Lower Respiratory Tract Infections Flashcards

1
Q

What are the predisposing factors to LRTI?

A
  • 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
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2
Q

What are the different syndromes of LRTI?

A
  • Bronchitis
  • Bronchiolitis
  • Pneumonia
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3
Q

What is acute bronchitis?

A

Inflammation & oedema of trachea and bronchi

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4
Q

What are the symptoms of acute bronchitis?

A
  • Cough (typically dry), dyspnoea & tachypnoea
  • Cough may be associated with retrosternal pain
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5
Q

What is the epidemiology of acute bronchitis?

A

Most frequent in winter, in children

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6
Q

What is the aetiology of acute bronchitis?

A

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

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

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7
Q

How is the diagnosis of acute bronchitis performed?

A

–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

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8
Q

How is acute bronchitis treated?

A

–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

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9
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).

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10
Q

What is the epidemiology of chronic bronchitis?

A
  • Affects 10-25% of adult population
  • Most common in men and >40yrs
  • Associated with smoking, pollution, allergens
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11
Q

What are the features of chronic bronchitis?

A
  • 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
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12
Q

What is bronchiolitis?

A

Inflammation and oedema of bronchioles

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13
Q

What is the epidemiology of bronchiolitis?

A
  • Primarily young children
  • Peaks in winter and early spring, in infants 2-10 months
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14
Q

What are the symptoms of bronchiolitis?

A

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

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15
Q

What is the aetiology of bronchiolitis?

A

•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

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16
Q

How would you diagnose bronchiolitis?

A
  • Chest x-ray
  • Full blood count
  • Microbiological diagnosis: usually nasopharyngeal aspirate of respiratory secretions sent for viral PCR
17
Q

How would you treat bronchioltis

A
  • Supportive: oxygen, feeding assistance
  • No clear evidence to support steroids, bronchodilators, ribavirin
  • Antibiotics only if complicated by bacterial infection
18
Q

What is pneumonia?

A

Infection affecting the most distal airways and alveoli

19
Q

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

A
  • 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
Q

What are the types of pneumonia according to acquisition?

A
  • 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
Q

What is the epidemiology of CAP?

A
  • 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
Q

What organisms cause ‘typical’ pneumonia?

A

Streptococcus pneumoniae

Haemophilus influenzae

Moraxella catarrhalis

Staphylococcus aureus

Klebsiella pneumoniae

23
Q

What organisms cause ‘atypical’ pneumonia?

A

Mycoplasma pneumoniae

Legionella pneumophilia

Chlamydophila pneumoniae

Chlamydophila psittaci

Coxiella burnetii

24
Q

What are the signs and symptoms of CAP?

A

•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
Q

What is the clinical presentation of Mycoplasma pneumoniae pneumonia?

A
  • 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
Q

What is the clinical presentation of Legionella pneumophilia pneumonia?

A
  • 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
Q

What is the clinical presentation of Chlamydophila pneumoniae pneumonia?

A
  • 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
Q

What is the clinical presentation of Chlamydophila psittaci pneumonia?

A
  • 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
Q

What is the usual presentation for infulenza infection?

A

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

–Convalescence takes 2-3 weeks

30
Q

What kind of patients usually get primary viral pneumonia?

A

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

31
Q

What is the clinical presentation of primary viral pneumonia?

A

–Cough, breathlessness, cyanosis

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

•S.pneumoniae, H.influenzae, S.aureus

32
Q

What non-microbial investigations would you do in CAP?

A
  • Routine observations: BP / pulse / oximetry
  • Bloods: including FBC / U&E / CRP / LFTs
  • Chest X-ray
33
Q

What microbiological investigations would you perform in CAP?

A

–Sputum Gram stain & culture

–Blood culture

–Pneumococcal urinary antigen

–Legionella urinary antigen (if relevant)

34
Q

What would you perform PCR or serology for?

A
  • 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
Q

What is a CURB 65 score?

A

A way of assessing the severity of pneumonia.

36
Q

Who should recieve the pneumoncoccal vaccination?

A

–Patients with chronic heart, lung and kidney disease

–Patients with splenectomy

–May repeat after 5 years in certain populations