Mannheimia haemolytica
| Mannheimia haemolytica | |
|---|---|
Scientific classification 
| |
| Domain: | Bacteria |
| Kingdom: | Pseudomonadati |
| Phylum: | Pseudomonadota |
| Class: | Gammaproteobacteria |
| Order: | Pasteurellales |
| Family: | Pasteurellaceae |
| Genus: | Mannheimia |
| Species: | M. haemolytica
|
| Binomial name | |
| Mannheimia haemolytica (Newsom & Cross, 1932) Angen et al., 1999[1]
| |
| Synonyms[1] | |
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Mannheimia haemolytica is a species of Gram-negative bacteria belonging to the family Pasteurellaceae. It is a facultatively anaerobic, non-spore-forming, and non-motile coccobacillus. M. haemolytica is a primary bacterial pathogen implicated in the bovine respiratory disease complex (BRDC), also commonly known as "shipping fever," particularly affecting cattle, sheep, and goats.
History
[edit]Mannheimia haemolytica was originally described as Pasteurella haemolytica by Newsom and Cross in 1932, based on bipolar organisms isolated from cases of pneumonia in sheep and cattle.[2] For decades, it was classified within the genus Pasteurella. However, advances in molecular taxonomy led to a reassessment of the [Pasteurella] haemolytica complex. In 1999, Angen and colleagues conducted a comprehensive study using DNA–DNA hybridization and 16S rRNA gene sequencing, which demonstrated sufficient genetic divergence to warrant creation of a new genus, Mannheimia.[3]
Pathogenesis
[edit]Mannheimia haemolytica primarily colonizes the upper respiratory tract of cattle and other ruminants but can become pathogenic under stress conditions such as transport, crowding, or viral infections. This bacterium secretes leukotoxins, endotoxins, and other virulence factors that damage respiratory tissues and impair host immunity, resulting in severe fibrinous pneumonia.[4]
Clinical signs
[edit]Affected cattle commonly exhibit symptoms such as fever, depression, reduced appetite, nasal discharge, coughing, and difficulty breathing. In severe cases, animals can rapidly progress to acute respiratory distress and death if untreated.[4]
Diagnosis
[edit]Diagnosis of Mannheimia haemolytica infection typically involves bacterial culture from nasal swabs, lung tissue, or bronchoalveolar lavage samples. Samples are commonly cultured on blood agar, where M. haemolytica forms characteristic β-hemolytic colonies. Confirmation is supported by biochemical tests and species-specific polymerase chain reaction (PCR) assays. In research and advanced diagnostic contexts, whole genome sequencing (WGS) is increasingly used to characterize isolates, monitor strain diversity, and investigate antimicrobial resistance.[5]
Treatment and prevention
[edit]Effective management of Mannheimia haemolytica infections involves prompt administration of appropriate antibiotics, such as macrolides (e.g., tulathromycin, gamithromycin), tetracyclines, or fluoroquinolones. However, the emergence of antimicrobial resistance, including multidrug-resistant strains, underscores the importance of prudent antibiotic use and the need for alternative control strategies.[6]
Preventative measures include vaccination programs targeting prevalent serotypes. Studies have shown that vaccines incorporating multiple serotypes, such as A1 and A6, or recombinant proteins like leukotoxin, can enhance protective efficacy.[7] In addition, good husbandry practices such as reducing stress, ensuring adequate ventilation, and avoiding overcrowding can reduce the risk of disease.[8]
References
[edit]- ^ a b "Mannheimia haemolytica (Newsome & Cross, 1932) Angen et al., 1999". Global Biodiversity Information Facility. Retrieved 7 June 2025.
- ^ Newsom, I. E.; Cross, F. (1932). "Some bipolar organisms found in pneumonia in sheep". Journal of the American Veterinary Medical Association. 80: 711–719.
- ^ Angen, Ole; Mutters, Rudolf; Caugant, Dag A.; Olsen, John E.; Bisgaard, Magne (1999). "Taxonomic relationships of the [Pasteurella] haemolytica complex as evaluated by DNA–DNA hybridizations and 16S rRNA sequencing with proposal of Mannheimia haemolytica gen. nov., comb. nov., Mannheimia granulomatis comb. nov., Mannheimia glucosida sp. nov., Mannheimia ruminalis sp. nov. and Mannheimia varigena sp. nov". International Journal of Systematic Bacteriology. 49 (1): 67–86. doi:10.1099/00207713-49-1-67. PMID 10028248.
- ^ a b Rice, J. A.; Carrasco-Medina, L.; Hodgins, D. C.; Shewen, P. E. (December 2007). "Mannheimia haemolytica and bovine respiratory disease". Animal Health Research Reviews. 8 (2): 117–128. doi:10.1017/S1466252307001375. PMID 18218156.
- ^ Crosby, WB; Pinnell, LJ; Richeson, JT; Wolfe, C; Castle, J; Loy, JD; Gow, SP; Seo, KS; Capik, SF; Woolums, AR; Morley, PS (13 August 2022). "Does swab type matter? Comparing methods for Mannheimia haemolytica recovery and upper respiratory microbiome characterization in feedlot cattle". Animal Microbiome. 4 (1): 49. doi:10.1186/s42523-022-00197-6. PMC 9375289. PMID 35964128.
- ^ Credille, Brent (December 2020). "Antimicrobial resistance in Mannheimia haemolytica: prevalence and impact". Animal Health Research Reviews. 21 (2): 196–199. doi:10.1017/S1466252320000109. PMID 33261661.
- ^ Confer, Anthony W.; Ayalew, Sahlu (December 2018). "Mannheimia haemolytica in bovine respiratory disease: immunogens, potential immunogens, and vaccines". Animal Health Research Reviews. 19 (2): 79–99. doi:10.1017/S1466252318000142. PMID 30616509.
- ^ Rice, J.A.; Carrasco-Medina, L.; Hodgins, D.C.; Shewen, P.E. (December 2007). "Mannheimia haemolytica and bovine respiratory disease". Animal Health Research Reviews. 8 (2): 117–128. doi:10.1017/S1466252307001375. PMID 18218156.
External links
[edit]- Overview of Mannheimia haemolytica infection – Merck Veterinary Manual