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101 Cards in this Set

  • Front
  • Back
Rhinovirus is a _____.

A. picornavirus
B. coronavirus
C. adenovirus
D. orthomyxovirus
E. paramyxovirus
A.
The capsid adhesin on Rhinovirus bind to what molecule(s) on nasopharynx epithelial cells?
ICAM1 and LDL-1
What is a special surface structure on Rhinovirus that aids in binding and viral release?
structual cleft or "canyon"
What's the genomic content of Rhinovirus?

What is it code for?
single strand (+) RNA.
RNA polymerase, protease, and 4 capsid proteins.
Is Rhinovirus enveloped?
No.
What temperature is Rhinovirus best grown under?
33 degree C (as in nasal mucosa).
Viral shedding peaks around days____.
A. 0-2
B. 2-4
C. 5-7
B.
What type(s) of body's defense against Rhinoviral replication?
This viral replicaiton occurs in cytoplasm. So endogenous IFN(αβγ), IL12 and mobilization of cytotoxic cells.

Humoral response also plays a role: IgA at mucosal surface.
Symptoms of common cold caused by Rhinovirus infection result from_____?(3)
1. edema,seromucinous exudation(protein eg. fibrinogen)
2. chemical mediators (bradykinin, histamine, prostaglandins, interleukins)
3. mininal epithelium destruction by virus
What are some key symptons of commom cold?
1. nasal discharge/obstruction
2. sneezing
3. sore/scrachy throat
4. cough (due to irritation of nasal discharge)
5. fever more common in infants
6. yellow/greenish exudate: organism in paranasal sinus
How long do the symptoms usually last?

When do the symptoms peak?
1-2 weeks.
Day 2-3.
What are some complications with common cold?
1. colonization by new flora due to damaged epithelium
2. sinusitis, otitis: due to inability to remove bacteria
3. asthma:inadequate INF-β response and preferential Th2 response with IgE production.
4. COPD
How is common cold diagnosed?
1. clinical presentation
2. culture
What kind of treatment do you give to patients with common cold?
symptomatic treatment:
1. antihistamine
2. anti-inflammatory drugs
3. warm saline gargles or anesthetic lozenges for sore throat.
What is warm saline used to treat?
sore throat
What is anesthetic lozenges used to treat?
sore throat
Are vaccines available for common cold?
No.(except influenza)
What are the two most important organisms that cause Pharyngitis?
1. rhinovirus
2. streptococcus pyogenes (Group A streptococci)
What is herpangina?
And it is caused by what organism?
Painful mouth infection caused by coxsackieviruses.
What are some observations of herpengina?
1. vesicular eruption of soft palate(usually tonsils and uvula)
2. fever
3. sore throat, pain on swallowing
Herpangina is most common in people of what age group?
Children: 3-10 yrs.
Describe the development steps of vesicular eruption.
punctate macule
erythematous papules
vesicular lesion
Streptococcus pyogenes is ____.
A. α hemolytic
B. β hemolytic
C. γ hemolytic
B
What is Streptococcus pyogenes' serological type?
A. A
B. B
C. C
D. D
E. G
A.
What is Streptococcus agalactiae's serological type?
A. A
B. B
C. C
D. D
E. G
B.
β hemolytic organisms include___.
A. type A and C
B. type A and B
C. type C and G
D. both choice B and C
D.
Give two examples of β hemolytic organisms.
1. streptococcus pyogenes
2. streptococcus agalactiae
What distinguishes β hemolytic organisms from α hemolytic organisms on a plate?
β hemolytic organisms: complete lysis.
α hemolytic organisms:partial lysis, appear green
What serologic group is γ hemolytic?
Type D.
Give some examples of type D streptococci.
streptococcus bovis
streptococcus faecalis
streptococcus faecium
Is streptococcus pyogenes GP or GN?
GP
Which organism is an invasive extracellular pathogen that causes strep throat?
streptococcus pyogenes
Which group of coxsackievirus is most common?
type A
What strategy does streptococcus pyogenes use to fight our immune system?
avoid phagocytosis:
1. capsule made of hyluronic acid: block neutrophils
2. M and F protein: avoid complement activation, activate phagocytosis by epithelial cells
What does the capsule of streptococcus pyogenes contain and what is its function?
hyluronic acid: block neutrophils.
What does the cell wall of streptococcus pyogenes contain?
group specific carbohydrate: can be used for serological typing and distinguish from other species.
What are some actions of M protein in streptococcus pyogenes?
1. bind to factor H to degrade C3b
2. binds fibrinogen: interfere with complement activation
3. stimulate uptake into epithelial cells
How does infection with streptococcus pyogenes cause rheumatic fever?
Body's defense to make antibodies against M protein. Sometimes the antibodies made cross react with cardiac myosin and actin, thus cause the disease.
What types of tissue does streptococcus pyogenes ahdere to?
many types (so it can infect many types of tissue).
What extracellular products do streptococcus pyogenes make?
1. hemolysins: SLO and SLS.
2. enzymes: hyaluronidase, streptokinase, DNAses, C5 peptidases.
3. pyrogenic exotoxin(SPE): type A,B,C,E,F.
What is the purpose of hemolysins?
1. lyse RBC : provide iron for bacterial growth
2. lyse phagocytes: protect bacteria from phagocytosis
What are the two hemolysins in streptococcus pyogenes?

Which one is immunogenic?
SLO and SLS
SLO
Since SLO is immunogenic, why do antibodies fail to form during skin infections?
SLO is inacivated by cholesterol and skin sterols.
Which liquidation enzyme produced by streptococcus pyogenes are used in stroke patients to dissolve the clot?
streptokinase
What liquidation enzymes fo streptococcus pyogenes produce?
1. hyaluronidase
2. streptokinase
3. DNAses
4. C5 peptidase
Which type of pyrogenic exotoxin(SPE) is used by streptococcus pyogenes to invade tissues?
Type B: potent protease
What are some actions of pyrogenic exotoxin(SPE)from streptococcus pyogenes?
1. superantigens: stimulate T cell response, massive cytokine release which lead to hypotension and shock
2. act on endothelial cells to cause capillary leakage.
Will antibody to extrecellular toxins from streptococcus pyogenes help protect the effect of these toxins?
Yes.
What are some effects of extrecellular toxins from streptococcus pyogenes?
1. pharyngitis
2. systemic shock, organ failure
What are some features of streptococcus pyogenes in convalescent carriers?
1. decrease in number
2. lack M protein
3. less infectious
How does streptococcus pyogenes spread?
1. direct person to person
2. food, water borne
What diseases do localized streptococcus pyogenes infection cause?
1. pharyngitis
2. scarlet fever
3. pyoderma(impertigo)
What is the usual duration of infectivity of streptococcus pyogenes?
2-3 weeks
Streptococcus pyogenes infection may be repetitive even with appropriate antibiotics. Why?
1. new strain (new M protein).
2. lack of development of protective anibody.
3. production by β-lactamase by other respiratory flora.
4. "resting" phase-less penicillin susceptible.
5. able to internalize into epithelial cells
What's the difference of pharyngitis in its symptomatic manifestations between small and older children?
In small children: little fever or excudate, complications such as spread to ears and sinuses.

Older children:
edema and redness of mucous membranes
purulent exudate
enlarged cervical nodes
high fever
What are is the symptomology of scarlet fever?
1. rash with deeper red areas
2. sandpaper like skin, peels after recovery
3. strawberry tongue
When does scarlet fever appear after infection with streptococcus pyogenes?
day 2
What is pyoderma/impertigo?
superficial skin infection
multiple vesicular lesions on an erythematous base that eventually crust over.
Which of the following age group is most susceptible to pyoderma?
A. 0-2 year old
B. 2-5 year old
C. 5-7 year old
D. 5-15 year old
B.
T/F: Strep A strains that cause pharyngitis usually have the same M types as ones that could cause impertigo.
F.
Which of the following age group is most susceptible to pharyngitis?
A. 0-2 year old
B. 2-5 year old
C. 5-7 year old
D. 5-15 year old
D.
What are some disease manifestations of invasive infections caused by group A streptococci?
1. bacteremia
2. focal infection: menigitis,pericarditis, pneumonia)
3. severe skin or soft tissue infections: erysipelas, cellulitis, necrotizing fasciitis or myositis.
Which age group is the most susceptible host to invasive group A streptococci?
ages 15-45: underlying disease may exist (ischemia, immunocompressed, IV drug use, neonate)
What is Erysipelas?
What can cause this?
Spreading of inflammation of dermis layer with involvemnet of cutaneous lymphatic vessels. Often seen on face, lower limbs.

Caused by invasive group A streptococci.
Cellulitis involves inflammation of which layer of skin?
A. dermis
B. deep dermis and subcutaneous tissue
C. deep subcutaneous
B.
What patients are at risk of developing cellulitis?
1. IV drug abuse
2. patients with impaired lymphatic drainage
Necrotizing fasciitis/myositis involves inflammation of which layer of skin?
A. dermis
B. deep dermis and subcutaneous tissue
C. deep subcutaneous
C.
It can get into blood and cause toxic shock.
Erysipelas, cellulitis, and necrotizing fasciitis/myositis can be cause by which organism?
Group A streptococci
Clostridium perfringens
What are some manifestations of toxic shock?
1. hypotension
2. renal failure
3. ARD (Adult Respiratory Distress syndrom)
4. DIC (disseminated intravescular coagulation)
5. liver failure
6. skin rash
Toxins from which type of organsim are common causes of toxic shock?
Group A streptococci
What is ARD?
Adult Respiratory distress syndrome: oftern cause by toxic shock.
What is DIC?
Disseminated Intravscular Coagulation: oftern cause by toxic shock.
What are some clinical manifestations of ARF(Acute Rheumatic Fever)?
pharyngitis:
carditis: usually limited
polyarthritis
chorea
subcutaneous nodules.
What is the cause of ARF?
Antibody made is cross-reactive with cardiac muscles.
What cells/tissue could be damaged during ARF?
Sarcolemma in cardiac myofibers
skeletal muscle
smooth muscle of endothelium
heart valve
neurons and subthalmic nuclei
ARF:
1. number of M-types involved
2. recurrence common?
3. preventible with antecedent strep infection?
4. follows respiratory infection?
5. follows skin infection?
1. lots
2. yes
3. yes
4. yes
5. no
PSGN:
1. number of M-types involved
2. recurrence common?
3. preventible with antecedent strep infection?
4. follows respiratory infection?
5. follows skin infection?
1. few
2. no
3. no
4. yes
5. yes
How do you diagnose ARF?
1. clinical and laboratory findings
2. culture and serology
What are some clinical manifestation of PSGN(acute post-strepcoccal glomerulonephritis?
1. proteinuria
2. hematuria
3. edema
4. high BP
5. low serum complement levels
When after throat infection does PSGN usually develop?after skin infection?
1. 10 days
2. 21 days
What is the pathogenic mechanism of PSGN?
immuno-complex onto glomeruli
What is the diagnosis of PSGN?
culture
detection of antistreptococcal antibodies (not useful for skin infections)
What is the DOC for group A streptococci? How long should it be adminstered?
oral penicillin for 10 days
Which drug should be used to treat group A streptococci infection if a patient is allergic to penicillin?
Erythromycin(macrolide)
Whis drug should be used in combination with penicillin if group A streptococci infection is very severe?
Clindamycin: shut down toxin synthesis
When should cephalosporin be used to treat group A streptococci?
anaphlylaxis type allergy
Is there vaccine available for group A streptococci?
No.
When are pyrogenic exotoxin(SPE) type A and C from streptococcus pyogenes produced?
After lysogenic convergion of streptococcus
Why does common cold cause excabertions in asthma?
1. host inadequate IFN-β respnse to suppress viral repication.
2. host exhibit Th2 response to make IgE instead og Th1 response.
What is the etiologic agent in diptheria?
Corynebacterium diptheriae
Corynebacterium diptheriae:
1. Gram stain
2. shape
1. GP
2. rod: club shape, chinese character
Where do Corynebacterium sp (other than Corynebacterium diptheriae) usually colonize?
skin
mucosal surfaces
How does diptheriae spread?
airborne
skin contact
Diptheria A/B toxin:
1. What is A's function?
2. What is B's function?
1. irreversibly catalyze ADP-ribosylation of elongation factor-2
2. bind to HB-EGF on host cells
How long is the incubation time for diptheriae?
2-6 days (intermediate length)
What tissues are most susceptible to diptheriae toxin?
cardiac
nerve
renal
What is key to diptheriae diagnosis?
clinical suspicion
What are some preventions toward diptheriae?
1. active immunization: toxoid-> antibody against B-fragment
2. passive immunization: equine antitoxin (must apply soon)
Which antibiotics can be used to treat diptheriae?
penicillin
erythromycin
Why do we still need to immunize people during convalenscent stage?
natural infection does not always induce protective levels of antitoxins.
What does the pseudomembrane formed during diptheriae infection contain?
fibrin
bacteria
necrotic cells
inflammatory cells