title: Virulence and drug susceptibility of Mycobacterium celatum.
abstract: The virulence and drug susceptibility of a clinical isolate of Mycobacterium celatum which showed smooth transparent (ST) and smooth opaque (SO) colonies were studied. While ST cells multiplied intracellularly and maintained their coccobacillary form in a human macrophage model of infection, SO cells formed long filaments and completely destroyed the phagocytes. In BALB/c mice, the ST variant, but not the SO variant, grew efficiently in the spleen, liver and lung. The ST variant was usually more resistant in vitro than the SO variant to drugs, with MIC values for clarithromycin (CLA), azithromycin (AZI), ciprofloxacin, sparfloxacin, amikacin, clofazimine, ethambutol and isoniazid being higher than those of the SO variant. In beige mice infected with the more highly virulent variant ST, CLA and AZI were the most active drugs in terms of viable count reduction in organs and mutant selection. Together, these observations indicate that the ST variant of M. celatum is a virulent form that can be efficiently inhibited in vivo by CLA and AZI.
authors.affiliation: Laboratory of Bacteriology and Medical Mycology1 and Laboratory of Ultrastructures2, Istituto Superiore di Sanitá, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Lanfranco
authors.initials: L
authors.lastname: Fattorini
authors.affiliation: Laboratory of Bacteriology and Medical Mycology1 and Laboratory of Ultrastructures2, Istituto Superiore di Sanitá, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Lucilla
authors.initials: L
authors.lastname: Baldassarri
authors.affiliation: Laboratory of Bacteriology and Medical Mycology1 and Laboratory of Ultrastructures2, Istituto Superiore di Sanitá, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Li
authors.affiliation: Laboratory of Bacteriology and Medical Mycology1 and Laboratory of Ultrastructures2, Istituto Superiore di Sanitá, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Ammendolia
authors.affiliation: Laboratory of Bacteriology and Medical Mycology1 and Laboratory of Ultrastructures2, Istituto Superiore di Sanitá, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Fan
authors.affiliation: Laboratory of Bacteriology and Medical Mycology1 and Laboratory of Ultrastructures2, Istituto Superiore di Sanitá, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Recchia
authors.affiliation: Laboratory of Bacteriology and Medical Mycology1 and Laboratory of Ultrastructures2, Istituto Superiore di Sanitá, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Iona
authors.affiliation: Laboratory of Bacteriology and Medical Mycology1 and Laboratory of Ultrastructures2, Istituto Superiore di Sanitá, Viale Regina Elena 299, 00161 Rome, Italy.
authors.forename: Graziella
authors.initials: G
authors.lastname: Orefici
mesh_terms: D000818:Animals; D004352:Drug Resistance, Microbial; D006801:Humans; D066298:In Vitro Techniques; D008264:Macrophages / Q000382:microbiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D009154:Mutation; D009161:Mycobacterium / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity* / Q000648:ultrastructure; D009164:Mycobacterium Infections / Q000209:etiology / Q000382:microbiology; D014774:Virulence