Comparison of four nonculture diagnostic tests for Chlamydia trachomatis infection

Chlamydia trachomatis (CT) is one of the commonest sexually transmitted diseases leading to urethritis, epididymitis, prostatitis in men and urethritis, cervicitis, endometritis and pelvic inflammatory disease, sometimes complicated by infertility and ectopic gestation in women. Since culture of fastidious bacteria in a monocellular medium is not available in most laboratories we compared direct immunofluorescence antigen detecting test (DFA) with three other nonculture tests-antigen detecting enzyme immunoassay (EIA), Papanicolaou staining (Pap) and Geimsa stain for endocervical swabs from women in reproductive age group.

Three hundred and fifty seven women between 16 and 41 years of age and attending family welfare clinics of IRR were evaluated for the presence pap smears. In 100 cases DFA staining was compared with Geimsa staining.

DFA test was positive in 60/357 (16.8%), EIA in 29 (8.1%) of cases and Pap smear in 37 (10%) cases. In the second group DFA was positive in 17 (17%) and Geimsa in 10 (10%) cases.

Amongst the four tests DFA showed maximum sensitivity. ELISA is less expensive but has lower sensitivity. Pap stain also has less sensitivity and good specificity, the quality of smear is likely to affect the diagnosis. Though Geimsa stain is cheapest, for chlamydial cervicitis in our experience it was not as sensitive as DFA. Thus each laboratory must decide the method depending on its resources.