Lower Respiratory Tract Infections Flashcards Preview

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Flashcards in Lower Respiratory Tract Infections Deck (36):
1

What are the predisposing factors to LRTI?

- Loss or suppression of cough reflex / swallow

   - e.g. stroke, coma, ventilation

- Ciliary defects e.g. PCD

- Mucus disorders e.g. CF

- Pulmonary oedema – fluid flooding alveoli

- Immunodeficiency: congenital or acquired (Multiple examples!)

- Macrophage function inhibition e.g. smoking

2

What are the different syndromes of LRTI?

- Bronchitis

- Bronchiolitis

- Pneumonia

3

What is acute bronchitis?

Inflammation & oedema of trachea and bronchi

 

4

What are the symptoms of acute bronchitis?

- Cough (typically dry), dyspnoea & tachypnoea

- Cough may be associated with retrosternal pain

5

What is the epidemiology of acute bronchitis?

Most frequent in winter, in children

6

What is the aetiology of acute bronchitis?

·Viruses are the usual cause (rhinovirus, coronavirus, adenovirus, influenza)

·Bacterial causes less common (H.influenzae, M.pneumoniae, B.pertussis)

7

How is the diagnosis of acute bronchitis performed?

–Diagnostic tests not indicated in mild presentations

–Vaccination & previous exposure history (e.g. influenza, B. pertussis) may exclude some organisms

–If needed, cultures of respiratory secretions may be helpful if looking for a specific cause, e.g. B. pertussis – but not routine

8

How is acute bronchitis treated?

–Supportive treatment for healthy patients

–Those with severe disease or co-morbidities may require oxygen therapy  or respiratory support

–Antibiotics only if bacterial cause is suspected or found

9

What is the definition of chronic bronchitis?

Cough productive of sputum on most days during at least 3 months of 2 successive years (which cannot be attributed to an alternative cause).

10

What is the epidemiology of chronic bronchitis?

- Affects 10-25% of adult population

- Most common in men and >40yrs

- Associated with smoking, pollution, allergens

11

What are the features of chronic bronchitis?

- If airflow obstruction present on spirometry = COPD

- Inflammation & oedema of airways is mediated by exogenous irritants (rather than infective agents)

- Patients have acute exacerbations mediated by same infective pathogens as acute bronchitis

12

What is bronchiolitis?

Inflammation and oedema of bronchioles

13

What is the epidemiology of bronchiolitis?

- Primarily young children

- Peaks in winter and early spring, in infants 2-10 months

14

What are the symptoms of bronchiolitis?

Acute onset wheeze, cough, nasal discharge, respiratory distress (grunting, retractions, nasal flaring)

15

What is the aetiology of bronchiolitis?

•Most commonly caused by RSV (75% of cases)

   - 80% children have evidence of previous RSV infection by 2yrs old

•Also caused by parainfluenza, adenovirus, influenza

16

How would you diagnose bronchiolitis?

-Chest x-ray

-Full blood count

-Microbiological diagnosis: usually nasopharyngeal aspirate of respiratory secretions  sent for viral PCR

17

How would you treat bronchioltis

-Supportive: oxygen, feeding assistance

-No clear evidence to support steroids, bronchodilators, ribavirin

-Antibiotics only if complicated by bacterial infection

18

What is pneumonia?

Infection affecting the most distal airways and alveoli

19

What are the two types of pneumonia (according to distribution)?

- Bronchopneumonia

- Characteristic patchy distribution centred on inflamed bronchioles & bronchi then subsequent spread to surrounding alveoli

- Lobar pneumonia

-Affects a large part, or the entirety of a lobe

-90% due to S.pneumoniae

20

What are the types of pneumonia according to acquisition?

•Community acquired pneumonia (CAP)

•Hospital acquired pneumonia (HAP)

-Pneumonia developing >48hrs after hospital admission

-Different causative organisms to CAP, especially if >5days after admission: enterobacteriaceae & Pseudomonas sp.

•Ventilator acquired pneumonia (VAP)

-Subgroup of HAP

-Pneumonia developing >48hrs after ET intubation & ventilation

•Aspiration pneumonia

-Subgroup of HAP

-Pneumonia resulting for the abnormal entry of fluids e.g. food, drinks, stomach contents, etc. into the lower respiratory tract

-Patient usually has impaired swallow mechanism

21

What is the epidemiology of CAP?

•Incidence of 1 per 100 people per year (common!)

•20-40% cases require hospital admission

•Peak age 50-70 years

•Peak onset midwinter to early spring

•Acquisition of organisms:

-Person-to-person or from a person’s existing commensals (S.pneumoniae, H.influenzae)

-From the environment (L. pneumophilia)

-From animals (C.psittaci) 

22

What organisms cause 'typical' pneumonia?

Streptococcus pneumoniae

Haemophilus influenzae

Moraxella  catarrhalis

Staphylococcus aureus

Klebsiella pneumoniae

23

What organisms cause 'atypical' pneumonia?

Mycoplasma pneumoniae

Legionella pneumophilia

Chlamydophila pneumoniae

Chlamydophila psittaci

Coxiella burnetii

24

What are the signs and symptoms of CAP?

•Symptoms

–Usually rapid onset

–Fever / chills

–Productive cough

–Mucopurulent sputum

–Pleuritic chest pain

–General malaise: fatigue, anorexia

•Signs

–Tachypnoea, tachycardia, hypotension

–Examination findings consistent with consolidation:

•Dull to percuss

•Reduced air entry, bronchial breathing

25

What is the clinical presentation of Mycoplasma pneumoniae pneumonia?

- Autumn epidemics every 4-8 years

- Commonest in children & young adults

- Main symptom is cough

- Diagnosis: serology (difficult to culture)

- Rare complications: pericarditis, arthritis, Guillain-Barre, peripheral neuropathy

26

What is the clinical presentation of Legionella pneumophilia pneumonia?

- Colonises water piping systems

- Outbreaks associated with showers, air conditioning units, humidifiers

- High fevers, rigors, cough: dry initially becoming productive, dyspnoea, vomiting, diarrhoea, confusion

- Bloods: deranged LFTs, SIADH (low sodium)

27

What is the clinical presentation of Chlamydophila pneumoniae pneumonia?

- 3-10% of CAP cases in adults

- Causes mild pneumonia or bronchitis in adolescents & young adults

- Incidence highest in the elderly – may experience more severe disease

28

What is the clinical presentation of Chlamydophila psittaci pneumonia?

- Associated with exposure to birds

- Consider in those with pneumonia, splenomegaly & history of bird exposure

- May also have rash, hepatitis, haemolytic anaemia, reactive arthritis

29

What is the usual presentation for infulenza infection?

–Fever, headache, myalgia, dry cough, sore throat

–Convalescence takes 2-3 weeks

30

What kind of patients usually get primary viral pneumonia?

Occurs more commonly in patients with pre-existing cardiac & lung disorders.

 

31

What is the clinical presentation of primary viral pneumonia?

–Cough, breathlessness, cyanosis

–Secondary bacterial pneumonia then may develop after initial period of improvement:

•S.pneumoniae, H.influenzae, S.aureus

32

What non-microbial investigations would you do in CAP?

•Routine observations: BP / pulse / oximetry

•Bloods: including FBC / U&E / CRP / LFTs

•Chest X-ray

33

What microbiological investigations would you perform in CAP?

–Sputum Gram stain & culture

–Blood culture

–Pneumococcal urinary antigen

–Legionella urinary antigen (if relevant)

34

What would you perform PCR or serology for?

• viral pathogens e.g. 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 – on blood)

35

What is a CURB 65 score?

A way of assessing the severity of pneumonia.

36

Who should recieve the pneumoncoccal vaccination?

–Patients with chronic heart, lung and kidney disease

–Patients with splenectomy

–May repeat after 5 years in certain populations

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