Respiratory Infections Flashcards
What is croup?
AKA laryngotracheobronchitis
This is a type of URTI usually caused by a virus, that causes a ‘barking’ cough, stridor and a hoarse voice. It usually only lasts 1 or 2 days
Name some signs of consolidation
- Increased vocal resonance
- Bronchial breathing
- Crackles on auscultation
- Dull on percussion
- Reduced chest expansion on affected side
How can strep. pneumonia be classified?
GRAM POSITIVE DIPLOCOCCI
What are the main organisms causing typical community-acquired pneumonia?
- Strep. pneumonia
- H. influenzae
- Morazella catarhallis
- Klebsiella
What are the main organisms causing atypical community-acquired pneumonia?
- Mycoplasma (particularly in young)
- Chlamydia
- Legionella
What are the symptoms of typical pneumonia?
Pyrexia, tachycardia, pleuritic pain, severe SOB, painful cough with rusty sputum
What are the symptoms of atypical pneumonia?
Moderate fever, relative bradycardia, no pleurisy, variable consolidation, dry cough
(also may have diarrhoea, erythema multiform, myalgia etc)
What is nosocomial pneumonia and how is it caused?
Hospital-acquired pneumonia (48h after admission), caused by:
- Oropharyngeal colonisation
- Predispositions eg. antacids, antibiotics, biofilms
- Ventilator associated e.g. pseudomonas aeruginosa, S.aureus
How can pneumonia be diagnosed clinically?
- Cough, fever and at least 1 other LRTI symptom
- New focal signs on chest exam (or radiographic features if CXR available)
- No other explanation for illness
How is the severity of CAP assessed using a specific tool?
CURB65
C - new onset confusion (AMTS score less than 8/10)
U - urea > 7mmol/l
R - respiratory rate > 29/min
B - diastolic blood pressure <60mmHg or SBP<90mmHG
Aged over 65
ALSO, hypoxaemia (<90%02), involvement of 2 or more lobes, and pre existing disease
How is CAP treated? (CURB65 3-5)
Amoxicillin (covers pneumococcus) and clarithromycin (covers atypical pathogens)
If staphylococcus is suspected, add flucloxacillin
How is severe CAP with sepsis treated ?
Pip/tazo - tazo is a beta lactamase inhibitor so allows a dual action
Under new guidelines:
Co-amoxiclav IV
Clarithromycin IV
How is HAP treated?
Pip/tazo
What are the symptoms of bronchitis?
Cough & other upper airway symptoms
NB - no consolidation on CXR
Is bronchitis usually viral or bacterial?
Viral - seldom needs hospital admission
What is the difference between bronchitis and bronchiectasis?
Bronchiectasis is a CHRONIC condition, due to repeated lung infections, causing irreversible WIDENING of the bronchi.
Bronchitis is inflammation of the bronchi, causing NARROWING.
Which diseases are associated with bronchiectasis?
Cystic fibrosis Youngs syndrome Pneumonia Immunodeficiency Rheumatological diseases IBD Bronchial obstruction and infection - TB
What are the symptoms of a lung abscess?
Weight loss, fever, non-specific
Clubbing
Commonly presents after pneumonia
Looks like an egg-shaped mixture of pus and gas on CXR
How is a lung abscess treated?
DRAIN FIRST
Then 8 weeks or more broad-spectrum abx
What is an empyema?
Pus in the pleural space that needs draining
What causes TB?
Mycobacterium tuberculosis
What percentage of people exposed and infected by TB will develop primary TB?
5%, the other 95% will have latent TB which will then reactivate
What are the symptoms of TB?
EARLY - Weight loss, fatigue, night sweats
LATE - Cough, haemopytsis, breathlessness, chest pain
MUCH LATER - bronchiectasis, fibrosis
You can get extra pulmonary features but these are much more likely in the IMMUNOSUPPRESSED
How is active TB investigated?
Chest X-ray (shows little, except miliary TB is dispersed)
Histology (caseating granuloma)
Microscopy and sputum culture (acid fast bacilli on ziehl-nielsen stain)
Contact tracing
How is latent TB tested?
Interferon-gamma release assays - skin test
Why does secondary TB occur in the immunosuppressed?
Normally the immune response keeps the mycobacteria inside the granuloma, but when it breaks down the bacteria is released and proliferates
How is active TB treated?
4 antibiotics (RIPE):
- Rifampicin (6 months)
- Isoniazid (6 months)
- Pyrazinamide (2 months)
- Ethambutamol (2 months)
NB - after 2 weeks they won’t be contagious anymore
What is the prophylactic treatment of TB?
BCG, attenuated strain of bacteria (following mantoux test)
In which case is a patient likely to get military TB?
Immunosuppressed at time of infection - they are unable to control the bacteria so it disperses.
How is CAP (CURB65 0-2) treated ?
Amoxicillin oral/IV
What are the core symptoms of epiglottitis?
Sore throat Breathlessness, that is eased on sitting forward Drooling Stridor Pain on swallowing Fever
Epiglottitis is a medical emergency - what should be done?
A-E assessment; if acute airway obstruction call an anaesthetist to INTUBATE the patient for O2 delivery.
NB - dont put in airways, they won’t work, and dont give a mask to a child as it will frighten them
After this, do Xray and give broad spectrum abx
What organism usually causes a sore throat
Strep A (pyogenes)
What organism usually causes epiglottitis?
Haemaphilius Influenzae B (Hib)
Which organism is most likely to cause empyema?
Klebsiella
If you suspect an empyema in the lungs, what investigations should be performed?
Before draining the empyema you must do:
- Ultrasound to look at site and amount of pus
- FBC (esp clotting factors and platelets) prior to needle insertion
After draining, give IV antibiotics
Which risk factors in a patient make them more likely to have pneumonia caused by klebsiella?
Diabetes
Alcohol excess
Immunocompromised
If a pleural effusion contains transudate what does this mean?
Transudate = low protein = disturbances in pressure caused by organ failure
If a pleural effusion contains exudate what does this mean?
Exudate = high protein = leaky capillaries from inflammation
Below what pH pleural fluid is empyema suspected?
7.2
What is aspiration pneumonia?
Bronchopneumonia that develops due to the entrance of foreign materials into the bronchial tree,[1] usually oral or gastric contents (including food, saliva, or nasal secretions)
It is often caused by an incompetent swallowing mechanism, such as occurs in some forms of neurological disease or injury including multiple sclerosis, CVA (stroke), Alzheimer’s disease or intoxication. An iatrogenic cause is during general anaesthesia for an operation and patients are therefore instructed to be nil per os (abbrev. as NPO), i.e. nothing by mouth, for at least four hours before surgery.
If a patient with COPD is not responding to oxygen, what step should be taken?
Non-invasive ventilation
What is the treatment for acute exacerbation of COPD?
1st line - Doxycycline for 5 days
2nd line - Trimethoprim for 5 days
What are the CENTOR criteria
A patient is likely to have bacterial tonsillitis if they have 3/4 of:
- Tonsillar exudate
- Tender glands
- Absence of cough
- Fever >38C
When should a sputum sample be taken from a patient with suspected TB?
Morning
What is lobar pneumonia and what are the risk factors?
Unilateral pneumonia, limited by anatomical boundaries, that starts distally and spreads inwards
RF: males, middle age, healthy
What is the most common pathogen in lobar pneumonia?
Strep. pneumonia
What is bronchopneumonia and what are the risk factors?
Bilateral patchy pneumonia around the small airways, not limited by anatomical boundaries
RF: extremes of age
What are the most common pathogens in bronchopneumonia?
Strep. pneumonia, H. influenza, Staph. aureus
What are the stages of lobar infection by strep. pneumonia?
- Congestion - lung parenchyma is partially consolidated with fluid, vascular enlargement
- Red hepatization/consolidation - red blood cells, neutrophils and fibrin form an exudate that fills the alveolar space
- Grey hepatization - red cells leave, but others stay
- Resolution - exudate cleared by macrophages and cough
What is consolidation?
When alveoli are filled with the products of disease (exudate), rather than air
What are the complications of pneumonia?
- Respiratory failure
- Hypotension (due to dehydration and vasodilatation)
- Atrial fibrillation (temporary)
- Pleural effusion (fluid exudation into pleural space)
- Empyema
- Lung abscess
- Sepsis