title: Emergence of ArmA and RmtB aminoglycoside resistance 16S rRNA methylases in Belgium.
abstract: OBJECTIVE
  16S rRNA methylase-mediated high-level resistance to aminoglycosides has been reported recently in clinical isolates of Gram-negative bacilli only from a limited number of countries. This study was conducted to investigate the occurrence of this type of resistance in clinical isolates of Enterobacteriaceae from two Belgian hospitals and the characteristics of the strains.
  
  
  METHODS
  We screened for high-level gentamicin, tobramycin and amikacin resistance in clinical isolates of Enterobacteriaceae consecutively collected between 2000 and 2005 at two laboratories by PCR for the armA, rmtA and rmtB 16S rRNA methylase genes. The beta-lactamase presence in the strains was also determined by phenotypic and genotypic methods.
  
  
  RESULTS
  Overall armA genes were detected in 18 Klebsiella pneumoniae, Escherichia coli, Enterobacter aerogenes, Enterobacter cloacae and Citrobacter amalonaticus whereas rmtB was detected in a single E. coli isolate. The rmtA gene was not found. All 16S rRNA methylase-bearing strains produced extended-spectrum beta-lactamases (ESBLs), predominantly type CTX-M-3, as well as various types of beta-lactamases. In the majority of the strains, the armA gene was carried by conjugative plasmids of the IncL/M incompatibility group whereas rmtB was borne by an IncFI plasmid.
  
  
  CONCLUSIONS
  This is the first report of the emergence of 16S rRNA methylases in Enterobacteriaceae in Belgium. The rapid spread of multidrug-resistant isolates producing both ESBLs and 16S rRNA methylases raises clinical concern and may become a major therapeutic threat in the future.
authors.affiliation: Laboratoire de Bactériologie, Cliniques Universitaires UCL de Mont-Godinne, 1 Av. Dr Gaston Thérasse, B-5530 Yvoir, Belgium. pierre.bogaerts@mont.ucl.ac.be
authors.forename: Pierre
authors.initials: P
authors.lastname: Bogaerts
authors.forename: Marc
authors.initials: M
authors.lastname: Galimand
authors.forename: Caroline
authors.initials: C
authors.lastname: Bauraing
authors.forename: Ariane
authors.initials: A
authors.lastname: Deplano
authors.forename: Raymond
authors.initials: R
authors.lastname: Vanhoof
authors.forename: Ricardo
authors.initials: R
authors.lastname: De Mendonca
authors.forename: Hector
authors.initials: H
authors.lastname: Rodriguez-Villalobos
authors.forename: Marc
authors.initials: M
authors.lastname: Struelens
authors.forename: Youri
authors.initials: Y
authors.lastname: Glupczynski
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003227:Conjugation, Genetic; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000235:genetics*; D006801:Humans; D008780:Methyltransferases / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000096:biosynthesis
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; C446079:16S rRNA - m7G methyltransferase; C506767:ArmA protein, E coli; D008780:Methyltransferases; D001618:beta-Lactamases