C. pneumoniae in atherothrombosis has not yet been accomplished since a wellestablished animal model and a system of genetic recombination are not yet available.…”

“…8 This test, based on specific C. pneumoniae peptides, is a semi-quantitative determination of specific IgG and IgA antibodies to C. pneumoniae. A result higher than 10 IU/mL was considered positive [9].…”

Emerging strategies in the diagnosis, prevention and treatment ofChlamydophila pneumoniaeinfections

“…However, in a subsequent investigation by the same group, they reported that ELISA tests had high specificity and sensitivity and showed a good correlation with MIF tests in sera from patients with respiratory tract diseases and from control children. Antibody titers determined by quantitative ELISA also showed an acceptable correlation with those determined by MIF [60] .…”

Does Respiratory Infection Due to Chlamydia pneumoniae Still Exist?

“…The common occurrence of C. pneumoniae infection is suggested by the high seroprevalence ($70%) observed in adults [2]. However, in recent studies [3][4][5], the prevalence of respiratory infections due to C. pneumoniae was reported to be much lower (,1.5%) than previously (6%-22%) [6].…”