title: Origin in Acinetobacter gyllenbergii and dissemination of aminoglycoside-modifying enzyme AAC(6')-Ih.
abstract: OBJECTIVE
  The aac(6')-Ih gene encoding aminoglycoside 6'-N-acetyltransferase type I subtype h [AAC(6')-Ih] is plasmid-borne in Acinetobacter baumannii where it confers high-level amikacin resistance, but its origin remains unknown. We searched for the gene in the genomes of a collection of 133 Acinetobacter spp. and studied its species specificity, expression and dissemination.
  
  
  METHODS
  Gene copy number was determined by quantitative PCR, expression by quantitative RT-PCR, MIC by microdilution and transfer by plasmid mobilization.
  
  
  RESULTS
  The aac(6')-Ih gene was present in the chromosome of the two Acinetobacter gyllenbergii of the collection and was detected in all seven A. gyllenbergii clinical isolates. They had indistinguishable flanking regions indicating that the gene was intrinsic to this species. A. baumannii PIS Aba23 promoters were provided by insertion of ISAba23, which disrupted the Pnative promoter in A. gyllenbergii. Both types of promoters were similarly potent in Escherichia coli and A. baumannii. Aminoglycoside MICs for A. baumannii harbouring pIP1858 were higher than for A. gyllenbergii due to gene dosage. The non-self-transferable plasmid could be mobilized to other A. baumannii cells by the broad host range plasmid RP4.
  
  
  CONCLUSIONS
  We have found the origin of aac(6')-Ih in A. gyllenbergii, a species isolated, although rarely, in humans, and documented that dissemination of this gene is restricted to the Acinetobacter genus.
authors.affiliation: Institut Pasteur, Unité des Agents Antibactériens, Paris, France.
authors.forename: Eun-Jeong
authors.initials: EJ
authors.lastname: Yoon
authors.affiliation: Institut Pasteur, Unité des Agents Antibactériens, Paris, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Goussard
authors.affiliation: Laboratory of Bacterial Genetics, National Institute of Public Health, Prague, Czech Republic.
authors.forename: Alexandr
authors.initials: A
authors.lastname: Nemec
authors.affiliation: EA4043, Faculté de Pharmacie, Université Paris Sud, Châtenay-Malabry, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Lambert
authors.affiliation: Institut Pasteur, Unité des Agents Antibactériens, Paris, France patrice.courvalin@pasteur.fr.
authors.forename: Patrice
authors.initials: P
authors.lastname: Courvalin
authors.affiliation: Institut Pasteur, Unité des Agents Antibactériens, Paris, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Grillot-Courvalin
mesh_terms: D000123:Acetyltransferases / Q000235:genetics* / Q000378:metabolism*; D000151:Acinetobacter Infections / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000145:classification* / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D000617:Aminoglycosides / Q000378:metabolism / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D004251:DNA Transposable Elements; D024881:Drug Resistance, Bacterial; D018628:Gene Dosage; D022761:Gene Transfer, Horizontal; D006801:Humans; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000032:analysis; D011401:Promoter Regions, Genetic; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D000123:Acetyltransferases; C056532:aminoglycoside N(6')-acetyltransferase