title: The occurrence of antimicrobial resistance and class 1 integrons among commensal Escherichia coli isolates from infants and elderly persons.
abstract: BACKGROUND
  The aim of our study was to compare the presence of the intI1 gene and its associations with the antibiotic resistance of commensal Escherichia coli strains in children with/without previous antibiotic treatments and elderly hospitalized/healthy individuals.
  
  
  METHODS
  One-hundred-and-fifteen intestinal E. coli strains were analyzed: 30 strains from 10 antibiotic-naive infants; 27 from 9 antibiotic-treated outpatient infants; 30 from 9 healthy elderly volunteers; and 28 from 9 hospitalized elderly patients. The MIC values of ampicillin, cefuroxime, cefotaxime, gentamicin, ciprofloxacin, and sulfamethoxazole were measured by E-test and IntI1 was detected by PCR.
  
  
  RESULTS
  Out of the 115 strains, 56 (49%) carried class 1 integron genes. Comparing persons without medical interventions, we found in antibiotic-naive children a significantly higher frequency of integron-bearing strains and MIC values than in healthy elderly persons (53% versus 17%; p < 0.01). Evaluating medical interventions, we found a higher resistance and frequency of integrons in strains from hospitalized elderly persons compared with non-hospitalized ones. Children treated with antibiotics had strains with higher MIC values (when compared with antibiotic-naive ones), but the integron-bearing in strains was similar. In most cases, the differences in resistance between the groups (integron-positive and negative strains separately) were higher than the differences between integron-positive and negative strains within the groups.
  
  
  CONCLUSIONS
  The prevalence of integrons in commensal E. coli strains in persons without previous medical intervention depended on age. The resistance of integron-carrying and non-carrying strains is more dependent on influencing factors (hospitalization and antibiotic administration) in particular groups than merely the presence or absence of integrons.
authors.affiliation: Department of Microbiology, University of Tartu, Ravila 19, 50411 Tartu, Estonia. epp.sepp@ut.ee
authors.forename: Epp
authors.initials: E
authors.lastname: Sepp
authors.forename: Jelena
authors.initials: J
authors.lastname: Stsepetova
authors.forename: Krista
authors.initials: K
authors.lastname: Lõivukene
authors.forename: Kai
authors.initials: K
authors.lastname: Truusalu
authors.forename: Siiri
authors.initials: S
authors.lastname: Kõljalg
authors.forename: Paul
authors.initials: P
authors.lastname: Naaber
authors.forename: Marika
authors.initials: M
authors.lastname: Mikelsaar
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016022:Case-Control Studies; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology*; D005243:Feces / Q000382:microbiology*; D005260:Female; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D032023:Integrons; D008297:Male; D008826:Microbial Sensitivity Tests
chemical_list: D000900:Anti-Bacterial Agents