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Microbiology > Exam #4: Viral Infections of the Resp. Tract > Flashcards

Exam #4: Viral Infections of the Resp. Tract Flashcards

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1
Q

What are the symptoms of the common cold? What symptoms differentiate a cold from a more serious infection?

A
  • Rhinitis (inflammation of the nasal passages)
  • Pharyngitis (sore throat)
  • Mild cough

Lack of:

  • High fever
  • Lower respiratory tract involvement
  • Dyspnea
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2
Q

What are considered severe respiratory tract infections?

A

Bronchiolitis

Pneumonia

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3
Q

What complications can be associated with the common cold?

A
  • OM
  • Sinus Infections
  • Exacerbations of asthma (seen in Rhinovirus C in school age children) & COPD in adults
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4
Q

What viruses are associated with the common cold?

A
  • Rhinovirus*
  • Non-SARS Coronavirus
  • Adenovirus
  • Coxsackievirus
  • Influenza B & C vs. A
  • Respiratory Syncytical Virus
  • Parainfluenza
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5
Q

List the characteristics of the Rhinovirus?

A
  • Picornavirus family member
  • Non-enveloped (stable in environment)
  • +ssRNA
  • Binds ICAM-1 receptor
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6
Q

What are the three types of Rhinovirus?

A

A, B, & C species

Note also that there are over 100 serotypes; thus, the immune system does generate a memory response, but there the response is serotype specific

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7
Q

How are Rhinoviruses transmitted?

A
  • Shed in respiratory secretions
  • Transmission though direct contact with nasal secretions, large droplets, & contaminated fomites
  • Extremely low incolum needed for infection
  • Incubation period is 1-3 days
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8
Q

Describe the Rhinovirus mechanism of action.

A

1) Virus attaches to cilia in the respiratory tract via ICAM-1
2) Absorption
3) Replication
4) Replication causes tissue damage & disruption of the epithelial layer= clear fluid out-pouring from the lamina propria
5) Host defenses activated from viral out-poruing & immune system begins to combat the virus
6) Antibody production leads to recovery & epithelium regenerates

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9
Q

How is the Rhinovirus treated?

A
  • Antihistamines
  • NSAIDs
  • Oral Decongestants

Symptomatic treatment only; NO antibiotics

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10
Q

Characteristics of the Non-SARS coronavirus.

A
  • Coronavirus (named by “corona” appearance under EM”
  • Enveloped
  • +ssRNA genome
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11
Q

Describe the mechanism of action of the Coronavirus. How is Non-SARS different from SARS?

A
  • Replicate in epithelial cells of respiratory tract
  • Optimal temp. for replication is 33-35 degrees C i.e. the cooler upper respiratory tract (vs. SARS that replicate better at body temperature)
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12
Q

How is the coronavirus transmitted?

A

Large droplets

*Infection more common in infants & children

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13
Q

What is the difference between the long term immune response to coronavirus & rhinovirus?

A
  • Rhinovirus= long term immune response to species

- Coronavirus= no memory response & reinfection to coronavirus can occur despite circulating antibodies

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14
Q

List the characteristics of the Adenovirus.

A
  • Adenovirus
  • Non-enveloped
  • dsDNA
  • Contains adenoviral fiber proteins that are used for attachment & are toxic to cells

Only DNA virus that causes the common cold

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15
Q

Which serotypes of Adenovirus most commonly cause infection of the respiratory tract?

A

1, 2, & 5

vs. 40 & 41 that more frequently cause gastroenteritis

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16
Q

How is the adenovirus transmitted?

A

Oral droplets, inhalation, & conjunctiva

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17
Q

How does the pathology of adenovirus differ from rhino & corona?

A
  • May enter lymphoid tissues following acute infection
  • Individuals can shed the virus for up to 18 months following infection (asymptomatic)
  • No seasonal pattern of disease i.e. patient with cold in the summer is more likely to have adenovirus than Rhinovirus or Coronavirus
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18
Q

What are the other illness associated with Adenoviruses?

A
  • Pharyngoconjunctival fever
  • Croup, bronchiolitis, & pneumonia
  • GI disease
19
Q

Which Adenovirus serotypes are associated with GI disease?

A

40 & 41

20
Q

To which of the viruses that cause the common cold is a vaccine avaliable?

A

Adenovirus 4 & 7 (live oral vaccine, given to military recruits)

21
Q

List the characteristics of the Coxsackievirus.

A
  • Enterovirus, a subfamily of picornovirus (like Rhinovirus) that can pass through the GI tract and remain infectious
  • Nonenveloped
  • +ssRNA
  • survive low pH of GI tract
  • Replication is fast & occurs in the cytoplasm
22
Q

What is the mode of transmission of the Coxsackivirus?

A

Fecal to oral transmission

23
Q

What can the Coxsackieirus cause in addition to the common cold?

A
  • Herpangina
  • Meningitis or encephalitis (rare)
  • Hand-Foot-&-Mouth
24
Q

What is Herpangina?

A
  • Abrupt onset fever
  • Small vesicles on soft palate that rupture & from white ulcers
  • More commonly a pediatric disease
25
Q

What are the symptoms of Hand-Foot-&-Mouth Disease

A
  • Fever
  • Vesicular lesions on soles of hand & feet on oral areas
  • More commonly a pediatric disease
26
Q

What is croup? What are the symptoms of croup?

A
  • Acute larygotracheobronchitis ( due to swelling of the subglottic region of the larynx)
  • Inspiratory stridor
  • “Seal-bark” cough

Note that a prodrome of common cold symptoms precipitates

27
Q

What is a classic radiographic sign of croup of CXR?

A

“Steeple Sign”

28
Q

What should be included in your differential diagnosis of croup?

A
  • FB airway obstruction

- Bacterial epiglotittis (HiB)

29
Q

How is croup treated? What is the important factor in the diagnostic algorithm?

A

Does the patient have stridor at rest?

Yes=

1) Oxygen
2) Racemic-Epi
3) Glucocorticoids

No= Humidified Air Hydration

30
Q

What is croup most commonly caused by? Specifically, what serotype of the virus is associated with acute croup?

A

Parainfluenza Virus

  • Type 1 is the most common cause of acute croup
  • Type 2 & 3 can also cause croup, but Type 3 is more commonly associated with lower respiratory tract infections

Also, RSV & Measles can cause croup

31
Q

List the characteristics of Parainfluenza.

A
  • Paramyxovirus family
  • Helical nucleocapsid
  • Envelope contains hemagglutinin & neuraminidase–targets for the immune system to recognize the virus
  • -ssRNA
  • RNA synthesis occurs in the cytoplasm
32
Q

How is the parainfulenza virus transmitted?

A

Large droplets & direct contact

33
Q

Describe the Parainfluenza virus mechanism of action.

A

Infection & replication in the ciliated epithelium of the respiratory tract

34
Q

What are the symptoms of influenza?

A
  • Myalgia
  • Headache
  • Fever/ shaking chills
  • Cough peaking between days 3-5
  • Fatigue & malaise
35
Q

How does the flu differ from the common cold?

A
  • Flu generally lasts longer than the common cold
  • Increased severity of symptoms
  • Pandemic outbreaks
36
Q

What is a pandemic?

A

An epidemic of infectious disease that has spread through human populations across a large region; for instance multiple continents, or even worldwide.

37
Q

What is the definition of pneumonia?

A

Inflammation of the lung parenchyma leading to abnormal gas exchange

38
Q

What are the symptoms of pneumonia?

A
  • Fever
  • Chills
  • Cough
  • Pleural chest pain
  • Increased respiratory rate
  • Wheezes & crackles
  • Hypoxia & cyanosis
39
Q

What virus typically causes primary influenza virus pneumonia?

A

Influenza Type A

40
Q

What are the symptoms of primary influenza virus pneumonia?

A

1-4 days following flu symptoms:

  • Increased cough
  • Tachypnea
  • Dyspnea
  • Acute respiratory distress

High Fatality Rate & typically a progressive decline in patient’s status

41
Q

How is primary influenza virus pneumonia diagnosed?

A

Sputum Gram Stain

  • Abundant PMN cells
  • Without significant number of bacteria

CXR
- Bilateral, midlung or lower lung infiltration that is more of an interstitial pattern (like atypical pneumonia) rather than a lobular or typical pneumonia

42
Q

What is bacterial influenza-associated pneumonia?

A

Pneumonia that onsets a week after influenza symptoms

43
Q

What are the symptoms of bacterial influenza-associated pneumonia?

A

Influenza symptoms that lessen, but are then followed by:

  • Increased cough
  • Return of fever
  • Respiratory distress

“Biphasic”

44
Q

What bacteria are most commonly associated with bacterial influenza-associated pneumonia?

A

1) S. pneumoniae

2) S. aureus & H. Influenza

Microbiology (49 decks)

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