FRCS Surgical Microbiology & Immunology 2

Question 1

What is the molecular mechanism of MRSA resistance to beta-lactam antibiotics?

Accepted Answer

Expression of an altered penicillin-binding protein (PBP2a) encoded by mecA

Answer

Production of extended-spectrum beta-lactamase (ESBL)

Answer

Overexpression of efflux pumps reducing intracellular antibiotic concentration

Answer

Reduced outer membrane permeability preventing antibiotic entry

Question 2

Which cytokines are the primary endogenous pyrogens responsible for fever in sepsis?

Accepted Answer

TNF-alpha and IL-1

Answer

IL-4 and IL-13

Answer

IL-10 and TGF-beta

Answer

IL-6 and IL-8 exclusively

Question 3

What initiates the classical pathway of complement activation?

Accepted Answer

C1q binding to antigen-antibody complexes

Answer

Mannose residues on microbial surfaces binding MBL

Answer

Spontaneous hydrolysis of C3 in plasma

Answer

Factor B binding to microbial surfaces

Question 4

Which antibiotic is currently the first-line treatment for severe Clostridioides (Clostridium) difficile infection?

Accepted Answer

Oral vancomycin or fidaxomicin

Answer

IV metronidazole

Answer

Oral amoxicillin-clavulanate

Answer

IV ciprofloxacin

Question 5

Which is the most significant risk factor for ventilator-associated pneumonia (VAP) in postoperative surgical patients?

Accepted Answer

Mechanical ventilation via endotracheal tube

Answer

Age over 65 years

Answer

Body mass index greater than 35

Answer

Pre-existing diabetes mellitus

Question 6

Which type of allograft rejection occurs within minutes to hours of transplantation and is mediated by pre-formed donor-specific antibodies?

Accepted Answer

Hyperacute rejection

Answer

Acute cellular rejection

Answer

Chronic allograft nephropathy

Answer

Graft-versus-host disease (GvHD)

Question 7

Which organism is the most common cause of catheter-associated urinary tract infections (CAUTI) in hospitalised surgical patients?

Accepted Answer

Escherichia coli

Answer

Staphylococcus aureus

Answer

Pseudomonas aeruginosa

Answer

Candida albicans