title: Antibiotic resistance patterns of Acinetobacter calcoaceticus-A. baumannii complex species from Colombian hospitals.
abstract: BACKGROUND
  Only automated phenotypic methods are currently used in Colombian hospitals for identifying isolates of the Acinetobacter calcoaceticus-A. baumannii complex (ACB). The phenotypical similarities in these species mean that they cannot be differentiated by manual or automated methods, thereby leading to their identification as A. baumannii, or ACB complex in clinical settings. Our objective was to identify to the species level 60 isolates, from four hospitals, evaluate their antibiotic susceptibility, and detect resistance-related genes.
  
  
  METHODS
  16S-23S rRNA internal transcribed spacer (ITS) region and rpoB gene partial sequences were amplified. Resistance genes for cephalosporin, carbapenem and aminoglycoside were detected by PCR. Possible mutations in the quinolone resistance-determining region (QRDR) were evaluated. The association of ISAba-1 with blaOXA and blaADC genes was determined by PCR. Amplification products of ITS region, rpoB gene and some resistance genes were sequenced and compared using the BLAST tool.
  
  
  RESULTS
  16S-23S rRNA ITS region and partial rpoB gene sequence analysis allowed 51isolates to be identified as A. baumannii, 8 as A. nosocomialis, and 1 isolate as A. pitti. A. baumannii isolates were highly resistant to all antibiotics tested, while the others were susceptible to ciprofloxacin and ampicillin/sulbactam. Quinolone resistance, found only in A. baumannii, was associated with mutations in the QRDR region of gyrA and parC genes.
  
  
  CONCLUSIONS
  This is the first investigation in Colombia that has identified ACB complex species using molecular methods, and determined differences in antibiotic resistance and resistance genes among the species. It is of the highest importance to identify isolates to the species level for future resistance and epidemiology studies in our region.
authors.affiliation: Instituto de Biotecnología, Universidad Nacional de Colombia-Sede Bogotá, Bogotá, Colombia. mtregueror@unal.edu.co
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Reguero
authors.forename: Olga Esther
authors.initials: OE
authors.lastname: Medina
authors.forename: María Andrea
authors.initials: MA
authors.lastname: Hernández
authors.forename: Diana Vanessa
authors.initials: DV
authors.lastname: Flórez
authors.forename: Emilia María
authors.initials: EM
authors.lastname: Valenzuela
authors.forename: José Ramón
authors.initials: JR
authors.lastname: Mantilla
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects*; D016954:Acinetobacter calcoaceticus / Q000187:drug effects*; D003105:Colombia; D024881:Drug Resistance, Bacterial; D006761:Hospitals; D006801:Humans