Diagnostic Tests for Lymphogranuloma Venereum (LGV)
The recommended diagnostic approach for lymphogranuloma venereum includes nucleic acid amplification testing (NAAT) for Chlamydia trachomatis followed by specific testing to identify LGV serovars (L1, L2, or L3), with serological testing as a supportive diagnostic method in certain cases. 1
Primary Diagnostic Tests
- Nucleic acid amplification tests (NAATs) are the most sensitive method for detecting Chlamydia trachomatis in clinical specimens and should be performed first 2, 1
- Standard NAATs will detect C. trachomatis but cannot distinguish between LGV serovars (L1-L3) and non-LGV serovars 2, 1
- After positive NAAT for C. trachomatis, specific testing to identify LGV serovars is required, typically through specialized PCR-based tests that can differentiate LGV strains 1, 3
- Specimens for NAAT should be collected from the site of infection: rectal swabs for proctitis, urethral swabs for urethritis, or aspirates from buboes 1, 4
Serological Testing
- Serological testing can support the diagnosis of LGV when clinical presentation is suggestive 2, 1
- Microimmunofluorescence (MIF) with titers ≥256 with appropriate clinical presentation suggests LGV 2, 1
- Complement fixation (CF) titers ≥64 with appropriate clinical presentation suggests LGV, with approximately 80% sensitivity at 2 weeks after infection 2, 1
- IgA anti-Major Outer Membrane Protein (MOMP) assay can identify a considerable proportion of anal LGV infections with 75.5% sensitivity and 74.3% specificity 5
Clinical Specimens
- For rectal LGV: rectal swabs are the preferred specimen, especially in men who have sex with men (MSM) who commonly present with proctocolitis 1, 6
- For inguinal syndrome: aspirate from buboes or lymph nodes for NAAT testing 1
- For urethral LGV: first-void urine or urethral swab for NAAT 4
Diagnostic Algorithm
- Initial screening: Perform NAAT for C. trachomatis on appropriate clinical specimens 2, 1
- If NAAT positive: Request LGV-specific testing to identify serovars L1, L2, or L3 1, 3
- Serological support: Consider serological testing (MIF or CF) as supportive evidence, especially in cases with typical clinical presentation but negative NAAT 2, 1
- Universal testing consideration: In high-risk populations (e.g., MSM), consider universal LGV testing of all C. trachomatis-positive rectal specimens, as approximately 51% of LGV cases may be asymptomatic 7
Important Considerations
- Routine commercial serologic tests have limited value for diagnosing acute LGV infections as they cannot distinguish between current and previous infections 2
- Specialized serological tests (MIF, CF) are typically available only in reference laboratories 2
- Post-treatment tests using NAAT should be scheduled a minimum of 3 weeks after completion of antimicrobial therapy to avoid false results 2
- Recent outbreaks of LGV, particularly among HIV-positive MSM, highlight the importance of testing for LGV in patients with proctitis or inguinal lymphadenopathy 1, 6