Intracellular bacteria in the pathogenesis of Escherichia coli urinary tract infection in children - PubMed (original) (raw)

. 2014 Dec 1;59(11):e158-64.

doi: 10.1093/cid/ciu634. Epub 2014 Aug 4.

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Intracellular bacteria in the pathogenesis of Escherichia coli urinary tract infection in children

Luciana Robino et al. Clin Infect Dis. 2014.

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.

Keywords: E. coli pathogenicity; intracellular bacterial communities; urinary tract infection.

© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

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Figures

Figure 1.

Figure 1.

Filamentous bacteria and exfoliated urothelial cells in urine samples suspicious for intracellular bacterial communities/isolated intracellular bacteria by light microscopy. Light microscopic images of exfoliated uroepithelial cells stained with Wright–Giemsa. A, Detached urothelial cells and filamentous bacteria. B and C, Dark stained cells with suspicious IBCs. Scale bar = 5 µm. Abbreviation: IBCs, intracellular bacterial communities.

Figure 2.

Figure 2.

Detection of intracellular bacterial communities (IBCs)/intracellular bacteria (IB) by confocal laser scanning microscopy in exfoliated urothelial cells in urine from children with Escherichia coli urinary tract infection. Confocal laser scanning microscopic images of exfoliated uroepithelial cells stained with uroplakine III primary antibodies (structural protein of bladder epithelial cells in red), Alexa Fluor 568 donkey antigoat immunoglobulin G secondary antibody, and specific antibodies for E. coli (green). Scale bar = 7 µm. A, Isolated IB. B, Small IBCs. C, IBCs.

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