Recovery of Mycobacterium tuberculosis from Löwenstein-Jensen media contaminated with other organisms.

Growth of contaminating organisms along with Mycobacterium tuberculosis on Löwenstein-Jensen (LJ) medium is common. However, there is no documented evidence on the decontamination procedure adopted in mycobacteriology laboratories to recover M. tuberculosis from the contaminants grown on LJ medium. At the National Institute for Research in Tuberculosis, of 1048 LJ slopes with M. tuberculosis received from intermediate reference laboratories, 98 (9%) were contaminated. Of these, 87 (89%) M. tuberculosis cultures were retrieved after decontamination with 1% cetrimide. The use of cetrimide as a decontaminating agent to retrieve M. tuberculosis cultures grown with contaminants is documented.