Comparison of Mycobacterium tuberculosis culture using liquid culture medium and Lowenstein Jensen medium in abdominal tuberculosis

Background Traditionally, the Lowenstein Jensen (LJ) medium has been used for culturing Mycobacterium tuberculosis. In abdominal tuberculosis (TB), the reported yield from tissue culture is between 20% and 60%. Liquid cultures are reported to give a higher yield but there is little data available in abdominal TB. Aim To compare the yield of TB culture with BACTEC 460TB liquid medium and LJ medium for patients with suspected abdominal TB and determine cost effectiveness. Methods This prospective study was done in consecutive cases with clinical, radiological, endoscopic/ surgical, and histological suspicion of abdominal TB. Tissue biopsies obtained at colonoscopy or surgery were processed and plated on LJ medium as well as the BACTEC 460TB system. NAP (rho-nitro-alpha-acetylamino-beta-hydroxy-propiophenone) differentiation was carried out to determine species. The cost of each method and cost per yield were calculated. Results Of the 29 cases, 22 cases (76%) were positive on BACTEC 460TB culture while 14 (48%) were positive on LJ medium giving a 64% increment in yield. However, the culture of one patient grew on LJ medium, where the BACTEC 460TB was negative. The additional cost of BACTEC 460TB is Rs. 460 and LJ is Rs. 40. Conclusions Samples from patients with abdominal TB should be processed on both liquid and LJ medium. For high yield, the use of a liquid culture medium system is essential.