|Thiophen-2-carboxylic acid hydrazide (TCH or T2H)
Growth of some mycobacteria is inhibited by TCH that has been incorporated in a specific media (Middlebrook 7H11 or TCH Agar 1
µg/ml or 5 µg/ml (Remel)). The test is useful to differentiate M. tuberculosis which grows on TCH medium from M. bovis whis doesn’t
Suspend culture in distilled water or saline then inoculate the TCH agar and a control medium using a sterile pipette (~ 0.1 ml).
Incubate in 5-10% CO2 at 33-37 °C for 14-21 days. Use positive and negative controls together with tested strain.
Negative - no growth of tested strain or growth is less than 1% compared with positive control
Positive - growth of tested strain is more than 1% of the growth of positive control
Mycobacterium turberculosis ATCC 25177 – resistant
Mycobacterium bovis ATCC 19210 – sensitive.
(c) Costin Stoica