Novel molecular transport medium used in combination with Xpert MTB/RIF ultra provides rapid detection of Mycobacterium bovis in African buffaloes

Charlene Clarke,David V Cooper,Tanya J Kerr,Michele A Miller,Paul D Van Helden,Katrin Smith,Robin M Warren,Samantha J Goldswain,Léanie Kleynhans,Christopher Helm,Wynand J Goosen

doi:10.1038/s41598-021-86682-5

Charlene Clarke, David V Cooper + Show 9 more

Open Access

https://doi.org/10.1038/s41598-021-86682-5

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Abstract

Mycobacterium bovis is the causative agent of bovine tuberculosis (bTB) in wildlife. Confirmation of M. bovis infection relies on mycobacterial culture, which is time-consuming. Collection and transportation of infectious material also pose a human health risk. PrimeStore Molecular Transport Medium (MTM) has been shown to effectively inactivate infectious organisms, making it a safe method for handling infectious samples. This study investigated an in-field sampling technique for rapid, safe detection of M. bovis in buffalo tissues. Potentially infected tissues from bTB test-positive buffaloes were swabbed at post-mortem examination and stored in PrimeStore MTM at ambient temperature until Xpert MTB/RIF Ultra testing was performed. Additionally, tissue samples were frozen and transported before homogenisation for culture and Ultra testing. Oral swabs were collected from M. bovis-unexposed buffaloes as a negative control cohort. Mycobacterium tuberculosis complex (MTBC) DNA was detected by Ultra in 13/16 tissue swabs and 9/16 matched tissue homogenates from culture-confirmed M. bovis-positive buffalo tissues. MTBC DNA was not detected in swabs from M. bovis-unexposed animals, showing the potentially high specificity of Ultra with PrimeStore swabs. PrimeStore MTM sample processing, in combination with the Ultra assay, has the potential to provide a safe, rapid post-mortem screening test for M. bovis in buffaloes.

Highlights

Bovine tuberculosis is an important zoonosis caused by Mycobacterium bovis (M. bovis) and is responsible for severe economic losses and disruption of conservation programs when livestock and wildlife are affected[1,2]
Each of these 16 culture-confirmed M. bovis positive tissue samples had a matching PrimeStore swab sample collected during post-mortem examination and stabilised in PrimeStore Molecular Transport Medium (MTM), and a pre-culture tissue homogenate aliquot
The findings from this study show that the Ultra assay combined with tissue swabs that were inactivated in PrimeStore MTM can accurately identify culture-confirmed M. bovis positive tissues from African buffaloes

Summary

Introduction

Bovine tuberculosis (bTB) is an important zoonosis caused by Mycobacterium bovis (M. bovis) and is responsible for severe economic losses and disruption of conservation programs when livestock and wildlife are affected[1,2]. African buffaloes (Syncerus caffer) are important wildlife maintenance hosts of M. bovis and serve as a source of infection for other susceptible mammals sharing the same h abitat[2]. This highlights the potential disease risk and importance of its c ontrol[1,2]. Ultra result for tissue homogenates MTB detected low MTB not detected MTB not detected MTB trace detected MTB not detected MTB detected very low MTB detected very low MTB not detected MTB not detected MTB detected low MTB detected low MTB detected very low MTB detected low MTB detected low MTB not detected MTB detected very low sample movement restrictions to laboratories due to the risk of spreading the disease. Movement restrictions placed on buffalo samples from locations with reportable diseases to laboratories may result in inadequate bTB surveillance in these areas[9]

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