Evaluation of commercial blood-containing media for cultivation of Mycobacterium haemophilum.

Mycobacterium haemophilum requires hemin for growth, and thus it is unlikely to be isolated by current routine methods. This study evaluated growth of M. haemophilum on commercially available blood agar and on different basal media and with other sources of hemin. The effect of dyes, crystal violet and malachite green, in controlling contamination was tested. Results showed that although M. haemophilum can grow on a variety of commercially prepared blood agars, contamination is a significant deterrent. Both malachite green and crystal violet inhibited the growth of contaminants without affecting the growth of M. haemophilum. The following medium (MMV: McBride's Mycobacterium Haemophilum) is recommended: Casman's blood agar base containing 5% sheep blood heated and 5 micrograms/mL crystal violet, prepared in screw-topped vials, tightly capped and incubated at 30 degrees C under atmospheric conditions.