Respiratory Infections Flashcards
what are the types of respiratory infections?
Types of respiratory infections
Bronchitis: inflammation of the bronchi
Pneumonia: inflammation of alveoli, they become fluid filled.
Tuberculosis
what are airway diseases where infection is large component?
Bronchiectasis: chronic dilation of the bronchi.
Cystic Fibrosis
what are diseases where infections cause flare ups?
acute exacerbations of COPD or Asthma
what is Bronchitis?
describe the 2 types
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
what is Community acquired pneumonia (CAP)?
what are the types?
inflammation of alveoli, they become fluid filled.
typical and atypical pneumonia
what is typical pneumonia?
symptoms?
- 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)
what is atypical pneumonia?
symptoms?
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
what is the aetiology of CAP?
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
what do these chest x rays show?
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
how do you assess the severity of CAP?
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
how to manage CAP?
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).
what are the complications of pneumonia?
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
Management of Empyema?
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.
what is tuberculosis?
symptoms?
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
what two types can TB be?
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
risk factors for TB?
Immunosuppression
Poor nutrition – alcohol and drug abuse
Homelessness
what does histology and CXR for TB show?
CXR: upper zone shadowing
Histology: Caseating Granulomas
Diagnosis of TB?
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
how does TB spread?
Can be spread by blood
Can spread into:
meninges (then into SC and brain)
musculoskeletal system
Genitourinary system
Gastrointestinal system
Pericardial system
treatment of TB?
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
Problems with TB treatment:
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.
how to control the spread of TB?
↓ 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).
Airways diseases where infection is large component: what is Bronchiectasis?
cause?
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
what are the symptoms of Bronchiectasis?
Symptoms
Patients produce Large volumes of sputum coughing up everyday
You will hear Crackles in chest +/- clubbing of fingers
