Lymphogranuloma venereum laboratory tests

Overview
Because of limitations in a commercially available test, diagnosis is primarily based on clinical findings. Direct identification of the bacteria from a lesion or site of the infection may be possible through testing for chlamydia but, this would not indicate if the chlamydia infection is LGV. However, the usual chlamydia tests that are available have not been FDA approved for testing rectal specimens. In a patient with rectal signs or symptoms suspicious for LGV, a health care provider can collect a specimen and send the sample to his/her state health department for referral to CDC, which is working with state and local health departments to test specimens and validate diagnostic methods for LGV.

Diagnosis
The diagnosis usually is made serologically (through complement fixation) and by exclusion of other causes of inguinal lymphadenopathy or genital ulcers. Serologic testing has a sensitivity of 80% after 2 weeks. Serologic testing may not be specific for serotype (has some cross reactivity with other chlamydia species) and can suggest LGV from other forms because of their difference in dilution, 1:64 more likely to be LGV and lower than 1:16 is likely to be other chlamydia forms (emedicine). For idenification of serotypes, culture is often used. Culture is difficult. Requiring a special media, cycloheximide-treated McCoy or HeLa cells, and yields are still only 30-50%. DFA, or direct fluorescent antibody test, PCR of likely infected areas and pus, are also sometimes used. DFA test for the L-type serovar of C trachomatis is the most sensitive and specific test, but is not readily available. If polymerase chain reaction (PCR) tests on infected material are positive, subsequent restriction endonuclease pattern analysis of the amplified outer membrane protein A gene can be done to determine the genotype. Recently a fast realtime PCR (Taqman analysis) has been developed to diagnose LGV. With this method an accurate diagnosis is feasible within a day. It has been noted that one type of testing may not be thorough enough.

Resources
CDC LGV