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YR3 Respiratory > Infectious lung disease- Aspergillosis, pneumonia > Flashcards

Infectious lung disease- Aspergillosis, pneumonia Flashcards

1
Q

Define Aspergillus Lung Disease and its 5 potential pulmonary manifestations depending on patient status

A

The clinical presentation of Aspergillus lung disease is determined by the interaction between fungus and host.

  1. Allergic bronchopulmonary aspergillosis
    • ​Hypersensitivity reaction to Aspergillus antigens
    • Typically seen in patients with asthma/C
  2. Aspergilloma (fungal ball)
    • Occurs in pre-existing lung cavities
    • commonly 2/2 tuberculosis/sarcoidosis
  3. Invasive aspergillosis
    • Invasion of hyphae to pulmonary parenchyma + spread to multiple organ sites
    • in severly immunocompromised individuals
  4. Chronic necrotising aspergillosis
    • indolent destructive process in patients without obvious immune compromise
    • With lung disease (COPD, pneumoconiosis, CF)
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2
Q

Define aspergilloma

A

Growth of an A. fumigates mycetoma ball in a pre-existing lung cavity (e.g. post-TB/sarcoidosis, old infarct or abscess)

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3
Q

Explain the pathogenesis of allergic bronchopulmonary aspergillosis (ABPA)

A
  • Colonisation of the airways by Aspergillus fumigatus → IgE and IgG-mediated immune responses
  • Asthmatics and CF patients
  • The release of proteolytic enzymes, mycotoxins and antibodies → airway damage
  • Causes bronchoconstriction + permanent damage (bronchiectasis)
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4
Q

Explain the pathogenesis of invasive aspergillosis

A

Inhalation of conidia in immunocompromised patients leads to colonisation in lung tissue

  • can disseminate to multiple organ sites via the haematogenous route
  • commonly occurs into the brain and skin, leading to tissue infarction at those sites.
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5
Q

Summarise the epidemiology of the 4 aspergillus lung diseases

A

uncommon

Allergic bronchopulmonary aspergillosis

⇒ asthmatics

⇒ CF

Invasive aspergillosis

⇒ immunocompromised- neutropaenic, steroids, AIDS

Chronic (necrotising) aspergillosis

⇒ COPD, pneumoconiosis, CF

⇒ no significant immunocompromise

Aspergilloma

⇒ TB, sarcoidosis

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6
Q

Recognise the presenting symptoms of Aspergillus lung disease

A

INVASIVE ASPERGILLOSIS

  • pleuritic chest pain due to peripheral lesions in lung
  • pleural rub
  • nasal ulcer, skin rash(es)- erythematous, slightly tender, raised lesion, with a necrotic, often ulcerated, centre (ecthyma gangrenosum)
  • dry cough
  • headache/seizure - intercranial disease
  • haemoptysis- can be severe

ASPERGILLOMA

  • haemoptysis- erosion of lesion into bronchial vessels
  • fever/malaise/weight loss
  • may be asymptomatic

ALLERGIC BRONCHOPULMONARY ASPERGILLOSIS

  • Difficult to control asthma
  • Recurrent episodes of pneumonia with wheeze, cough, sputum, dyspnoea, fever and malaise
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7
Q

Identify appropriate investigations for Aspergillus lung disease

A

Chest X-ray

  • Allergic Bronchopulmonary aspergillosis- consolidation, distended, mucus-filled bronchi
  • Invasive aspergillosis- nodules, consolidation, non-specific infiltrates, ground glass opacities, pleural effusion
  • Aspergilloma- round mass with crescent of air + adjacent pleural thickening

CT chest

  • as for CXR, just more sensitive
  • may need brain + sinuses in IA to check for spread

Cytology/histology

  • Sputum culture- may be negative in aspergilloma as no communication with bronchial tree
  • Bronchoalveolar lavage
  • Tissue culture- biopsy = DIAGNOSTIC

Serology

  • EIA- aspergillus GM antigen (lavage or serum)
  • IgG antibodies to Aspergillus
  • FBC- eosinophilia
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8
Q

Describe + explain the appearance of invasive aspergillosis on CT

A
  • Nodules surrounded by a ground-glass appearance (halo sign)
  • This is caused by haemorrhage into the tissue surrounding the fungal invasion
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9
Q

Define pneumonia

A

Infection + inflammation of the distal lung parenchyma with consolidation or interstitial lung infiltrates

Categorised according to causative organism

note- consolidation = refers to build up of denser material in alveoli + terminal bronchioles

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10
Q

Explain some of the different categories of penumonia

A
  • Community acquired pneumonia (CAP)
  • Hospital acquired pneumonia (HAP)
  • Viral pneumonia
  • Aspiration pneumonia
  • Pneumonia in the immunocompromised
  • Atypical (Mycoplasma, Chlamydia, Legionella)
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11
Q

State the most common typical + atypical causative organisms for CAP

A

TYPICAL (80%)

  1. Streptococcus pneumoniae = most common
  2. Haemophilus influenzae = 2nd most, adults
  3. Staphylococcus aureus (including MRSA)
  4. Group A streptococci
  5. Moxarella catarrhalis = COPD patients

ATYPICAL (20%)

  1. Mycoplasma pneumoniae
  2. Chlamydophila pneumoniae
  3. Legionella pneumophila
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12
Q

Most common causative organims for viral CAP?

A
  • Influenza A/B
  • Respiratory syncytial virus
  • Adenovirus
  • Rhinovirus
  • Coronavirus
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13
Q

Which pneumonia can be caused by air conditioning?

A

Legionella

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14
Q

Which pneumonia causes Q fever?

A

Coxiella burnetii

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15
Q

What are the requirements for a pneumonia to be hospital acquired?

A

Acquired after at least 48 hours of admission to hospital and is not incubating at the time of admission

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16
Q

What are the most common causative organisms for HAP?

A

Early onset HAP (<5days) most likely Streptococcus pneumoniae (commonest also in CAP)

Late onset HAP >5 days = caused by microorganisms acquired in hospital:

  • MRSA
  • Pseudomonas aeruginosa
  • E. coli
  • Klebsiella pneumoniae

GRAM NEGATIVE

17
Q

State some patient groups that may suffer from aspiration pneumonia

A

Commonly occurs in patients with altered mental status who have an impaired gag or swallowing reflex.

Inhalation into lower airways → lung injury → bacterial infection

  • stroke
  • myasthenia
  • bulbar palsies
  • oesophageal disease
  • poor dental hygiene
18
Q

Which pathogens may be responsible for penumonia in the immunocompromised?

A
  • Strep pneumoniae aka pneumococcus
  • Fungal + parasitic infections may occur
  • H. Influenza
  • RSV
19
Q

Most common CAP causative organisms?

A
  • Haemophilus influenzae
  • Staphylococcus aureus (including MRSA)
  • group A streptococci
  • Moxarella catarrhalis
  • Mycoplasma pneumoniae
  • Chlamydophila pneumoniae
  • Legionella pneumophila
20
Q

State some risk factors for CAP

A
  • age >65 years
  • residence in a healthcare setting
  • COPD + other pre-existing lung disease
  • smoking
  • intubation + mechanical ventilation
  • alcohol abuse
  • poor oral hygiene
    • Bacteria in dental plaques are shed into the saliva and aspirated into the LRT causing infection.
  • immunodeficiency, chronic disease
  • contact with children + patients with pneumonia
21
Q

Summarise the epidemiology of pneumonia

A

Globally LRTIs are the most deadly disease- 3 million deaths p/a

Incidence of CAP appears to be significantly higher in men than in women.

HAP is more common in ICU patients + those who have recently had major surgery, and those who have been in hospital for a long time

22
Q

What are the presenting symptoms of pneumonia?

A
  • Cough with increasing sputum production
    • usually thick yellow/green
  • Dyspnoea
  • Pleuritic chest pain
  • Fever/rigors
  • Confusion
  • Malaise/anorexia
  • Haemoptysis
23
Q

What are the signs of pneumonia on examination?

A
  • Tachypnoea
  • Tachycardia
  • Cyanosis
  • Asymmetrical chest expansion
  • Diminished resonance on percussion
  • On auscultation:
    • Crackles/rhonci
    • Increased vocal resonance (99)
    • Increased tactile vocal fremitus
  • Confusion and may be hypothermic – elderly
24
Q

Identify appropriate investigations for pneumonia

A

Bloods:

  • LFTs
  • U+Es
    • CKD = poor prognostic factor
  • CRP
    • >100 mg/L makes pneumonia likely
    • <20 mg/L makes penumonia highly unlikely
  • FBC
    • Leukocytosis
    • WBC count > 15 x109/L indicates a bacterial aetiology
  • ABG

Cultures:

  • Sputum/pleural fluid MC+S
  • Urine MC+S- pneumococcal + legionella urine antigen tests
  • Blood cultures
  • Bronchoalveolar lavage
  • PCR/viral serology - if unresponsive to Abx

Imaging:

  • CXR- 1st line
    • shows consolidation
  • CT if CXR unclear/diagnostic uncertainty
25
Q

What is the name of the scoring system for assessment of the severity of penumonia?

A

CURB-65

1 point for each:

  • Confusion – abbreviated mental test <8
  • Urea >7mmol/l
  • RR > 30
  • BP < 90 systolic and/or 60 diastolic
  • Age >65

0 – 1: home treatment if possible

2: hospital therapy

3 or more: severe pneumonia – consider ICU

26
Q

How is pneumonia treated?

A

1: Supportive:

  • O2 if SaO2 = <94% (COPD<88%)
  • CPAP, BiPAP or ITU care for ARDS
  • IV fluid resuscitation
  • Vasopressors- if in shock/hypotension
  • Analgesia (IV paracetamol)

2: Start broad spectrum empirical antibiotics

  • If clinical diagnosis, whilst waiting for blood cultures
  • Mild: oral amoxicillin
  • Moderate: IV/oral amoxicillin + clarithromycin
  • Severe: IV co-amoxiclav + clarithromycin

3: Immediately order CXR

  • Confirm diagnosis

4: Switch from empirical antibiotics to pathogen-targeted antibiotics as soon as specific pathogens are identified

27
Q

Which Abx do you do to treat aspiration pneumonia?

A

cephalosporin IV + metronidazole IV

28
Q

State some indicators of clinical instability that prevent discharge

A

Fever in past 48hrs or >1 of:

  • SBP <90 mmHg
  • HR >100/minute
  • RR >24/minute
  • Arterial SaO2 <90% or PaO2 <60 mmHg in room air.
29
Q

State some preventative measures for pneumonia. What groups are eligable for these measures?

A
  • Pneumococcal vaccine
  • Haemophilus influenzae type B vaccine

These are only usually given to high risk groups (e.g. elderly, splenectomy)

30
Q

Identify the possible complications of pneumonia

A

RESP

  • Pleural effusion
  • Pneumothorax
  • Empyema (pyothorax)
  • Necrotising pneumonia
  • Localised suppuration (e.g. abscess)
    • Symptoms of abscesses:
      • Swinging fever
      • Persistent pneumonia
      • Copious/foul-smelling sputum
  • ARDS

SYSTEMIC

  • Septic shock
  • Acute renal failure

CARDIAC

  • Pericarditis
  • Arrhythmias
  • ACS
  • HF
31
Q

Summarise the prognosis for patients with pneumonia

A

Most resolve within treatment within 1-3 weeks

For patients admitted to hospital, mortality = 5-15%

Risk factors associated with increased 30-day mortality:

  • bacteraemia
  • admission to the ICU (20-50% mortality)
  • comorbidities (cardiovascular, pulmonary, or neurological disease)
  • infection with multidrug-resistant pathogen (S. aureus, P. aeruginosa, Enterobacteriaceae)
32
Q

Which bacterial pneumonia is the most common? Patients at risk?

A

Common in elderly, alcoholics, post-splenectomy, immune-suppressed, patients with HF/lung

33
Q

Which pneumonia can complicate influenza? How is it treated?

A

Staphylococcal

  • Bilateral cavitating bronchopneumonia
  • Tx: flucloxacillin +/- rifampicin

YR3 Respiratory (6 decks)

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