LRTIs And Pneumonia Flashcards
Who do LRTIs affect and how bad are they?
95% of LRTIs are to those >65yrs
World wide biggest cause of death in the elderly
Which microbiota affect the respiratory tract?
Common - viridans streptococci, neisseria Spp (multiple species), anaerobes Candida Sp
Less common: Streptococcus pneumoniae, Haemophilus influenza
Other: pseudomonas, E.coli
Majority get through microaspirations in alveolar
Defences of the respiratory tract
NUCO-ciliary clearance
Cough & sneezing reflex
Respiratory mucosal immune system lymphoid follicles of the pharynx and tonsils, alveolar macrophages, secretory IgA and IgG
Alveolar microbiota - prevents organisms entering and establishing
Explain the course of a typical infection within the lungs
- Alveolar macrophage fails to stop pathogens
- Cytokines recruit more macrophages- systemic
- Inflammation = increased permeability (inc blood supply to region)
- More WBCs/ proteins
Course of a typical infection outside the lungs
- Inflammatory mediators (cytokines/ chemokines) systemic
- Activates bone marrow/ more CO/ raised body temp
- Dysregulation - signs of tissue/ organ injury -> multi-organ failure
What three things cause dysregulation?
- The pathogen
- Host factors
- Drugs
Give some examples of pathogen/ virulence factors
Chlamydia pneumoniae- ciliostatic factor
Mycoplasma pneumoniae- shear off cilia
Influenza virus - reduces mucus velocity (up to 12wk post infection)
Strep pneumoniae/ neisseria meningitides- split immunoglobulin (IgA)
Pneumococcus - capsule inhibits phagocytosis
Mycobacterium/ nocardia/ legionella - resistant to phagocytosis
Give some examples of host factors
> 65yrs
Smoking/ alcohol/ drugs
Chronic lung diseases (bronchiectasis/ cystic fibrosis)
Aspiration (change in consciousness/ dysphagia/ wearing denatures while sleeping)
Immunocompromised
Metabolic - malnutrition, hypoxaemia, acidosis, uraemia
Co-infection with viruses (abnormal ciliary function)
Give examples of drugs which cause dysregulation
Antacids
PPI - increases risk of pneumonia
H2 antagonist - myelosuppression (rare, long term)
Antipsychotics - unclear association
60% increase in risk older ppl, atypical antipsychotics associated fatal pneumonia
ACE inhibitors - associated reduced risk
Glucocorticosteroids - ICS increase risk
Give examples of URTIs and some causes
Most commonly caused viruses:
Rhinovirus, coronavirus, influenza, parainfluenza
Bacterial super- infection common with sinusitis and otitis media, can -> mastoiditis, meningitis, brain abscess
Rhinitis (common cold) Pharyngitis Epiglottis Laryngitis Tracheitis Sinusitis Otitis media
Give examples of LRTIs
Bronchi + alveolar
Bronchitis:
Bronchiolitis
Bronchiectasis
Pneumonia:
Empyema (pus filled pockets in pleural space)
Lung abscess
What is acute bronchitis? Symptoms, causes, treatment
Inflammation of medium sized airways
Mainly in smokers
Cough, fever, increased sputum, increased dyspnoea
CXR normal
Triggers: chemicals, pollen, pathogen
Organisms:
Viruses, S. Pneumoniae, H. Influenza, M. Catarrhalis
Bronchodilator, physiotherapy +/- antibiotics
What are the different types of pneumonia?
All LRTIs involving inflammation of the lung alveoli
Community acquire pneumonia - outside healthcare
Hospital acquired pneumonia - 48hrs post admission
Ventilated acquired pneumonia - 48hrs post intubation & ventilation
What’s the pathology of pneumonia, what’s the difference between lobar and bronchopneumonia?
Acute inflammatory response
Exudation of fibrin- rich fluid
Neutrophil & macrophage infiltration
Displaces air
Lobar pneumonia - affects one lobe
Bronchopneumonia - patchy areas, crackles on breathing and auscultations dull
What microorganisms cause community acquired pneumonia?
No microbiological ID made in most cases
Typical (85%): Strep Pneumoniae Haemophillus influenza (underlying chronic lung disease) Moraxella catarrhalis Staph aureus & MRSA Viruses
Atypical (15%): Mycoplasma Legionella (H20 sources) Coxiella burnetii (farm animals) Chlamydia pneumoniae Chlamydia Psittaci (birds)
Diagnosing CaP and assessing severity
Diagnosis:
Clinical syndrome + imaging finding
- cough, dyspnoea, pleurisy, fever, tachycardia, organ dysfunction (hypotension, mental status change), crackles, bronchial breathing
Imaging - consolidations/ infiltrates/ cavitation NEVER normal
Use CURB- 65 to asses when to admit:
Confusion, urea >7mmol/l, Rr >30, BP <90 syto & <60 diastolic, >65yrs
Score 2-5 manage as severe
<2 mild - managed in community
Investigations for moderate -> severe CAP
FBC Urea and electrolytes C reactive protein Arterial blood gases CXR
Microbiological samples:
Sputum/ induced
Blood culture
Bronchoalveolar lavage fluid
Nose/ throat swabs or NPAs
Urine (antigen for legionella/ pneumococcus)
Serum (antibody) - usually collect presentation and 10-14 days later
Managing LRTIs
Mild CaP: treat empirically
Moderate: blood cultures/ sputum culture/ urinary streptococcal antigen, legionella (+PCR)/ viral screen
Severe: moderate + bronchoscopic specimens
Differential diagnosis for LRTIs
Heart failure + pulmonary oedema
Pulmonary embolism
Atelectasis (collapse lung tissue)
Aspiration/ chemical pneumonitis
Drug reactions
Lung cancer
Vasculitis
Acute exacerbation bronchiectasis
Interstitial lung disease
Treatment of CAP
Antibiotics (empirical regimes can differ hospital/ allergy status/ comorbidities)
General approach 5-7 days mild CaP
7-10 severe
UHL antibiotics:
Mild- moderate - amoxicillin Or doxycycline OR erythromycin/ clarithromycin
Moderate- severe - hospital admission co-amoxiclav & clarithromycin/ doxycycline
Complications of CaP
Initial infection progression - empyema, lung abscess, bacteraemia
Non resolving CAP: delayed clinical response/ closed space infections/ bronchial obstruction (e.g. tumour)/ subacute, chronic CAP (Tb/ fungal)
Aetiology of hospital acquired pneumonia and management
Staphylococcus aureus MRSA Enterobacteriaciae Pseudomonas SPP Fungi (Candida sp)
Management:
Cover SA + gram negative enteric bacilli + typical/ atypical pathogens co-amoxiclav
Pseudomonas risk - anti pseudomonas beta lactam (piperacillin/ tazibactam/ ceftazidime) or anti-pseudomonal
Fluroquinolone
MRSA risk - vancomycin/ linezolid
UHL: first line co-amoxiclav, second line/ ITU piperacillin/ tazibactam OR meropenem
What is aspiration pneumonia? Who’s at risk? Treatment
Aspiration of exogenous material or endogenous secretions into respiratory tract
Common in patients with neurological dysphagia (strokes), epilepsy, alcoholics, drowning
At risk groups - nursing home residents, drug overdose
Mixed infection - viridans streptococci and anaerobes
Moderate- severe: co-amoxiclav
What are different types of immunosuppressed patients most at risk of in terms of microorganisms? HIV, neutropenia, bone marrow transplant, splenectomy
HIV - pneumocystitis jirovecci , TB, atypical mycobacteria
Neutropenia - fungi e.g. aspergillus spp
Bone marrow transplant - cytomegalovirus virus
Splenectomy - encapsulated organisms e.g. S pneumoniae, H influenza, malaria
