FRCS Surgical Microbiology & Immunology 3

Question 1

What is the primary mechanism of action of ciclosporin in post-transplant immunosuppression?

Accepted Answer

Inhibition of calcineurin, preventing NFAT-mediated IL-2 gene transcription

Answer

Inhibition of mTOR, blocking IL-2 receptor signalling downstream

Answer

Depletion of circulating B lymphocytes via complement-mediated lysis

Answer

Competitive antagonism at glucocorticoid receptors

Question 2

Which organism is the causative agent of cat-scratch disease?

Accepted Answer

Bartonella henselae

Answer

Pasteurella multocida

Answer

Capnocytophaga canimorsus

Answer

Francisella tularensis

Question 3

What is the Gram stain appearance and arrangement of Streptococcus pyogenes (Group A Streptococcus)?

Accepted Answer

Gram-positive cocci arranged in chains

Answer

Gram-negative rods arranged in pairs

Answer

Gram-positive cocci arranged in clusters

Answer

Gram-negative diplococci

Question 4

Which fungal organism is most commonly responsible for invasive fungal infections in immunosuppressed or critically ill surgical patients?

Accepted Answer

Candida albicans

Answer

Aspergillus fumigatus

Answer

Cryptococcus neoformans

Answer

Histoplasma capsulatum

Question 5

What is the principal aim of prophylactic antibiotics administered in clean-contaminated surgery?

Accepted Answer

To reduce the bacterial inoculum at the operative site below the threshold for infection

Answer

To treat any established postoperative infection empirically

Answer

To eliminate all postoperative infectious complications

Answer

To substitute for inadequate surgical hand antisepsis

Question 6

Which blood-borne virus carries the highest risk of transmission to a healthcare worker following a single needlestick injury from an infected source?

Accepted Answer

Hepatitis B virus (HBV) in an unvaccinated worker

Answer

Human immunodeficiency virus (HIV)

Answer

Hepatitis C virus (HCV)

Answer

Cytomegalovirus (CMV)

Question 7

What is the primary mechanism by which bacterial biofilms confer increased resistance to antibiotics?

Accepted Answer

Impaired antibiotic penetration through the extracellular matrix and altered bacterial metabolic state

Answer

Increased horizontal gene transfer of resistance genes within the biofilm

Answer

Exclusive upregulation of efflux pump expression in sessile bacteria

Answer

Induction of specific antibiotic-degrading enzyme production