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.

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

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