New diagnostic methods are effective for more quickly diagnosing multidrug-resistant tuberculosis and for distinguishing Mycobacterium avium-complex pulmonary disease (MAC-PD) from pulmonary tuberculosis, according to two studies in the April 1 issue of the American Journal of Respiratory and Critical Care Medicine.

In the first study, Marinus Barnard, from National Health Laboratory Services in Cape Town, South Africa, and colleagues tested a commercially available molecular assay to detect rifampicin and isoniazid resistance in 536 smear-positive sputum samples from patients at high risk of multidrug-resistant Mycobacterium tuberculosis. They found that 97 percent of samples gave interpretable results within one to two days. The sensitivity, specificity, and positive and negative predictive values were all greater than 94 percent compared with conventional results.

In the second study, Seigo Kitada, M.D., from National Hospital Organization National Toneyama Hospital in Osaka, Japan, and colleagues tested an enzyme immunoassay to detect serum IgA antibody to glycopeptidolipid core antigen specific for M. avium complex in 70 patients with MAC-PD, 18 with M. avium complex contamination, 37 with pulmonary tuberculosis and 76 healthy subjects. They found that antibody levels were significantly higher in patients with MAC-PD. A cutoff of 0.7 U/mL had a high sensitivity and specificity for diagnosing the disease. Antibody levels correlated well with disease extent by computed tomography.

"The enzyme immunoassay kit is useful for the rapid diagnosis of MAC-PD and for differentiating MAC-PD from pulmonary tuberculosis and, if validated by studies in other populations, could find wide application in clinical practice," Kitada and colleagues conclude.

Abstract - Barnard
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Abstract - Kitada
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Prepared jointly by the editors of RN and HealthDay's Physicians' Briefing (www.physiciansbriefing.com).