title: Molecular characterization and drug susceptibility profile of aMycobacterium aviumsubspeciesaviumisolate from a dog with disseminated infection.
abstract: Mycobacterium avium-intracellularecomplex (MAC) infections have been described in many mammalian species, including humans and pets. We isolated and molecularly typed the causative agent of a rare case of disseminated mycobacteriosis in a dog. We identified the pathogen asM. aviumsubspeciesaviumby sequencing the partial genesgyrBandrpsA. Considering the zoonotic potential of this infection, and in an attempt to ensure the most effective treatment for the animal, we also determined the drug susceptibility profile of the isolate to the most common drugs used to treat MAC disease in humans. The pathogen was testedin vitroagainst the macrolide clarithromycin, as well as against amikacin, ciprofloxacin, rifampicin, ethambutol and linezolid, by the resazurin microdilution assay. It was found to be sensitive to all tested drugs apart from ethambutol. Despite the fact that the pathogen was sensitive to the therapies administered, the dog's overall clinical status worsened and the animal died shortly after antimicrobial susceptibility results became available. Nucleotide sequencing of theembBgene, the target gene most commonly associated with ethambutol resistance, showed new missense mutations when compared to sequences available in public databases. In conclusion, we molecularly identified the MAC pathogen and determined its drug susceptibility profile in a relatively short period of time (7 days). We also characterized new genetic mutations likely to have been involved in the observed ethambutol resistance. Our results confirmed the usefulness of both thegyrBand therpsAgenes as biomarkers for an accurate identification and differentiation of MAC pathogens.
authors.affiliation: Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Armas
authors.affiliation: Veterinary Laboratory San Marco, Padua, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Furlanello
authors.affiliation: Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Camperio
authors.affiliation: Veterinary Laboratory San Marco, Padua, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Trotta
authors.affiliation: Veterinary Laboratory EmatosVetLab, Rome, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Novari
authors.affiliation: Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Marianelli