P1253 - A Novel Point-of-Care DNA Stool Testing Kit for Infectious Diarrhea: Utility in Resource-Limited Settings

Sunday, October 22, 2023

3:30 PM – 7:00 PM PT

Location: Exhibit Hall

Has Audio

Presenting Author(s)

Quarshie Glover, MBChB

University of Wisconsin Hospitals and Clinics
Madison, WI

Quarshie Glover, MBChB¹, Abigail Mapes, ¹, Fauzia Osman, MPH², Kim Hee. Chang, PhD¹, Dawd Siraj, MD, MPH¹
¹University of Wisconsin Hospitals and Clinics, Madison, WI; ²University of Wisconsin Hospital and Clinics, Madison, WI

Introduction: Infectious diarrheal diseases are one of the leading causes of worldwide morbidity and mortality. The incidence of diarrhea is higher in Low-Middle-Income countries, where more than 90% of deaths from diarrheal disease occurs. Diagnostic tests for infectious diarrhea are not readily available in low-middle-income countries. Our study evaluates a novel, cost-effective, easy-to-use DNA stool testing kit for infectious diarrhea that can easily be rolled out in low-resource settings and has comparable performance to current testing modalities in the USA in terms of diagnostic utility.

Methods: 435 stool samples were tested using the novel stool testing Kit (GoDx) in groups of 8 using floating microspheres DNA extraction followed by RPA amplification and lateral flow assay detection. Pathogens tested include C. difficile, Campylobacter Jejuni, Salmonella enterica Typhimurium, Shigella spp., STEC (stx1, stx2), Vibrio spp., and Yersinia enterocolitica. The same samples were tested using Biofire (gold standard), and the results were compared. Descriptive analysis was summarized as raw counts and frequencies and compared using Fisher’s exact test. We conducted specificity and sensitivity analysis of the two diagnostic tests using the diagnostic testing package in STATA. Graphical illustrations were conducted using two-way line graphs with custom margins and axis. All analyses with p-values ≤0.05 were significant. All analyses were conducted using STATA version 17.

Results: Results show high sensitivity for most pathogens. Example of >93% for C. difficile. Specificities were >97% for all pathogens except c-diff with a specificity of 75.8%. Positive predictive value was highest for salmonella 83.3%, with values for C. difficile, Campylobacter jejuni, Shigella spp, Vibrio spp ranging from 56.1% to 65%. STEC was 46.1%. Negative predictive values for all pathogens were above 97%. Table 1. The concordance between Biofire and GoDx for C. difficile testing was 80%. All other organisms showed a concordance of greater than 97%

Discussion: Our study confirms that GoDx is a novel diagnostic tool for diarrheal pathogens with a statistically comparable sensitivity, specificity, positive and negative predictive values with the current gold standard testing kit, BioFire. In addition, the simplicity of the technology and cheaper price both to healthcare systems and to patients makes GoDx an ideal diagnostic test to be implemented in low- and middle-income countries.

Table 1: Sensitivity, specificity, and predictive values
	Biofire
	Negative	Positive	Pr	Se (95% CI)	Sp (95% CI)	PPV (95% CI)	NPV (95% CI)
GoDx
A: C. difficile
Negative	248	7	24.8%	93.5 (91.2 – 95.8)	75.8 (71.8 – 79.9)	56.1 (51.4 – 60.8)	97.2 (95.7 – 98.8)
Positive	79	101
B: Campylobacter
Negative	405	1	4.1%	94.4 (92.3 – 96.6)	97.1 (95.6 – 98.7)	58.6 (54.0 – 63.2)	99.8 (99.3 – 100)
Positive	12	17
C: STEC
Negative	416	6	2.8%	50.0 (45.3 – 54.7)	98.3 (97.1 – 99.5)	46.1 (41.5 – 50.8)	98.6 (97.5 – 99.7)
Positive	7	6
D: Salmonella
Negative	401	4	6.7%	86.2 (83.0 – 89.4)	98.8 (97.7 – 99.8)	83.3 (79.8 – 86.8)	99.0 (98.1 – 99.9)
Positive	5	25
E: Yersinia
Negative	427	3	0.7%	0.0 (0.0 – 0.0)	98.9 (97.8 – 99.9)	0.0 (0.0 – 0.0)	99.3 (98.5 – 100)
Positive	5	0
F: Vibrio
Negative	429	3	1.1%	40 (35.4 – 44.6)	99.8 (99.3 – 100)	66.7 (62.2- 71.1)	99.3 (98.5 – 100)
Positive	1	2
G: Shigella
Negative	411	4	3.9%	76.5 (72.5 – 80.5)	98.3 (97.1 – 99.5)	65.0 (60.5 – 69.5)	99.0 (98.1 – 99.9)
Positive	7	13
Se = Sensitivity, Sp = Specificity, PPV = Positive Predictive Value, NPV = Negative predictive value, pr = Prevalence

Table: Table 1: Sensitivity, specificity, and predictive values

Disclosures:

Quarshie Glover indicated no relevant financial relationships.

Abigail Mapes indicated no relevant financial relationships.

Fauzia Osman indicated no relevant financial relationships.

Kim Chang indicated no relevant financial relationships.

Dawd Siraj indicated no relevant financial relationships.

Quarshie Glover, MBChB¹, Abigail Mapes, ¹, Fauzia Osman, MPH², Kim Hee. Chang, PhD¹, Dawd Siraj, MD, MPH¹. P1253 - A Novel Point-of-Care DNA Stool Testing Kit for Infectious Diarrhea: Utility in Resource-Limited Settings, ACG 2023 Annual Scientific Meeting Abstracts. Vancouver, BC, Canada: American College of Gastroenterology.