Respiratory Infectious Disease Powerpoint Flashcards

1
Q

What are three mechanisms by which bacteria cause disease?

A
  • Toxin production
  • Host immune response
  • Bacterial proliferation and invasion
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2
Q

What are three mechanisms by which viruses cause disease?

A
  • Cytopathic effect (viral infection disrupts normal cell physiology which can lead to cell death and disease)
  • Host immune response
  • Tumorigenesis (viral infection promotes uncontrolled proliferation of infected cells)
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3
Q

What are five features of the respiratory tract that help rid the system of potential pathogens?

A
  1. Mucociliary lining of the nasal cavity
  2. Change in direction of the airway from the sinuses to the pharynx (location of adenoids)
  3. The ciliary elevator
  4. Normal flora competition (Staphylococci)
  5. Alveolar macrophages eliminate microorganisms in the lungs
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4
Q

What are two main obstacles that a microorganisms must overcome in order to initiate infection in the respiratory tract?

A
  1. Avoid/survive the mucous layers of the URT which would eventually lead to swallowing the pathogen
  2. Must also avoid phagocytosis or be able to survive and/or multiply in the phagocytic cell
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5
Q

What pathogens are associated with the Common cold?

A

Almost exclusively viral infections (many types, Rhinoviruses most common)

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6
Q

What pathogens are associated with Sinusitis?

A

Bacterial secondary infections (several types, S. pneumoniae and H. influenza are most common)

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7
Q

What pathogens are associated with Pharyngitis?

A

Viral and Bacterial infections (viruses make up about 90% of the cases here). Important bacterial infections include those of S. pyogenes and C. diphtheriae.

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8
Q

What pathogens are associated with Laryngitis/Croup?

A

Mostly viral infections (Parainfluenza virus and Respiratory Syncytial virus (RSV)). Associated: Epiglottitis.

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9
Q

How do Rhinoviruses infect the cells lining the nasal passage and the pharynx (initiating cold infection)?

A

They attach utilizing the intercellular adhesion molecule (ICAM) ICAM-1 of the cells.

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10
Q

What are the features of Rhinovirus?

A
  • RNA virus
  • Icosahedral Nucleocapsid
  • Nonenveloped
  • ss (+) Nonsegmented Genome (Class IV)
  • Picornaviridae
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11
Q

What are the two most common causes of community acquired acute bacterial rhinosinusitis infections?

A
  • Streptococcus pneumoniae

- Haemophilus influenzae

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12
Q

What are two other potential bacterial pathogens for Sinusitis (Rhinosinusitis)?

A
  • Streptococcus pyogenes

- Staphylococcus aureus

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13
Q

What are symptomatic treatments for Sinusitis (Rhinosinusitis)?

A
  • Oral hydration w/ nasal saline washes and steam. [This is the one thing that has been proven to shorten the length and severity of infection]
  • Acetominophen and decongestants
  • Mucolytics
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14
Q

What are antibiotic treatments for Sinusitis (Rhinosinusitis)?

A

Initial therapy recommendation is Amoxicillin (Augmentin) or Azithromycin (for people allergic to penicillin)

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15
Q

What are the traits of S. pyogenes?

A
  • Bacteria
  • Gram (+)
  • Cocci
  • Catalase (-)
  • Beta hemolytic
  • Bacitracin sensitive
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16
Q

Certain strains of S. pyogenes can cause scarlet fever. How do they do this?

A

They secrete certain streptococcal pyogenic exotoxins: ssa, speA and speC
These toxins are superantigens!

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17
Q

What are the traits of Corynebacterium diphtheriae?

A
  • Bacteria
  • Gram (+)
  • Bacilli
  • Non-spore forming
  • Non-motile
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18
Q

Why is C. diphtheriae so dangerous?

A

It produces diphtheria toxin which is an A-B exotoxin. This comes from genes from a lysogenized phase.

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19
Q

What can happen if diphtheria toxin reaches the blood stream?

A

It can result in myocarditis (heart failure) and neuritis (temporary paralysis of limbs, soft palate and diaphragm)

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20
Q

How do the turbinate bones (“baffle plates”) protect the respiratory system?

A

Covered in mucus that collects particles not filtered by nasal hairs. The baffle plates cause the air to swirl as it passes over causing a swirling pattern that forces the potential pathogens to make contact with the mucus covering the nasal passages.

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21
Q

Where is the Mucociliary Escalator?

A

Covers most of the bronchi, bronchioles, and nose. It contains goblet cells.

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22
Q

What are the two basic parts of the Mucociliary Escalator?

A
  1. Mucus-producing goblet cells

2. Ciliated epithelium

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23
Q

How does the Mucociliary Escalator work?

A

It’s a major barrier against infection.

  • Cilia are continually beating, pushing mucus up and out into the throat.
  • Micro-organisms that could potentially infect the respiratory tract are caught in the sticky mucus and moved up the mucociliary escalator.
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24
Q

What paralyzes the cilia of the mucociliary escalator?

A

Smoking

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25
Q

What are defenses of the upper respiratory tract?

A
  • Nasal hair
  • Ciliary escalator
  • Mucus
  • Involuntary responses such as coughing and sneezing
  • Secretory IgA
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26
Q

What is the normal biota of the upper respiratory tract?

A

Moraxella, nonhemolytic and alpha-hemolytic streptococci, Corynebacterium and other diphtheroids, Candida albicans. [Also, S. pyogenes, S. pneumoniae, H. influenzae, N. meningitidis & Staph. aureus often present as normal biota]

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27
Q

What are the defenses of the lower respiratory tract?

A
  • Mucus
  • Alveolar macrophages
  • Secretory IgA
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28
Q

What is the normal biota of the lower respiratory tract?

A

NONE

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29
Q

In order to establish respiratory tract infection, what conditions must be met?

A
  1. There must be sufficient “dose” of microorganisms inhaled in order to establish infection.
  2. Infectious particles must be airborne.
  3. Airborne particles must be viable in air.
  4. Organism must be deposited on tissue susceptible to infection.
  5. Colonization must occur. (facilitated by adherence factors and immune evasion factors of the pathogenic microorganism)
  6. Disease symptoms happen.
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30
Q

What usually causes the common cold (rhinitis)? When is it most common? What symptom does it usually not have?

A
  • Rhinoviruses
  • Winter months
  • Typically does not cause fever
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31
Q

What symptoms are often seen with the common cold (and it’s progression)?

A
  • Starts with nasal stuffiness, sneezing and a headache
  • Nasal cavity then fills with fluid (rhinorrhea).
  • Tiredness, watery eyes (lacrimation), sore throat, slight fever, and anorexia are common in moderate to severe cases.
  • If infection makes it to the lower respiratory tract, there may be a cough
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32
Q

What type of cold is not seen in the winter?

A

Adenovirus infections can be seen all year round.

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33
Q

How can Rhinitis be spread?

A
  • Person to person
  • Hand to hand contact
  • Fomites
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34
Q

When do cold symptoms reach their peak?

A

2-5 days post infection (cells are completely regenerated by day 14 post infection)

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35
Q

What is possible during a common cold that results in a change from clear nasal secretions to purulent nasal secretions?

A

Secondary bacterial infections by normal flora.

36
Q

How do you diagnose common cold?

A

Dependent on patients symptoms and time of year. Lab cultures of viruses and serologic testing is rarely performed.

37
Q

What is the treatment for the common cold?

A

Supportive therapy!

38
Q

What is the definition of Acute Rhinosinusitis?

A

Inflammation or infection of the mucosa of the nasal passages.
AND
at least one of the paranasal sinuses that typically lasts no longer than 4 weeks.

39
Q

What are the two most common causes of community acquired bacterial rhinosinusitis?

A
  1. Strep. pneumoniae

2. Haemophilus influenzae

40
Q

What are other potential bacterial pathogens responsible for acute bacterial rhinosinusitis?

A
  • Strep. pyogenes

- Staph. aureus

41
Q

What are symptoms of Sinusitis (Rhinosinusitis)?

A
  • Sneezing
  • Rhinorrhea
  • Nasal congestion (w/ postnasal drip)
  • Aural fullness (pressure in the ear)
  • Facial pressure
  • Headache
  • Sore throat
  • Cough
  • Fever
  • Muscle aches
42
Q

What predisposes an individual to bacterial secondary infection (sinusitis)?

A

Viral URI!!

43
Q

What type of sinusitis is rare and how is it usually identified?

A

Fungal sinusitis.

Usually identified after antibacterial drugs fail to clear the sinus infection

44
Q

What is the most common cause of fungal sinusitis?

A

Aspergillus fumigatus

45
Q

How do you treat immunocompetent individuals with fungal sinusitis?

A

Through mechanical removal of the fungal pathogen.

46
Q

What happens in immunocompromised individuals with fungal sinusitis?

A

It can cause more severe infections leading to eye and brain involvement

47
Q

What causes MOST CASES of Sinusitis (Rhinosinusitis)?

A

VIRUSES

48
Q

How long is recovery with sinusitis?

A

Symptoms resolve in 5-7 days. Most people recover without treatment.

49
Q

What do bacterial sinus infections follow?

A

Can follow the common cold, dental extractions, and rhinitis due to allergies.

50
Q

When is sinusitis (rhino sinusitis) more common?

A

More likely in winter months.

Coincides with the common cold.

51
Q

How many of children and adult viral rhinosinusitis infections progress to acute bacterial infections?

A

2% of adult

10% of children

52
Q

What do you base diagnosis of sinusitis on?

A

Patient’s clinical signs and symptoms.

53
Q

What causes of sinusitis are difficult to differentiate?

A

Viral and bacterial

54
Q

When is a diagnosis of Acute Bacterial Rhinosinusitis in adults likely?

A

When an adult patient has moderate symptoms of rhinosinusitis that persists beyond 7 days or severe symptoms of any duration that include facial swelling or tooth pain.

55
Q

When is a diagnosis of Acute Bacterial Rhinosinusitis in children likely?

A

When a child presents with moderate symptoms of rhino sinusitis for longer than 10-14 days OR when there are severe symptoms of any duration that include a fever of >39C or >102F with facial swelling or pain.

56
Q

What treatment is recommended for viral and bacterial rhinosinusitis?

A

viral - symptomatic treatment

bacterial - antibiotic treatment (broad spectrum)

57
Q

What are symptomatic treatments for viral sinusitis?

A
  • Oral hydration with nasal saline washes and steam. [one thing proven to shorten length and severity of infection]
  • Acetaminophen and decongestants
  • Mucolytics
58
Q

What are antibiotic treatments for bacterial sinusitis?

A

Initial therapy recommendation is amoxicillin (Augmentin) or azithromycin

59
Q

What is the most common URT infection (URI)? What can cause it?

A
  • Pharyngitis

- Can be caused by many different microorganisms

60
Q

How many sore throats/pharyngitis is caused by viruses in adults and children?

A

Adults - 90%

Children - 60-75%

61
Q

What is the most common bacterial cause of acute pharyngitis?

A

Streptococcus pyogenes

62
Q

What are seven predominant viral causes of pharyngitis?

A
  1. Rhinoviruses
  2. Coronaviruses
  3. Adenoviruses
  4. Parainfluenza virus
  5. Influenza A and B viruses
  6. Respiratory Syncytial virus
  7. Epstein-Barr virus
63
Q

What disease and occurrence is associated with Rhinovirus Pharyngitis ?

A
  • Common Cold

- Common occurance

64
Q

What disease and occurrence is associated with Coronavirus Pharyngitis?

A
  • Common Cold

- Common occurrence

65
Q

What disease and occurrence is associated with Adenovirus Pharyngitis?

A
  • Pharyngoconjunctival fever and acute respiratory disease

- Common in military recruits and boarding schools

66
Q

What disease and occurrence is associated with Parainfluenza virus Pharyngitis?

A
  • Cold and croup

- Common in children

67
Q

What disease and occurrence is associated with Respiratory syncytial virus Pharyngitis?

A
  • Bronchiolitis and croup

- Common in children

68
Q

What disease and occurrence is associated with Epstein-Barr virus Pharyngitis?

A
  • Infectious mononucleosis

- Common in adolescents during winter

69
Q

What disease and occurrence is associated with Influenza A and B virus Pharyngitis?

A
  • Influenza

- Common during flu season

70
Q

What are common findings in bacterial and viral pharyngitis?

A
  • Fever
  • Sore throat
  • Edema
  • Hyperemia of tonsils and pharyngeal walls
71
Q

What findings STRONGLY suggest viral pharyngitis?

A
  • Conjunctivitis
  • Cough
  • Hoarseness
  • Inflammation of the mucous membrane
  • Diarrhea
72
Q

What do patients with Strep. pyogenes pharyngitis present with?

A

Fever and severe pain upon swallowing (sudden onset)

73
Q

What may also be present with Strep. pyogenes pharyngitis?

A
  • Headache
  • Nausea
  • Vomiting
  • Abdominal pain
  • Red tonsils with/without exudate
  • Enlarged, tender cervical lymph nodes
74
Q

What is used to diagnose suspected S. pyogenes infections?

A

Rapid strep test

75
Q

When should treatment for Strep. pyogenes pharyngitis start? Why is it important to treat with antibiotics?

A
  • Within 9 days of first signs of infection

- Antibiotic treatment is necessary to block the development of glomerulonephritis and rheumatic fever

76
Q

What age group is Pharyngitis due to Group A (GAS) S. pyogenes associated with?

A

Children 5-15 years old

77
Q

When is pharyngitis most common?

A

Winter or spring in temperate climates.

78
Q

What is the most common cause of Pharyngitis?

A

VIRUSES

79
Q

What is the course of pharyngitis? How is it spread?

A
  • Usually self-limiting infections

- Spread by person to person contact and following contact with contaminated fomites

80
Q

How is viral pharyngitis initiated?

A
  1. Virus gains access to the mucosal cells lining the nasopharynx.
  2. Replication initiates in these cells.
  3. Damage to host cells is common at these sites of replication.
81
Q

How is bacterial pharyngitis initiated?

A
  1. S. pyogenes attaches to the mucosal epithelial cells using its M protein, lipoteichoic acid, and fibronectin-binding protein (protein F).
  2. Capsule is composed of hyaluronic acid (HA) and prevents phagocytosis by macrophages.
  3. Invasion virulence factors include protease and hyaluronidase.
82
Q

What culturing and tests are used to diagnose Pharyngitis?

A
  • Viral infections rarely culture
  • S. pyogenes cultures are most accurate way to diagnose these infections but can take 1-2 days to complete
  • Rapid antigen detection tests are used clinically
83
Q

What is the treatment for all cases of pharyngitis?

A

Supportive care

84
Q

What treatment is suggested for viral pharyngitis?

A
  • Acetaminophen

- Warm saline gargles

85
Q

What treatment is suggested for S. pyogenes Pharyngitis?

A

Penicillin or Erythromycin for those allergic to penicillin.