## Virulence Factors of Pseudomonas aeruginosa ### Correct Virulence Factors (Options 0, 1, 2) **Key Point:** P. aeruginosa possesses multiple virulence mechanisms that enable pathogenesis in immunocompromised hosts and chronic respiratory infections. | Virulence Factor | Mechanism | Clinical Significance | | --- | --- | --- | | Exotoxin A | ADP-ribosylates elongation factor-2 (EF-2), inhibiting protein synthesis | Systemic toxicity; similar mechanism to diphtheria toxin | | LPS (Endotoxin) | O and H antigens; triggers inflammatory cascade via TLR4 | Pyrogenicity, shock, tissue damage | | Capsule | Hyaluronic acid mimics host tissue; antiphagocytic | Immune evasion; poor antibody recognition | | Pili/Flagella | Adhesion and motility | Initial colonization | | Elastase & Proteases | Tissue destruction | Hemorrhage, necrosis | | Pyoverdine | Iron-chelating siderophore | Nutrient acquisition in biofilms | ### Why Teichoic Acid is WRONG **High-Yield:** Teichoic acid is a **Gram-positive** cell wall component found in bacteria like *Staphylococcus aureus* and *Streptococcus pyogenes*. P. aeruginosa is Gram-negative and lacks a thick peptidoglycan layer; instead, it has an outer membrane with LPS. **Clinical Pearl:** The absence of teichoic acid in P. aeruginosa is one reason it is intrinsically resistant to many β-lactam antibiotics — the outer membrane excludes large molecules, and it lacks the peptidoglycan targets that make Gram-positives susceptible. **Mnemonic:** **TAPE** for P. aeruginosa virulence — **T**oxin A, **A**dhesins (pili), **P**yoverdine/Proteases, **E**ndotoxin (LPS). Teichoic acid is for Gram-positives only.
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.