pathology of pulmonary infection Flashcards
what three factors affect the affect likelyhood of a lung infection?
- microorganism pathogenicity
- capacity to resist infection
- population risk
what is a primary microorganism?
a microogranism able to infect anyone
what is a fucultative microorganism?
a microorganism that needs a little ‘help’ when infecting a host eg. the host is less able to resist infection
what is an opportunistic microorgansim?
a microorganism that can’t infect a host unless the hosts capacity to resist infection is very compomised
what two factors affect a patient’s capacity to resist infection?
- state of defence mechanisms
- age of patient
name some URTI
- Coryza - common cold
- Sore throat syndrome
- Acute Laryngotracheobronchitis (Croup)
- Laryngitis
- Sinusitis
- Acute Epiglottitis
when is acute epiglottiitis a problem?
in children as their thrachea is smaller so an inflammation of the epiglottis may cause the airway to be obstructed
which microorganisms cause acute epiglottitis?
- haemophilus influenzae
- group A beta haemolytic streptococci
- rarely caused by parainfluenza virus 4
- some other viruses
name some LRTI
bronchitis
bronchiolitis
pneumonia
what are the respiratory tract defence machanisms?
- macrophage-mucociliary escalator system
- general immune system
- respiratory tract secretions
- upper respiratory tract as filter eg. nasal hairs
how are particles and microorganisms removed from the terminal bronchioles and proximal alveoli?
macrophages phagocytose particles and pathogens then transport to lymph nodes via lymph
where does the mucociliary escalator begin?
the respiratory bronchioles
how can the influenza virus cause bacterial lung infections ?
the influenza virus is cytopathic and destroys the cells of the mucociliary excalator. this means that the defence mechanism to bacteria is compromised and secondary infection is much more likely
how can pneumonia be classified according to aetiology?
Community Acquired Pneumonia Hospital Acquired (Nosocomial) Pneumonia Pneumonia in the Immunocompromised Atypical Pneumonia Aspiration Pneumonia Recurrent Pneumonia
what is nosocomial pneumonia?
hospital acquired pneumonia?
what is hypostatic pneumonia?
usually occurs in elderly people with cardiac failure, extra secretions in the lung, oedema in the lung or suppressed cough reflex. All these thing leads to accumulation of fluid in the lung which acts as a ‘petri dish’ for bacteria.
what is bronchopneumonia?
an acute infection causes acute inflammation in very local areas of the lung, these areas become filled with pus, this is called local consolidation.
what is local consolidation?
the building of pus in certain localise areas in the lung during a pneumonia infection
Is pleural effusion likely in bronchopneumonia?
no as the infection is isolated in specific areas and so won’t spread to the pleura
where is bronchopneumonia most likely to be found in the lungs?
the base
what does bronchopneumonia look like on an x-ray?
- often bilateral
- basal
- patchy opacification
what does lobar pneumonia look like on an xray?
complete opacification of one lobe only
what causes lobar pneumonia?
caused by a primary pathogen, infects a whole lobe as the body’s response to the pathogen is vigorous
do most pneumonias resolve?
yes
what are the complications of pneumonia that affect the pleura?
-pleurisy (inflammation of pleura) pleural effusion (extra fluid in pleural space) pleural empyema (pus in pleural space)
what are the complications of pneumonia caused by organisation?
- mass lesion
- cryptogenic organising pneumonia COP
- constrictive bronchiolitis
what are some complications/ outcomes of pneumonia?
- conditions of the pleura
- problems with organisation
- lung abscess
- bronchiectasis
what is COP?
cryptogenic organising pneumonia. its an inflammation of the bronchioles, not actually an infection though
which organisms cause lung abscesses?
staph aureus, some pneumococci and klebsiella
what is metastatic in pyaemia?
pus travels in the blood to the lung causing an abcess
what is bronchiectasis?
pathological dilatation of bronchi
what are the causes of bronchiectasis?
- Severe Infective Episode
- Recurrent Infections - many causes
- Proximal Bronchial Obstruction
- Lung Parenchymal Destruction
what are the causes of recurrent lung infection?
- Local Bronchial Obstruction eg. Tumour, Foreign body
- Local Pulmonary Damage eg. Bronchiectasis
- Generalised Lung Disease eg. Cystic Fibrosis, COPD
- Non-Respiratory Disease eg. Immunocompromised (HIV, other), Aspiration
how can aspiration occur which will cause aspiration pneumonia?
- vomiting
- oesophageal lesion
- obstetric anaesthesia
- neuromuscular disorders
- sedation
what is type I respiratory failure?
PaO2 <8 kPa (PaCO2 normal or low)
what is type II respiratory failure?
PaCO2 >6.5 kPa (PaO2 usually low)
