Comparison of two gamma interferon release assays and tuberculin skin testing for tuberculosis screening in a cohort of patients with rheumatic diseases starting anti-tumor necrosis factor therapy.

Gamma interferon release assays (IGRAs) are increasingly used for latent Mycobacterium tuberculosis infection (LTBI) screening in patients with rheumatic diseases starting anti-tumor necrosis factor (anti-TNF) therapies. We compared the performances of two IGRAs, an enzyme-linked immunospot release assay (T-SPOT.TB) and an enzyme-linked immunosorbent assay (QuantiFERON-TB Gold In Tube [QFT-GIT]), to that of tuberculin skin testing (TST) for LTBI screening of 157 consecutive rheumatic patients starting anti-TNF therapies. Among 155 patients with valid results, 58 (37%) were positive by TST, 39 (25%) by T-SPOT.TB assay, and 32 (21%) by QFT-GIT assay. IGRAs were associated more strongly with at least one risk factor for tuberculosis (TB) than TST. Risk factors for a positive assay included chest X-ray findings of old TB (TST), advanced age (both IGRAs), origin from a country with a high TB prevalence, and a positive TST (T-SPOT.TB assay). Steroid use was negatively associated with a positive QFT-GIT assay. The agreement rate between IGRAs was 81% (kappa rate = 0.47), which was much higher than that observed between an IGRA and TST. If positivity by either TST or an IGRA was required for LTBI diagnosis, then the rate of LTBI would have been 46 to 47%, while if an IGRA was performed only for TST-positive patients, the respective rate would have been 11 to 17%. In conclusion, IGRAs appear to correlate better with TB risk than TST and should be included in TB screening of patients starting anti-TNF therapies. In view of the high risk of TB in these patients, a combination of one IGRA and TST is probably more appropriate for LTBI diagnosis.

Usefulness of enzyme-linked immunospot assay (Elispot) compared to tuberculin skin testing for latent tuberculosis screening in rheumatic patients scheduled for anti-tumor necrosis factor treatment.

OBJECTIVE: Treatment with tumor necrosis factor (TNF) antagonists in patients with rheumatic diseases has been associated with increased rates of tuberculosis due to reactivation of latent Mycobacterium tuberculosis (MTb) infection (LTBI). Diagnosis of LTBI is based mainly on the tuberculin skin test (TST), which has certain limitations. METHODS: We compared the TST with an enzyme-linked immunospot interferon-gamma (IFN-gamma) release assay (Elispot; T SPOT TB) for the diagnosis of LTBI in 70 patients with various rheumatic diseases starting treatment with anti-TNF agents. All patients underwent a standard initial evaluation for LTBI including clinical examination, chest radiograph, and standard TST. Freshly isolated peripheral blood mononuclear cells were stimulated ex vivo with MTb-specific antigens (ESAT-6 and CFP10), and IFN-gamma-producing cells were counted (Elispot assay). RESULTS: Twenty-seven patients (38.6%) were TST+ and 16 were Elispot+ (22.8%). The overall level of agreement between the 2 tests was 72.8%, being much higher in patients who were TST- (39/43, 90.6%) than in those who were TST+ (12/27, 44.4%). Discordant results were observed in 19 patients (27.1%). Among TST- patients (n = 43), 4 were Elispot+ (9.3%); we also identified 15 Elispot- patients among 27 TST+ patients (55.6%). Multivariate analysis showed that a history of bacillus Calmette-Guérin (BCG) vaccination was associated with TST+/Elispot- discordant results (p = 0.01), whereas steroid use was linked to TST-/Elispot+ discordant results (p = 0.04). CONCLUSION: Elispot assay is a useful test for diagnosis of LTBI in rheumatic patients scheduled for anti-TNF therapy and identification of patients with false-positive TST results due to previous BCG vaccination.

Poststreptococcal reactive arthritis with thoracic spine involvement in an adult.

It is controversial whether poststreptococcal reactive arthritis (PSReA) is an entity separate from acute rheumatic fever (ARF) or is a forme fruste of ARF. Although there are many case series of PSReA in children, this entity is not common in adults. We describe an adult patient with polyarthritis and thoracic spine involvement attributed to PSReA.