pathology of pulmonary infection

Question 1

what three factors affect the affect likelyhood of a lung infection?

Answer 1

• microorganism pathogenicity
• capacity to resist infection
• population risk

Question 2

what is a primary microorganism?

Answer 2

a microogranism able to infect anyone

Question 3

what is a fucultative microorganism?

Answer 3

a microorganism that needs a little ‘help’ when infecting a host eg. the host is less able to resist infection

Question 4

what is an opportunistic microorgansim?

Answer 4

a microorganism that can’t infect a host unless the hosts capacity to resist infection is very compomised

Question 5

what two factors affect a patient’s capacity to resist infection?

Answer 5

• state of defence mechanisms

- age of patient

Question 6

name some URTI

Answer 6

• Coryza - common cold
• Sore throat syndrome
• Acute Laryngotracheobronchitis (Croup)
• Laryngitis
• Sinusitis
• Acute Epiglottitis

Question 7

when is acute epiglottiitis a problem?

Answer 7

in children as their thrachea is smaller so an inflammation of the epiglottis may cause the airway to be obstructed

Question 8

which microorganisms cause acute epiglottitis?

Answer 8

• haemophilus influenzae
• group A beta haemolytic streptococci
• rarely caused by parainfluenza virus 4
• some other viruses

Question 9

name some LRTI

Answer 9

bronchitis
bronchiolitis
pneumonia

Question 10

what are the respiratory tract defence machanisms?

Answer 10

• macrophage-mucociliary escalator system
• general immune system
• respiratory tract secretions
• upper respiratory tract as filter eg. nasal hairs

Question 11

how are particles and microorganisms removed from the terminal bronchioles and proximal alveoli?

Answer 11

macrophages phagocytose particles and pathogens then transport to lymph nodes via lymph

Question 12

where does the mucociliary escalator begin?

Answer 12

the respiratory bronchioles

Question 13

how can the influenza virus cause bacterial lung infections ?

Answer 13

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

Question 14

how can pneumonia be classified according to aetiology?

Answer 14

Community Acquired Pneumonia
Hospital Acquired (Nosocomial) Pneumonia
Pneumonia in the Immunocompromised
Atypical Pneumonia
Aspiration Pneumonia
Recurrent Pneumonia

Question 15

what is nosocomial pneumonia?

Answer 15

hospital acquired pneumonia?

Question 16

what is hypostatic pneumonia?

Answer 16

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.

Question 17

what is bronchopneumonia?

Answer 17

an acute infection causes acute inflammation in very local areas of the lung, these areas become filled with pus, this is called local consolidation.

Question 18

what is local consolidation?

Answer 18

the building of pus in certain localise areas in the lung during a pneumonia infection

Question 19

Is pleural effusion likely in bronchopneumonia?

Answer 19

no as the infection is isolated in specific areas and so won’t spread to the pleura

Question 20

where is bronchopneumonia most likely to be found in the lungs?

Answer 20

the base

Question 21

what does bronchopneumonia look like on an x-ray?

Answer 21

• often bilateral
• basal
• patchy opacification

Question 22

what does lobar pneumonia look like on an xray?

Answer 22

complete opacification of one lobe only

Question 23

what causes lobar pneumonia?

Answer 23

caused by a primary pathogen, infects a whole lobe as the body’s response to the pathogen is vigorous

Question 24

do most pneumonias resolve?

Answer 24

yes

Question 25

what are the complications of pneumonia that affect the pleura?

Answer 25

-pleurisy (inflammation of pleura)
pleural effusion (extra fluid in pleural space)
pleural empyema (pus in pleural space)

Question 26

what are the complications of pneumonia caused by organisation?

Answer 26

• mass lesion
• cryptogenic organising pneumonia COP
• constrictive bronchiolitis

Question 27

what are some complications/ outcomes of pneumonia?

Answer 27

• conditions of the pleura
• problems with organisation
• lung abscess
• bronchiectasis

Question 28

what is COP?

Answer 28

cryptogenic organising pneumonia. its an inflammation of the bronchioles, not actually an infection though

Question 29

which organisms cause lung abscesses?

Answer 29

staph aureus, some pneumococci and klebsiella

Question 30

what is metastatic in pyaemia?

Answer 30

pus travels in the blood to the lung causing an abcess

Question 31

what is bronchiectasis?

Answer 31

pathological dilatation of bronchi

Question 32

what are the causes of bronchiectasis?

Answer 32

• Severe Infective Episode
• Recurrent Infections - many causes
• Proximal Bronchial Obstruction
• Lung Parenchymal Destruction

Question 33

what are the causes of recurrent lung infection?

Answer 33

• 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

Question 34

how can aspiration occur which will cause aspiration pneumonia?

Answer 34

• vomiting
• oesophageal lesion
• obstetric anaesthesia
• neuromuscular disorders
• sedation

Question 35

what is type I respiratory failure?

Answer 35

PaO2 <8 kPa (PaCO2 normal or low)

Question 36

what is type II respiratory failure?

Answer 36

PaCO2 >6.5 kPa (PaO2 usually low)