A comparison of two methods for the diagnosis of lymphogranuloma venereum

A recent outbreak of lymphogranuloma venereum (LGV) within the men who have sex with men (MSM) community and their requirement for extended therapy has highlighted the need for laboratory tests that differentiate LGV- from non-LGV-associated serovars of Chlamydia trachomatis. Two previously described methods were evaluated against 495 clinical specimens referred to the Sexually Transmitted Bacteria Reference Laboratory (London, UK): (i) PCR amplification of a 1.1 kb region of the ompI gene followed by restriction enzyme digestion (ompI RFLP-PCR); and (ii) real-time PCR targeting a 36 bp deletion present within the polymorphic membrane protein H gene of LGV-associated serovars (pmpH real-time PCR). For specimens that could be categorized using both methods, a 94.7 % (390/412) concordance was achieved. Eighty-three specimens were found to be untypeable by ompI RFLP-PCR due to a failure to amplify the 1.1 kb fragment. Of these 83 untypeable specimens, 19 were determined to be an LGV-associated serovar by pmpH real-time PCR. Despite the high level of concordance, there were differences found in the technical complexity of the two methods. The pmpH real-time PCR exhibited greater sensitivity, a more rapid turnaround time and a lower technical requirement. Whilst the ompI RFLP-PCR was not as robust as a laboratory diagnostic method, it did enable serovar-level identification. LGV infection remains an important threat to the health of high-risk MSM in Europe. In conclusion, the two methods for the detection of LGV from clinical samples were found not only to have a high concordance (94.7 %) but also to be complementary, and could be used in an integrated way to aid LGV detection.