Infectious Disease I

Question 1

Name seven histological response patterns to infection.

Answer 1

• Acute suppurative
• Mononuclear
• Granulomatous
• Chronic inflammation & scaring
• Cytopathis/cytoproliferative
• Necrotizing

Question 2

Describe the normal, physiological barriers to infection.

Answer 2

• Skin – Squamous epithelium
• RT – Ciliated columnar
• GI – Ciliated columnar with mucus
• GU – Squamous, columnar, uroepeithelium

Question 3

Acute Supportive Infection Pneumonia

Answer 3

• Streptococcus pnummonia
• Lobar on X-ray
• Pathological stages
  o Edema
  • Serous exudate (fibrin)
  o Acute inflammation
  • PMN
  • Platelets
  • Complement
  • Coagulation cascade
  • Consolidation (gross appearance)
  • Red & grey hepatatization
  • Loose spongy consistency
  o Resolution
  • Macrophage cleanup inflammatory infiltrated
  • Architecture restoration

Question 4

Acute Supportive Infection Endocarditis

Answer 4

• S. aureus
  o Gram T+
  o Pyogenic
  o Pathogenicty island = virulence factors
• Pathological stages
  o Bacteria on fibrin on valve surface
  o Inflamatory lesions destroy valve ring (PMN)
  o Hemodyamic decompensation
  o Systemic infections if vegetations break off
  o Rapid death

Question 5

Mononuclear Infectious Agents

Answer 5

-	Typhoid fever
   o	Fecal contamination of food & water
        •	Small bowel infection
        •	Lives in macrophages = payer’s patches, spleen & liver
            •	Abdominal pain, headache, constipation
            •	Bacteremia
  o	Osteomyalysis
            •	Ulceration
            •	Bleeding
            •	Perforation
            •	Rose spots on abdomen
      •	Weeks 1-2: Detect in Blood
      •	Weeks 3-4: Detect in urine & stool
-	Salmonella Typhi
   o	Gram + 
   o	Human host
   o	Intracellular
   o	Rod with flagella

Question 6

Granulomatous Infection Tuberculosis

Answer 6

o	Granuloma formation
   •	X-ray
       •	Diffuse in upper quadrants
       •	Miliary ganulomas
   •	IFN-γ 
       •	macrophage activation
       •	Epithelioid granuloma formation
       •	CD8 T-cells can lyse infected macrophages
       •	Caseous necrosis
       •	Liquifaction
       •	Hemorrhage
   •	Lipoarabinomanan
       •	Inhibits macrophage activation
   •	Chronic State
       •	Cavity lung disease
       •	Intestianal disease
-	M. tubercoulosis
      o	Acid fast
-	Intracellualar in macrophage phagosomes

Question 7

Granulomatous Infection Schistomosiasis

Answer 7

-	Schistosoma sp. 
   o	Fresh water blood flukes
   o	Invasive larva penetrate skin
   o	Adults develop in mesenteric vein
   o	Adopt host antigens
      •	Limited immune response
   o	Deposit eggs
   o	Eggs elicit immune response
      •	Acute
        •	IFN-γ and TNF
        •	Eosinophils
      •	Chronic
        •	TH2 response
        •	IL4, 5 & 13
           o	Favor fibrosisi
        •	Eosinophilic infiltrate
        •	Denseense fibrosis
        •	Granuloma formation 
           o	more severe than TB
           o	Collagen and Eosinophils diff. from TB
       •	Lecision in bowel
       •	Hepatic lecsions
           o	Still function
       •	Can shed eggs from bowel
   o	Pipestem fibrosis
      •	Portal triad within obliteration of the vein lumen
        •	Ascites & varicose veins
        •	Hepatocytes are not killed so still function!
        •	No dramatic change in LFS
    •	vein hypertension
    •	Fibrosis
    •	Toortity
    •	Ascites
  o	Bladder
     •	Hematuria
Squamous cell carcinoma of bladder

Question 8

Chronic Inflammation & Scarring

Answer 8

• Epeyema
  o Aerobic & anaerobic bacteria from upper respiratory flora
  o Pus in existing cavity i.e. pleural cavity
  o Walled off fibrous cavity with liquefied central cavity
  o Macrophages, lymphocytes & plasma cells surround areas of continuing bacterial growth
  o Treat by drainig through bronchus or chese
  o Scaring and restriction of lung capacity
• On histology see dense chronic inflamtion (lots of blue dots) next to new vessels & fibrous tissue
• Gross appearance
  o Normal pleura = shinny
  o Abnormal = Shaggy and yellow (pus)

Question 9

Cytopathic and/or Cytoproliferative Influenza

Answer 9

• Influenza A
• RNA A
• Genetic recombination
• H Antingen
  o Hemagglutination fusion with host cell
• N Antigen
  o Allows virus to uncoat
• Infect ciliated epithelium

Pulmonary Pathology
-	Primary viral pneumonia
    o	Edema
    o	Necrosis of ciliated epithelium
    o	Lymphocytic infiltrates in submucosa
-	Secondary bacterial pneumonia
    o	Acute suppurative inflammation
    o	S. aureus
-	X-ray
    o	Fluffy interstitial infiltrates
    o	Both lungs
-	Histology
    o	Lymphocyte infiltration in bronchial submucosa
    o	Lose superficial epithelium
    o	Fibrin
    o	Changes in areolar membrane
        •	Hyline membrane (look glassy)
        •	Stains VERY Pink
        •	Non-specific effect on airspace
-	Avian Flu & 1918 virus
       o	Hgh cytokine levels
       o	Cellular encroachment on the airspace
       o	Systemic damage
             •	Lesions in airways, lyphocytic nodules & interstitial pneumonias

Question 10

Cytopathic and/or Cytoproliferative CMV

Answer 10

CMV

• DNA herpes virus
• Opportunistic infection

Pneumonia
-	Focal necrosis
-	Little local inflammation
-	
Other organs
-	Ulceration of intestine
-	Focal necrosis
-	Retinitis (fluffy white areas)
-	Kidney

Cytopathic Effect

• Large intranuclear inclusions
• Enlarged cells
• OWL EYE NUCLEUS

Detection

• Measure viral load to determin latent or disease state infection
• Fluorescent antibody
• PMN nuclei are highlighted
• Molecular assyas surpass antigen
• PCR

Question 11

Cytopathic and/or Cytoproliferative Measles\Rubeola

Answer 11

Morbillivirus

• RNA virus
• 1 strain
• H antigen binds CD46 (complement regulation)
• Multiply within epithelial & mononuclear cells
• T-cell response necessary
• Ab for prevetion does not stop disease process

Pnumonia
-	Peribronchiolar
-	Interstitial lymphocytic & mononuclear infiltrate
-	Lymphoid hyperplasia
-	Multinucleate syncytial cells
o	Warthin-Finkeldey giant cells

Other Organs
- Koplik spots

Cytopathic Effect
- Multinucleate giant cells

Question 12

Necrotizing Infection Amebic Colitis

Answer 12

Entamoeba histolytica
-	Protozoan
-	Infectious cysts (fecal-oral transmission)
-	Invasive & motile trophozite
o	Kill PMNs
o	Also kills bacteria = steril abscess
o	Liquified tissue

Amebic Colitis Disease
o	Flask-shaped ulcers
•	See normal gastric epithelial on either side of ulcer
o	Liver abscess
o	Liquefied necrotic tissue
o	Histology
•	Lack of PMNS
•	Large pink ameba at edges of the ulcer
•	Look like macrophages

Question 13

Necrotizing Infection Pseudomembranous colitis

Answer 13

Clostridium difficile

• Gram +
• Rods
• Spore forming
• Aneorobic
• Spores stable in environment (soil)
• Fecal oral transmission

Pseudomembranous Disease
   -	Large bowel 
   -	After antibiotic use
   -	Cytotoxins A & B
        o	Cause epithelial cells to contract & become rounded
   -	Dirrhea
   -	Pseudomembrane formation
        o	Fibrin
        o	Infllammatory cells
        o	Bacteria
        o	Dead cells
-	Histology
        o	Pseudomembrane
        o	Mushroom looking above normal epithelium
      o	Volcano irrupting from normal intestinal linning

Question 14

Little Inflammation Cryptococcal meningitis

Answer 14

Cryptococcus neoformans
-	Encapsulated yeast
   o	Virulence 
   o	Little acute inflatory response
   o	Loose granulomas
-	Nitrogen rich soil
-	Respiratory infection

Cryptococcal meningitis

• Insidous onset
• Chronic meningititis
• Hydrocephalus
• Phagocytosis by lung macrophages
• Dissemeniated disease
  o Raised umbilicated lesions

-	Gross appearance
    o	Gelatinous appearance on meninges
-	Stains
    o	Mucicarmine stain shows capsuals
    o	Melanin stain
    o	India ink

-	Diagnosis
    o	India ink
    o	Antigen detection
    o	Culture
        •	Brown color from melanin like product