Respiratory Infections

Question 1

what are the types of respiratory infections?

Answer 1

Types of respiratory infections
Bronchitis: inflammation of the bronchi
Pneumonia: inflammation of alveoli, they become fluid filled.
Tuberculosis

Question 2

what are airway diseases where infection is large component?

Answer 2

Bronchiectasis: chronic dilation of the bronchi.
Cystic Fibrosis

Question 3

what are diseases where infections cause flare ups?

Answer 3

acute exacerbations of COPD or Asthma

Question 4

what is Bronchitis?
describe the 2 types

Answer 4

Bronchitis: inflammation of the bronchi
Acute bronchitis:
Happens in previously well people
Cough ± Sputum
Cause: usually viral infections
May be complicated by secondary bacterial infection
Patient usually recovers by themselves
Recurrent bronchitis:
Cough + Sputum over at least 2 months
Cause: usually bacterial infections
Look for underlying sinus infection, post-nasal drip and bronchiectasis

Question 5

what is Community acquired pneumonia (CAP)?
what are the types?

Answer 5

inflammation of alveoli, they become fluid filled.
typical and atypical pneumonia

Question 6

what is typical pneumonia?
symptoms?

Answer 6

1. Typical Pneumonia
   Patient has pre-existing disease
   E.g. lung disease that predisposes them to infection
   Abrupt onset (2-3 days)

Symptoms:
Purulent sputum (contains pus)
Pleuritic pain (when breathing in)
Marked systemic upset (high temperature, sweats, tachycardia etc.)
You may hear crackles or rubs in area of lung that is infected
Patients will respond to β-lactams (penicillin)

Question 7

what is atypical pneumonia?
symptoms?

Answer 7

Atypical Pneumonia:
Patient was previously well (no underlying lung disease)
Insidious onset (1-2wks)

Symptoms:
Dry cough,
Shortness of breath
Mild systemic upset
Wheeze
No response to β-lactams

Question 8

what is the aetiology of CAP?

Answer 8

Different pathogens will cause pneumonia (in table)
Pathogens causing typical pneumonia = Black
Pathogens causing atypical pneumonia = Red
Most common cause of pneumonia is Strep Pneumoniae pathogen

Atypical Pneumonia:
Mycoplasma:
↑ in winter
↑ in epidemics
Legionella:
Lives in damp cold water
Often found in pipes/taps - cause outbreaks
↑ in Sep/Oct
50% of infections are related to travel

Question 9

what do these chest x rays show?

Answer 9

Pathogens that cause typical pneumonia will cause lobar pneumonia 🡪 affect a particular lobe.
Look for opacity (white) over area of lobe infected:
Right upper lobe pneumonia [1]
Right middle lobe Pneumonia [2]:
Loss of right heart border
Right lower lobe pneumonia [3]:
loss of right hemi diaphragm
Left upper lobe Pneumonia with cavitation (air filled areas) (caused by TB, Klebsiella)
You can see black dots in area of inflammation
Left lower lobe pneumonia:
loss of diaphragm +/- heart border

Question 10

how do you assess the severity of CAP?

Answer 10

We assess the severity of CAP using the CURB score:
Confusion
Urea (↑ beyond normal)
Respiratory rate (↑)
BP (low)
65 (age >65)
Score 1-2 = safe for oral treatment antibiotics
Score >2 = iv antibiotics
Score ≥4 = intensive care

Question 11

how to manage CAP?

Answer 11

Non-severe cases: Oral antibiotics - amoxicillin or macrolide
Severe cases: IV antibiotics - iv co-amoxiclav and iv macrolide
In severe cases a combination of antibiotics are used if we are unsure if typical or atypical pneumonia to cover both typical and atypical pathogens
Antibiotic policies vary between hospitals and year to year (based on prevalence of organisms in that community).

Question 12

what are the complications of pneumonia?

Answer 12

Acute Respiratory failure
Lung abscess - Treated by using a longer antibiotic course or surgery to remove that infected area of the lung.
Parapneumonic effusion - Irritation of pleura in the area around the pneumonia can cause increase in fluid in pleural space.
Simple Parapneumonic Effusion - fluid in pleural space is sterile
Complex Parapneumonic Effusion - fluid in pleural space is infected with bacteria
Empyema - pus gathers in pleura space.
From simple to empyema:
↑ organisation of fluid
↑ thickening of pleura
Example of pleural fluid: opacity is not confined to a particular lobe

Question 13

Management of Empyema?

Answer 13

Antibiotics - penicillin, metronidazole
Drainage of fluid
Surgery - break down adhesions so you can clear fluid.
Decortication: use telescope to go in, break down adhesions and clear whole pleural lining out.

Question 14

what is tuberculosis?
symptoms?

Answer 14

TB is caused by Mycobacterium Tb
Predominantly effects the lungs (as transmitted through respiratory particles)
Symptoms (insidious onset):
Productive cough
Night sweats
Fever
Weight loss
Haemoptysis

Question 15

what two types can TB be?

Answer 15

TB can be active or latent
Latent TB:
Occurs once you have been exposed to TB
TB lives in lung but is not active - you will not experience any symptoms
Can become active in stress and immune suppressions

Question 16

risk factors for TB?

Answer 16

Immunosuppression
Poor nutrition – alcohol and drug abuse
Homelessness

Question 17

what does histology and CXR for TB show?

Answer 17

CXR: upper zone shadowing
Histology: Caseating Granulomas

Question 18

Diagnosis of TB?

Answer 18

Test sputum for acid fast bacilli (positive sign)
If lymph nodes are enlarged, aspirate them and send to lab:
Microbiology culture - acid fast bacilli (positive sign)
Histology - look for Caseating Granulomas
Perform bronchoscopy if patient not making sputum to obtain deep samples from within the lungs.
Test for HIV (because ↑ risk of getting TB)
Test Vitamin D levels
Low vitamin D levels were associated developing tuberculosis

Question 19

how does TB spread?

Answer 19

Can be spread by blood
Can spread into:
meninges (then into SC and brain)
musculoskeletal system
Genitourinary system
Gastrointestinal system
Pericardial system

Question 20

treatment of TB?

Answer 20

4 different antibiotics:
Isoniazid (H), pyrazinamide (Z), rifampicin (R), ethambutol (E)
Initially treatment is for two months with all four antibiotics
Then another 4/10 months with two antibiotics
If it is just lung or lymph nodes involved = 4 months
If it effects CNS = 10 months
Combination therapy is given to help avoid the pathogen developing resistance

Question 21

Problems with TB treatment:

Answer 21

Resistant bugs (MDR-TB + XDR-TB)
Drugs interactions
Side-effects (see below)
Hepatitis is a big worry, (inflammation of liver)
Because of SE, patients stop taking drugs so pathogen develops resistance.

Question 22

how to control the spread of TB?

Answer 22

↓ overcrowding
Better Nutrition, child health
Possible immunisation
Only immunise in areas of high incidence or if you come from outside UK from area of high incidence.
Chemoprophylaxis for latent TB –> 6 months isoniazid or 3 months isoniazid and rifampicin.
Done for patients who are at high risk of reactivation (e.g patients who are immune supressed).

Question 23

Airways diseases where infection is large component: what is Bronchiectasis?
cause?

Answer 23

Bronchiectasis: chronic dilation of the bronchi.
Cause: Recurrent or chronic infection - Chronic bronchial dilation (loss of elasticity) –> poor mucus clearance (allows mucus to pool) –> greater infection –> greater bronchial dilatation.
Infection is initiator and driver of disease

Question 24

what are the symptoms of Bronchiectasis?

Answer 24

Symptoms
Patients produce Large volumes of sputum coughing up everyday
You will hear Crackles in chest +/- clubbing of fingers

Question 25

aetiology of Bronchiectasis?

Answer 25

Aetiology:
Post-Infection (previous case of TB or Pneumonia) –> damaged airways –>… [cycle]
Recurrent Aspiration - Damage of bronchial airways
Mechanical obstruction (tumour) –> dilation of bronchi
Auto immune disease link –> Rheumatoid A, IBD
They cause damage to bronchial airways
Immune deficiency
Disease that causes poor mucociliary clearance:
CF
Primary ciliary dyskinesia.

Question 26

how to investigate Bronchiectasis?

Answer 26

CXR:
Difficult to see on CXR (only 50% sensitivity)
May be able to see cystic changes in the lung
See tramlines (where bronchi wall is dilated more than usual and is lined with mucus [white])
Sputum culture - identify organisms that cause Bronchiectasis
Gold standard –> CT scan

Question 27

Management of Bronchiectasis?

Answer 27

Damage is irreversible
Main Aim: Trying to clear phlegm from the lungs to prevent further damage
This can be done via:
Physiotherapy:
Huffing: a breathing technique to move mucus from smaller airways to larger airways
Flutter device: used to clear airways
Postural drainage: tilting the head down to clear secretions from the middle and lower lobes
Bronchodilators:
Inhalers that cause bronchodilation to keep airways open to release sputum collecting there.
Antibiotics:
Acute infection: patient given 10-14 days course
Chronic infection: patient given long term antibiotics
Long term antibiotics target pseudomonas aeruginosa
They can be nebulised or inhaled colomycin or tobramycin
Oral macrolides

Question 28

what is cystic fibrosis?

Answer 28

Autosomal recessive condition.
Mutation giving defect in CFTR gene –> abnormal membrane chloride channel –> less water, giving stickier mucus.
This causes impaired muscus clearance –> damage to airways –> bronchiectasis
CF is a common cause of bronchiectasis

Question 29

investigations and treatment for CF?

Answer 29

Investigations:
Genetic testing to look for mutation
Sweat test - abnormal composition of chloride ions in sweat

Treatment:
Aggressive management of bronchiectasis by early physiotherapy (2x daily)
Lung transplantation
Advances in drug that target defect in CFTR to help lung function
Pancreatic enzyme supplements
Insulin

Question 30

what are diseases where infections cause flare ups?

Answer 30

When you have underlying lung disease and infection causes exacerbations
COPD

Question 31

what are the exacerbations in COPD?

Answer 31

Caused by infections
Leads to
↑ breathlessness
↑ sputum volume
Green sputum
Additional features:
sore throat, nasal discharge, unexplained fever, ↑ wheeze, ↑ cough ↑ respiratory rate, ↑ heart rate.

Question 32

Treatment for COPD?

Answer 32

For green sputum –> 5-day course of antibiotics
Patient can go home
More severe exacerbations –> 5-day course of steroids (prednisolone)
patient usually admitted into hospital.

Question 33

how to assess severity of exacerbations of COPD?

Answer 33

We asses the severity of COPD via:
Chest x rays - evidence of pneumonia
Blood gasses - if stats less 92% patient at risk of respiratory failure
ECG - risk of MI
DECAF score - predicts mortality
D – dyspnoea (breathless) score
E – low eosinophil (immune suppression)
C – is there consolidation
A – is there acidosis (marker of acute type 2 respiratory failure)
F – Atrial fibrillation –> cardiac compromise

Question 34

what are exacerbations in asthma?

Answer 34

due to infections
Infection is often viral or allergic (but can be bacterial)
Managed similar to exacerbations of COPD, but with greater emphasis on steroid use
Monitor PEFR (use diaries) to asses severity of exacerbations.
If hospitalised, must be 24 hours without using nebulisers before can go home