Which virulence factor enables Brachyspira to penetrate the intestinal mucus layer?

Which virulence factor enables Brachyspira to penetrate the intestinal mucus layer?

• A. Hemolysin production
• B. Attraction to mucus produced by goblet cells
• C. Flagella provide motility and mucus layer penetration
• D. NADH oxidase to help with oxygen tolerance

Answer: (C)

The main idea here is that moving through the mucus barrier is an active, motility-dependent process. Brachyspira is a spirochete whose flagella are located in the periplasm (the axial filaments), giving it a corkscrew-like motion. That specialized motility lets the bacterium swim through the thick, viscous mucus produced by goblet cells and reach the underlying epithelium. Crossing that mucus layer is a key step for colonization and disease, so the flagellar motor is the virulence factor that directly enables this penetration. Other factors don’t provide the same functional advantage. Hemolysin production would contribute to tissue damage, not the ability to traverse the mucus barrier. Attraction to mucus might help localize the organism, but without the active movement through mucus, it wouldn’t penetrate effectively. NADH oxidase relates to managing oxygen exposure rather than crossing the mucus. Thus, flagella-driven motility best explains how Brachyspira penetrates the intestinal mucus layer.

The main idea here is that moving through the mucus barrier is an active, motility-dependent process. Brachyspira is a spirochete whose flagella are located in the periplasm (the axial filaments), giving it a corkscrew-like motion. That specialized motility lets the bacterium swim through the thick, viscous mucus produced by goblet cells and reach the underlying epithelium. Crossing that mucus layer is a key step for colonization and disease, so the flagellar motor is the virulence factor that directly enables this penetration.

Other factors don’t provide the same functional advantage. Hemolysin production would contribute to tissue damage, not the ability to traverse the mucus barrier. Attraction to mucus might help localize the organism, but without the active movement through mucus, it wouldn’t penetrate effectively. NADH oxidase relates to managing oxygen exposure rather than crossing the mucus. Thus, flagella-driven motility best explains how Brachyspira penetrates the intestinal mucus layer.