Granulomatous Diseases Flashcards
(31 cards)
What is granulomatous disease?
Type of chronic inflammation
Secondary response to endogenous or exogenous antigen
What cells are predominant in granulomatous disease?
○ Macrophages
○ Epithelioid macrophages (activated)
○ Multi-nucleated giant cells
If neutrophils = pyogranuloma
What causes granulomatous disease?
Microbial agents
Autoimmune diseases
Foreign bodies
Idiopathic conditions
Bacteria that cause granulomatous disease
○ Rhodococcus equi
○ Mycobacterium spp. - Johne’s and bTB
○ Actinobacillus spp. - Wooden tongue
○ Burkholderia mallei - Glanders
○ Brucella spp.
Superficial mycoses which cause granulomatous disease
Candida albicans
Aspergillus fumigatus
Systemic mycoses which cause granulomatous disease
Histoplasma capsulatum
Blastomyces dermatitidis
Coccidioides immitis
Cryptococcus neoformans
Rhodococcus equi
Intracellular gram +ve bacterium
1. Produces molecules which suppress acidification of phagosome-lysosome
2. Proliferates within macrophage leading to lysis
3. Strong cell mediated inflammation response
4. cytokines activate macrophages and neutrophils leading to pyogranuloma
Virulent forms produce a plasmid encoding for vapA
vapA
virulence associate protein A
* Allows bacteria to survive within macrophages
How does Rhodococcus equi affect foals
Infects via inhalation
* Leads to pyogranulomatous bronchopneumonia
* Can also cause ulcerative enterocolitis inside Peyer’s patches
Johne’s Disease
Mycobacterium avium paratuberculosis (MAP)
* Acid fast gram +ve nonmotile intracellular bacillus
* Causes chronic enteritis in cattle (ileum and LI)
○ Leads to diarrhoea
○ Progressive emaciation
○ Death
* Needs high concentration of iron
○ Highest in ileocecal region
How do cows get infected with MAP?
Ingested with contaminated faeces, milk, colosseum, water
How do cows get infected with MAP?
Ingested with contaminated faeces, milk, colosseum, water
Mechanism of Johne’s Disease
Once bacteria reaches epithelium over Peyer’s patches
○ Reach macrophages within Peyer’s patches
○ Mycobacterium inhibits phagosome-lysosome
○ Prolonged incubation
○ Persistent proliferation of macrophages
○ Thickening of intestinal lamina propria - filled with macrophages
○ Granulomatous enteritis
bTB
Bovine Tuberculosis
Mycobacterium bovis
* Intracellular aerobic gram +ve non-motile coccobacilli
* Acid fast (mycolic acids and high lipid content in cell wall)
Mechanism of bTB
○ Mycobacteria survive in macrophages
○ T-cell immune mediate response produces INFgamma
Recruits more macrophages
Virulence factors of bTB
○ Cord factor
Inhibits chemotaxis
○ Lipoarabinomannan (LAM)
Induces activation of macrophages to secrete more TNFalpha
○ ESAT-6
Lysis of phagosomes
Helps expansion of granuloma
Wooden tongue
Actinobacillus lignieresii
* Aerobic. non-motile gram -ve coccobacilli
Commonly affects soft tissue of head and neck
Oral cavity commensal
Mechanism of Wooden Tongue
○ Mucosal trauma leads to local invasion
○ Causes local infection
○ Spread via lymphatics
○ Leads to pyogranulomatous lymphadenitis
Glanders
Burkholderia mallei
* Non-motile gram-ve bacillus
Highly contagious
Zoonotic disease
Notifiable disease
Infection caused by ingestion/inhalation of infected excretion
Pathogenesis not fully understood
* Bacteria can cross intestinal mucosa and cause septicaemia
Virulence factors of glanders
○ Glycocalyx biofilm
○ Adhesins
○ BpaB protein - involved in adhesion to target cells
Brucellosis
Brucella suis - pigs
Brucella canis - dogs
Brucella ovis - sheep
Brucella melitensis - sheep and goats
All are zoonotic except B. ovis
Transmission by contact with infected tissues, secretions or excretions
○ Milk
○ Urine
○ Fetal tissues
○ Placenta
Brucella canis - dogs
Epididymitis
Placentitis
Discospondylitis
Brucella ovis - sheep
Epididymitis
Placental lesions
Brucella melitensis - sheep and goats
Inflammation in mammary glands and pregnant uterus
