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بسم الله الرحمن الرحيم

بسم الله الرحمن الرحيم. Department of Pathology Faculty of veterinary medicine. Bacterial diseases BY Dr. SHEREIN SAEID. Mechanism of bacteria-induced injury:. Intracellular bacteria Extracellular bacteria. Intracellular bacteria. Damage the host tissues by:

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بسم الله الرحمن الرحيم

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  1. بسم الله الرحمن الرحيم

  2. Department of Pathology Faculty of veterinary medicine

  3. Bacterial diseasesBYDr. SHEREIN SAEID

  4. Mechanism of bacteria-induced injury: • Intracellular bacteria • Extracellular bacteria

  5. Intracellular bacteria • Damage the host tissues by: invasion to host cells and may form toxins.

  6. Extracellular bacteria • Damage the host tissues by : their ability to adhere to the host cells and producetoxins.

  7. Bacterial toxins • Endotoxines • Exotoxines

  8. Endotoxines • (a) Lipopolysaccharide( LPS ) in nature. (b) Structural components of the outer cell wall of gm–ve bacteria. (c)Non specific toxines. • (d) Their biological activity include induction of fever, septic Shock, and acute respiratory distress syndrome.

  9. Exotoxines • Harmful product secreted by bacteria. • Specific for each bacteria. • Includes different Enzymes as;Leucocidins,Hemolysins,Hyalourinidase,Coagulases,andFibrinolycins.

  10. Inflammatory Response To Bacterial agents • SuppurativePolymorphnuclear Inflammation. • Mononuclear inflammation. • Granulomatous inflammation. • Necrotizing inflammation.

  11. SuppurativePolymorphnuclear Inflammation • Neutrophilsattracted to pyogenic bacteria which release chemo attractants that evoke this response.

  12. Mononuclear inflammation • Mononuclear cells is a------ • i) Common features of All chronic inflam. Process. As in Leptospira • ii) In response to intracellular bacteria & spirochetes in acute inflam. Process.

  13. Granulomatous inflammation • Distinctive form of mononuclear inflam. Evoked by slow dividing infectious agents as M. tuberculosis.

  14. Necrotizing inflammation • Rapid and Severe tissue damage in which cell death is the dominant feature evoked by v.strong toxins which secreted from C. perfringens.  

  15. (1)Pasteurellosis

  16. Pasteurellosis Definition: • A group of diseases affecting different species of An. • caused by; P. multocida P. hemolytica.

  17. Pasteurellosis Cattle: • Hemorrhagic septicemia . • Pneumonic pasteurellosis. • Meningitis in calves. • Mastitis in cows.

  18. Pasteurellosis Sheep: • Septicemia. • Enzootic pneumonia. • Mastitis in ewes.

  19. Pasteurellosis • Poultry:Fowl cholera. • Horse:Hemorrhagic septicemia. • Rabbit:Snuffles. • Man and Rodents: Tularemia ( P. tularenses)

  20. Hemorrhagic septicemia • Definition: *Per acute fatal disease of cattle *Caused by P.multocida *Characterized by (i) Fibrinohemorrhagic interstitial Pneumonia. (ii) Hemorrhagic gastroenteritis.

  21. Hemorrhagic septicemia • Pathogenesis • The organism is a normal inhabitant in the nasopharyngeal mucosa. • Impaired local or systemic defense mechanism ( stress,transportation,bad environment,crowding) • Proliferation of the m.oInvasion of the mucosa to bloodSepticemia

  22. Hemorrhagic septicemia • Lesions: 1. Per acute edematous form Characterized by subcutaneous edema of the throat and brisket resulting in asphyxia and death. 2. Petechial hemorrhages all over the serous membranes. 3. Accumulation of bloody stained fluid ( serosanguinous fluid ) in body cavities. 4. Swollen and hemorrhagic L.N. 5. Fibrinohemorrhagic interstitial pneumonia. 6. Acute hemorrhagic gastroenteritis.

  23. Hemorrhagic septicemia

  24. Hemorrhagic septicemia

  25. Pneumonic pasteurellosis(shipping fever)(OAT CELL Pnumonia ) • Definition: *Severe acute disease of cattle *Caused by P. hemolytica. *Characterized by fibrinous or fibrinonecrotic bronchopneumonia (lobar) *Usually following transportation (shipping fever)

  26. Pneumonic pasteurellosis • Pathogenesis: *Impaired defense mechanism (transportation) Proliferate in nasopharynx then Invade the lung *The m.o release endotoxines ( leukotoxin) and (cytotoxins ) Capillary thrombosis, necrosis and fibrinous pneumonia. *Leukotoxin & Cytotoxin affect leucocyte w’ accumulate in the inflamed alveoli transforming them into oat like plant ( oat cells).

  27. Pneumonic pasteurellosis • Lesions (i) MACRO: 1-Reddish black to grayish brown consolidated areas in the cranioventral regionof the lungs. 2-Gelatinous thickening of the interlobular septa. 3-Areas of necrosis with white boundaries &deep central red zone. 4-Marbling appearance of the lung as a result of septal edema and congestion intermixed with different stages of pneumonia(red and grey hepatization), necrotic areas, and normal areas.

  28. Pneumonic pasteurellosis

  29. Pneumonic pasteurellosis

  30. Pneumonic pasteurellosis

  31. Lobar pneumonia(Pasteurellosis)

  32. Lung hepatization(Pasteurellosis)

  33. Pneumonic pasteurellosis • (ii) MICRO: • Severe fibrinous pleuropneumonia with 4 stages • Severe thickening of the interlobular septa with serofibrinous exudates & dilated bl.vs. • Vasculitis&Thrombosis of capillaries& arterioles • Areas of coagulative necrosis with macrophages inside the alveoli (oat shaped cells) ( PATHOGNOMONIC LESIONS ) OAT CELL PNEUMONIA

  34. Lung hepatization (Pasteurellosis)

  35. Lung hepatization (Pasteurellosis)

  36. (OAT CELL Pnumonia )

  37. (2)Mycoplasmosis

  38. Mycoplasmosis • Definition: A group of diseases affecting different species of animals caused by Mycoplasma organism.

  39. Mycoplasmosis • Goats: *Contagious Caprine PleuroPneumonia. ( C.C.P.P ) *Poly arthritis. • Sheep and swine: * Enzootic pneumonia.

  40. Mycoplasmosis • Cattle: • Contagious Bovine PleuroPneumonia ( C.B.P.P ). • Mycoplasmal bronchitis and pneumonia in calves(Cuffing pneumonia) • Poly arthritis in calves. • Abortion in cows.

  41. Contagious Bovine PleuroPneumonia(CBPP) • Definition: *Contagious infectious disease of cattle *Characterized by • (i) Fibrinous pleuropneumoniain acute cases. • (ii) Sequestra formationin subacute and chronic cases.

  42. Contagious bovine pleuropneumonia • Cause: Mycoplasma mycoides bovis ( Small Colony )

  43. Contagious bovine pleuropneumonia R.O.I : Deep Inhalation of infected droplets as upper respiratory tract is quite resistant.

  44. Contagious bovine pleuropneumonia • Pathogenesis : 1- Mycoplasma inhaled deeply into the small bronchioles inflammation of bronchial wall invasion of the interlobular Connective tissue septa inflam.followed by edema then…………… spread to alveoli ………then secrete toxin w’ lead to …….. acute vasculitis, thrombosis & necrosis.

  45. Pathogenesis : 2- Necrosed area become demarcated &surrounded by f.c.t---------Sequestrum 3. Mycoplasma remain viable in sequestra for years and severe coughingrupture of the fibrous capsule of the sequestra liberating organism to lymph space reinfection of the animal occurred or expelled outside and infect or other animals.

  46. Contagious bovine pleuropneumonia • Lesions (i) MACRO: 1. Severe fibrinonecrotic pneumonia (caudal lobes) with fibrinous pleuritis. 2. Gelatinous thickening of the interlobular septa. 3. Dilated lymphatics (beaded appearance). 4. Typical marbling appearance in acute stages. 5. Sequestra formation ( PATHOGNOMONIC LESION ) (necrotic areas surrounded by C.T. capsule).

  47. Contagious bovine pleuropneumonia

  48. Contagious bovine pleuropneumonia

  49. Contagious bovine pleuropneumonia

  50. Contagious bovine pleuropneumonia

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