# Strep-CaDI: A fast, accurate, and sensitive point-of-care test for Group A Streptococcus

> **NIH NIH R43** · BURST DIAGNOSTICS LLC · 2023 · $279,557

## Abstract

SUMMARY
The current rapid antigen detection tests for group A strep lack sensitivity and result in upwards of 10 million unnecessary
antibiotic treatments provided to children each year. Current diagnostic methods utilized when a patient presents at a clinic
with a sore throat include a throat swab and rapid strep test. A positive rapid test results in antibiotic prescription, but due
to the low sensitivity of existing rapid strep immunoassays, physicians often prescribe antibiotics as a precaution while
waiting for culture results after a negative rapid test. It is estimated that up to 70% of these doses are unnecessary,
contributing to the rise in antimicrobial resistance. While ELISAs and molecular (PCR-based) assays with improved
sensitivity have been reported to reduce unnecessary antibiotic treatment, these tests rely on laboratory instrumentation and
significant infrastructure, making them unsuitable for point-of-care settings and rural clinics, and impossible to implement
as at-home testing protocols for telemedicine purposes. Thus, there is an urgent unmet need for an improved, ultrasensitive
rapid strep test that could reduce the unnecessary use of antibiotics, stemming the increase in antimicrobial resistance and
preserving the gut microbiome of children. Furthermore, if an improved rapid strep test could be optimized for robustness
and ease of use, as well as sensitivity, it could be performed at home enabling telemedicine protocols and reducing the need
for a potentially infected individual to expose frontline healthcare workers. The outcome of this project will be a proof-of-
principle demonstration of an ultrasensitive rapid strep test with onboard reagents that requires a simple swab insertion step
to initiate to completion with limits of detection 10-100x lower than current dipstick methods. Improved sensitivity will be
achieved through use of the Capillary-Driven Immunoassay (CaDI) technology in which we are able to integrate all steps
of highly sensitive, laboratory-performed ELISAs (washing, labeling, and amplification) on a simple microfluidic device
without requiring instrumentation or highly trained personnel. This first-in-its-class microfluidic point-of-care (POC) device
will be realized through the following aims. First, proof of concept for a Strep-CaDI rapid strep test will be demonstrated
for the ultrasensitive detection of Streptococcus pyogenes antigen in spiked buffer through antibody screening and assay
parameter optimization. Secondly, the bacterial extraction method and corresponding CaDI parameters and device design
will be optimized for use with clinical samples spiked with whole bacteria. The final, optimized design will be compared to
current market solutions to compare assay sensitivity (LOD), time to result, and complexity (steps to result). Lastly, to
increase the likelihood of approval for at-home use and to provide a clear market advantage over current solutions, we will
prototype (through modeling, 3D ...

## Key facts

- **NIH application ID:** 10699852
- **Project number:** 1R43AI172708-01A1
- **Recipient organization:** BURST DIAGNOSTICS LLC
- **Principal Investigator:** Zachary David Call
- **Activity code:** R43 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $279,557
- **Award type:** 1
- **Project period:** 2023-08-01 → 2024-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10699852

## Citation

> US National Institutes of Health, RePORTER application 10699852, Strep-CaDI: A fast, accurate, and sensitive point-of-care test for Group A Streptococcus (1R43AI172708-01A1). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10699852. Licensed CC0.

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