title: Molecular characterization and antibiotic resistance of Enterococcus species from gut microbiota of Chilean Altiplano camelids.
abstract: BACKGROUND
  Enterococcus is one of the major human pathogens able to acquire multiple antibiotic-resistant markers as well as virulence factors which also colonize remote ecosystems, including wild animals. In this work, we characterized the Enterococcus population colonizing the gut of Chilean Altiplano camelids without foreign human contact.
  
  
  METHODS
  Rectal swabs from 40 llamas and 10 alpacas were seeded in M-Enterococcus agar, and we selected a total of 57 isolates. Species identification was performed by biochemical classical tests, semi-automated WIDER system, mass spectrometry analysis by MALDI-TOF (matrix-assisted laser desorption/ionization with a time-of-flight mass spectrometer), and, finally, nucleotide sequence of internal fragments of the 16S rRNA, rpoB, pheS, and aac(6)-I genes. Genetic diversity was measured by pulsed field gel electrophoresis (PFGE)-SmaI, whereas the antibiotic susceptibility was determined by the WIDER system. Carriage of virulence factors was explored by polymerase chain reaction (PCR).
  
  
  RESULTS
  Our results demonstrated that the most prevalent specie was Enterococcus hirae (82%), followed by other non-Enterococcus faecalis and non-Enterococcus faecium species. Some discrepancies were detected among the identification methods used, and the most reliable were the rpoB, pheS, and aac(6)-I nucleotide sequencing. Selected isolates exhibited susceptibility to almost all studied antibiotics, and virulence factors were not detected by PCR. Finally, some predominant clones were characterized by PFGE into a diverse genetic background.
  
  
  CONCLUSIONS
  Enterococcus species from the Chilean camelids' gut microbiota were different from those adapted to humans, and they remained free of antibiotic resistance mechanisms as well as virulence factors.
authors.affiliation: Departamento de Tecnología Médica, Universidad de Antofagasta, Antofagasta, Chile.
authors.forename: Katheryne
authors.initials: K
authors.lastname: Guerrero-Olmos
authors.affiliation: Departamento de Tecnología Médica, Universidad de Antofagasta, Antofagasta, Chile.
authors.forename: John
authors.initials: J
authors.lastname: Báez
authors.affiliation: Departamento de Tecnología Médica, Universidad de Antofagasta, Antofagasta, Chile.
authors.forename: Nicomédes
authors.initials: N
authors.lastname: Valenzuela
authors.affiliation: Departamento de Tecnología Médica, Universidad de Antofagasta, Antofagasta, Chile.
authors.forename: Joselyne
authors.initials: J
authors.lastname: Gahona
authors.affiliation: Servicio de Microbiología, Hospital Universitario Ramón y Cajal, Madrid, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Del Campo
authors.affiliation: Departamento de Tecnología Médica, Universidad de Antofagasta, Antofagasta, Chile.
authors.forename: Juan
authors.initials: J
authors.lastname: Silva
keywords: Enterococcus; PFGE; antibiotic resistance; camelids; molecular identification; virulence factors