Afb Detection Fluroscence Smear Microscopy Infected Smear

Fifty years after effective chemotherapy, tuberculosis (TB) still remains leading infectious cause of adult mortality. The aim of present study was to evaluate diagnostic utility of papanicolaou (Pap) stain induced fluorescence microscopic examination of salivary smears in the diagnosis of pulmonary TB. Routinely collected sputum specimens from persons suspected to have tuberculosis who attended community clinics were stained with auramine O and were evaluated using 2 different excitatory light sources (MVP and LED); these specimens were then Ziehl-Neelsen stained and reexamined using light microscopy. Two microscopists independently evaluated all smears. Bacterial culture provided the gold standard. Sputum smear microscopy is the only diagnostic test available in most resource-limited settings for the evaluation of patients with symptoms suggestive of pulmonary tuberculosis (TB). Since the initial description of the auramine O fluorescence microscopy technique by Hagemann in 1937, numerous reports have confirmed the superior diagnostic performance of fluorescence microscopy, compared with Ziehl-Neelsen (ZN) staining and light microscopy. In a systematic review of 18 studies, Steingart et al. reported that fluorescence microscopy of auramine-stained smears provides similar specificity and increased sensitivity (mean improvement of 10%), compared with light microscopy of ZN-stained smears. In addition to increased sensitivity, fluorescence microscopy also allows more-rapid screening of sputum smear specimens. From an operational perspective, this is highly advantageous, particularly when high numbers of samples are screened per day, because the majority of laboratory time is spent confirming negative smear results. According to the International Union Against Tuberculosis and Lung Disease technical guidelines for sputum microscopy, at least 5 min of screening is required to correctly identify a negative smear result when conventional light microscopy is used 8. However, under routine field conditions, the time spent per slide is often far less than the minimum required.