# Systematic review on the laboratory methodology for conducting wastewater and environmental surveillance for Salmonella

## TL;DR

This systematic review evaluates lab methods for detecting Salmonella in wastewater and surface waters, highlighting the need for standardized protocols to improve surveillance.

## Contribution

The study identifies six methodological pathways and highlights the lack of standardized protocols and quality control in Salmonella wastewater surveillance.

## Key findings

- Grab sampling is the most commonly used method for wastewater and surface water sampling.
- Fewer than 14% of studies reported comprehensive quality control measures.
- Six distinct methodological pathways for Salmonella detection were identified.

## Abstract

Wastewater and environmental surveillance (WES) is a valuable supplementary tool to clinical surveillance for infectious diseases, especially in low- and middle-income countries. This systematic review evaluates laboratory methods for detecting Salmonella spp. in wastewater and contaminated surface waters, focusing on methodological diversity, feasibility, and the need for standardized protocols.

The review was performed using protocol registered with PROSPERO (ID: CRD42024573052) following PRISMA 2020 guidelines. The review was funded by the European Commission’s Health Emergency Preparedness and Response Authority (HERA) and the World Health Organization (WHO). Search was conducted in PubMed, EMBASE, and Web of Science (last update: May 31, 2025). Studies describing sampling and laboratory methods for Salmonella detection in wastewater or contaminated surface waters were included. Exclusion criteria were incomplete methodology, non-peer-reviewed status, or non-English publication. Data extraction and quality assessment were performed independently by two authors. Results were synthesized narratively due to high methodological variability.

Of 2,007 records, 94 studies from 36 countries met inclusion criteria. Grab sampling was most common, followed by trap and composite sampling. Detection methods included culture, PCR, and sequencing. Six methodological pathways were identified. Fewer than 14% of studies reported comprehensive quality control. Substantial heterogeneity in sampling, handling, and testing protocols affected reproducibility and comparability.

Evidence generated was constrained due to inconsistent reporting of quality control and validation criteria. Most studies lacked critical methodological details for reproducibility and scale-up. Harmonized, context-adapted protocols and minimum reporting standards are needed, along with leveraging existing surveillance infrastructure for rapid implementation of Salmonella WES in diverse settings.

https://www.crd.york.ac.uk/PROSPERO/view/CRD42024573052, identifier PROSPERO (CRD42024573052).