Mannheimia haemolytica serovars associated with respiratory disease in cattle in Great Britain

Oliver Grace,Geoffrey Foster,Katharine Baxter-Smith,Jennifer Thacker,Colin Mason,Jane Errington

doi:10.1186/s12917-021-03121-3

Oliver Grace, Geoffrey Foster + Show 4 more

Open Access

https://doi.org/10.1186/s12917-021-03121-3

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Abstract

BackgroundMannheimia haemolytica is commonly associated with respiratory disease in cattle worldwide as a cause of fibrinous pneumonia, bronchopneumonia and pleuritis. M. haemolytica is further subdivided into 12 serovars, however not all are considered to be pathogenic in cattle. The study aim was to determine the most common serovars of M. haemolytica associated with respiratory disease in cattle in Great Britain, which is currently unknown and could be useful information for clinicians when considering preventative strategies.ResultsOne hundred four M. haemolytica isolates isolated from bovine clinical pathology and post-mortem samples from pneumonia cases between 2016 and 2018 were tested using a multiplex PCR assay to identify M. haemolytica serovars A1, A2 and A6. 46 isolates (44.2%) typed as M. haemolytica serovar A1, 31 (29.8%) as M. haemolytica serovar A2 and 18 isolates (17.3%) as M. haemolytica serovar A6. Nine isolates (8.7%) were not A1, A2 or A6 so were considered to belong to other serovars or were not typable.ConclusionThis study highlights the importance of M. haemolytica serovars other than A1 which may be responsible for respiratory disease in cattle and could help guide the veterinarian when making choices on preventative vaccination programmes.

Highlights

Mannheimia haemolytica is commonly associated with respiratory disease in cattle worldwide as a cause of fibrinous pneumonia, bronchopneumonia and pleuritis
The results of specificity testing of the M. haemolytica Polymerase Chain Reaction (PCR) assay confirmed that all M. haemolytica serovar A1, A2 and A6 strains were correctly identified
The largest proportion of isolates (44.2%) typed as M. haemolytica serovar A1, 29.8% typed as M. haemolytica serovar A2 and 17.3% typed as A6

Summary

Introduction

Mannheimia haemolytica is commonly associated with respiratory disease in cattle worldwide as a cause of fibrinous pneumonia, bronchopneumonia and pleuritis. M. haemolytica is further subdivided into 12 serovars, not all are considered to be pathogenic in cattle. The study aim was to determine the most common sero‐ vars of M. haemolytica associated with respiratory disease in cattle in Great Britain, which is currently unknown and could be useful information for clinicians when considering preventative strategies. Mannheimia haemolytica is associated with respiratory disease in cattle and sheep worldwide. There are twelve serovars of M. haemolytica, based on capsular antigens and labelled A1, A2, A5, A6, A7, A8, A9, A12, A13, A14, A16 and A17. M. haemolytica serovars A1, A2 and A6 are the most prevalent worldwide [4] and are readily isolated from the nasopharynx of healthy cattle.

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