title: Intracellular bacteria in the pathogenesis of Escherichia coli urinary tract infection in children.
abstract: BACKGROUND
  Uropathogenic Escherichia coli (UPEC) is the most common agent of urinary tract infection (UTI). The classic model of pathogenesis proposes the ascent of UPEC by the urethra and external adherence to the urothelium. Recently, the ability of UPEC to invade urothelial cells and to form intracellular bacterial communities (IBCs) has been described.
  
  
  METHODS
  The objective of the present study was to determine the presence of intracellular bacteria (IB) in children with UTI caused by E. coli and to characterize its virulence attributes and its relation with clinical outcomes. One hundred thirty-three children with E. coli UTI who attended a reference children's hospital between June and November 2012 were included. Urine samples were analyzed by optical and confocal microscopy looking for exfoliated urothelial cells with IB. Phylogenetic group and 24 virulence factors of UPEC were determined using multiplex polymerase chain reaction. Medical records were analyzed.
  
  
  RESULTS
  The presence of IB was detected in 49 of 133 (36.8%) samples by confocal microscopy, in 30 cases as IBC, and in 19 as isolated intracellular bacteria (IIB). Only 50% of these cases could be detected by light microscopy. Seventy-four medical records were analyzed, 34 with IBC/IIB, 40 without IB. Any virulence gene was associated with IBC/IIB. The presence of IBC/IIB was associated with recurrent UTI (odds ratio [OR], 3.3; 95% confidence interval [CI], 1.3-9; P = .017), especially in children without urinary tract functional or morphological abnormalities (OR, 8.0; 95% CI, 2.3-27.4; P = .000). IBCs were associated with lower urinary tract syndrome (OR, 3.6; 95% CI, 1.1-11.8; P = .05) and absence of fever (P = .009).
  
  
  CONCLUSIONS
  IBCs/IIB could explain a high proportion of children with recurrent UTI.
authors.affiliation: Departamento de Bacteriología y Virología, Facultad de Medicina, Universidad de la República, Instituto de Higiene.
authors.forename: Luciana
authors.initials: L
authors.lastname: Robino
authors.affiliation: Departamento de Microbiología, Instituto de Investigaciones Biológicas Clemente Estable.
authors.forename: Paola
authors.initials: P
authors.lastname: Scavone
authors.affiliation: Departamento de Bacteriología y Virología, Facultad de Medicina, Universidad de la República, Instituto de Higiene.
authors.forename: Lucia
authors.initials: L
authors.lastname: Araujo
authors.affiliation: Departamento de Bacteriología y Virología, Facultad de Medicina, Universidad de la República, Instituto de Higiene Laboratorio Central, Centro Hospitalario Pereira Rossell.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Algorta
authors.affiliation: Departamento de Microbiología, Instituto de Investigaciones Biológicas Clemente Estable.
authors.forename: Pablo
authors.initials: P
authors.lastname: Zunino
authors.affiliation: Departamento de Pediatria, Centro Hospitalario Pereira Rossell, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
authors.forename: María Catalina
authors.initials: MC
authors.lastname: Pírez
authors.affiliation: Departamento de Bacteriología y Virología, Facultad de Medicina, Universidad de la República, Instituto de Higiene.
authors.forename: Rafael
authors.initials: R
authors.lastname: Vignoli
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology*; D005260:Female; D006801:Humans; D007223:Infant; D042541:Intracellular Space / Q000382:microbiology; D008297:Male; D012189:Retrospective Studies; D014552:Urinary Tract Infections / Q000382:microbiology*; D019459:Urothelium / Q000166:cytology / Q000382:microbiology
keywords: E. coli pathogenicity; intracellular bacterial communities; urinary tract infection
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