TABLE 6

Various types of media used in the mycobacteriology laboratorya

MediumbDescription
Solid egg based (supports good growth of most mycobacteria)
    LJGood for M. tuberculosis complex; inferior for NTM recovery; although CO2 is not essential to initiate growth, it stimulates earlier and more luxuriant growth
    Gruft modification of LJContains antibiotics (penicillin and nalidixic acid) that may be useful to control excessive contamination; although CO2 is not essential to initiate growth, it stimulates earlier and more luxuriant growth
Agar based (less contamination due to more simple formulation and thus less likely to support growth of contaminants)
    Middlebrook 7H10Transparent, so colonies can be more easily observed; requires incubation with 5 to 10% CO2 for maximum yield
    Middlebrook 7H117H10 agar enriched with casein digest; transparent, so colonies can be more easily observed; requires incubation with 5 to 10% CO2 for maximum yield; stimulates more luxuriant growth of drug-resistant M. tuberculosis complex bacteria
    Mitchison's selective 7H10 and 7H11Contain the antibiotics carbenicillin, polymyxin B, trimethoprim lactate, and amphotericin B; suppressive for most contaminants; McClatchy et al. found higher yield of mycobacteria on selective 7H11 medium than on nonselective 7H11 mediumc; can be used in conjunction with nonselective media to increase culture yields
    TLA systemThinly poured plates of Middlebrook 7H11 agar; microcolonies can be detected and work-up can be started earlier than with traditional solid media; this method can be labor-intensive, but for laboratories that cannot afford automated broth detection systems, the time to detection with TLA is equivalent, without the expense of an instrument
  • a See references 75 and 335.

  • b LJ, Löwenstein-Jensen; TLA, thin-layer agar.

  • c See reference 336.