# A Novel Loop-Mediated Isothermal Amplification (LAMP) Primer Set for Detecting the STY2879 Gene of Salmonella enterica Serovar Typhi in Raw Milk

## TL;DR

This study develops a low-cost, fast test to detect typhoid-causing bacteria in raw milk, suitable for use in low-resource areas.

## Contribution

A novel LAMP primer set for detecting the STY2879 gene of Salmonella Typhi in raw milk with high sensitivity and specificity.

## Key findings

- The novel primer set detected as few as 2000 genomes in 2% raw milk and 1000 genomes in 1% raw milk within 30 minutes.
- The test uses a colorimetric readout, enabling on-site detection in remote and low-resource settings.
- The method does not require preprocessing and operates at a constant temperature of 65°C.

## Abstract

Milk-borne outbreaks remain a significant issue in low-income countries due to unhygienic practices. Currently, there are no known easily accessible and low-cost diagnostic tests that can detect Salmonella enterica subsp. enterica serovar Typhi, the causative agent of typhoid fever, in raw milk samples at high specificity, sensitivity, and speed without preprocessing. Early detection of Salmonella enterica subsp. enterica serovar Typhi in food matrices is critical for preventing infection prior to consumption and reducing disease burden. Using colorimetric loop-mediated isothermal amplification, we screened 15 novel and two previously published primer sets. We identified one novel primer set capable of detecting the STY2879 gene in as few as 2000 genomes in 2% v/v raw milk reactions and 1000 genomes in 1% v/v raw milk reactions of Salmonella enterica subsp. enterica serovar Typhi after 30 minutes of incubation in a 65° C water bath. The colorimetric readout offers promising potential applications for on-site detection in remote and low-resource settings where infection with Salmonella enterica subsp. enterica serovar Typhi remains a public health concern.