8.1 Lower Respiratory Tract Infections Flashcards
Give examples of lower respiratory tract infections
Acute Bronchitis (not the same as Chronic Bronchitis!) Bronchiectasis Bronchiolitis Empyema Lung Abscess Pneumonia
What is acute bronchitis
inflammation of the large airways of the lung – bronchi.
What is bronchiectasis?
Bronchiectasis is a permanent dilatation and thickening of the airways associated with chronic cough, sputum production, bacterial colonization, and recurrent infection
What is broncholitis?
Bronchiolitis is a viral infection of the bronchioles, the smallest air passages in the lungs.
What causes bronchiolitis?
Respiratory Syncytial virus - commonly occurs in children under 1 years of age.
What is empyema?
Empyema is a collection of pus in the pleural cavity, usually associated with pneumonia but may also develop after thoracic surgery or trauma
What is a lung abscess?
localised collection of pus within the lung that leads to cavity formation usually with a thick wall.
How would a lung abscess appear on an x ray?
Radiological imaging typically demonstrates the presence of air-fluid levels in the cavity.
What commonly causes lung abscesses?
Abscesses occur most commonly when microbial infection causes necrosis of the lung parenchyma.
When might a lung abscess cause a purple tissue cough?
If necrosis of lung parenchyma is communicating with an airway
What is pneumonia?
Pneumonia is a general term denoting inflammation of the lung parenchyma due to infection. Cellular exudate accumulates in alveolar spaces
What is Pneumonitis?
Inflammation of the lung parenchyma due to non-infective causes such as physical or chemical damage
What is lobar pneumonia?
Pneumonia localised to particular lobe/s of the lung
What is bronchopneumonia?
Diffuse patchier spread of pneumonia across lung tissue
How are pneumonia’s classified?
- Source of infection - where it was acquired and other aetiological factors
- Infecting organism
What are common causative organisms of community acquired pneumonia?
Streptococcus Pneumoniae
It is less commonly caused by Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae and Staphylococcus aureus.
What is the most common cause of pneumonia in smokers?
Streptococcus Pneumoniae
Smoking associated with COPD increased risk of infection with haemophilus influenza and mortadella catarrhalis
What are atypical organisms that may cause community acquired pneumonia?
Atypical organisms = lack a cell wall
Mycoplasma Pneumoniae
Chlamydia Pneumoniae
Legionella Pneumoniae
What is nosocomial pneumonia?
A nosocomial or hospital acquired pneumonia is defined as an infection of the lower respiratory tract in hospitalised patients, occurring > 48 hours after admission and was not incubating at the time of admission
What are important causative organisms of nosocomial pneumonia?
Gram negative bacteria and Staphylococcus aureus, including MRSA
What is aspiration pneumonia?
Aspiration of food, drink, saliva or vomitus can lead to pneumonia.
What individuals are prone to aspiration pneumonia?
individuals whose level of consciousness is altered, due to anaesthesia, alcohol or drug abuse or have swallowing related problems due to neuromuscular problems or oesophageal disease.
What are causative agents of aspiration pneumonia?
Causative organisms include oral flora & anaerobes, though in-hospital aspiration increases risk for pseudomonas aeruginosa infection
What are causes of pneumonia in the immunocompromised patient?
Pneumocystis jiroveci, Aspergillus spp., Cytomegalovirus and others.
What are clinical features of pneumonia?
malaise, fever and cough productive of sputum (purulent, or rusty coloured due to blood).
Pleuritic chest pain, dyspnoea, tachycardia, organ dysfunction if there is dysregulation
What should be considered in a patient with a persistent dry cough that does not resolve over time?
atypical pneumonia caused by Mycoplasma pneumoniae or Chlamydophila pneumoniae
What pneumonia’s are rapid onset?
Pneumococcal or staphylococcal
How is the severity of pneumonia assessed?
assessed using the CURB 65 score, where the presence of 2 or more features is an indication for hospital treatment, and patients with high scores may require ICU treatment
What is the CURB 65 assessment?
C – New mental confusion U – Urea > 7 mmol/L R – Respiratory rate > 30 per minute B – blood pressure (systolic BP < 90 or DBP <60 mmHg) Age > 65 years
What will a chest x-ray of pneumonia reveal?
usually reveal shadowing in at least one section of the lung field. Consolidation
What investigative procedures are done in patients with suspected pneumonia?
X-ray Microbiology - gram stain and culture of sputum Blood culture - in severely ill U&E C reactive protein Arterial blood gass
What factors must be considered in patients with pneumococcal pneumonia?
Age High CURB 65 score Very high or low white cell count Absence of fever Extensive x-ray shadowing Hypoxaemia Rise in blood urea
What are the general management measures for pneumonia?
Encourage to drink Anti-pyretic drugs (paraceptamol) Stronger analgesics for pleural pain In severe cases = IV fluids and O2 Antibiotics
How are community acquired pneumonia’s treated?
Target organism is pneumococcus
Treat with amoxicillin or related antibiotics
How are atypical pneumonia’s treated?
macrolides (erythromycin/clarithromycin) or tetracyclines (doxycycline)
NOT penicillin
How is nosocomial pneumonia treated?
Most likely gram negative organisms
IV co-amoxiclav
What are possible complications of pneumonia?
Pleural effusion
Empyema
Lung abscess formation
What is the leading cause of death in the elderly
Lower respiratory tract infections
Why are lower respiratory tract infections so common?
Lungs are not sterile - normal alveolar microbiota, aspiration (most common) , blood stream spread, direct spread
What is the lower respiratory tract?
The respiratory tract under the bifurification of the trachea
What are the defences of the respiratory tract?
Muco-ciliary clearance mechanisms Nasal hairs Ciliated columnar epithelium Cough and the sneezing reflex Respiratory mucosal immune system Lymphoid follicles of the pharynx and tonsils Alveolar macrophages Secretory IgA and IgG Alveoli microbiota
What is the typical course of a lower respiratory tract infection?
Pathogen enters alveolar space, alveolar macrophage fails of stop pathogen multiplying and infecting tissue. Activated macrophages stimulates cytokine production. Cytokines recuit more macrophages and causes inflammatory response. Inflammation increased blood flow and delivery of WBCs
How does a LRTI have systemic affects?
Inflammatory mediators produced (cytokines/chemokines) travel in systemic circulation
Activates bone marrow/more cardiac output/ raised body temp
Dysregulation of other organs
What causes dysregulation of response to infection?
The pathogen
Host factors
Drugs
What host factors are risk factors for LRTI?
65years+ Smoking Alcohol/drugs Chronic lung diseases Aspiration Immunocompromised Metabolic Co infection
What drugs increase risk of LRTI?
Antacids (PPI/H2 antagonist)
Antipsychotics
ACE inhibitors
Glucocorticoids (inhaler)
What are common upper respiratory tract infections?
Rhinitis Pharyngitis Laryngitis Tracheitis Sinusitis Otitis media
What are symptoms of acute bronchitis?
Cough, fever, increase sputum production, dyspnoea
How is pneumonia differentiated from acute bronchitis?
CXR - normal in acute bronchitis, abnormal in pneumonia
What are common causative organisms of acute bronchitis?
S. Pneumoniae
H.influenza
M. Catarrhalis
How is acute bronchitis managed?
Physiotherapy
Antibiotics ( if not caused by virus)
Bronchodilation
What is ventilated acquired pneumonia?
48hours post intubation and ventilation. Sub category of hospital acquired pneumonia
What happens to the alveoli in pneumonia?
Become inflammed, secrete exudate and accumulation of inflammatory cells. Displacement of air with exudate.
What does a normal lung sound like on auscultation?
Vesicular breathing
Why might a crackling sound be heard in the lung on auscultation?
Due to presence of fluid such as in pneumonia
Exposure to birds is a risk factor of which type of pneumonia?
Chlamydophila Psittaci
What pneumonia may be caused by farm animal exposure?
Coxiella burnetii
What will auscultation of the lungs with pneumonia sound like?
Bronchial breathing and crackling
What medication should be given to pneumonia patients needing hospital admission?
Co-amoxiclav and clarithromycin / doxycycline
How do we prevent pneumonia’s?
Flu vaccine - every year to high risk patients
Pneumococcal vaccine - every 5 years
Chemoprophylaxis
Smoking advice
