Infection Flashcards
Management of pneumonia
Assess using ABC
Treat hypotension/shock from infection
Assess for dehydration (common if acutely unwell and fever) - consider IV fluid support
Investigations to assess severity
Antibiotics
Analgesia for pleuritic chest pain e.g. paracetamol 1g/6h or NSAID
If no improvement e.g. hypoxic despite oxygen then consider CPAP to recruit lung parenchyma and improve oxygenation. But if patient is hypercapnic, they will require ventilation. If no changes in PaCO2 or hypoxia, refer to ICU
Investigations for severity of pneumonia (management of pneumonia)
CXR
Oxygen saturation and ABG if SaO2 <92% or severe pneumonia
FBC, U and E, LFT, CRP
Blood cultures (CURB-65 criteria at least 2)
Sputum cultures (CURB-65 criteria at least 3 or if 2 and not had antibiotics)
Urine pneumococcoal antigen (CURB-65 criteria at least 2) or Legionella antigen (CURB-65 criteria at least 3)
Viral throat swabs (consider) and mycoplasma serology
Pleural fluid aspirated for culture (CURB-65 criteria at least 2)
IF immunocompromised or on ICU, consider bronchoscopy or bronchoalveolar lavage
Describe each part of CURB-65 score
Confusion (abbreviated mental test less than 9)
Urea >7mmol/L
Respiratory rate (at least 30/min)
Blood pressure (<90/60mmHg)
Age (at least 65)
Indications depending on CURB-65 score
0-1: home treatment if possible
At least 2: hospital therapy
At least 3: indicates severe pneumonia and should consider ICU referral
What is pneumonia
Infection of lung parenchyma caused by a lower respiratory tract infection
Epidemiology of pneumonia
Community-acquired pneumonia is 5-11 per 1000 adults
Of these 1-3 per 1000 will require hospitalisation and mortality is those hospitalised is up to 14%
Most common organism causing pneumonia
Streptococcus pneumoniae (60-75%)
Organisms that can cause pneumonia
Streptococcus pneumoniae
Haemophilus influenzae
Mycoplasma pneumoniae
Staphylococcus aureus (found more commonly in ICU patients)
Legionella species and Chlamydia psittaci
Gram-negative bacilli, often hospital-acquired or immunocomprimised e.g. Pseudomonas (especially those with COPD)
Viruses
What % of pneumonia cases are caused by viral infections (including influenza)
15%
Symptoms of pneumonia (name 4)
*Fever Rigors Malaise Anorexia *Dyspnoea *Cough with purulent sputum (classically rusty with pneumococcus) Haemoptysis *Pleuritic chest pain
Signs of pneumonia (name 4)
*Percussion - dull
*Auscultation - crackles, bronchial breathing
*Septicaemia - Rigors
*Respiratory failure - Cyanosis, Tachypnoea
Herpes labialis (pneumococcus)
Confusion
Tachycardia
Hypotension
Signs of consolidation (diminished expansion, increased vocal resonance)
Pleural rub
Complications of pneumonia
Pleural effusion Empyema Lung abscess Respiratory failure Septicaemia Pericarditis Myocarditis Cholestatic jaundice AKI
What is an acute ooryza
Permenant dilation and thickening of the airways
Aetiology of acute ooryza
Infection by rhinovirus: spread by droplets and close personal contact
Pathophysiology of acute ooryza
Virus binds to ICAM-1 receptors -> releases inflammatory mediators by unknown mechanism
Epidemiology of acute ooryza
Extremely prevalent.
Multiple regional strains.
Clinical presentation of acute ooryza
Incubation period of 12hrs - 5 days.
Then, malaise, mild pyrexia, sore throat and watery nasal discharge.
Treatment of acute ooryza
Symptomatic.
Nasal decongestants, ibuprofen for malaise.
Epidemiology of TB
- 6 mil new cases/yr (37% unexpected/undiagnosed)
- 3% and 20% of previously treated are drug resistant
- 5 million deaths/yr
What % of TB cases have a co-infection with HIV
12%
True or False:
Leading cause of death worldwide (1.5 million/year)
True
Epidemiology of TB specific to UK
~8000/year or 12 per 100000
73% born outside UK
70% in deprived areas
30% with pulmonary disease (wait>4months from symptoms to treatment)
What bacteria causes TB
Mycobacterium tuberculosis
Pathophysiology of acute TB infection
Occurs when containment by immune system (macrophages and T-cells) is inadequate.
Can arise from primary infection or re-activation of previously latent disease.
How is TB transmitted
Via inhalation of aerosol droplets containing bacterium.
Means only pulmonary disease is communicable.
Pathophysiology of latent TB infection
Infection without disease due to persistent immune system containment (i.e. granuloma formation prevents bacteria growth and spread).
Positive skin/blood testing shows evidence of infection but patient is asymptomatic and non-infectious.
Risk factors of re-activation by TB or latent TB
New infection (<2 years) HIV Organ transplantation Immunosuppression (includes corticosteroids) Silicosis Illicit drug use Malnurition High-risk settings (homeless shelter, prison) Low socio-economic status Haemodialysis
Most common site in body of TB disease
Lungs (pulmonary) - 52%
Other sites (not lungs) in body of TB infection
Extra-thoracic lymph nodes (24%) Intra-thoracic lymph nodes (12%) Pleural (9%) Gastrointestinal (6%) Spine, Other bone, Miliary, Meningitis, GU
Treatment of pneumonia
BAPP Breathing: Maintain oxygen saturation levels Antibiotics: treat underlying cause Pain = give analgesics Pneumococcal vaccines for those at risk
Possible methods of invasion in pneumonia
Inhibition of IgA
Pneumolysins - inhibit ciliary beating
Damage of epithelial cells by prior infection
Use of platelet aggregating factor receptor pathway to reach the alveoli
People at higher risk of pneumonia and thus get a pneumococcal vaccine
Diabetics
Immunosuppressed
>65 years old
Complications of pneumonia
Respiratory failure (due to ARDS) Septic shock (release of cytokines in blood) Pleural effusion Empyema Lung abscess Hypotension
Cause of respiratory failure from pneumonia
Acute Respiratory Distress Syndrome
Cause of hypotension from pneumonia
Dehydration
Sepsis
Ix of pneumonia
CXR (shows infiltrates)
Sputum sample analysis (causative organism)
Monitor oxygen sats
Bloods - Raised WCC and inflammatory markers
Urinary antigen test - pneumococcal or Legionella antigen
Arterial blood gas (ABG)
