pathology of infectious diseases II - lecture notes - julia Flashcards
where does salmonella typhi grow?
- normally in bowel flora
- but not normal flora - almost always causes disease
- can then grow inside cells
how is salmonella typhi transmitted?
introduced to GI tract by contaminated water and food
what types of cells does salmonella typhi invade?
monocyte-macrophage type cells
what can salmonella typhi produce?
endotoxin antigens with virulence functions
what is monocuclear inflammation?
one nucleus - macrophages and lymphocytes usually in specialized patches in bowel wall (peyer’s patches)
how does S. typhi invade tissues?
- enters thorugh lymphatics in small intestine
- then can move to liver, kidney
what are the consequences of typhoid fever?
can result in perforation of the bowel and bleeding - patient can die of massive GI hemorrhage
what will typhoid fever look like (gross)?
- rose spots on skin
- nodules on small bowel
- in later disease will have lesions in small bowel
what will typhoid fever look like in the liver (histologically)
- some normal hepatocytes, but aggregation of mononuclear cells, most of which have intercellular bacteria = typhoid nodule
- does not elicit chemokines that bring in neutrophils, so no neutrophils
what will typhiod fever look like in the small bowel (histologically)?
- mucosa almost entirely destroyed
- almost all cells mononuclear
- peyers patch will have necrosis in the center
what will the stool of a patient with typhoid fever look like (histologically)?
sheets of mononuclear cells and RBCs
what is granulomatous inflammation? what will it look like histologically?
- causes granuloma
- mononuclear cells around outside
- cells in middle include giant cells and then a lot of cells that are derived from mononuclear cells
what can cause granulomatous inflammation?
mycobacterium tuberculosis
how does tuberculosis infect cells and grow?
can be taken up by macrophages and multiply within the non-acidificed phagosomes
what immune resoponse does TB cause?
- delayed-type hypersensitivity
- CD4 cells stimulate TNF-alpha and IFN gamma secretion => macrophage activation and epithelioid granuloma formation
- CD8 cells can lyse infected macrophages
what factors induce granulomas?
- glycolipid factors induce them
- lipoarabinomanan (similar to LPS) inhibits macrophage activation
what is the pattern of development of TB?
- granulomatous inflammation
- caseation necrosis
- liquefaction
- => tissue destruction and hemorrhage
how is TB acquired?
almost always inhaled source
what does an early TB lesion look like? (gross, xray)
- caseous necrosis - yellow region lymph nodes can have those
- xray will have white areas - cosolidated regions - but areas where there’s air - indicates that the process has gone from complete consolidation to causing cavity that’s attached to the airway - makes it easy to spread
- tends to grow in upper lobes
what does TB look like histologically?
- epithelioid cells - look like epi cells but aren’t actually - began lives as macrophage/monocyte
- lines lots of pink cytoplasm - lots of squamous epithelium
- langhans giant cells - frequently seen in granulomas
- granulomas coalesse - less and less blood supply - get completely bland and pink region - caseation area of caseous necrosis can be surrounded by fibrous tissue in late development
what is empyema?
pus in any cavitary space
what causes empyema?
mixed aerobic and anaerobic bacteria, frequently associated with aspirated upper respiratory flora (ie so bacteria often come from mouth and respiratory tract)
what does abscess and empyema in the lung look like? (gross)?
shaggy, yellow visceral pleura with adherent chronic inflammatory mix of bacteria
what does abscess and empynema in lung look like (histologically)?
where there used to be a single layer of pleural cells, now have cavity full of inflammatory cells, mostly lymphocytes and plasma cells granulation tissue replacing normal pleural surface edge will have dense chronic inflammation
what causes caseation necrosis to form? what does it look like histologically?
- granulomas coalesce - less and less blood supply - make completely bland, pink area = caseation necrosis
how does empyema form?
- acute suppruative process with tissue destruction => walled-off, fibrous cavity with liquefied central cavity
what cells are involved in formation of abscess and empyema?
macrophages, lymphocytes and plasma cells surround areas of continuing bacterial growth
how would you treat a lung abscess or empyema?
drainage through the bronchus or chest wall
what are the potential complications of a lung abscess or empyema?
scarring and restriction of lung capacity
