Mycoplasma hyopneumoniae

Mycoplasma hyopneumoniae
Phylum	Firmicutes
Class	Mollicutes
Order	Mycoplasmatales
Family	Mycoplasmataceae
Genus	Mycoplasma
Species	M.hyopneumoniae

Introduction

Mycoplasma hyopneumoniae is a very small, gram positive bacterial pathogen. It is round in shape and stores its DNA in a nucleolus and in fibrillar cytoplasmic material.

Culture of M. hyopneumoniae is difficult and time-consuming and requires specialised media. It grows slowly, requires 5-10% carbon dioxide and produces an acid colour shift. Because of the time taken, contamination is very common, especially with other Mycoplasmas.

Pathogenesis

M. hyopneumoniae adheres to the cilia of the respiratory tract, causing ciliostasis, clumping and loss. This is followed by loss of epithelial cells and goblet cells. This reduces the efficacy of mucociliary clearance and allows the colonisation of the secondary pathogens that are usually involved in Enzootic Pneumonia.

M. hyopneumoniae also alters many other aspects of the host’s immune system, including B and T lymphocyte driven immunity, alveolar macrophages and the production of pro-inflammatory cytokines.

Mononuclear infiltration of peribronchiolar and perivascular areas is the basis of pneumonic lesions and often causes the formation of lymphoid nodules when disease is chronic, as it often is.

Pathogenicity and severity of disease are stipulated by the presence and interaction of M. hyopneumoniae with other pathogens.

Diseases

M. hyopneumoniae causes enzootic pneumonia in pigs.

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References

Animal Health & Production Compendium, Mycoplasma hyopneumoniae datasheet, accessed 25/06/2011 @ http://www.cabi.org/ahpc/