Scensidin

Multi-colour flow cytometry was applied to determine T-cell-specific interferon-gamma, interleukin-2 and tumour necrosis factor-alpha expression in children with tuberculosis and non-tuberculosis mycobacterial lymphadenopathy (NTM-L). In vitro stimulation of peripheral blood mononuclear cells with purified protein derivative from Mycobacterium tuberculosis (tuberculin) and M. avium (sensitin) revealed differential recognition of tuberculin and sensitin in both study groups. Ratios of tuberculin-specific and sensitin-specific T-cell proportions in individual patients discriminated between children with tuberculosis or NTM-L. These findings have the potential to improve the differential diagnosis of mycobacterial infections.

Skin testing with Mycobacterium avium sensitin (MAS) RS 10/2 and purified protein derivative (PPD) was conducted on patients with pulmonary disease due to M. avium complex (MAC) or Mycobacterium tuberculosis (MTB) and no known immunodeficiency. Reactions > or = 5 mm to either MAS or PPD were present in 37 (84%) of 44 MAC patients and 28 (97%) of 29 MTB patients. MAC patients had a mean MAS reaction of 13.8 (+/-8.3) mm and a mean PPD reaction of 3.5 (+/-8.6) mm (P < .001). MTB patients had a mean MAS reaction of 17.9 (+/-9.4) mm and a mean PPD reaction of 22.9 (+/-11.4) mm (P < .001). MAS-dominant skin tests (MAS reaction > or = 5 mm larger than PPD reaction) were present in 32 (73%) of 44 MAC patients and 1 (3%) of 29 MTB patients. MAS-dominant skin tests had a specificity of 97% for discriminating MAC disease from MTB disease.

Background: A positive tuberculin skin test (TST) may indicate cross-reacting immunity to non-tuberculous mycobacteria (NTM) and not latent tuberculosis infection (LTBI). Objectives: To assess misclassification of LTBI, as assessed by skin testing with Mycobacterium avium sensitin (MaS), and to determine how this misclassification affects the analysis of risk factors for LTBI. Methods: In a population-based survey, participants underwent skin testing with M. tuberculosis purified protein derivative (PPD) and MaS. A PPD-dominant skin test was a reaction that was ≥ 3 mm larger than the MaS reaction; a MaS-dominant skin test was a reaction that was ≥ 3 mm larger than the PPD reaction. Results: Of 447 randomly selected persons, 135 (30%) had a positive PPD test. Of these, 21 (16%) were MaS- dominant, and were therefore attributable to NTM and misclassified as LTBI. PPD reactions of 5-14 mm were more likely to be misclassified than those ≥ 15 mm (OR = 5.0, 95%CI 1.9-13.2). Adjusting for misclassification had only a small impact on the analysis of risk factors for LTBI. Conclusions: A substantial number of individuals who are diagnosed with LTBI are actually sensitized to NTM. Using dual skin testing would reduce misdiagnosis and prevent unnecessary treatment.