76 - LRT Infections

Question 1

Frequent aetiological agents of acute bronchitis

Answer 1

Viral URTI

Question 2

Frequent aetiological agent of acute exacerbation of chronic bronchitis

Answer 2

Usually pneumococci and/or H influenzae

Question 3

Symptoms of acute exacerbation of chronic bronchitis/COPD

Answer 3

Sputum becomes more purulent, bloody

Question 4

Less-virulent H influenzae and S pneumoniae

Answer 4

Higher-numbered pneumococci, unserotyped H influenzae

Question 5

Frequent aetiological agent of bronchiolitis

Answer 5

RSV (particularly common under one year)

Question 6

Effect of RSV on adults

Answer 6

Acute bronchitis symptoms, which can last a few weeks

Question 7

Why does RSV cause bronchiolitis in under-ones?

Answer 7

Babies still have antibodies against RSV from mother.
Antibodies form immune complexes with virus.
C’ activation, etc, which causes more-severe inflammation than in older children without maternal antibodies

Question 8

Effect of bronciholitis on ventilation

Answer 8

Gas is trapped in bronchioles.
On inspiration, bronchioles are opened.
On expiration, bronchioles collapse (no cartilage), trapping air. This manifests as a long expiratory wheeze.

Question 9

Types of pneumonia
1
2
3

Answer 9

1) Acute bacterial
2) Typical pneumonia
3) Atypical pneumonia

Question 10

Acute bacterial pneumonia common aetiological agents 
1
2
3
4
5
6
7

Answer 10

Pneumococci (~80% of non-nosocomial cases. ~50% of nosocomial cases)
H influenzae
Staph (nosocomial)
Klebsiella (nosocomial)
Legionella (often immunocompromised, EG older)
TB
Chlamydophila

Question 11

Chlamydophila pneumoniae, psittacae

Answer 11

Intracellular bacteria, same family as Chlamydia trachomatis.

Have replicative and infective forms.

Question 12

Chlamidophila species that can cause pneumonia

Answer 12

Chlamydophila pneumoniae and psittacae

Question 13

C psittacae vector

Answer 13

Birds.

Live harmlessly in birds, unless bird is stressed (EG: when captured).

Question 14

Typical pneumonia

Answer 14

Sudden onset, sputum is purulent and bloody.

Restricted to one lobe

Question 15

Atypical pneumonia

Answer 15

Chronic
Sputum not bloody, purulent.
Not restricted to one lung section, diffuse through lungs.

Question 16

Bacterial cause of atypical pneumonia

Answer 16

Mycoplasma pneumonia

Question 17

Causes of atypical pneumonia 
1
2
3
4
5
6

Answer 17

Mycoplasma
Chlamydia
M. catarrhalis (can also cause otitis media) 
Influenza
RSV
Adenovirus

Question 18

Chlamydia that can cause pneumonia in babies (particularly first month of life)

Answer 18

Chlamydia trachomatis

Question 19

How do infants get C trachomatis pneumonia?

Answer 19

From infected mother.

Question 20

Where does inflammation from typical pneumonia tend to be?

Answer 20

Alveoli

Question 21

Where does inflammation from atypical pneumonia tend to be?

Answer 21

Interstitial tissue

Question 22

Examples of fungal causes of pneumonia
1
2
3

Answer 22

Histoplasma
Aspergillius
Pneumocystis

Question 23

Bacteria which can cause lung abscesses

Answer 23

Mixed anaerobes.

Question 24

Empyema

Answer 24

Pus in the pleural space

Question 25

Aetiological agent of empyema

Answer 25

S aureus, as a secondary infection from pneumonia

Question 26

Why make a specific diagnosis of pneumonia?
1
2

Answer 26

1) Appropriate antibiotic prescribing

2) Notifiable pathogens

Question 27

Examples of notifiable pathogen-caused pneumonias 
1
2
3
4
5

Answer 27

SARS, MERS
Influenza (H5N1)
Legionella spp
Bioterrorism agents (anthrax, yersinia)
Community-acquired MRSA

Question 28

Ways to specifically diagnose pneumonia
1
2
3

Answer 28

Clinical
Radiological
Lab

Question 29

Clinical considerations of pneumonia 
1
2
3
4
5
6

Answer 29

1) Community- or hospital-acquired
2) Severity index (becoming less used)
3) Underlying illness: COPD, ADIS, cystic fibrosis
4) Occupation (contact with animals, air quality, air conditioning)
5) Travel
6) Homelessness

Question 30

Bacteirum that can be in potting mix for gardening

Answer 30

Legionella longbeachii

Question 31

Bacterium that can be from animal furs

Answer 31

Bacillus anthraxis

Question 32

Infection particularly associated with homelessness in Melbourne

Answer 32

Tuberculosis

Question 33

Types of specimens for pneumonia diagnosis 
1
2
3
4
5
6
7

Answer 33

1) Properly collected sputum
2) Transtracheal aspirate
3) Aspiration via tracheostomy, endotracheal tube
4) Aspiration via bronchoscope
5) Pleural tap (if effusion)
6) Lung biopsy (by needle or open)
7) Blood for culture and serology

Question 34

Properly collected sputum

Answer 34

Coughed from lungs, observed by a clinician.

NOT spit - same organisms are in saliva that can cause pneumonia

Question 35

Culture diagnosis of pneumonia
1
2
3
4

Answer 35

1) Look for purulent part of sample.
2) Plate purulent sample, gram stain.
3) Look for polymorphonuclear cells (must be present).
4) Look for buccal bacteria, as this indicates contamination.

Question 36

Ways to collect sputum with less contamination than coughing

Answer 36

Transtracheal tube, tracheostomy, endotracheal tube, aspiration via bronchoscope

Question 37

How to take a sample with a bronchoscope

Answer 37

Inject a small amount of saline, take sample

Question 38

Use of a pleural tap

Answer 38

If pleural space is purulent, probably the same agent that caused pneumonia

Question 39

Lung biopsy by needle
1
2
3

Answer 39

1) Relatively non-invasive, performed by a radiologist.
2) Radiologist locates area of interest, inserts needle between ribs to site of inflammation.
3) Perform in unresolved pneumonia, not in standard pneumonia

Question 40

Is blood cultured from a pneumonia patient often positive for pneumonia-causing organism?

Answer 40

No

Question 41

Transtracheal tube

Answer 41

Anaesthatise patient with a local.

Insert needle into cricothyroid space, insert into lungs.

Question 42

When is serological diagnosis of pneumonia useful?

Answer 42

When bacterium is hard to grow.

Question 43

Examples of bacteria that are diagnosed with serological techniques for pneumonia
1
2
3
4

Answer 43

1) Mycoplasma pneumonie
2) Legionella pneumophila
3) Chlamydophila, Chlamydia
4) Coxiella burnetii

Question 44

Cause of typhus fever

Answer 44

Ricketsia prowazechii (spread by insects)

Question 45

What do you look for in a serological test?

Answer 45

Specific IgM, rising titre

Question 46

Which aetiological agents for pneumonia are tested for with antigen detection?

Answer 46

Common viruses (RSV, influenza, parainfluenza, etc), Bordatella, Legionella pneumophila type 1

Question 47

How is the sample for antigen detection taken?

Answer 47

Tube inserted into nose, fluid form nose taken

Question 48

When is an URT swab useful for diagnosing LRT infection?

Answer 48

When it is a viral infection. Bacteria living in URT can cause LRTI, but viruses do not live here normally

Question 49

Best-guess antibiotics prescribed for community acquired pneumonia

Answer 49

Pen G/Amoxycillin + doxycycline/macrolide

Pen G for pneumococcus.
Tetracyclines and macrolides are effective for less-common bacteria (EG: mycoplasma are resistant to Pen G, as have no cell wall)

Question 50

Why is using penicillin and tetracyclines together unusual?

Answer 50

When treating meningitis, are antagonistic

Question 51

When do you modify best-guess antibiotic prescription

Answer 51

If severe, if there are specific risk factors, if you known the causative organism

Question 52

Examples of vaccines for pneumonia
1
2
3

Answer 52

1) Influenza vaccine
2) Pneumococcal vaccines (23-valent polysaccharide, 13-valent conjugate)
3) Coxiella (Q fever)