Lower respiratory tract infections

Question 1

Name the most common LRTIs

Answer 1

• Tracheitis
• Bronchitis
• Pneumonia
• Abscesses
• Bronchiolitis

Question 2

What are predisposing factors to LRTIs? Give examples

Answer 2

• Loss os suppression of cough reflex/swallow= stroke, coma, ventilation
• Ciliary defects=PCD
• Mucus disorders=CF
• Pulmonary oedema=fluid flooding alveoli
• Immunodeficiency: congenital or acquired
• Macrophage function inhibition=smoking

Question 3

What types of bacteria cause LRTIs?

Answer 3

• Strep pneumoniae
• Haem influenzae
• Staph aureus
• Klebsiella pneumonia
• Mycoplasma pneumoniae
• Chlamydophila pneumoniae
• Legionella pneumophila
• Mycobacterium tuberculosis

Question 4

What types of viruses cause LRTIs?

Answer 4

• Influenza
• Parainfluenza
• Adenovirus
• Respiratory syncytial virus

Question 5

What types of fungi cause LRTIs?

Answer 5

• Aspergillus
• Candida
• Pneumocystitis jiroveci

Question 6

Describe acute bronchitis

Answer 6

• Inflammation & oedema of trachea & bronchi
• Cough (dry)-associated with retrosternal pain, dyspnoea, tachypnoea
• Frequent in winter
• Children under 5yrs
• Viruses: rhino/corona/adenovirus, influenza
• Bacterial: less common m.pneumoniae, H.influenzae, B.pertussis

Question 7

How is acute bronchitis diagnosed &treated?

Answer 7

D= vaccination? previous exposure, cultures of secretions, tests not indicated
T=Supportive, antibiotics if bacterial, Severely affected may require O2/resp support

Question 8

Describe chronic bronchitis

Answer 8

• Productive cough on most days during at least 3mnths of 2 successive years
• Men & >40yrs
• Associated w/smoking, pollution, allergens
• Airflow obstruction present on spirometry=COPD
• Exogenous irritants= inflammation & oedema of airways
• Acute exacerbations= same pathogens as acute bronchitis

Question 9

Describe Bronchiolitis

Answer 9

• Paeds: infants 2-10mnths
• Inflammation & oedema of bronchioles
• Acute onset, wheeze, cough, rest distress, nasal discharge
• Peak in winter
• RSV, parainfluenzae, adenovirus, influenza

Question 10

How is Bronchiolitis diagnosed & treated?

Answer 10

D= CXR, full blood count, microbiological diagnosis

T=Supportive, O2, feeding assistance(NG?), antibiotics if complicated by bacterial infection

Question 11

What is pneumonia and what are the 2 anatomical patterns shown by pneumonia?

Answer 11

• Infection affecting most distal airways, alveoli, formation of inflammatory exudate
  1) Bronchopneumonia= Patchy distribution centred on inflamed bronchioles/bronchi, spread to surrounding alveoli
  2) Lobar pneumonia= Affects part/entire lobe, S.pneumoniae

Question 12

What are the types of pneumonia?

Answer 12

• Community acquired (CAP)
• Hospital acquired (HAP)= >48hrs after hospital admission, enterobacteriaceae & pseudomonas sp.
• Ventilator acquired (VAP)= subgroup of HAP, developing >48hrs after ET intubation/ ventilation
• Aspiration pneumonia= subgroup of HAP, abnormal entry of fluids into LRT, impaired swallowing mechanism

Question 13

What are the ‘typical’ causative organisms of CAP?

Answer 13

• Strep pneumoniae
• Haem influenzae
• Moraxella catarrhalis
• Staph aureus
• Klebsiella pneumoniae

Question 14

What are the ‘atypical’ causative organisms of CAP?

Answer 14

• Fail to respond to penicillin/sulpha drugs or no organism identified
• Mycoplasma pneumoniae
• Legionella pneumophilia
• Chlamydophila pneumoniae
• Chlamydophila psittaci
• Coxiella burnetii

Question 15

What are the signs & symptoms of CAP?

Answer 15

• Rapid onset
• Fever/chills
• Productive cough
• Mucopurulent sputum-RUSTY
• Pleuritic chest pain
• General malaise/fatigue/anorexia
• Tachypnoea
• Tachycardia
• Hypotension
• Dull percussion
• Reduced air entry, bronchial breathing

Question 16

What non-microbiological investigations can be done for suspected CAP? How is it treated

Answer 16

• Routine obs: pulse/BP/ox
• CXR
• Bloods: FBC/U&E/CRP?LFTs
• Amoxycillin

Question 17

What is the clinical presentation of Mycoplasma pneumoniae?

Answer 17

• Autumn epidemics
• Children & young adults
• Cough
• Diagnosed by serology
• Rare complications: pericarditis, arthritis, Guillain-Barre, peripheral neuropathy

Question 18

What is the clinical presentation of Legionella pneumophilia?

Answer 18

• Colonising water piping/ air con systems, showers
• High fever, rigors, dry cough becoming productive, dyspnoae, vomiting, confusion, diarrhoea
• Bloods: deranged LFTs, low sodium

Question 19

What is the clinical presentation of Chlamydophilia pneumoniae?

Answer 19

• 3-10% CAP cases in adults
• Mild pneumonia/bronchitis in young adults/adolescents
• Elderly also affected

Question 20

What is the clinical presentation of Chlamydophilia psittaci?

Answer 20

• Exposure to birds
• Pneumonia, splenomegaly, history of bird exposure
• Rash, hepatitis, haemolytic anaemia, reactive arthritis

Question 21

What are the clinical presentations of:

• primary viral pneumonia
• Secondary bacterial pneumonia

Answer 21

• Primary= commonly in patients with pre-existing cardiac & lung disorders, cough, S.O.B, cyanosis
• Secondary= May develop after initial period of improvement: S. pneumonia, H. influenza, S.aureus

Question 22

What microbiological investigations for inpatients with suspected CAP can be carried out?

Answer 22

• Sputum Gram stain & culture
• Blood culture
• Pneumococcal urinary antigen
• Legionella urinary antigen followed by..
• PCR or serology

Question 23

On what organisms is PCR carried out?

Answer 23

• Viral pathogens= influenza
• Mycoplasma pneumoniae
• Chlamydophilia sp

Question 24

How is the severity of CAP assessed?

Answer 24

• CURB65
• Confusion
• Urea: >7mmol/l
• Respiratory rate: >30
• Blood pressure: systolic: 65

Question 25

How are LRTIs prevented?

Answer 25

• Pneumococcal vaccination: S.pneumoniae, chronic heart/lung/kidney disease, splenectomy
• Influenza vaccination (annually): Over 65s, chronic disease, co-morbidities