Pseudomonas aeruginosa exotoxin A causes tissue injury in invasive infections by which mechanism?

• A Hydrolysis of lecithin in cell membranes
• B Zinc-dependent cleavage of synaptobrevin at peripheral motor nerve endings
• C Activation of adenylate cyclase via ADP-ribosylation of Gs alpha
• D ADP-ribosylation of elongation factor 2, inhibiting protein synthesis ✓

Explanation

Exotoxin D is an AB toxin that ADP-ribosylates diphthamide residue on elongation factor 2, halting translation and killing host cells; it acts like diphtheria toxin mechanistically. Cleavage of SNARE proteins is botulinum toxin, Gs ADP-ribosylation is cholera toxin, and lecithinase is Clostridium perfringens alpha toxin. Recognising this shared EF-2 mechanism is the discriminating point.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.