Auramine phenol staining of smears for screening acid fast bacilli in clinical specimens

Tuberculosis is a major threat to the public health allover world. Out of the total tuberculosis cases reported globally, more than half are reported from African continent and India. Two to three fold rises in tuberculosis cases has been reported in the last two decades. Early diagnosis and treatment is one of the effective tools to control the rapid spread of disease. The aim of this study was to find out the value of auramine phenol (AP) staining technique in diagnosis of the suspected tuberculosis cases. A total of 2000 samples which included sputum (746), gastric aspirates (380), urine (336), endometrial biopsy (150), pleural fulids (146), Synovial fluids (67), ascitic fluids (35), cerebrospinal fluids (43), bone marrow (18), lymph node biopsy (11), pericardial aspirates (6), skin biopsy (4), peritoneal fluids (2), and stool (1) were included in the study. Sample were subjected for decontamination procedure by using standard Petroffs method. The deposit smears were stained by auramine phenol (AP stain) and Ziehl-Neelsenstaining (ZN stain) and specimens were cultured for Mycobacterium tuberculosis. Of the total positive isolates 69.23% were having pulmonary tuberculosis and 30.76 had extrapulmonary tuberculosis Genitourinary tuberculosis was the most common diagnosis among the extrapulmonary tuberculosis followed by chronic synovitis, bursitis, meningitis, septic arthritis and pericardial effusion. Out of 130 positive samples 70 by culture, 66 smears were positive by auramine phenol stain and 62 were positive by ZN stain. A total of 27 samples were tested positive only by AP staining technique, which included (12) pulmonary and (15) extrpulmonary samples. The endometrial biopsy and pericardial fluid samples showed positive for acid fast bacilli by AP stain only, whereas ZN stain and culture technique failed to demonstrate any bacilli in the same sample. Auramine stain showed high sensitivity (47.14%) and specificity (96.58%). Result of the present study showed that the auramine stain is a better method for screening samples from the suspected cases of tuberculosis sample especially pulmonary and extrapulmonary cases where bacilli count is usually low.