Brucella, Listeria, Corynebacterium, Pasteurella Pathology PDF

# Pathology ## Brucella - Gram-negative, facultative, non-spore forming, coccobacilli with intracellular tropism. - Types of Brucella found in different animals: - **B. abortus** - Cattle - **B. melitensis** - Sheep, goat - **B. ovis** - Sheep? - **B. suis** - Pigs - **B. canis...

# Pathology ## Brucella - Gram-negative, facultative, non-spore forming, coccobacilli with intracellular tropism. - Types of Brucella found in different animals: - **B. abortus** - Cattle - **B. melitensis** - Sheep, goat - **B. ovis** - Sheep? - **B. suis** - Pigs - **B. canis** - Dogs - **B. neotomae** - Wood desert rats - Brucella contains plasmids, pili, pimbriae, capsule, exotoxins, and lipopolysaccharides (LPS). - The ability of Brucella to hide inside macrophages makes it difficult to diagnose the disease and also makes treatment of the disease difficult. - When Brucella enters the body, it goes inside the macrophages. - Treatment is difficult because Brucella hides inside macrophages. ## Phases of Brucella Infection - **Acute phase:** Brucella infects epithelial cells of the genital system and lungs in pregnant fetuses. - **Chronic phase:** Brucella localizes in reticuloendothelial cells. - In pregnant animals, Brucella localizes in the genital system and can infect the fetus. This can result in abortion or sterility. - Brucella can also infect the male genital system. ## Pathogenesis of Brucella - Transmission is through ingestion, inhalation, and reaching the oral and pharyngeal cavities. - Ingestion is the most dominant route. - Brucella can penetrate intact skin, conjunctiva, and through wounds. - Important routes of contamination include: - Contamination of the udder or through wounds during animal handling - Mucosal membrane contamination in those working in laboratories. - Rectal palpation of pregnant animals. ## Gross Examination: - **Male:** Enlarged, inflamed testes. Pyogranulomatous exudate obstructs the epididymis (epididymitis). - Unilateral or bilateral. In the case of infertility, the exudate will be sterile. - **Female:** - **Placenta:** Cotyledons are hemorrhagic, swollen, and the placenta is filled with yellowish exudate. - Brucella attacks the cotyledons and causes hemorrhaging, which can lead to abortion. The yellowish exudate is present in the placenta. - **Aborted fetus:** Hepatomegaly and fibrinous polyserositis. ## Microscopic Examination of Brucellosis: 1. **Uterus:** Trophoblastic cells, which are the primary target cell in the placenta, are swollen and filled with coccobacilli. There is neutrophilic, necrotic, and histolytic inflammation associated with necrosis, edema, fibrin deposition, and vasculitis. - **Inflamatory changes:** Sever infiltration of neutrophils, lymphocytes, plasma cells, and few eosinophils. 2. **Mammary Gland:** Multi-focal interstitial mastitis and accumulation of macrophages between acini. - Inflammation of the internal organs and hepatomegaly. 3. **Aborted fetus:** Pleuro-pneumonia, fibrinous inflammation of internal organs, and hepatomegaly. 4. **Lymph nodes:** Hyperplasia, granulomatous lymphadenitis, and neutrophils. ## Pasterella - Normal inhabitants of the mucous membrane of the nasopharynx and oral cavity. - Under stress factors, Pasterella can become pathogenic. - Pathogenic factors include: - Climate change - Transportation ## Pathogenesis: - Infection: Ingestion or inhalation. Commensal bacteria change to pathogenic under stress. - Colonization: Bacteria colonize and proliferate. - Toxins: Two toxins - endotoxin and leucotoxin. - Damage: Cause damage to alveolar macrophages, neutrophils, and platelet aggregation. - Procoagulant activity: ↑ procoagulant activity, resulting in changes in coagulation. - Fibrinolytic activity: ↓ fibrinolytic activity, leading to fibrinous inflammation and deposition of fibrin in the lungs. ## Clinical Signs: - **Pulmonary signs:** Pasterullosis - Fever - Nasal discharge - Respiratory signs - Motor disturbance - Edema in the throat, brisket, asphyxia, and then death - Dyspnea - Ghar-ghar sound on respiration, only in camels. ## Gross Examination of Pasterullosis: 1. **Edema** in the neck and brisket. 2. **Lungs:** Marbled and consolidated with fibrinous pleuritis. - Consolidation is due to the deposition of fibrin. 3. **Generalized petechias** on serosal surfaces in the intestines, heart, lungs, and skeletal muscles. 4. **Superficially swollen lymph nodes.** ## Microscopic Examination: - Fibrinous bronchopneumonia with fibrin deposits and infiltration of neutrophils, macrophages, and lymphocytes in the lung alveoli. - There are toxins and bacteria, resulting in hemorrhagic septicemia. ## Leptospirosis - Leptospira is related to kidney and urine in humans and animals. - Characterized by renal and hepatic failure, eye affection, and abortion and mastitis. - Bacteria in the urinary system can cause infection. - Transmission is via: - Direct: Contaminated urine - Indirect: Contact with contaminated feed - Vascular Leptospirosis: Infection of the liver and eye. Blood can be disseminated through the body. - Direct contamination of urine can lead to intact abortion. ## Clinical Signs: 1. **Urinary:** Hemoglobinurea (bloody urine). 2. **Liver: Anemia** 3. **Tectus:** Yellowish color of feces and urine due to the destruction of red blood cells. 4. **Reproductive:** abortion in the 7th-11th months of pregnancy. 5. **Mastitis** 6. **Eye:** Eye affection (moon blindness), mainly in equines. - **Moon blindness:** Periodic opthalmia, or equine recurrent uveitis. This causes temporary blindness in equines. - **Uveitis:** Inflammation of the uvea, which is the middle layer of the eye (iris, choroid, and ciliary body). The eye is infiltrated by macrophages, plasma cells, and lymphocytes. ## Gross Examination of Leptospirosis: - **Kidneys:** Hemorrhage and radiating pale streaks. Yellow fat (arrow) and medulla (star) are yellow due to jaundice. - **Aborted fetus:** Nephritis. - **Horses:** Blindness. - **Dogs:** Spleen calcification. ## Microscopic Examination of Leptospirosis: 1. **Leptospira:** Has tropism for epithelial cells of the proximal convoluted tubules (cortex) and epithelial cells of the loops of Henle (medulla), resulting in nephritis. 2. **Interstitial nephritis:** Ribrin is deposited around renal tubules, resulting in the tubules shrinking in size and being infiltrated by inflammatory cells and fibrin; the tubules eventually disappear. ## Glanders - Caused by *Pseudomonas mallei*. - Affects the lower respiratory system. - Causes pneumonia. ## Transmission: - Direct or indirect contact, or through injury or abrasion. - Animals shed bacteria by breathing, eating food, and drinking water. ## Pathogenesis: - Ingestion or entry through an injury or the respiratory tract. - Bacteria multiply, spread throughout the body, and disseminate to the lymph nodes. - Formation of abscesses and swelling in the pharyngeal, lymph nodes, spleen, and liver. - Bacteria enter the blood and disseminate to the trachea, submaxillary lymph nodes, mesenteric lymph nodes, and internal organs. Abscess formation, suppurative inflammation, and abscess. ## Clinical Signs: 1. **Respiratory mucosa and lungs affected:** - Discharge and purulent inflammation. - Catarrhal 2. **Ulceration in the** **nasal** **mucosa.** 3. **Paray and abscess** in the superficial lymph nodes. ## Forms of Glanders: Nasal, Pulmonary, and Cutaneous Forms 1. **Nasal form: ** - Nasal discharge from nostrils, which becomes grayish or yellowish. - **Nodules:** Liquifactive necrosis, dehydrated to form caseous necrosis, surrounded by infiltration with eosinophils. - **Ulceration:** Ulcers become star-shaped, leading to perforation of the septum. The perforations cause the formation of abscesses and *suppurative inflammation* in the lungs, resulting in the formation of caseous granulomas. 2. **Pulmonary form:** - **Caseous pneumonia:** Caseous pneumonia can cause pyogranuloma due to the chemotaxis of neutrophils, which cause necrosis, and the phagocytic action of macrophages, which are unable to break down the debris. Epithelial cells then combine to form multi-nucleated giant cells, causing pyogranuloma through necrosis, necrosis, and active, pyo-granulomatous inflammation. 3. **Cutaneous form:** Usually chronic. - Infection can spread to all body parts. - The infection begins in the subcutaneous layer of the skin, causing lymphangitis and swollen lymph nodes in the limbs. - Crater-like rodent ulcers occur on the ventral abdomen. ## Salmonella - **Gram-negative** bacteria - Belong to the family *Enterobacteriaceae*. - Usually found in the intestinal tract. - Can infect all animals, especially small animals. - Causes severe diarrhea and death in cats. - Transmission: Ingestion of contaminated food and water. The transmission route is oral and fecal. ## Pathogenesis: - **Salmonella Typhimurium** can infect several species. - Contamination of the feed and oral cavity can occur during handling. - Salmonella reaches the intestinal tract and then the blood, causing illness. - Bacteria then spread to the brain, joints, lungs, kidneys, and liver, causing infection. ## Clinical Signs: 1. **Pre-acute form:** - Newborn calves or foods. - Depression, dullness, and death within 1-2 days. - Nervous signs. 2. **Acute form:** - In adult cattle, fever and abortion in the 6th-9th months. - Polyarthritis. - Sever diarrhea. - Dehydration, mucous, and diarrhea are all causes of death in the intestinal tract. 3. **Chronic form:** - In adult Cattle, intermittent fever, persistent diarrhea, severe emaciation, fibrinous enteritis with hemorrhage, liver necrosis, enlarged gall bladder in pigs, button ulcer, meningitis, arthritis, fibrinous polyserositis, enlarged lymph nodes, olygosis, and petechiation of skin. ## Staphylococcal Infection - Normal inhabitants of the skin, nasal cavities, and lower gut in animals. S. aureus causes purulent lesions in the skin, which form abscesses and mastitis. **Botulism** can result from inflammation of the spermatic cord. - Transmission: Direct or indirect contact with wounds. ## Pathogenesis: - Destruction of cells, neutrophils (which attack the microbes), and suppuration (the formation of pus) during infection. ## Clinical Signs: - Abscesses, which are common in the case of surface wounds or nails, are well-known. ## Corynebacterium Infection - **Chinese letter arrangement** of cells. - Organisms: - *Coryne pyogens* - *Coryne ovis* - **Pseudotuberculosis:** - Disease: Suppurative lesions or caseous lymphadenitis in ovine. Ulcerative lymphadenitis in swine. - Multiple abscesses are common in sheep. Abscesses often break open spontaneously, releasing cheesy material and creating a suppurative lesion. ## Listeriosis - Caused by *Listeria monocytogenes*. - More zoonotic. - Ruminants are infected when they eat stored silage or feed that is not acidic, which does not prevent the overgrowth of bacteria. ## Pathogenesis: - Infection begins in the intestines and then moves to the lymph nodes; from there, it spreads to the blood and then to the liver and spleen. - If the patient is immunocompetent, the bacteria probably won’t reach the brain or fetus; if they are immunocompromised, those are the most common areas the bacteria will reach. - Bacteria can survive in phagocytic cells (engulfed by the phagocyte's cells, which are a part of the immune response), which enables them to spread more easily. ## Forms of Listeria: 1. **Nervous form:** Circling disease. - The *trigeminal nerve* is affected by *Listeria*, and causes *abscesses* in the *brain stem*, *pons*, and *medulla oblongata*, making the animal *circle* and causing the disease *circling disease*. 2. **Septicemic form:** Generalized form. - Causes necrotic foci in the liver. 3. **Abortion form:** Occurs in the last quarter of pregnancy. - The pathogenic lesion is *focal hepatic necrosis* of the *aborted fetus*. ## Clinical Signs in the 3 Forms: - **Fever** - **Animal walks in circles** - **Abortion, movement** - **Torticollis** ## _This is a translation of a document written in Arabic, so there may be inaccuracies. It's important to double-check the information against other reputable sources._