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Clinical Pathology G > Lower respiratory disease > Flashcards

Lower respiratory disease Flashcards

1
Q

What are the 4 causes of pneumonia?

A

Community acquired
Hospital acquired
Ventilator acquired
Aspiration

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2
Q

What are some 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

Macrophage function inhibition e.g. smoking

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3
Q

What are some bacteria that cause LRTIs?

A
  • Streptococcus pneumoniae
  • Haemophilus influenzae
  • Staphylococcus aureus
  • Klebsiella pneumonia
  • Mycoplasma pneumoniae
  • Chlamydophila pneumoniae
  • Legionella pneumophila
  • Mycobacterium tuberculosis
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4
Q

What are some viruses that cause LRTIs?

A
  • Influenza
  • Parainfluenza
  • Respiratory syncytial virus
  • Adenovirus
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5
Q

What are some fungi that cause LRTIs?

A
  • Aspergillus sp.
  • Candida sp.
  • Pneumocystitis jiroveci
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6
Q

What are the different syndromes of LRTI?

A

bronchitis, bronchiolitis, pneumonia

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7
Q

What is acute bronchitis?

A

Inflammation & oedema of trachea and bronchi
Cough (typically dry), dyspnoea & tachypnoea
Cough may be associated with retrosternal pain

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8
Q

What are the causes of 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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9
Q

How is acute bronchitis diagnosed?

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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10
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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11
Q

What is chronic bronchitis and who does it generally affect?

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)

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

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12
Q

What is the pathology behind chronic bronchitis?

A

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

If airflow obstruction present on spirometry = COPD

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13
Q

What is bronchiolitis and hat are the symptoms?

A

Inflammation and oedema of bronchioles

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

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14
Q

Who does bronchiolitis typically affect?

A

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

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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15
Q

How is bronchiolitis diagnosed?

A

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

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16
Q

How is bronchiolitis treated?

A

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

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17
Q

What is pneumonia?

A

Infection affecting the most distal airways and alveoli

Formation of inflammatory exudate

18
Q

What are the two anatomical patterns of pneumonia?

A

Bronchopneumonia and Lobar pneumonia

19
Q

What are the features of bronchopneumonia?

A

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

20
Q

What are the features of lobar pneumonia?

A

Affects a large part, or the entirety of a lobe

90% due to S.pneumoniae

21
Q

How do you define hospital acquired pneumonia (HAP)?

A

Pneumonia developing >48hrs after hospital admission

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

22
Q

How do you define ventilator acquired pneumonia (VAP)?

A

Subgroup of HAP

Pneumonia developing >48hrs after ET intubation & ventilation

23
Q

How do you define aspiration pneumonia?

A

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

24
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)
25
Q

How are the bacterial causes of CAP divided?

A

Bacterial causes often divided into ‘typical’ and ‘atypical’

‘Atypical pneumonia’ traditionally described 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 – still considered in a separate group as clinical presentation and treatment is slightly different

26
Q

What are typical organisms that cause CAP?

A 
Streptococcus pneumoniae
Haemophilus influenzae
Moraxella  catarrhalis
Staphylococcus aureus
Klebsiella pneumoniae
27
Q

What are atypical organisms that cause CAP?

A 
Mycoplasma pneumoniae
Legionella pneumophilia
Chlamydophila pneumoniae
Chlamydophila psittaci
Coxiella burnetii
28
Q

What are the symptoms of pneumonia?

A 
Usually rapid onset
Fever / chills
Productive cough 
Mucopurulent sputum
Pleuritic chest pain
General malaise: fatigue, anorexia
29
Q

What are the signs of pneumonia?

A

Tachypnoea, tachycardia, hypotension
Examination findings consistent with consolidation:
Dull to percuss
Reduced air entry, bronchial breathing

30
Q

What is the clinical presentation of pneumonia caused by mycoplasma pneumoniae?

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

31
Q

What is the clinical presentation of pneumonia caused by legionella pneumophilia?

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)

32
Q

What is the clinical presentation of pneumonia caused by chlamydophila pneumoniae?

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

33
Q

What is the clinical presentation of pneumonia caused by Chlamoydophila psittaci?

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

34
Q

What is the clinical presentation of influenza?

A

Fever, headache, myalgia, dry cough, sore throat

Convalescence takes 2-3 weeks

35
Q

What is the clinical presentation of primary viral pneumonia?

A

Primary viral pneumonia occurs more commonly in patients with pre-existing cardiac & lung disorders

Cough, breathlessness, cyanosis

Secondary bacterial pneumonia then may develop after initial period of improvement:
S.pneumoniae, H.influenzae, S.aureus

36
Q

How is primary viral pneumonia diagnosed?

A

viral antigen detection in respiratory samples using PCR

37
Q

What are some non-microbiological investigations for CAP?

A

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

38
Q

What are the microbiological investigations for inpatients with CAP?

A

Sputum Gram stain & culture

Blood culture

Pneumococcal urinary antigen

Legionella urinary antigen

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)
39
Q

Why should we bother establishing a diagnosis?

A

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

40
Q

What schemes are in place for prevention of LRTIs?

A

Pneumococcal vaccination (S. pneumoniae)

  • Patients with chronic heart, lung and kidney disease
  • Patients with splenectomy
  • May repeat after 5 years in certain populations

Influenza vaccination for vulnerable groups (annually)

  • Over 65s
  • Chronic disease, multiple co-morbidities
41
Q

How is disease severity of CAP assessed?

A

CURB65 score for pneumonia

Confusion
Urea
Resp rate
BP

Age

(If 2 or more of these factors is a problem, admit to hospital)

Clinical Pathology G (23 decks)

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