Faculty Collaboration Database

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. J Clin Microbiol 2017 Feb;55(2):519-525

Date

12/09/2016

Pubmed ID

27927919

Pubmed Central ID

PMC5277522

DOI

10.1128/JCM.01939-16

Scopus ID

2-s2.0-85011977894 (requires institutional sign-in at Scopus site)   6 Citations

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 (stx₁ and 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 stx₁ and stx₂ and 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 stx₁ or stx₂ or were found to be positive for serotype O:157 when analyzed using alternative molecular methods. All 4 false-negative stx₁ or stx₂ results 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 stx₁ and stx₂ following 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.

Author List

Faron ML, Ledeboer NA, Connolly J, Granato PA, Alkins BR, Dien Bard J, Daly JA, Young S, Buchan BW

Authors

Blake W. Buchan PhD Professor in the Pathology department at Medical College of Wisconsin
Nathan A. Ledeboer PhD Vice Chair, Professor in the Pathology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Bacteriological Techniques
Carbohydrate Epimerases
Costs and Cost Analysis
Escherichia coli Infections
Feces
Humans
Immunoenzyme Techniques
Molecular Diagnostic Techniques
Prospective Studies
Retrospective Studies
Sensitivity and Specificity
Shiga Toxin
Shiga-Toxigenic Escherichia coli
Time Factors
Transaminases