title: Amoxicillin-clavulanic acid resistance in fecal Enterobacteriaceae from patients with cystic fibrosis and healthy siblings.
abstract: BACKGROUND
  The present study set out to detect and identify amoxicillin-clavulanic acid (AMC)-resistant Enterobacteriaceae in fecal samples of two patients with cystic fibrosis (CF) and their respective siblings.
  
  
  METHODS
  Fecal Enterobacteriaceae were enumerated onto EMB agar containing amoxicillin (AMX). A total of 173 CF isolates and 41 sibling isolates were grouped into seven Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) clusters and identified through 16S rRNA and rpoB sequence analysis.
  
  
  RESULTS
  The fecal microbiota of patients with CF revealed a higher prevalence of AMX resistant Enterobacteriaceae compared to that of their healthy siblings. Whereas all selected isolates of healthy siblings were assigned to Escherichia coli, isolates of patients with CF belonged to Klebsiella oxytoca (58.4%), E. coli (28.3%), Klebsiella variicola (7.5%) or Citrobacter sp. (5.8%). All tested CF isolates showed a high resistance rate to AMX, and a lower level of resistance to the combination with clavulanic acid. In contrast, all tested sibling isolates were susceptible for both AMX and AMC.
  
  
  CONCLUSIONS
  The higher abundance of AMX resistance in the investigated patients with CF suggests that frequent AMC administration may be one of the major contributing factors in the proliferation of Enterobacteriaceae and the development of resistant strains in the gastrointestinal tract.
authors.affiliation: Laboratory of Microbiology, Faculty of Sciences, Ghent University, Belgium.
authors.forename: Gwen
authors.initials: G
authors.lastname: Duytschaever
authors.forename: Geert
authors.initials: G
authors.lastname: Huys
authors.forename: Linda
authors.initials: L
authors.lastname: Boulanger
authors.forename: Kris
authors.initials: K
authors.lastname: De Boeck
authors.forename: Peter
authors.initials: P
authors.lastname: Vandamme
mesh_terms: D019980:Amoxicillin-Potassium Clavulanate Combination / Q000494:pharmacology / Q000627:therapeutic use*; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D003550:Cystic Fibrosis / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects*; D005243:Feces / Q000382:microbiology*; D006801:Humans; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
chemical_list: D000900:Anti-Bacterial Agents; D019980:Amoxicillin-Potassium Clavulanate Combination
keywords: Amoxicillin–clavulanic acid; Antibiotic resistance; Cystic fibrosis; Enterobacteriaceae; Gut microbiota