Respiratory Tract Infections (pneumonia)

Question 1

How is the mechanical host defense mechanisms?

Answer 1

1. Nasal hair
2. Mucociliary apparatus (finger ling projects so that if something gets into lung, its smothered in mucous and expelled)
3. IgA secretion (prevents colonization)
4. Saliva
5. Coughing
6. Epiglottic reflexes
7. Alveolar lining fluid

Question 2

How does something invade the host’s lungs?

Answer 2

1. ) Colonization happens first ( adherence of microorganisms to epithelial surfaces of upper airways) –> then have infection
2. ) The lungs secretions contain non-specific inhibitors of microorganisms

Question 3

How does microorganisms have defense against the host?

Answer 3

1. ) Microbes can have surface adhesions, pili, exotoxins, and proteolytic enzymes that degrade IgA thus PROMOTE colonization
2. ) Alveolar macrophages: eliminate organisms by phagocytosis and produce cytokines and recruit into the lungs –> local area becomes acidic and hypoxic (low O2 in blood) –> impairs phagocytic activity

Question 4

What is fibronectin? What does it do?

Answer 4

Host defense mechanism

Inhibits adherence of bacteria to cell surfaces –> prevents colonization

Question 5

What is special about respiratory secretions?

Answer 5

They contain non-specific inhibitors of microorganisms

Question 6

What are some patient factors that can interfere with host defenses? What do they do?

Answer 6

1. Altered level of consciousness –> compromise epiglottic closure –> aspiration
2. Smoking - disrupts mucociliary function and macrophage activity
3. Viruses (influenza) - impairs alveolar macrophage function and mucociliary clearance –> increased risk of secondary bacterial infection (esp. S. aureus)
4. ) Alcohol –> impairs cough and epiglotic reflexes –> aspiration
5. ) Ventilators
6. ) immunosuppression (malnutrition, immunosuppressive therapy, HIV)
7. ) Elderly

Question 7

What is community acquired pneumonia (CAP)?

Answer 7

Pneumonia developing outside the hospital or < 48h after hospital admission

Question 8

How does community acquired pneumonia develop?

Answer 8

1. ) Aspiration (common for bacterial pneumonia)
   - If something gets into lungs and defenses are normal –> it will get expelled
   - If doesn’t get expelled, infection can happen
2. ) Aerosolization
   - Droplets –> viruses
3. ) Bloodborne (not common)

Question 9

What are the specific pathogens that can cause CAP?

Answer 9

1. ) Strep. pneumoniae
2. ) H. Influenzae
3. ) Mycoplasma pneumoniae
4. ) Legionella pneumophila
5. ) Chlamydophila pneumoniae
6. ) Staph. aureus
7. ) Viral (rhinovirus, influenza)

Question 10

What antibiotics have activity against atypicals?

Answer 10

1. ) Macrolides
2. ) FQ
3. ) tetracyclines

Question 11

What are the common specific pathogens commonly encountered for CAP in outpatient setting?

Answer 11

O SMH C

1. ) Strep pneumoniae
2. ) Mycoplasma
3. ) H. Influenzae
4. ) Chlamydophila

Question 12

What are the common specific pathogens commonly encountered with CAP in inpatient (non-ICU?)

Answer 12

II SMH CL

1. ) Strep. pneumoniae
2. ) Mycoplasma pneumoniae
3. ) H. influenzae
4. ) Chlamydophila
5. ) Legionella
6. ) aspiration
7. ) respiratory viruses

Question 13

What are the common specific pathogens encountered with CAP in inpatient (ICU) setting?

Answer 13

1. ) Strep. pneumoniae (most common)
2. ) Legionella (most common)
3. ) Staph aureus

Question 14

What is the most common pathogen for bacteria pneumonia cases?

Answer 14

Streptococcus pneumoniae

Question 15

What is a risk factor for drug resistant S. pneumoniae?

Answer 15

Prior antibiotic therapy

Extreme age (<6, > 65)

Co-morbid conditions

immunocompromised

Question 16

How is mycoplasma pneumoniae infection spread?

Answer 16

Person-to-person contact

Question 17

Why can’t you get a gram stain with mycoplasma pneumoniae?

Answer 17

B/c mycoplasma has no cell wall

Question 18

How is staph. aureus and CAP connected?

Answer 18

Staph. aureus related CAP incidence is closely coincided with INFLUENZA`

Specifically it is more likely in patients POST-INFLUENZA

Question 19

How can we test for MRSA in CAP ?

Answer 19

Can do a negative swab. If negative, we can stop vancomycin b/c not likely to have pneumonia secondary to MRSA

Question 20

What are the clinical presentation of CAP? (S/Sx)

Answer 20

1. ) SUDDEN onset of fever
2. ) Shortness of breath
3. ) Pleuritic chest pain
4. ) Productive cough (thick, purulent; may be rust color; hemoptysis)

Can be different in elderly

Question 21

How does the s/sx of CAP in elderly differ to regular?

Answer 21

Similar except that classic symptoms may be absent (i.e. fever, mild increase in WBC)

Can also have altered mental status

Question 22

What does a PE typically look like in pts with CAP?

Answer 22

1. ) HR increases (tachycardia)
   - pulse increases 10bpm for every 1 C elevation
2. ) Increase blood pressure
3. ) Tachypnea
4. ) Cyanosis (know that have major compromising of respiratory system)
5. ) Evidence of consolidation

Question 23

What is evidence of consolidation on PE? What is it suggestive of?

Answer 23

1. ) Dullness to percussion
2. ) Decreased breath sounds over affected area
3. ) inspiratory crackles
4. ) Egophony (E –> A changes)

Is clinical presentation for CAP but also is suggestive of bacterial etiology

Question 24

What other tests can you look at to look for CAP?

Answer 24

1. ) Chest radiography
2. ) Sputum exam
3. ) Cultures

Question 25

Why is getting a chest radiograph important for CAP?

Answer 25

Is the ONLY way to determines diagnostically if pt has bacterial pneumonia or viral bronchitis

Question 26

In adults with CAP, should gram stain and culture of lower respiratory secretion be obtained at diagnosis?

Answer 26

No if in outpatient setting Yes, is recommended in pts if in HOSPITAL setting who are: 1. ) severe CAP; esp if intubated 2. ) Being empircally treated for MRSA or P. aeruginosa 3. ) previously infected with MRSA or P. aeruginosa; esp if prior RTI

Question 27

In adults with CAP, should you get blood cultures at time of diagnosis?

Answer 27

NO if in outpatient setting or if managed in hospital setting YES, if patient is in hospital setting who: 1. ) classified as severe CAP 2. ) Being empirically treated for MRSA or P. aeruginosa 3. ) Previously infected with MRSA or P. aeruginosa, esp if prior RTI

Question 28

What is the criteria for severe CAP?

Answer 28

Major (need 1) 1. ) respiratory failure requiring mechanical ventilation 2. ) septic shock with need for vasopressors (severe drop in BP) Minor (need ≥ 2) 1. ) RR ≥ 30 breaths/min 2. ) hypotension requiring aggressive fluid resuscitation 3. ) Confusion 4. ) Uremia (BUN ≥ 20) 5. ) Leukopenia (WBC < 4,000) 6. ) THrombocytopenia (PLT < 100,000) 7. ) Hypothermia