CP18 - Lower Respiratory Tract Infections

Question 1

what factors would predispose a patient to LRTIs?

Answer 1

1. loss or suppression of cough reflex/ swallowing - risk of aspirating food, drinks etc.
2. ciliary defects - increased risk of infections
3. mucous disorders - increased risk of infections, CF
4. pulmonary oedema
5. immunodeficiency
6. macrophage function reduction, eg. due to smoking

Question 2

which bacteria cause LRTIs?

Answer 2

strep pneumoniae
h influenzae
staph aureus
Klebsiella pneumonia
mycoplasma pneumoniae
chlamydophilla pneumoniae
legiononella pneumophila
mycobacterium tuberculosis

Question 3

which viruses cause LRTIs?

Answer 3

influenza
parainfluenza
RSV
adenovirus

Question 4

which fungi cause LRTIs?

Answer 4

aspergillus
candida
pneumocystitis jiroveci

Question 5

define LRTIs

Answer 5

anything affecting the respiratory system below the larynx

Question 6

what is bronchitis?

Answer 6

inflammation of the large airways (bronchi)

Question 7

what is bronchiolitis?

Answer 7

inflammation of the bronchioles

Question 8

what is acute bronchitis?

Answer 8

inflammation and oedema of the trachea and bronchi, generally a mild illness

Question 9

what is the presentation of acute bronchitis?

Answer 9

dry cough, dyspnoea and tachypnoea, cough may be associated with retrosternal pain
most frequent in winter, and children under the age of 5

Question 10

which organisms are responsible for acute bronchitis?

Answer 10

most commonly rhinovirus, coronavirus, adenovirus, influenza
bacteria less common
H. influenza
Mycoplasma pneumoniae
B. pertussis

Question 11

what investigations are needed to confirm the diagnosis of acute bronchitis?

Answer 11

none in mild presentations, vaccination and past medical history may exclude some organisms.
resp cultures may be useful to single out a cause, but this is uncommon

Question 12

how is acute bronchitis managed?

Answer 12

supportive treatment in healthy patients
oxygen therapy or respiratory support in patients with severe disease or co-morbidities
antibiotics if bacterial cause is suspected/found

Question 13

what is chronic bronchitis?

Answer 13

cough, productive of sputum on most days during at least 3 months of 2 successive years, which cannot be attributed to an alternative cause

Question 14

what are the risk factors for chronic bronchitis?

Answer 14

men, over 40s, smoking, pollution, allergens

mediate inflammation and oedema, but acute exacerbations are mediated by same infective pathogens as acute

Question 15

how does bronchiolitis present?

Answer 15

primarily in paeds, 2-10 months
acute onset wheeze, cough, nasal discharge, respiratory distress
peaks in winter and early spring

Question 16

what are the symptoms of respiratory distress?

Answer 16

grunting, retractions, nasal flaring

Question 17

what are the causes of bronchiolitis?

Answer 17

RSV most common

others - parainfluenza, adenovirus, influenza

Question 18

how is bronchiolitis diagnosed?

Answer 18

chest xray
FBC
nasopharyngeal aspirate of respiratory secretions sent for viral PCR

Question 19

how is bronchiolitis treated?

Answer 19

supportive treatment - oxygen, feeding assistance.
antibiotics only given if complicated by a bacterial infection
no evidence for use of steroids, bronchodilators, ribavirin

Question 20

what is pneumonia?

Answer 20

formation of inflammatory exudate in the most distal airways and alveoli

Question 21

what is the presentation of community acquired pneumonia?

Answer 21

very common
usually rapid onset symptoms - fever/chills, productive cough, mucopurulent sputum, pleuritic chest pain, general malaise, fatigue, anorexia

Question 22

what are the signs of CAP?

Answer 22

tachypnoea, tachycardia, hypotension, dull to percuss, reduced air entry and bronchial breathing

Question 23

what is mucopurulent sputum?

Answer 23

sputum containing pus with WBCs, cellular debris, dead tissue, serous fluid and viscous liquid

Question 24

what organisms are responsible for a typical CAP?

Answer 24

s. pneumoniae
H. influenza 
M. catarrhalis
S. aureus
Klebsiella pneumoniae

Question 25

what non microbiological investigations need to be undertaken to diagnose pneumonia?

Answer 25

BP, pulse, oximetry, bloods - FBC, U&E, CRP, LFT; CXR to locate consolidation and differentiate which type of pneumonia it is

Question 26

what microbiological investigations need to be done if CAP is suspected and when?

Answer 26

moderate-severe CAP based on score>2 on CURB65 | sputum gram stain and culture, blood culture, PCR or serology for viral antigens, m. pneumonia, Chlamoydophila sp.

Question 27

how is CAP treated?

Answer 27

low severity - amoxicillin moderate - amoxicillin and clarythromycin high - co-amoxiclav and clarithromycin asap choice of antibiotic depends on the CURB65 score

Question 28

what are the 2 anatomical patterns of pneumonia?

Answer 28

1. bronchopneumonia - characteristic patch distribution centred on inflamed bronchioles and bronchi then subsequent spread to surrounding alveoli 2. lobar pneumonia - affects a large part or the entirety of a lobe, clear line of demarcation seen on CXR. almost always S. pneumoniae

Question 29

why is it important to know where the pneumonia was acquired from?

Answer 29

it informs the course of treatment

Question 30

what are the various types of pneumonia?

Answer 30

CAP hospital acquired pneumonia ventilator acquired pneumonia aspiration pneumonia

Question 31

when does hospital acquired pneumonia develop?

Answer 31

>48 hours post hospital admission, divided into early onset (2-5 days) and late onset (5+ days) late onset causative organisms - enterobacteriae and pseudomonas

Question 32

what is ventilator acquired pneumonia?

Answer 32

a subgroup of HAP, develops >48h post ET intubation and ventilation ET = endotracheal

Question 33

what is aspiration pneumonia?

Answer 33

pneumonia that is caused by the abnormal entry of fluids - food, drinks, stomach contents into the LRT usually due to an underlying impairment in the swallowing mechanism

Question 34

what are the atypical organisms causing CAP?

Answer 34

``` dont respond to penicillin or sulpha drug treatment mycoplasma pneumoniae Legionella pneumophila chlamoydophila pneumoniae chlamoydophila psitacchi coxiella burnetti ```

Question 35

how does M. pneumoniae present?

Answer 35

commonest in children and young adults main symptom - cough diagnosis through serology complications - pericaridits, arthritis, guillain barre, peripheral neuropathy, all rare

Question 36

legionella pneumophila

Answer 36

colonises water piping systems, outbreaks associated with showers, AC units, humidifiers. high fevers, cough dry initially productive later, riggers, dyspnoea, D&V, confusion bloods - deranged LFTs, SIADH

Question 37

chlamoydophila pneumoniae

Answer 37

mild pneumonia or bronchitis in adolescence and young adults. incidence highest in the elderly. they may experience more severe disease

Question 38

chlamoydophila psittaci

Answer 38

associated with exposure to birds, consider splenomegaly and history of bird exposure in patients with pneumonia. may also have a rash, hepatitis, haemolytic anaemia, reactive arthritis

Question 39

influenza

Answer 39

usually produces uncomplicated disease - fever, headache, myalgia, dry cough, sore throat. primary viral pneumonia occurs more commonly in patients with pre-existing cardiac and lung disorders or are immunocompromised observe cough, breathlessness and cyanosis in these patients secondary bacterial pneumonia may develop after initial improvement. diagnosis - viral antigen detection in resp samples using PCR

Question 40

why is it important to establish a diagnosis in pneumonia?

Answer 40

optimise antibiotic selection limit the use of broad spectrum agents identify organisms of epidemiological significance identify antibiotic resistance and monitor trends identify new or emerging pathogens

Question 41

what is Guillain-Barre syndrome?

Answer 41

acute disorder of the peripheral nerves, often preceded by a respiratory infection, causing weakness and often paralysis of the limbs

Question 42

what is peripheral neuropathy?

Answer 42

damage of peripheral nerves

Question 43

what are rigors?

Answer 43

a sudden feeling of cold with shivering accompanied by a rise in temperature, often with copious sweating

Question 44

what is SIADH?

Answer 44

syndrome of inappropriate antidiuretic hormone secretion - too much ADH

Question 45

CURB65 scoring

Answer 45

1 point each for 1. confusion 2. urea >7mmol/L 3. resp rate >=30 4. BP =65

Question 46

how is CURB65 scoring used?

Answer 46

0-1 - low 2 - moderate 3-5 - high severity

Question 47

how can LRTIs be prevented?

Answer 47

1. pneumococcal vaccination for patients with a chronic heart, lung and kidney disease, and those with splenectomy 2. annual influenza vaccination for those over 65 and those with chronic diseases or co-morbidities