Fluorescent microscopy for detection of acid fast bacilli in bovine lungs and lymph node

A study was undertaken to demonstrate the acid fast bacilli in the impression smears and bovine tissue sections by the fluorescence microscopy technique. Out of 252 necropsies conducted, 24 cases withcaseous lung lesions suggestive for bovine pulmonary tuberculosis were taken. Impression smears were prepared from the caseated mass of lung lesions and stained by the Ziehl-Neelsen (ZN) method. Acid- fast bacilli were observed. Staining by HiFluo Phenol free kit and examination under fluorescent microscope showed red-orange fluorescence rods which were considered positive for tuberculosis by fluorescent microscopy. Similarly, in cryosections out of twelve cases found positive for acid fast bacilli and in additional six cases in which acid fast bacilli could not be demonstrated, red-orange fluorescence (rods) against dark background were observed and considered positive. Thus, a total of 18 cases (75%) revealed acid-fast bacilli by fluorescent microscopy as against only 12 cases (50%) found positive by ZN staining.