# P-729. Limit of Detection and Inclusivity of a Research-Use-Only (RUO) Prototype of a Multiplexed Sample-to-Answer Diagnostic System for Identification of Sexually Transmitted Infections from Vaginal Swabs and Penile Urine

## TL;DR

This study evaluates a new diagnostic test for sexually transmitted infections, showing it can detect low levels of multiple pathogens from different sample types.

## Contribution

The study presents the limit of detection and inclusivity data for a prototype STI diagnostic panel in a point-of-care setting.

## Key findings

- The limit of detection varied from 0.28 to 275 genome copies per mL across pathogens.
- The panel showed no reactivity limitations with 43 tested strains at near-LoD levels.
- In silico analysis predicts >99.7% reactivity for three of the four pathogens.

## Abstract

Untreated sexually transmitted infections adversely impact sexual health and reproductive outcomes. bioMérieux is developing the BIOFIRE® SPOTFIRE® Sexually Transmitted Infection (STI) Panel, a molecular test designed for a point-of-care setting to detect Chlamydia trachomatis, Mycoplasma genitalium, Neisseria gonorrhoeae, and Trichomonas vaginalis from vaginal swabs (Vswabs) or penile urine collected in eNAT® medium. This study evaluated the limit of detection (LoD) and inclusivity of the pathogen assays in a RUO panel prototype.Table 1.Limit of Detection and Inclusivity Assessment of the RUO BIOFIRE® SPOTFIRE® Sexually Transmitted Infection Panel

Limit of Detection and Inclusivity Assessment of the RUO BIOFIRE® SPOTFIRE® Sexually Transmitted Infection Panel

Serial dilutions of reference isolates, quantified to determine genome copies using droplet digital PCR assays targeting single-copy genes, were spiked into negative clinical matrices and used to determine the 95% LoD for each pathogen. Inclusivity was assessed empirically using 43 PCR-quantified strains spiked into negative matrices at near-LoD genome equivalent (GE) levels as well as in silico using sequence data available at the time of analysis.

See Table 1 for study results. The LoD of the reference isolates varied from 275 GE/mL for N. gonorrhoeae to 0.28 GE/mL for T. vaginalis. All analytes besides T. vaginalis had equivalent LoDs in both sample matrices, with 10-fold greater sensitivity for T. vaginalis in contrived urine samples. Inclusivity testing of 43 organism strains at 5-20X LoD showed no reactivity limitations with equivalent reactivity in both sample matrices. In silico assessments based on assay primer homology to > 900 available sequences predict > 99.7% reactivity for 3 /4 analytes on the panel; an assessment of the degree of reactivity impairment for 2.6% of M. genitalium sequences is planned.

This study suggests the BIOFIRE® SPOTFIRE® STI Panel will be capable of detecting low levels and multiple strains of clinically relevant C. trachomatis, M. genitalium, N. gonorrhoeae, and T. vaginalis strains from appropriate specimens.

All Authors: No reported disclosures