(18) Lower respiratory tract infections Flashcards
1
Q
What are the board types of LRTI?
A
- tracheitis (trachea)
- bronchitis (bronchus)
- bronchiolitis (bronchioles)
- pneumonia (lung)
2
Q
What are the 2 different categories of bronchitis?
A
- acute
- chronic (acute exacerbations)
3
Q
What are the 4 different types of pneumonia?
A
- community acquired (CAP)
- hospital acquired (HAP)
- ventilator acquired (VAP)
- aspiration
4
Q
What are the predisposing factors to LRTI?
A
- loss or suppression of cough reflex/swallow
- ciliary defects
- mucous disorders
- pulmonary oedema
- immunodeficiency (congenital or acquired)
- macrophage function inhibition
5
Q
Loss or suppression of cough reflex/swallow is a predisposing factor to LRTI. What may this occur in?
A
- stroke
- coma
- ventilation
6
Q
A predisposing factor to LRTI is ciliary defects eg. PCD. What is PCD?
A
Primary ciliary dyskinesia
Autosomal recessive genetic disorder that causes defects in the action of cilia lining the respiratory tract
7
Q
Mucous disorders are a predisposing factor to LRTI. Give an example
A
Cystic fibrosis
8
Q
Macrophage function inhibition is a predisposing factor to LRTI. What may it be caused by?
A
Smoking
9
Q
Which bacteria cause LRTIs?
A
- strep. pneumoniae
- haemophilus influenzae
- staph. aureus
- klebsiella pneumonia
- mycoplasma pneumoniae
- chlamydophila pneumoniae
- legionella pneumophila
- mycobacterium tuberculosis
10
Q
Which viruses cause LRTIs?
A
- influenza
- parainfluenza
- respiratory syncytial virus
- adenovirus
11
Q
Which fungi cause LRTIs?
A
- aspergillus sp
- candida sp
- pneumocystitis jiroveci
12
Q
What is acute bronchitis?
A
Inflammation and oedema of the trachea and bronchi
13
Q
What are the symptoms of acute bronchitis?
A
- cough (typically dry)
- dyspnoae
- tachypnoea
Cough may be associated with retrosternal pain
14
Q
When and who is acute bronchitis common in?
A
- most frequent in winter
- most common in children under 5
15
Q
What organisms cause acute bronchitis?
A
Viruses are the usual cause
- rhinovirus
- coronavirus
- adenovirus
- influenza
Bacterial causes are less common
- H. influenzae
- M. pneumoniae
- B. pertussis
16
Q
How would you diagnose acute bronchitis?
A
- diagnostic tests not indicated in mild presentations
- vaccination history and previous exposure (eg. influenza, B. pertussis) history may exclude some organisms
17
Q
What may be helpful in acute bronchitis diagnosis if looking for a specific causes?
A
If needed, cultures of respiratory secretions may be helpful if looking for a specific cause eg. B. pertussis
But this is not routine
18
Q
What treatment would you give for acute bronchitis?
A
- supportive treatment for healthy patients
- those with severe disease of co-morbidity may require oxygen therapy or respiratory support
19
Q
Should antibiotics be given for acute bronchitis?
A
Usually viral
Antibiotics only if bacterial cause is suspected or found
20
Q
What is the definition of chronic bronchitis?
A
Cough productive of sputum on most days during at least 3 months of 2 successive years (which cannot be attributed to an alternative cause)
21
Q
How common is chronic bronchitis?
A
Affects 10-25% of the population
- most common in men and >40 years old
22
Q
What is chronic bronchitis associated with?
A
- smoking
- pollution
- allergens
23
Q
If somebody with chronic bronchitis has airflow obstruction present on spirometry, what is this diagnosed as?
A
COPD
24
Q
In chronic bronchitis, what is inflammation and oedema of the airways mediated by?
A
Exogenous irritants (rather than infective agents)
25
Can patients with chronic bronchitis have acute exacerbations?
Yes, patients have acute exacerbations mediated by the same infective pathogens as acute bronchitis
26
What is bronchiolitis?
Inflammation and oedema of the bronchioles
27
Who is bronchiolitis common in and when does it peak?
Primarily paediatrics
Infants 2-10 months
Peaks in winter and early spring
28
What are the signs and symptoms of bronchiolitis?
- acute onset wheeze
- nasal discharge
- respiratory distress (grunting, retractions, nasal flaring)
29
What organisms cause bronchiolitis?
Most commonly caused by RSV (75% of cases) - 80% of children have evidence of previous RSV infection by 2 years old
Also caused by
- parainfluenza
- adenovirus
- influenza
30
How would you diagnose bronchiolitis?
- chest x-ray
- full blood count
- microbiological diagnosis:
31
How would you carry out a microbiological diagnosis of bronchiolitis?
Usually nasopharyngeal aspirate of respiratory secretions sent for viral PCR
32
How would you treat bronchiolitis?
- supportive - oxygen, feeding assistance
- no clear evidence to support steroids, bronchodilators, ribavirin
- antibiotics only if complicated by bacterial infection
33
What is pneumonia?
Infection affecting the most distal airways and alveoli - formation of inflammatory exudate
34
What are the two anatomical patterns of acute bacterial pneumonia?
1. bronchopneumonia
| 2. lobar pneumonia
35
Bronchopneumonia is one of the two anatomical patterns of pneumonia. What is it?
Characteristic patchy distribution centred on inflamed bronchioles and bronchi then subsequent spread to surrounding alveoli
36
Lobar pneumonia is one of the two anatomical patterns of pneumonia. What is it?
Affects a large part, or the entirety of a lobe. 90% due to S. pneumoniae
37
What is the definition of hospital acquired pneumonia (HAP)?
- pneumonia developing >48 hours after hospital admission
| - different causative organisms to CAP, especially if >5 days after admission: enterobacteriaceae and pseudomonas sp
38
What is the definition of ventilator acquired pneumonia (VAP)?
- subgroup of HAP
| - pneumonia devleoping >48 hours after ET intubation and ventilation
39
What is the definition of aspiration pneumonia?
- subgroup of HAP
- pneumonia resulting from the abnormal entry of fluids e.g. food, drinks, stomach contents etc. into the lower respiratory tract
- patient usually has impaired swallow mechanism
40
Describe the epidemiology of CAP?
- 1 per 100 people per year
- 20-40% cases require hospital admission
- peak age = 50-70
- peak onset = midwinter to early spring
41
How are organisms acquired in CAP?
- person-person or from a person's existing commensals
- from the environment
- from animals
42
In CAP, which organisms may be spread person-person?
S. pneumoniae
| H. influenzae
43
In CAP, which organisms may be a acquired from the environment?
L. pneumophilia
44
In CAP, which organisms may be acquired from animals?
C. psittaci
45
Bacterial causes of CAP are often divided into which two categories?
- typical
| - atypical
46
What was 'atypical pneumonia' traditionally described as?
Cases which failed to respond to penicillin or sulpha drugs and no organism could be identified
(now this is recognised to be caused by 'atypical' organisms)
47
When are the 'typical' organisms associated with CAP?
- streptococcus pneumoniae
- haemophilus influenzae
- moraxella catarrhalis
- staphylococcus aureus
- klebsiella pneumoniae
48
What are the 'atypical' organisms associated with CAP?
- mycoplasma pneumoniae
- legionella pneumophila
- chlamydophila pneumoniae
- chlamydophila psittaci
- coxiella burnetii
49
What are the clinical symptoms of bacterial CAP?
- usually rapid onset
- fever/chills
- productive cough
- mucopurulent sputum
- pleuritic chest pain
- general malaise: fatigue, anorexia
50
What are clinical signs of bacterial CAP? (typical)
- tachypnoea
- tachycardia
- hypotension
- examination findings consistent with consolidation (dull to percuss, reduced air entry, bronchial breathing)
51
What is the epidemiology of atypical pneumonia caused by mycoplasma pneumoniae?
- autumn epidemics every 4-8 years
| - commonest in children and young adults
52
Guillain-Barre syndrome can occur as a complication of atypical pneumonia caused by mycoplasma pneumoniae. What is it?
Rapid-onset muscle weakness as a result of damage to the peripheral nervous system (auto-immune)
53
What is the main symptom of atypical pneumonia caused by mycoplasma pneumoniae?
Cough
54
How would you diagnose atypical pneumonia caused by mycoplasma pneumoniae?
Serology (difficult to culture)
55
What are some rare complications associated with atypical pneumonia caused by mycoplasma pneumoniae?
- pericarditis
- arthritis
- Guillain-Barre syndrome (peripheral neuropathy)
56
What are outbreaks of atypical pneumonia caused by legionella pneumophilia associated with?
Colonises water piping systems
Outbreaks associated with showers, air conditioning units, humidifiers
57
What are the signs and symptoms of atypical pneumonia caused by legionella pneumophila?
- high fevers
- rigors
- cough (dry initially becoming productive)
- dyspnoea
- vomiting
- diarrhoea
- confusion
58
What would you see on a blood test with atypical pneumonia caused by legionella pneumophila?
- deranged LFTs
| - SIADH (low sodium)
59
Which atypical bacteria causes 3-10% of CAP cases in adults?
Chlamydophila pneumoniae
60
What does chlamydophila pneumonia cause?
Atypical bacteria
Causes mild pneumonia or bronchitis in adolescents and young adults
Incidence highest in the elderly - may experience more severe disease
61
The atypical pneumonia bacteria, chlamydophila psittaci, is associated with exposure to what?
Birds
62
Which bacteria should you consider in patients with pneumonia, splenomegaly and bird exposure?
Chlamydophila psittaci
63
In atypical pneumonia caused by chlamydophila psittaci, the patient may also have what?
- rash
- hepatitis
- haemolytic anaemia
- reactive arthritis
64
Influenza virus usually produces uncomplicated disease but may also cause primary viral pneumonia. What are the symptoms of uncomplicated disease caused by influenza?
- fever
- headache
- myalgia
- dry cough
- sore throat
(convalescence takes 2-3 weeks)
65
Who does primary viral pneumonia occur more commonly in?
Patients with pre-existing cardiac and lung disorders
66
What are the symptoms of primary viral pneumonia caused by influenza?
- cough
- breathlessness
- cyanosis
67
What may develop after initial period of improvement after primary viral pneumonia?
Secondary bacterial pneumonia
S. pneumoniae
H. influenzae
S. aureus
68
How would you diagnose viral pneumonia?
Viral antigen detection in respiratory samples using PCR
69
What are the non-microbiological investigations into CAP?
- routine observations (BP, pulse, oximetry)
- bloods: FBC, U&E, CRP, LFTs
- chest X-ray
70
When are microbiological investigations recommended for CAP?
Recommended for all moderate-severe CAP based on CURB65 score >2 (BTS guideline 2009)
71
Give some examples of microbiological investigations for CAP
- sputum gram stain and culture
- blood culture
- pneumococcal urinary antigen
- legionella urinary antigen
- PCR or serology
72
What would you do PCR/serology for in CAP?
- viral pathogens eg. influenza (PCR of respiratory samples)
- mycoplasma pneumoniae (PCR of respiratory samples preferable, complement fixation: interpret with caution)
- chlamydophila sp (complement fixation test most widely available)
73
Why should be bother establishing a diagnosis for LRTI/CAP?
- optimise antibiotic selection
- limit the use of broad spectrum agents
- identify organisms of epidemiological significance
- identify antibiotic resistance and monitor trends
- identify new or emerging pathogens
74
How do you assess disease severity in CAP?
```
C onfusion
U rea > 7mmol/l
R espiratory rate > 30
B lood pressure
65 years
```
(give score of 1 for each feature present)
75
What do CURB-65 scores indicate?
score = 0 = low severity = treat at home
score = 1 = low severity = home
score = 2 = moderate = treat in hospital
score = 3-5 = high = treat in hospital: assess for ITU admission
(This must be use in conjunction with clinical judgement)
76
You would do ABC management for CAP as well as with any unwell or septic patient. What does A involve?
Airway
Ensure an open, patent and maintained airway
77
You would do ABC management for CAP as well as with any unwell or septic patient. What does B involve?
Breathing
Asses respiratory rate and saturations
Provide supplemental oxygen to reach prescribed target
78
You would do ABC management for CAP as well as with any unwell or septic patient. What does C involve?
Circulation
Assess blood pressure and heart rate
Gain IV access to give IV fluids if haemodynamically unstable
79
What should you do after ABC when managing a CAP patient?
Prompt empirical antibiotic therapy
80
Give some presentative methods against LRTIs?
- pneumococcal vaccination (S. pneumoniae)
| - influenza vaccination for vulnerable groups (annually)
81
Who would you give a pneumococcal vaccination to?
- patients with chronic heart, lung and kidney disease
- patients with splenectomy
- may repeat after 5 years in certain populations
82
Who would you give an influenza vaccination to?
- over 65s
| - chronic disease, multiply co-morbidities
