BP: Shigella, E.Coli, Borrelia + Campylobacter

Shigella

Gram-negative, non-motile enteric bacterium that causes shigellosis and invades the colon

uses a type III secretion system and spreads cell-to-cell by actin-based motility

What disease does Shigella cause?

Shigellosis, ranging from watery diarrhea to dysentery

What part of the body does Shigella mainly infect?

The colon

What is a major Shigella virulence system?

Type III secretion system

How does Shigella enter intestinal tissue?

It crosses through M cells and invades epithelial cells

How does Shigella move between host cells?

By actin-based intracellular spread

What immune response is strongly associated with Shigella infection?

Strong inflammation with neutrophil recruitment

What did the Nickerson paper show about bile salts and Shigella?

Bile salts promoted biofilm formation and changed virulence-related behavior

E. coli

Gram-negative rod

some strains are normal flora, while pathogenic strains cause intestinal and extraintestinal disease

What E. coli pathotype is associated with bloody diarrhea and HUS?

EHEC or STEC

What major toxin is produced by EHEC?

Shiga toxin

What lesion does EHEC form on epithelial cells?

Attaching and effacing lesions

What pathogenicity island is important in EHEC?

The LEE pathogenicity island

What does intimin bind during EHEC infection?

Tir

What did Martins 2022 show about gut commensals and EHEC?

Some commensals increased virulence gene expression and pedestal formation

Borrelia

Spirochete that causes Lyme disease and relies heavily on immune evasion and persistence rather than classic toxins

What disease does Borrelia burgdorferi cause?

Lyme disease

How is Borrelia transmitted?

By tick bite

Does Borrelia mainly rely on classic toxins?

No, it mainly relies on immune evasion and persistence

What is one major immune evasion strategy of Borrelia?

Antigenic variation, including VlsE

How does Borrelia evade complement?

By binding host complement regulators like factor H

What did Williams 2024 show about Borrelia and humoral immunity?

Borrelia suppressed antibody responses to an unrelated antigen

Campylobacter jejuni

Gram-negative, helical, microaerophilic bacterium with polar flagella that causes campylobacteriosis

What disease does C. jejuni cause?

Campylobacteriosis

What food source is commonly associated with Campylobacter?

Poultry

What toxin is associated with Campylobacter virulence?

Cytolethal distending toxin, or CDT

What neurologic complication is strongly linked to Campylobacter?

Guillain-Barré syndrome

Why is molecular mimicry important in Campylobacter infection?

Because bacterial structures can resemble host gangliosides and trigger autoimmunity

What did Campylobacter show about calgranulin C?

It inhibited Campylobacter through zinc sequestration