EXAM #1: REVIEW Flashcards
What are the three major components of the innate immune system that defend against viral infection??
1) Type I IFN (alpha and beta IFN)
2) NK Cells
3) Macrophages
What is the general mechanism by which NK cells kill virally infected cells?
Perforin and granzyme, which induce apoptosis
What are the two ways that NK cells are induced to kill virally infected cells?
1) PAMPs and/or absence of MHC Class I
2) ADCC
- IgG is bound to virally infected cell
- CD16 of NK cells binds Fc portion of antibody
*Perforin and granzyme are released, triggering apoptosis
What cytokines/ cellular product mediate the anti-viral effects of macrophages?
1) TNFa
2) NO
List five functions of antibodies in an anti-viral response.
1) Prevention of viral binding to target cell
2) Opsonization
3) Complement activation
4) NK cell activation/ ADCC
5) Downregulation of viral gene expression
What innate immunity cells predominate in the response against intracellular bacteria?
1) Marcophages
2) NK cells
Outline how macrophages and NK cells are activated to produced an anti-bacterial (intracellular) response?
1) Macrphages activated to release IL-12
2) IL-12 activates NK cells
3) NK cells release IFN-gamma (Type II IFN)
4) IFN-gamma further activates macrophages
5) Macrophages release NO, which is a potent antibacterial measure
What is the adaptive immune response to intracellular bacteria?
T-cells are activated to produce IFN-gamma, which activates macrophages
List the major complications of acute otitis media.
1) TM rupture
2) Tympanosclerosis
3) Cholesteatoma
4) Mastoiditis
5) Lateral sinus thrombosis
6) Meningitis/ brain abscess
How acute bacterial sinusitis treated?
1) Amoxicillin
2) Nasal decongestants
3) Mucolytics
What are the major complications of acute bacterial sinusitis?
1) Meningitis
2) Cavernous sinus thrombosis
3) Boney invasion of the orbit
What is the hemolysis pattern of S. pyogenes?
Beta
What complement pathway is specifically inhibited by polysaccharide capsules?
Alternative pathway
How does S. pyogenes evade the immune system?
- Produces M protein
- M protein prevents complement activation
How does S. pneumoniae evade the immune system?
C3 protease
What is the major mechanism of immunity against spirochetes?
Adaptive immunity
What is the major role of cell-mediated immunity (Th1) in spirochete infections?
Clearing the infection
*Vs. Th2 that prevents reinfection
What cell type mediates the innate immune response against fungal infections?
Neutrophils
*Partly why neutropenic patients are so susceptible to C. albicans
What is the major adaptive immune mechanism against fungal infections?
Cell mediated immunity (Th1)
What is the major immune mechanism against Plasmodium? What stage of infection is being targeted?
Th1 vs. the intrahepatic stage
List four ways that parasites evade the immune system.
1) Conceal in gut lumen
2) Coat with host proteins
3) Produce enzymes that cleave bound antibodies
4) Inhibition of complement activation*
List the four major organisms that cause infectious diarrhea.
1) E. coli
2) Salmonella
3) Shigella
4) C. diff
How is H. pylori treated?
1) PPI + amoxicillin
2) PPI + clarithromycin + tinidazole
What is quadruple therapy for h. pylori?
1) Bismuth subsalicylate
2) TCN
3) Metronidazole
4) Omeprazole
Why is duration of diarrhea an important historical feature to ask about?
Less than 2 weeks= infectious
More than 2 weeks= not infectious
What are the two major non-inflammatory diarrheas?
1) V. cholerae
2) ETEC
What is the empiric treatment for chlamydia?
1) Ceftriaxone
2) Azithromycin
What are the non-infectious etiologies of a presentation similar to a CNS infection?
1) Neoplasia
2) Collagen vascular disorder
3) Medications
What are the expected CSF findings in bacterial meningitis?
- WBC: 1,000 - 5,000 (highest)
- Protein: 100- 500
- Neutrophils*
- Glucose less than 40
What are the expected CSF findings in tuberculous meningitis?
- WBC: 50-300
- Protein: 50-300
- Mononuclear
- Glucose less than 45
What are the expected CSF findings in viral meningitis?
- WBC: 50 - 1,000
- Protein: less than 200
- Mononuclear
- Glucose greater than 45
What are the expected CSF findings in cryptococcal meningitis?
- WBC: 20 - 500
- Protein: greater than 45
- Mononuclear
- Glucose less than 40
*Also, high opening pressure
If a CSF sample shows neutrophils, what is the etiology?
Bacterial
If a CSF sample has a glucose higher than 45, what is the etiology?
Viral
What are the two most common causes of viral meningitis?
1) Enterovirus
2) Herpes
What three pathogens are associated with subacute/ chronic meningitis?
1) MTB
2) T. pallidum (syphillis)
3) B. burgdorferi (lyme)
In a patient that has undergone neurosurgery, what bacterial pathogens are you concerned about causing meningitis?
1) Coagulase negative staphylococci
2) P. aeruginosa
What drug is used to cover coagulase negative staphylococci?
Vancomycin
What drug is used to cover P. aeruginosa?
4th generation cephalosporin e.g. Ceftazidime
What is the appropriate initial therapy for cryptococcal meningitis?
1) Amphotericin B or fluconazole
2) Measures to reduce ICP
What is a “fever” in a neutropenic patient?
1) Core temp greater than 38.0 or 100.4 F for an hour
2) Oral temp greater than 38.3 C/ 101.0 F
In a child between 3 and 36 months, what what lead you to suspect occult bactermia as a source of fever?
1) WBC count greater than 15K
2) Temp greater than 39 C
When are parenteral antibiotics indicated in a 3-36 month old with a fever without a source?
1) Ill appearing/ toxic appearance
2) Unstable
3) Abnormal lab findings
4) Unimmunized child
If you are going to start parenteral antibiotics indicated in a 3-36 month old with a fever without a source, what antibiotic should you use? What organisms are you targeting?
Ceftriaxone to target:
- S. pneumoniae
- S. aureus
- N. meningitidis
- H. influenza
What are the two most common causes of a “classic” fever of unknown origin in an adult?
Infection vs. malignancy
What criteria define severe sepsis?
1) Hypotension– SBP less than 90 mmHg or MAP less than 70 mmHg
2) Tissue hypoperfusion–elevated lactate
3) Urine Output less than 0.5mL/kg/hr
4) Acute Lung Injury– PaO2/FiO2 less than 250
5) Bilirubin greater than 4.0
6) Creatinine greater than 2.0
7) Platelets less than 100,000
What is the sequelae of pathologic events that occurs in sepsis?
1) Distributive shock
2) Myocardial depression
3) Bone marrow suppression
4) Activation of the clotting cascade
5) Organ dysfunction
