Article

Mycobacterium canariasense sp. nov.

Laboratorio de Micobacterias, Servicio de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
International Journal of Systematic and Evolutionary Microbiology (Impact Factor: 2.8). 10/2004; 54(Pt 5):1729-34. DOI: 10.1099/ijs.0.02999-0
Source: PubMed

ABSTRACT A novel rapidly growing, non-pigmented mycobacterium was isolated from blood samples obtained from 17 patients with febrile syndrome. Bacterial growth occurred at 30 and 37 degrees C on Löwenstein-Jensen medium and also on MacConkey agar without crystal violet. Strains contained alpha- and alpha'-mycolates in their cell wall. Sequence analysis of the hsp65 and 16S rRNA genes identified the isolates as rapidly growing mycobacteria. Sequences of both genes were unique within the mycobacteria. DNA-DNA hybridization showed that the isolates had less than 15 % reassociation with 13 other recognized rapidly growing mycobacteria. The name Mycobacterium canariasense sp. nov. is proposed for this novel opportunistic pathogen, which is most closely related to Mycobacterium diernhoferi. The type strain is 502329T (= CIP 107998T = CCUG 47953T).

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    ABSTRACT: Atypical mycobacteria are ubiquitous in nature and widely distributed in water, soil and animals. Although a large number of species have been identified, only a few have clinical interest in humans. The most prevalent rapidly growing mycobacteria (RGM) in human infections are Mycobacterium fortuitum group, M. chelonae group and M. abscessus; other species are minority and only referred to opportunistic infections. During the past three decades we have observed a notable increment of infections caused by RGM, both localized and disseminated, as well as nosocomial outbreaks of contaminated medical equipment. Pulmonary, skin and soft tissue are the most frequent locations. Other infections include keratitis, endophthalmitis, arthritis, osteomyelitis, endocarditis, meningitis, peritonitis, urinary tract infection, chronic otitis media after tympanostomy tube implantation and catheter-related bacteremia. They are mostly due to accidental inoculation from trauma, surgery, injection or aspiration. There is no evidence of interhuman transmission. The microbiological diagnosis of RGM infections includes direct microscopic observation of the microorganism in clinical samples and culture in selective media: Löwenstein-Jensen solid medium and Middlebrook 7H9 broth. The identification to the species level is really important to direct the antimicrobial treatment. The taxonomic identification is performed by phenotypic, biochemical and chromatographic techniques, as well as molecular biology techniques: solid-phase hybridization, nucleic acid sequencing (16S rRNA gene) or polymorphism analysis of restriction fragments of the hsp65 gene (PRA or PCR-RFLP). The treatment of infections caused by RGM differs from that of other mycobacteriosis like tuberculosis, owing to the variable in vitro susceptibility of this group. The RGM are resistant to conventional antituberculous drugs but can be susceptible to other broad spectrum antibiotics. The susceptibility to antibiotics varies among different species. The broth microdilution is the recommended method to determine it. Susceptibility tests offer guidance on clinical treatment. In this chapter, we comment relevant aspects of human infections by rapidly growing mycobacteria, including biology, epidemiology, pathology, microbiological diagnosis, taxonomic identification, antimicrobial susceptibility and treatment.