TABLE 12

Critical concentrations for testing M. tuberculosis in solid and liquid mediaa

DrugCritical concn of drug (μg/ml)
LJ mediumb7H10 agarb7H11 agarbMGIT960bVersaTREKc
Isoniazidd0.20.2 (1.0)0.2 (1.0)0.1 (0.4)0.1 (0.4)
Rifampin40.01.01.01.01.0
Ethambutol2.05.07.55.05.0
Pyrazinamide100.0300.0
Streptomycin4.02.02.01.0
Amikacin30.04.01.0
Kanamycin30.05.06.02.5
Capreomycin40.04.02.5
Ethionamide40.05.010.05.0
Cycloserine30.0
PAS1.02.08.04.0
Ofloxacin4.02.02.02.0
Levofloxacin1.01.5
Moxifloxacine0.5/2.00.5/2.0
Linezolid1.0
  • a LJ, Löwenstein-Jensen; 7H10 agar, Middlebrook 7H10 agar; 7H11 agar, Middlebrook 7H11 agar; PAS, para-aminosalicylic acid.

  • b See reference 221.

  • c See reference 343.

  • d Some laboratories may test an additional higher isoniazid concentration (shown in parentheses) to differentiate between low- and high-level isoniazid resistance.

  • e Two concentrations are proposed by the WHO. In programs using ofloxacin or levofloxacin and moxifloxacin, possible testing is for moxifloxacin only at both concentrations (0.5 and 2.0 μg/ml) or test ofloxacin or levofloxacin at its appropriate level, and moxifloxacin at the higher concentration (2.0 μg/ml). In programs using ofloxacin or levofloxacin only, test only these drugs. For programs using only moxifloxacin, testing is performed with the higher concentration (2.0 μg/ml) of moxifloxacin only.