streptococcus equi field trial data
TRANSCRIPT
Maine Biotechnology Services, Inc. 2014
Streptococcus equi “Strangles” Rapid
Stall Side Test
Release of Field Trial Data
Maine Biotechnology Services, Inc. 2014
Development of Stall Side Test
Resulted from multi-directional collaborationsUMO, U-Kentucky, MBS, Diagnostic Innovations
Address need for rapid identification of Strangles (+) horsesEnabling Barn Manager to take appropriate
actions days before PCR results available. Follow up with confirmatory PCR expected.
Maine Biotechnology Services, Inc. 2014
Prototype Rapid Test Developed
Sensitivity Quantitative PCR done on Strep equi culture Enabled assessment of sensitivity Artificial swabs with known bacterial counts
tested Limit of sensitivity ~ 50 CFU (colony forming
units) per strip Clinical target: 1000 organisms, as recommended
by Dr. John Timoney University of Kentucky
Maine Biotechnology Services, Inc. 2014
Sensitivity:
Maine Biotechnology Services, Inc. 2014
Prototype Rapid Test Developed
SpecificityBank of Strep equi and Strep zoo clinical
isolates provided by Dr. Causey Isolates were tested and compared the signal
to the CF32 Strep equi reference strain at 16 cells per strip.
Maine Biotechnology Services, Inc. 2014
The data on clinical isolates supports specificity for Strep equi with no cross reactivity to Strep zoo isolates.
Test against known CFU of Strep equi. UMO provided known concentrations of
Strep equi via the CFU metric Provided both bacteria in water and in saline
To evaluate possible effect of saline or water nasal flushes
Results show detection limit of 50-500 CFULimit of detection needed for clinical application
reported to be 1000 CFU Dr. John Timoney, University of Kentucky
Maine Biotechnology Services, Inc. 2014
Summary:Specificity metrics show no cross reactivity to the Strep zoo ancestor of Strep equi subsp. equiSensitivity as determined by
Quantitative PCR CFU Indicates that the prototype can detect 50-100 CFU
Maine Biotechnology Services, Inc. 2014
Nasal Swabs taken from 10 healthy horses.
UMO performed nasal swabs (2 per horse) on 10 horses documented as healthy
Prototype Strep equi test run to validate no cross reactivity with equine nasal flora
Negative swabs were spiked to assess interference with nasal natural flora
Maine Biotechnology Services, Inc. 2014
Results
Diagnostic Innovations
Maine Biotechnology Services, Inc. 2014
Summary Monoclonal antibodies to Strep equi Prototype rapid assay designed Strep equi CF32 reference strain Q-PCR Strep equi and zoo clinical isolates
specificity. Nasal swabs from healthy horses tested Spiked nasals swabs tested Ready to take the rapid test to the field.
Maine Biotechnology Services, Inc. 2014
Test Components
Diagnostic Innovations
Maine Biotechnology Services, Inc. 2014
Clinical Trial, 23 horses in Maine December 2013, barn in Cumberland
Maine was stricken with a highly contagious respiratory disease
May have been started via purchase of a yearling in Texas that showed signs of a mild respiratory illness.
Attending Veterinarian, Dr. Martha Smith
Maine Biotechnology Services, Inc. 2014
Clinical Trial: Compare PCR to rapid stall side assay 23 horses dual nasal swabs
1 sent to UC Davis for Quantitative PCR1 run on Rapid Stall side assay
Health histories during outbreak recorded. Random selection of samples also tested
for Streptococcus zooepidemicus. Ancestor of Streptococcus equi. subsp. equi
Maine Biotechnology Services, Inc. 2014
Diagnostic Test Metrics:• Specificity
•refers to the cross reactivity profile of the test
• Sensitivity
•refers to the lowest detectable load of bacteria
• Positive Predictive Value (PPV)
•is the proportion of patients with positive results, who are correctly diagnosed
• Negative Predictive Value (NPV)
•is the proportion of patients with negative results, who are correctly diagnosed.
Maine Biotechnology Services, Inc. 2014
Results:Disease + Disease - Total
Test + 5 (TP) 2 (FP) 7 (PPV Denominator)Test - 0 (FN) 16 (TN) 16 (NPV Denominator)
5 18 23
Positive Predictive Value: TP / (TP + FP) x 100 = 72%
Negative Predictive Value: TN / (TN + FN) x 100 = 100%
Sensitivity: TP / (TP + FN ) x 100 = 100 %
Specificity : TN / (TN + FP) x 100 = 88%
Take away message from this small clinical trial is: The test may have false positives, but it does not show the propensity for false negatives. It errs on
the side of safety for the barn managers with a 100% NPV and 100% Sensitivity metric.
Both (–) Strep zoo
Maine Biotechnology Services, Inc. 2014
Questions for End User How might you incorporate this test in your
practice What rapid test attributes are most
important to you? (cost, ease of use, time, et al..)
Can you identify any weaknesses for the commercialization of this test?
Questions, concerns?