title: Clinical Evaluation and Cost Analysis of Great Basin Shiga Toxin Direct Molecular Assay for Detection of Shiga Toxin-Producing Escherichia coli in Diarrheal Stool Specimens.
abstract: The Shiga Toxin Direct molecular assay (ST Direct) relies on nucleic acid amplification and solid array-based amplicon detection to identify Shiga toxin-producing Escherichia coli (STEC) in preserved stool specimens. Genes encoding Shiga toxin (stx1and stx2), as well as the E. coli serotype O:157-specific marker rfbE, are simultaneously detected within 2 h. ST Direct was evaluated using 1,084 prospectively collected preserved stool specimens across five clinical centers. An additional 55 retrospectively collected, frozen specimens were included to increase the number of positive specimens evaluated. Results were compared to results from routine culture and an enzyme immunoassay (EIA) specific for the recovery and identification of STEC. ST Direct was found to be 93.2% sensitive and 99.3% specific for detection of stx1and stx2and 95.7% sensitive and 99.3% specific for detection of E. coli serotype O:157. All specimens with false-positive results were found to contain stx1or stx2or were found to be positive for serotype O:157 when analyzed using alternative molecular methods. All 4 false-negative stx1or stx2results were reported for frozen, retrospectively tested specimens. In all cases, the specimens tested positive for stx by an alternative FDA-cleared nucleic acid amplification test (NAAT) but were negative for stx1and stx2following nucleic acid sequence analysis. Based on these data, culture and EIA-based methods for detection of STEC are only 33% sensitive compared to molecular tests. A retrospective cost analysis demonstrated 59% of the cost of routine stool culture to be attributable to the identification of STEC. Taken together, these data suggest that ST Direct may provide a cost-effective, rapid molecular alternative to routine culture for the identification of STEC in preserved stool specimens.
authors.affiliation: The Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Faron
authors.affiliation: The Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Ledeboer
authors.affiliation: The Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Connolly
authors.affiliation: Laboratory Alliance of Central New York, Syracuse, New York, USA.
authors.forename: Paul A
authors.identifier: 0000-0002-5068-1137
authors.initials: PA
authors.lastname: Granato
authors.affiliation: Laboratory Alliance of Central New York, Syracuse, New York, USA.
authors.forename: Brenda R
authors.initials: BR
authors.lastname: Alkins
authors.affiliation: Childrens Hospital of Los Angeles, Los Angeles, California, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Dien Bard
authors.affiliation: University of Utah Primary Children's Hospital, Salt Lake City, Utah, USA.
authors.forename: Judy A
authors.initials: JA
authors.lastname: Daly
authors.affiliation: TriCore Laboratories, Albuquerque, New Mexico, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Young
authors.affiliation: The Medical College of Wisconsin, Milwaukee, Wisconsin, USA bbuchan@mcw.edu.
authors.forename: Blake W
authors.identifier: 0000-0002-4111-048X
authors.initials: BW
authors.lastname: Buchan
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods; D002238:Carbohydrate Epimerases / Q000235:genetics; D003365:Costs and Cost Analysis; D004927:Escherichia coli Infections / Q000175:diagnosis*; D005243:Feces / Q000382:microbiology*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods; D025202:Molecular Diagnostic Techniques / Q000191:economics* / Q000379:methods*; D011446:Prospective Studies; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D022621:Shiga Toxin / Q000235:genetics*; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics / Q000302:isolation & purification*; D013997:Time Factors; D000637:Transaminases / Q000235:genetics
chemical_list: D022621:Shiga Toxin; D000637:Transaminases; D002238:Carbohydrate Epimerases; C061272:perosamine synthetase
keywords: STEC; Shiga toxins; microarray; molecular diagnostics