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Updated: Aug 30, 2026

Identification of Mycobacterium Species by DNA Microarray Chip Method
Published on: June 24, 2025
Growth on blood agar discriminates Mycobacterium avium and Mycobacterium intracellulare
M Drancourt1, M-J Gévaudan, C Truffot
1Fédération de Microbiologique Clinique, Hôpital de la Timone, Assistance Publique-Hôpitaux de Marseille, et Unité des Rickettsies IFR48, Faculté de Médecine, 13385 Marseille cedex 5, France. Michel.Drancourt@medecine.University-mrs.fr
Abstract:
Mycobacterium intracellulare and Mycobacterium avium (MAC) require specialized culture and identification procedures. To simplify the diagnosis, we inoculated reference strains, and 85 M. avium and 12 M. intracellulare clinical isolates, on egg-based and sheep blood agar. After 5 days of culture, there were significantly more colonies on sheep blood than on egg-based agar for M. avium (ratio: 250.5 +/- 209) but not for M. intracellulare (ratio: 0.44 +/-0.11). Using a ratio > or = 20, the sensitivity of the identification of an MAC isolate as M. avium was 97.65%, the specificity was 100%, and the positive predictive value was 100%. Differential growth on egg-based and blood agar is an aid to the identification of MAC isolates.
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