RESP - Respiratory infections Flashcards
Cx of bacterial pneumonia (4)
- abscess
- pleural adhesions
- empyema
- infarct (occaional)
Define primary & post-primary tuberculosis
Primary: no previous infection/exposure
Post-primary: fresh infection in previously sensitised individual or reactivation of previously dormant primary lesion
How is tuberculosis infection established?
TB enters by airway -> tends to lodge peripherally: focus of primary infection (Gohn focus) at the apex of lower lobe or apex of upper lobe. Area of fibrosis underneath pleura. With reactive organisms, hilar lymph node is enlarged. Gohn complex = Gohn focus + hilar lymph node
Describe Necrotising granulomatous inflammatory process (TB histological pattern in the lung)
- multinuclear cells
- epithelioid
- small lymphocytes
- caseous necrosis in the centre
Describe miliary tuberculosis
Primary invasion in venous system. TB all throughout the body
What are the pathological features of acute necrotising viral pneumonia?
- necrosis of bronchial epithelium
- acute inflammatory exudate in bronchial lumen
- haemorrhage into alveoli
- inflammatory infiltration into surrounding alveoli
When do you see viral inclusion bodies?
-Adenovirus-cytomegalovirus
Describe 3 types of aspergillosis
- allergic bronchopulmonary aspergillosis
- proximal airways
- mucoid impaction
- structure of airways maintained - Bronchopulmonary aspergillosis
- distal airways
- granulomatous inflammatory destruction of airways - Angio-invasive aspergillosis
- invasion of pulmonary arteries/veins
- haemorrhagic infarction
What are the common fungal causes of pneumonia?
- aspergillosis
- Cryptococcus neoformans (can spread systemically -> can form a mass lesion in the brain)
- pneumocystitis
All more common in immunocompromised
What are the host risk factors in resp infection?
- immune status
- type of compromise - age
- normal flora change with age & other factors
- social changes (day care, college)- infants & elderly - structural/physiological abnormalities
- e.g. bronchiectasis, tumour, CF
What are examples of URTI & their causative agents?
- pharyngitis: group A strep, viruses
- sinusitis: viruses, strep pneumoniae, H. influenzae, fungi
- otitis media: Strep pneumoniae
- epigolttitis: H. influenzae type B
Specimen collection for culture for
- pharyngitis: throat swab
- sinusitis: sinuses swab (surgical)
- otitis media: diagnosed clinically. rarely obtain tympanocentesis
- epiglottitis: direct swab of epiglottis. blood cultures
Describe Bordetella pertussis
- Gram negative rod
- very difficult to culture (fastidious)
- Ix: PCR & serology
- Rx: macrolide Abx within 3 weeks
- notifiable disease
- vaccine available
What are the common respiratory tract viruses & their usual clinical associations?
- Influenza A, B: seasonal & pandemic influenza, pneumonia
- Parainfluenza types 1, 2, 3: Group, bronchiolitis, pneumonia
- Rhinovirus: mild URTI
- Respiratory syncitial virus: Croup, bronchitis, pneumonia
- Adenovirus: mild infection.
- Coronavirus: mild URTI, SARS & MERS
- Human metapneumovirus: usually mild URTI
- Human bocavirus: usually mild URTI
What are the 3 most common organisms of typical pneumonia?
- Streptococcus pneumoniae
- Haemophhilus influenzae
- Staphylococcus aureus