Characterization of Mannheimia haemolytica in beef calves via nasopharyngeal culture and pulsed-field gel electrophoresis

Journal of Veterinary Diagnostic Investigation : Official Publication of the American Association of Veterinary Laboratory Diagnosticians, Inc
Sarah F CapikRobert W Murray

Abstract

Mannheimia haemolytica is a major bacterial component of bovine respiratory disease (BRD); unfortunately, very little is known about M. haemolytica transmission dynamics among cattle. Identifying potential variation in M. haemolytica populations over time and induction of nasopharyngeal colonization and subsequent shedding are 2 areas where knowledge is lacking. In our study, 2 separate loads of 20 mixed-origin, male calves were purchased through an order buyer on different dates. Deep nasopharyngeal cultures (NPC) were performed on all calves on arrival and, if M. haemolytica-negative, a second screening culture was obtained. Calves that were negative on 2 initial NPCs (NEG; n = 4) were subsequently challenged with a previously isolated field strain of M. haemolytica in both the upper and lower respiratory tract, individually housed, and then monitored for M. haemolytica shedding via NPCs at 0.5, 1, 3, 5, 7, and 9 days postchallenge. Naturally M. haemolytica-positive calves (2 per load) were kept for additional daily cultures (POS; n = 4). Individual calf M. haemolytica status for both the POS and NEG groups was inconsistent between study days. Additionally, pulsed-field gel electrophoresis performed on isolates from the posit...Continue Reading

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Citations

Sep 22, 2018·Journal of Veterinary Diagnostic Investigation : Official Publication of the American Association of Veterinary Laboratory Diagnosticians, Inc·John D LoyBing Wang
Mar 8, 2017·Journal of Microbiological Methods·John Dustin Loy, Michael L Clawson

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Methods Mentioned

BETA
electrophoresis
bronchoalveolar
biopsy

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