Mpox infection investigation using multiplexed syndromic diagnostics: Evaluation of an AusDiagnostics multiplexed tandem PCR (MT-PCR) syndromic panel

Background

Detection of mpox virus during investigation of viral vesicular rash illness is required to identify mpox infection.

Objectives

This study evaluated the performance of a research-use-only (RUO) AusDiagnostics MT-PCR syndromic assay containing an mpox virus target.

Methods

The analytical specificity and limit of detection (LoD) of the AusDiagnostics MT-PCR mpox assay was verified using control material. Clinical performance was evaluated using anonymised residual nucleic acids extracted from swab specimens previously tested for mpox virus using a laboratory developed test (LDT). Residual nucleic acids were derived from consecutive sample panels collected during two periods in the 2022 mpox outbreak.

Results

The AusDiagnostics MT-PCR assay demonstrated an LoD of 35 input copies of mpox virus and correctly detected all relevant members of a specificity panel (n = 34). 175 residual nucleic acids were included in the study with a prevalence of mpox of 40.0% (95%CI 32.7–47.6). The AusDiagnostics MT-PCR mpox assay demonstrated an accuracy of 98.9% (95%CI 93.8–99.9), sensitivity of 94.2% (95%CI 85.2 – 98.1) and specificity of 100% (95%CI 95.6 -100), when compared to the LDT qPCR assay. The AusDiagnostics MT-PCR mpox assay detected additional vesicular rash pathogens in 26.8% samples. Co-detection with other vesicular rash pathogens was described in 12.8% of mpox virus detected samples

Conclusions

Performance of the RUO AusDiagnostics MT-PCR mpox assay was comparable to an LDT qPCR for the detection of mpox virus in nucleic acids extracted from swab specimens. The RUO AusDiagnostics MT-PCR mpox assay facilitated the simultaneous detection of additional infective etiologies of vesicular rash syndromes.