Growth on blood agar discriminates Mycobacterium avium and Mycobacterium intracellulare.
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.
Drancourt
M
M
Fédération 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
Gévaudan
M-J
MJ
Truffot
C
C
Jarlier
V
V
D000362:Agar; D015169:Colony Count, Microbial; D003470:Culture Media; D015342:DNA Probes / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D006801:Humans; D009162:Mycobacterium avium / Q000235:genetics / Q000254:growth & development*; D015269:Mycobacterium avium Complex / Q000235:genetics / Q000254:growth & development*; D015270:Mycobacterium avium-intracellulare Infection / Q000382:microbiology*; D009693:Nucleic Acid Hybridization; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics
D003470:Culture Media; D015342:DNA Probes; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D000362:Agar