Aims: This study aimed to characterize the impact of lytic and temperate bacteriophages on the genetic and phenotypic diversity of Mannheimia haemolytica from feedlot cattle.
Methods And Results: Strictly lytic phages were not detected from bovine nasopharyngeal (n = 689) or water trough (n = 30) samples, but Myoviridae- or Siphoviridae-like phages were induced from 54 of 72 M. haemolytica strains by mitomycin C, occasionally from the same strain. Phages with similar restriction fragment length polymorphism profiles (RFLP ≥70% relatedness) shared common host serotypes 1 or 2 (P < 0·0001). Likewise, phages with similar RFLP tended to occur in genetically related host bacteria (70-79% similarity). Host range assays showed that seven phages from host serotypes 1, 2 and 6 lysed representative strains of serotypes 1, 2 or 8. The genome of vB_MhM_1152AP from serotype 6 was found to be collinear with P2-like phage φMhaA1-PHL101.
Conclusions: Prophages are a significant component of the genome of M. haemolytica and contribute significantly to host diversity. Further characterization of the role of prophage in virulence and persistence of M. haemolytica in cattle could provide insight into approaches to control this potential respiratory pathogen.
Significance And Impact Of The Study: This study demonstrated that prophages are widespread within the genome of M. haemolytica isolates and emphasized the challenge of isolating lytic phage as a therapeutic against this pathogen.
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http://dx.doi.org/10.1111/jam.12185 | DOI Listing |
Front Vet Sci
January 2025
Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
Introduction: Antimicrobial resistance (AMR) is a growing threat to the efficacy of antimicrobials in humans and animals, including those used to control bovine respiratory disease (BRD) in high-risk calves entering western Canadian feedlots. Successful mitigation strategies require an improved understanding of the epidemiology of AMR. Specifically, the relative contributions of antimicrobial use (AMU) and contagious transmission to AMR emergence in animal populations are unknown.
View Article and Find Full Text PDFVet Microbiol
January 2025
Purdue University, Department of Animal Sciences, West Lafayette, IN 47907 USA. Electronic address:
Mannheimia haemolytica is one of the most common causative agents of bovine respiratory disease (BRD); however, antibiotic resistance in this species is increasing, making treatment more difficult. Integrative-conjugative elements (ICE), a subset of mobile genetic elements (MGE), encoding up to 100 genes have been reported in Mannheimia haemolytica genomes to confer multidrug resistance, including resistance to antibiotics commonly used in the treatment of BRD. However, the presence of antibiotic resistance genes (ARGs) does not always agree with phenotypic resistance.
View Article and Find Full Text PDFMicroorganisms
December 2024
Beef Cattle Institute, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
Metaphylaxis or treating the entire population of cattle at arrival with an antimicrobial has been studied extensively in the cattle industry; however, little information is available on the impacts of treating only a proportion of the population with antimicrobials at arrival. The study objective was to determine potential associations between the proportion of animals in a pen treated with antimicrobial therapy with pen performance and nasopharyngeal microbiome. Yearling steers (n = 160) were randomly allocated to study pens (n = 40) and pens were systematically randomized to one of two antimicrobial treatments (META: all four head received tulathromycin; MIXED: two of four head randomly selected to receive tulathromycin).
View Article and Find Full Text PDFVet Sci
December 2024
Biovet Inc., Division of Antech Diagnostics and Mars Petcare Science & Diagnostics Company, Saint-Hyacinthe, QC J2S 8W2, Canada.
The bovine respiratory disease complex (BRD) is a multifactorial disease caused by various bacterial and viral pathogens. Using rapid pathogen detection techniques is helpful for tailoring therapeutic and preventive strategies in affected animals and herds. The objective of this study was to report the frequency of 10 pathogens by multiplex RT-qPCR on samples submitted for BRD diagnosis to a diagnostic laboratory (Biovet Inc.
View Article and Find Full Text PDFVet Microbiol
February 2025
School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia.
Clinical signs of respiratory disease are common in Lao goats. To identify the causative agents involved in this clinical syndrome, a matched case-control study was conducted across 70 smallholder goat holdings in Savannakhet province. Fifty paired nasal swab samples were collected from goats with respiratory signs (cases) and unaffected (control) goats from 27 goat holdings.
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