title: Community carriage of ESBL-producing Escherichia coli is associated with strains of low pathogenicity: a Swedish nationwide study.
abstract: Community carriage of ESBL-producing Escherichia coli (EPE) is common worldwide and there is a need to understand the connection between carriage and infection. We compared the molecular characteristics of EPE among Swedish community carriers with those of EPE causing invasive infections.
  
  
  
  We collected 2134 faecal samples from randomly selected Swedish inhabitants and examined them for the presence of EPE. All participating volunteers answered a questionnaire about putative risk factors for EPE carriage. Suspected EPE isolates (n = 418) from patients with bloodstream infection (BSI) were collected from Swedish laboratories. Isolates were genotypically and phenotypically characterized.
  
  
  
  Our results show that the EPE population found in carriers generally had lower pathogenicity compared with the isolates from BSIs, since carriers had a lower proportion of E. coli belonging to phylogroup B2, ST131 and ST131 subclone H30-Rx. Isolates from carriers also had lower levels of multiresistance. The Swedish carriage rate of EPE was 4.7% (101/2134) among healthy volunteers. Risk factors associated with carriage were travel to countries in Asia (OR = 3.6, 95% CI = 1.4-9.2) and Africa (OR = 3.6, 95% CI = 1.7-7.7) and a diet without pork (OR = 0.5, 95% CI = 0.3-0.8 for pork eaters).
  
  
  
  E. coli host factors previously associated with higher pathogenicity were all more common in BSIs compared with carriers. This indicates that the risk of invasive infection with EPE may be relatively modest in many community carriers and that EPE carriage of high-risk strains should be the focus of attention for prevention.
authors: Public Health Agency of Sweden, Stockholm, Sweden.|Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Stockholm, Sweden.
authors: Sofia
authors: S
authors: Ny
authors: Public Health Agency of Sweden, Stockholm, Sweden.
authors: Sonja
authors: S
authors: Löfmark
authors: National Veterinary Institute, Uppsala, Sweden.
authors: Stefan
authors: S
authors: Börjesson
authors: National Veterinary Institute, Uppsala, Sweden.
authors: Stina
authors: S
authors: Englund
authors: Public Health Agency of Sweden, Stockholm, Sweden.
authors: Maj
authors: M
authors: Ringman
authors: Public Health Agency of Sweden, Stockholm, Sweden.
authors: Jakob
authors: J
authors: Bergström
authors: Infectious Disease Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden.|Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.
authors: Pontus
authors: P
authors: Nauclér
authors: Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Stockholm, Sweden christian.giske@karolinska.se.|Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden.
authors: Christian G
authors: CG
authors: Giske
authors: Public Health Agency of Sweden, Stockholm, Sweden.
authors: Sara
authors: S
authors: Byfors
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D016470:Bacteremia / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D003430:Cross-Sectional Studies; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D005243:Feces / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases