VMC 311: Systematic Veterinary Bacteriology and Mycology (2+1)

PATHOGENESIS

• Transmissions are usually veneral, vertical or by aerosols and many important avian mycoplasmas are egg transmitted.
• Various stress factors predispose the mycoplasmal infection. They parasitic mycoplasma tends to adhere firmly to the host’s mucous membranes with specific attachment structures.
  The organisms are extra cellular and produce haemolysins, proteases, nucleases and other toxic factors like capsular carbohydrates, ammonia that can lead to death of host cells or to a chronic infection.
• Some pathogenic species have a predilection for mesenchymal cells lining joints and serous cavities.
• The respiratory tract and lungs are most frequent sites of infection.
• Mycoplasmas are capable of destroying the cilia of cells in the respiratory tract, thus predisposing secondary bacterial invasion.
• The fibrinous exudates frequently present in infections protects them from antibody and antimicrobial drugs.

Host	Species	Disease
Poultry	M.gallisepticum	Chronic Respiratory Disease (CRD) and air sac disease in chicken Infectious sinusitis in chicken
Turkeys	M.synoviae M.meleagridis	Infectious synovitis Airsacculitis and bursitis
Cattle	M.mycoides subsp mycoides (Small colony type) M.bovis M.bovigenitalium	Contagious Bovine Pleuro Pneumonia (CBPP) Mastitis, arthritis, pneumonia, abortion and genital infection Vaginitis, arthritis, seminal vesiculitis and mastitis
Goats	M.mycoides subsp Capri M.mycoides subsp mycoides (Large colony type)	Contagious Caprine Pleuro Pneumonia (CCPP) Pneumonia, septicaemia, polyarthritis and mastits
Sheep	M.agalactiae	Contagious agalactia
Pigs	M.hyorhinis M.hyosynoviae M.hyopneumoniae	Polyserositis and chronic arthritis in young pigs Polyarthritis in adult Enzootic pneumoniae of pigs