On-farm colorimetric detection of Pasteurella multocida, Mannheimia haemolytica, and Histophilus somni in crude bovine nasal samples

Ana Pascual-Garrigos,Jennifer Koziol,Josiah Levi Davidson,Grigorii Rudakov,Jon P Schoonmaker,Aaron Ault,Timothy Johnson,Murali Kannan Maruthamuthu,Deepti Pillai,Mohit S Verma

doi:10.1186/s13567-021-00997-9

Ana Pascual-Garrigos, Jennifer Koziol + Show 8 more

Open Access

https://doi.org/10.1186/s13567-021-00997-9

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Abstract

This work modifies a loop-mediated isothermal amplification (LAMP) assay to detect the bovine respiratory disease (BRD) bacterial pathogens Pasteurella multocida, Mannheimia haemolytica, and Histophilus somni in a colorimetric format on a farm. BRD causes a significant health and economic burden worldwide that partially stems from the challenges involved in determining the pathogens causing the disease. Methods such as polymerase chain reaction (PCR) have the potential to identify the causative pathogens but require lab equipment and extensive sample processing making the process lengthy and expensive. To combat this limitation, LAMP allows accurate pathogen detection in unprocessed samples by the naked eye allowing for potentially faster and more precise diagnostics on the farm. The assay developed here offers 66.7–100% analytical sensitivity, and 100% analytical specificity (using contrived samples) while providing 60–100% concordance with PCR results when tested on five steers in a feedlot. The use of a consumer-grade water bath enabled on-farm execution by collecting a nasal swab from cattle and provided a colorimetric result within 60 min. Such an assay holds the potential to provide rapid pen-side diagnostics to cattle producers and veterinarians.

Highlights

Bovine respiratory disease (BRD) is known to be the most common cause of morbidity and mortality in cattle affecting 16% of all beef cattle [1] and causing up to 75% feedlot morbidity in North America [2]
We present the percent concordance between in-lab and onfarm loop-mediated isothermal amplification (LAMP) as well as between polymerase chain reaction (PCR) and on-farm LAMP using unprocessed mucus collected from steers (Table 1 and Additional file 7)
Determining a threshold for colorimetric visualization LAMP reaction reagents were set to increasing pH to visualize color change (Figure 3)

Summary

Introduction

Bovine respiratory disease (BRD) is known to be the most common cause of morbidity and mortality in cattle affecting 16% of all beef cattle [1] and causing up to 75% feedlot morbidity in North America [2]. It is estimated to cost up to $900 million annually in the beef industry alone [3] This economic burden includes animal weight loss, labor expenses, pharmaceutical costs, and BRD is an umbrella term used to describe a condition caused by bacteria, viruses, or co-infection [5, 6]. It is detected by observing clinical signs such as nasal discharge, depression, anorexia, cough, and fever [4]. These clinical signs are insufficient for determining the underlying causative pathogen. One method for determining which pathogen is causing BRD involves taking a nasal swab sample from the suspected animal and sending it to a diagnostic laboratory, where tests are carried out to identify pathogens [7]

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Conclusion