Lecture 5: Pneumonia

Question 1

Pneumonia in the elderly?

Answer 1

Increased RR - 69%

Crackles - 80%

consolidation - 30%

fevers/chills - 50%

non-pulmonary - 20% (eg. delirium)

Question 2

Development of Pneumonia? Risk factors?

Answer 2

Aspiration of streptococcus pneumonia that has colonised the nasopharynx is the most common (65%)

Haemophilius influenza (12%)

Staphylococcus aureus (2%)

(NB: Viral causes are important (8-16%) but are not treatable with antibiotics so you might get better you might not)

Risk factors:

• age < 2 or >65
• chronic lung disease
• smoking (impaired cilia function)
• Immune dysfunction

Question 3

Streptococcus pneumoniae is a?

Answer 3

Alpha-haemolytic streptococcus in the viridins group to s. mitis and it colonises the nasopharynx in 5-10% of adults and 20-40% of children.

-Can cause Pneumonia-

can also cause septic arthritis, perotinitis, endocarditis in children as well.

Question 4

Pneumococcal virulence?

Answer 4

• Pneumococcal surface protein A - (PspA) binds to epithelial cells and also prevents deposition of C3b
• Choline binding protein - binds to Ig receptor on epi cells allowing transport into cells
• Pneumlysin (toxin) - lyses neutrophils and epithelial cells
• Polysaccharide capsule - prevents phagocutosis and complement depostion
• PspC - prevents activation of complement cascade
• Pili - contribute to colonisation and cytokine production (TNFa) during invasion.
  *

Question 5

Investigations to determine if it’s pneumonia and the cause?

Answer 5

CXR is done primarily

Sputum culture is yield dependent and contaminated

nasopharyngeal swab - viral PCR if +ve can stop antibiotics

Blood cultures

Urine ICT - (immuno chromatography test)

Serology - acute and convalescent

Question 6

Treatment for S. pneumoniae?

Answer 6

Antibiotics are required unless proven its viral - most doctors will continue to give antibiotics anyway.

Oral antibiotics will be fine for most people, IV dosing may be required. Penicillin is starting to become resistant but not in an all or nothing way like MRSA is. There is just REDUCED SUSCEPTABILITY.

Question 7

What are macrolides?

Answer 7

A class of broad spectrum (eg. erythromycin) antibiotics with:

• Limited activity against gram negative bacteria
• Active against streptococci, staphylococci and other causes of pneumonia
• treatment of chlamydia (azithromycin as single dose)

Question 8

Adverse effects of macrolides antimicrobials?

Answer 8

GIT upset - erythromycin is an agonist of motilin receptor = nausea, diarrhoea

Sudden death - increases QT interval (very very low risk)

Durg-drug interaction are common