Evaluation of the Phenol Ammonium Sulfate Sedimentation Smear Microscopy Method for Diagnosis of Pulmonary Tuberculosis

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Abstract
We compared the sensitivity and specificity of the phenol ammonium sulfate (PhAS) sediment smear microscopy method for detection of acid-fast bacilli with those of direct smear microscopy, using culture results for Mycobacterium tuberculosis as the “gold standard.” The sensitivities of the PhAS and direct smear methods were 85% (465 of 547) and 83% (454 of 547), respectively, and the specificity of each method was 97%. The PhAS method was better accepted by the laboratory technicians and safer but necessitates an overnight sedimentation, which delays reporting of results until 1 day after sputum collection.