Detection of Shiga toxin-producing and other diarrheagenic Escherichia coli by the BioFire FilmArray® Gastrointestinal Panel in human fecal samples.
The purpose of this investigation was the evaluation of the performance of the BioFire FilmArray® Gastrointestinal (FA-GI) Panel, a multiplexed molecular stool screening assay, for the detection of diarrheagenic Escherichia coli (DEC), with emphasis on Shiga toxin-producing E. coli (STEC). A dilution series of 12 STEC reference strains was tested with the FA-GI Panel to assess the analytical sensitivity. A total of 389 patient samples were analyzed with the FA-GI Panel and confirmation of the detected DEC was attempted with an in-house culture-based polymerase chain reaction (PCR) method. All Shiga toxin genes, except the one encoding Stx2f, were detected in bacterial dilutions ranging from 10(4) to 10(2) colony-forming units (CFU)/ml. eae + stx2f + STEC was misclassified as enteropathogenic E. coli (EPEC). Different sensitivities for various gene targets present in one isolate led to differing identifications depending on the concentration. Using the in-house method as a reference, the FA-GI Panel had a sensitivity of 90.6 % [confidence interval (CI) 75.0 %-98.0 %] and a specificity of 97.2 % (CI 94.9 %-98.6 %) for STEC detection in feces. At least one DEC was reported in 35.5 % (171/389) of the patient specimens, with EPEC being the most prevalent (n = 71). Only 59.7 % of the detected DEC could be confirmed, presumably because the comparator method was not applied directly on feces. The FA-GI Panel could not detect the stx2f subtype, misclassified certain pathogens, and the high detection rate of EPEC needs further investigation. Nevertheless, we believe that this sensitive and convenient system will prove to be an invaluable tool for the rapid diagnosis of most DEC infections, but culturing of the detected microorganisms should always be attempted.
Department of Microbiology, National Reference Centre for STEC/VTEC, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, 1090, Brussels, Belgium. klara.derauw@uzbrussel.be.
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K
De Rauw
Department of Microbiology, National Reference Centre for STEC/VTEC, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, 1090, Brussels, Belgium.|LaCAR MDX Technologies, Liège, Belgium.
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L
Detemmerman
Department of Microbiology, National Reference Centre for STEC/VTEC, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, 1090, Brussels, Belgium.
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J
Breynaert
Department of Microbiology, National Reference Centre for STEC/VTEC, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, 1090, Brussels, Belgium.
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Piérard
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001431:Bacteriological Techniques / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D003967:Diarrhea / Q000175:diagnosis* / Q000382:microbiology; D004926:Escherichia coli / Q000145:classification* / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000175:diagnosis* / Q000382:microbiology; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D022621:Shiga Toxin / Q000235:genetics; D055815:Young Adult
D022621:Shiga Toxin