Diagnostic utility of serologic markers for genital chlamydial infection in STD patients in Chennai, India.

OBJECTIVES To evaluate the diagnostic utility of serological markers for C. trachomatis in different clinical groups of STD patients. METHODS Blood and genital swab specimens were collected from symptomatic STD patients (n=143) attending the STD out patient clinic at the Institute of STDs, Government General hospital, Chennai who enrolled for the study. Serological determination for IgM, IgA and IgG antibodies to C. trachomatis was done using commercial kits. PCR analysis was performed on genital swab samples by using plasmid and major outer membrane protein (MOMP) based primers and patients who were positive by both PCR assays were considered as proven cases of C. trachomatis infection. The serological marker positivity was analysed with PCR positivity. RESULTS Serologic positivity by IgM, IgA and IgG was 22.4%, 28.7% and 58.7% respectively. The PCR analysis showed 44 (30.8%) cases with confirmed C. trachomatis infection. Seropositivity for IgM (34.1% (15/44) vs. 17.2% (17/99); P<0.05) as well as for IgA (40.9% (18/44) vs. 23.2% (23/99); P<0.05) significantly correlated to PCR positivity, while significant correlation was not seen with IgG positivity. The overall seropositivity (IgM/IgA/IgG) in the study population was 68.5%. CONCLUSIONS The observations of the present study indicate a high exposure rate to chlamydial infection in STD clinic patients in India. The study also suggests the usefulness of serology instead of PCR to trace chlamydial etiology, especially in deep-seated upper genital tract diseases and to facilitate better clinical management as there was good correlation between serology and PCR positivity.