title: First report of mefA and msrA/msrB multidrug efflux pumps associated with blaTEM-1 β-lactamase in Enterococcus faecalis.
abstract: OBJECTIVE
  Enterococcus faecalis is thought to possess a great deal of intrinsic resistance to several antimicrobial agents. In this study we identified ampicillin- and erythromycin-resistant clinical isolates of E. faecalis and sought to identify the resistance mechanisms among these isolates.
  
  
  METHODS
  Twelve isolates of E. faecalis were collected from 12 different patients. Identification of the isolates and their susceptibility patterns were determined using the Phoenix automated phenotypic identification criteria. PCR amplification and sequencing were used to detect β-lactamase production. Colony blotting was performed in order to screen for multidrug efflux pump production. Extraction and N-terminal sequencing of the multidrug efflux pumps was carried out.
  
  
  RESULTS
  The E. faecalis isolates showed high resistance to erythromycin and ampicillin, with minimum inhibitory concentrations of >16 μg/ml. PCR amplification and sequencing showed that isolates produced TEM-1 β-lactamase. Colony blotting showed that these isolates harbored multidrug efflux pump genes. Multidrug efflux pump extraction, purification, and sequencing showed the distribution of mefA and msrA/msrB efflux pumps.
  
  
  CONCLUSIONS
  Two resistance mechanisms among E. faecalis are described - the production of TEM β-lactamase and mefA and msrA/msrB efflux pumps. These results are of great interest because this is the first report of the co-existence of these resistance mechanisms among E. faecalis strains.
authors.affiliation: Université de Carthage, Institut Supérieur des Sciences et Technologies de l'Environnement de Borj-Cedria, Technopôle de Borj-Cedria, BP-1003, Hammam-Lif 2050, Tunisia. chdoula77@yahoo.fr
authors.forename: Chedly
authors.initials: C
authors.lastname: Chouchani
authors.forename: Allaaeddin
authors.initials: A
authors.lastname: El Salabi
authors.forename: Rim
authors.initials: R
authors.lastname: Marrakchi
authors.forename: Leila
authors.initials: L
authors.lastname: Ferchichi
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Walsh
mesh_terms: D000595:Amino Acid Sequence; D000668:Ampicillin Resistance / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D024901:Drug Resistance, Multiple, Bacterial; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004917:Erythromycin / Q000494:pharmacology; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D008969:Molecular Sequence Data; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004917:Erythromycin; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1