Chlamydia infection in patients with and without cervical intra-epithelial lesions tested by real-time PCR vs. direct immunofluorescence

ABSTRACT

This study compares the detection rates of Chlamydia trachomatis by two techniques, direct immunofluorescence (IMF) and real time polymerase chain reaction (PCR), in patients with and without intra-epithelial cervical lesions (SIL) in Recife. We conducted a transversal study involving 35 women with SIL and 35 without SIL attended at Ambulatório Especializado da Mulher, Recife, Brazil. They were tested for Chlamydia trachomatis using two techniques, direct IMF or real time PCR. The rates of Chlamydia trachomatis detection were compared and the association with intra-epithelial cervical lesions was determined using the chi-square test at a 5 percent level of significance. Concordance between the tests was evaluated using kappa. The global prevalence of Chlamydia infection was 47.1 percent by direct IMF and 58.6 percent by real time PCR. A significant association was observed between Chlamydia diagnosis and presence of intra-epithelial cervical lesions, with about 80 percent positive results by direct IMF and 77.1 percent by real time PCR. However, the detected rate of infection with Chlamydia trachomatis was significantly greater in patients without intra-epithelial cervical lesions tested by real time PCR (40 percent) when compared to direct IMF (14.3 percent). The concordance between the tests was weak, with a kappa coefficient of 0.4. Both real time PCR and direct IMF detected elevated rates of Chlamydia infection in patients with intra-epithelial cervical lesions (80 percent) but the tests were discordant when patients without cervical lesions were tested, possibly because sensitivity of real time PCR is greater.