RT Journal Article SR Electronic T1 Polymerase chain reaction for detection of Chlamydia trachomatis in conjunctival swabs JF British Journal of Ophthalmology JO Br J Ophthalmol FD BMJ Publishing Group Ltd. SP 497 OP 500 DO 10.1136/bjo.81.6.497 VO 81 IS 6 A1 Elfath M Elnifro A1 Christopher C Storey A1 David J Morris A1 Andrew B Tullo YR 1997 UL http://bjo.bmj.com/content/81/6/497.abstract AB AIMS/BACKGROUND Ocular Chlamydia trachomatis infection in the west occurs as ophthalmia neonatorum, acquired from the mother, or adult paratrachoma which is also associated with current genital tract infection. Accurate rapid laboratory diagnosis facilitates management, but the relative merits of antigen detection or DNA amplification tests are unresolved. METHODS A polymerase chain reaction (PCR) test was developed which amplified part of the plasmid shared by all the serovars of C trachomatis. Conjunctival swabs were tested using an in house immune dot-blot test (IDBT) for chlamydial lipopolysaccharide antigen, a commercial direct fluorescent antibody (DFA) test for chlamydial elementary bodies, and the PCR (DNA extracted using guanidinium lysis buffer). RESULTS The PCR achieved a detection limit of 100 plasmid copies (10 elementary bodies). In a combined retrospective and prospective clinical evaluation, the PCR and IDBT gave identical results with 21 positive and 57 negative eye swabs. However, interpretation of the DFA test required meticulous examination of the stained smear, sometimes by two microscopists. CONCLUSIONS The PCR is likely to play an increasing role in the diagnosis of ocular C trachomatisinfection because of its excellent sensitivity and specificity.