# Diagnostic Accuracy of Multiplex NAAT/PCR and Culture Against Salmonella spp.: A Comparison of Meta-Analytical Methods

## TL;DR

This study compares the accuracy of fast NAAT/PCR tests and traditional culture methods for diagnosing Salmonella infections, finding both to be highly accurate but with different performance patterns.

## Contribution

The paper introduces a comparative analysis of multiple meta-analytical models to assess diagnostic accuracy of Salmonella tests, highlighting model-dependent variability.

## Key findings

- Multiplex NAAT/PCR showed high specificity (>98%) but variable sensitivity (85.5–94.8%) depending on the statistical model used.
- Culture remained highly accurate (97.17% sensitivity, 96.06% specificity) but with wide credible intervals indicating study variability.
- Bayesian models provided narrower confidence intervals for sensitivity compared to SCS and BHSROC models.

## Abstract

Background: Non-typhoidal (NT) Salmonella spp. constitutes a major cause of foodborne illness. Culture is the gold standard, but it is time consuming, whereas multiplex nucleic acid amplification tests (NAATs)/Polymerase Chain Reaction (PCR) offer faster detection with variable reported performance. Objectives: To compare the diagnostic accuracy of multiplex NAAT/PCR and culture for Salmonella spp. using various statistical models with or without a gold standard assumption. Methods: A systematic search (PubMed, Web of Science, Scopus; up to April 2024) identified 44 studies (55 comparisons). Diagnostic performance was evaluated using the frequentists bivariate model (BM) and Split Component Synthesis (SCS) and the Bayesian bivariate models (BBMs) and hierarchical summary ROC (BHSROC). Results: Across models, multiplex NAAT/PCR demonstrated high specificity (>98%) but model-dependent variability in sensitivity (85.5–94.8%), consistently substantial between study heterogeneity and threshold variation. The BM and BBM yielded a higher sensitivity estimate with narrower non-overlapping confidence intervals while SCS and BHSROC models, which are more robust to threshold differences, produced more conservative estimates with wider uncertainty. In Bayesian latent class analyses, culture remained highly accurate (Se: 97.17%, 95% CrI: 70.3–99.99; Sp: 96.06%, 95% CrI: 78.9–99.99), but with wide credible intervals indicating variation between studies, perhaps due to the different protocols used. Conclusion: Model choice affects inferred diagnostic accuracy, particularly when high heterogeneity is present. Both multiplex NAAT/PCR and culture showed high accuracy; hence, a combination of the two tests could optimise rapid diagnosis and treatment. Future research should include cost effectiveness and decision analysis to update the diagnostic algorithms.