Which pathogen is classically associated with post-infectious Guillain-Barré syndrome and what is the mechanism?

Which pathogen is classically associated with post-infectious Guillain-Barré syndrome and what is the mechanism?

• A. Campylobacter jejuni; molecular mimicry leading to autoimmune nerve damage.
• B. Salmonella Typhi; toxin-mediated nerve damage.
• C. Shigella dysenteriae; cross-reactivity causing neuropathy.
• D. ETEC; direct nerve invasion.

Answer: (A)

The concept being tested is how an immune response after an infection can mistakenly attack peripheral nerves, leading to Guillain-Barré syndrome. Campylobacter jejuni is the classic trigger. Its surface structures, especially lipooligosaccharides, resemble nerve gangliosides such as GM1 and GD1a. This molecular mimicry drives the production of anti-ganglioside antibodies that bind to peripheral nerves, activating the immune system and causing demyelination or axonal injury. The resulting autoimmune attack explains the progressive weakness and areflexia that can follow a GI illness. The other pathogens listed can cause gastroenteritis, but they are not classically associated with Guillain-Barré syndrome through this cross-reactive autoimmune mechanism.

The concept being tested is how an immune response after an infection can mistakenly attack peripheral nerves, leading to Guillain-Barré syndrome. Campylobacter jejuni is the classic trigger. Its surface structures, especially lipooligosaccharides, resemble nerve gangliosides such as GM1 and GD1a. This molecular mimicry drives the production of anti-ganglioside antibodies that bind to peripheral nerves, activating the immune system and causing demyelination or axonal injury. The resulting autoimmune attack explains the progressive weakness and areflexia that can follow a GI illness. The other pathogens listed can cause gastroenteritis, but they are not classically associated with Guillain-Barré syndrome through this cross-reactive autoimmune mechanism.