title: Differences in antimicrobial susceptibility of pigmented and unpigmented colonial variants of Mycobacterium avium.
abstract: Unpigmented colonial variants were isolated from pigmented Mycobacterium avium isolates recovered from patients with acquired immunodeficiency syndrome and the environment. The variants were interconvertible: the rate of transition from unpigmented to pigmented type was 4.0 x 10(-5) variants per cell per generation. The unpigmented variants were more tolerant to antibiotics, especially beta-lactams, and Cd2+ and Cu2+ salts than were their pigmented parents. Both pigmented and unpigmented variants of the strains produced beta-lactamase, although beta-lactamase did not appear to be a determinant of beta-lactam susceptibility. Pigmented variants grew more rapidly in a number of commonly used mycobacterial media, were more hydrophobic, and had higher carotenoid contents than their unpigmented segregants.
authors: Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg 24061.
authors: R S
authors: RS
authors: Stormer
authors: J O
authors: JO
authors: Falkinham
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000150:complications*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002338:Carotenoids / Q000096:biosynthesis; D003470:Culture Media; D004352:Drug Resistance, Microbial; D006801:Humans; D008826:Microbial Sensitivity Tests; D015269:Mycobacterium avium Complex / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D015270:Mycobacterium avium-intracellulare Infection / Q000150:complications / Q000382:microbiology*; D010860:Pigments, Biological / Q000096:biosynthesis*; D012988:Soil Microbiology; D001618:beta-Lactamases / Q000096:biosynthesis
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D010860:Pigments, Biological; D002338:Carotenoids; D001618:beta-Lactamases