Use of amplified Mycobacterium tuberculosis direct test (Gen-probe Inc., San Diego, CA, USA) in the diagnosis of tubercular synovitis and early arthritis of knee joint

Abstract

Background:The diagnosis of knee joint tuberculosis, especially in early stages of synovial disease, has more often been based on clinicoradiological suspicion, with no single test claiming to be a dependable rapid diagnostic test with high sensitivity and specificity. Nuclear amplification tests in vogue like the polymerase chain reaction have shown variable sensitivity and false positivity rates in various studies. We evaluated the role of Amplified Mycobacterium tuberculosis Direct Test (AMTDT) or Genprobe in the diagnosis of knee joint tuberculosis in early, especially, early synovitis and arthritis cases.Patients and Methods:Thirty two patients of suspected knee joint tuberculosis were subjected to diagnostic arthroscopy during the study period. The synovial fluid and tissue were subjected to mycobacterial culture, histopathology, and AMTDT. A comparative analysis of the sensitivity and specificity of this new test with culture and histopathology was done and the time taken for reporting was calculated for each test.Results:Out of 32 tissue samples, 8 were found to be positive with mycobacterial culture [Lowenstein Jensen (LJ)/Bactec], 11 were positive with histopathology, and 5 were found to positive with AMTDT. The sensitivity of AMTDT was found to be 62.5% and specificity was 100% with a P value of 0.083. The results were obtained earliest with AMTDT with a mean reporting time of 1.2 days, while the results of histopathology were obtained in a mean time of 6.8 days, BacT alert in 22.5 days, and conventional LJ medium culture results in 48.6 days.Conclusion:AMTDT or Genprobe is a rapid diagnostic test for early diagnosis of tubercular arthritis, but has low sensitivity in knee joint tuberculosis. Nuclear amplification tests are still far from being a single promising alternative to conventional tests in cases of joint tuberculosis. Routine use of arthroscopic biopsies in all suspected cases is helpful in the early diagnosis of knee joint tuberculosis.

Osteoarticular TB specimen yield rates. Large joint analysis at a single centre.

“…8 PCR for TB diagnosis has gained popularity firstly for its rapid yield of results, usually within hours in well-organized centres. 7,8,10,14 Secondly the sensitivity to Rifampicin is determined relatively fast, versus in MC&S. 10 For synovial fluid in osteoarticular TB, PCR sensitivity for diagnosis was reported at (63%) by Aggarwal et al 11 The latter figure is similar to the one in our study (63%) it is well within a range from 32 to 78% that is reported in the literature. 7,8 There has been a reported further improvement with a modified version of PCR namely, the Nested type.…”

“…based on adequate history taking, clinical examination, and/or typical radiological changes. 11,12 Naturally, high-index cases would then be treated empirically based on a clinical impression suggestive of osteoarticular TB diagnosis. 8 However, this practice has lost favour due to an upsurge in cases of drug-resistant TB, therefore, fostering a need for drug sensitivity analysis to be determined before initiation of any anti-TB chemotherapy.…”

TB specific intracellular cytokines production in Synovial liquid for diagnosis of tuberculous arthritis

“…In the last decades, nucleic acid-based amplification (NAA) tests have emerged as important tools for diagnosing TB. Unfortunately, these tests have a high specificity (100%) but low sensitivity (32%-78%) [11][12][13]. In our patient, the first PCR test was negative, perhaps due to the small volume extracted (3 mL).…”

“…The use of interferon-gamma release assay (IGRA) has recently shown promising results in diagnosing active extrapulmonary TB [10][11][12][13][14], with a sensitivity of 67%-93% and a specificity of 69%-78% on peripheral blood samples [15,16].…”

HIV Infection and Osteoarticular Tuberculosis: Strange Bedfellows

“…[ 11 , 12 ]. In the case of synovial fluid, PCR tests have shown moderate sensitivity (63%) but excellent specificity (92–100%) [ 13 ]. Thus PCR tests are a useful and very convenient test for OA-TB, but synovial biopsy should be performed in patients with a negative test.…”