Microaerophilic conditions promote growth of Mycobacterium genavense.
Our studies show that microaerophilic conditions promote the growth of Mycobacterium genavense in semisolid medium. The growth of M. genavense at 2.5 or 5% oxygen was superior to that obtained at 21% oxygen in BACTEC primary cultures (Middlebrook 7H12, pH 6.0, without additives). By using nondecontaminated specimens, it was possible to detect growth with very small inocula (25 bacilli/ml) of 12 different M. genavense strains (from nude mice) within 6 weeks of incubation under low oxygen tension; conversely, with 21% oxygen, no growth of 8 of 12 (66.7%) M. genavense strains was detected (growth index, <10). The same beneficial effect of 2.5 or 5% oxygen was observed in primary cultures of a decontaminated clinical specimen. Low oxygen tension (2.5 or 5%) is recommended for the primary isolation of M. genavense. Microaerophilic cultivation of other atypical mycobacteria, especially slow-growing (e.g., Mycobacterium avium) and difficult-to-grow (e.g., Mycobacterium ulcerans) species, is discussed.
Mycobacteriology Unit, Department of Microbiology, Institute of Tropical Medicine, Antwerp, Belgium. realini@microbiol.itg.be
L
L
Realini
K
K
De Ridder
J
J
Palomino
B
B
Hirschel
F
F
Portaels
D017088:AIDS-Related Opportunistic Infections / Q000382:microbiology; D000332:Aerobiosis; D000818:Animals; D003470:Culture Media; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009161:Mycobacterium / Q000254:growth & development* / Q000302:isolation & purification; D009164:Mycobacterium Infections / Q000150:complications / Q000382:microbiology; D010100:Oxygen; D013997:Time Factors
D003470:Culture Media; D010100:Oxygen