Misdiagnosis of tuberculosis: Sputum culture is a useful diagnostic tool in Quetta, Pakistan

Tuberculosis (TB) is a major contagious disease caused by Mycobacterium tuberculosis and is endemic in many countries of the world. It is estimated that worldwide one third human population are infected with TB. There is little use of sputum culture regarding diagnosis of tuberculosis in TB endemic areas. The undertaken study evaluated the importance of TB sputum culture than other diagnostic tools among the doctors, and patients affected from active infectious pulmonary tuberculosis. The study was carried out at Fatima Jinnah General and Chest Hospital Quetta, Balochistan from January 2008 to December 2008. A total of 2237 suspected TB patient’s samples were sent for the TB diagnosis. Among the suspected TB samples, 244 (10.9%) samples were subjected for TB culture and smear microscopy, in which 119 (48.7%) samples were from female patients, while 125 (51.3%) were obtained from male patients. Of the 244 TB culture samples, 93 (38.11%) were positive, while the remaining 151 (61.8%) cases showed negative culture result. 82 of the 93 culture-positive patients were positive for acid fast bacilli (AFB) on sputum smear microscopy; however 11 samples were negative for AFB on smear analysis but positive for TB culture. Among the 244 samples, 91 (37.2%) cases were smear positive, while 153 (62.7%) were smear negative. These findings highlight the importance of suggesting sputum culture in the diagnosis of tuberculosis in the high prevalence area of Quetta.