Name two key salivary antimicrobial components and their actions.

Name two key salivary antimicrobial components and their actions.

• A. Lysozyme breaks bacterial cell walls; lactoferrin sequesters iron and inhibits growth; peroxidase systems also have antimicrobial effects.
• B. Albumin binds pathogens; amylase digests starch; lipase disrupts membranes.
• C. Defensins neutralize toxins; lactoperoxidase oxidizes proteins; catalase degrades hydrogen peroxide.
• D. Immunoglobulin A neutralizes pathogens; lysozyme has no antimicrobial effect.

Answer: (A)

Saliva contains several immediate defense proteins that act together to limit microbial growth, including enzymes that damage cells, metal-binding proteins that starve microbes of nutrients, and oxidizing systems that inactivate microbial enzymes. Lysozyme is a muramidase that cleaves the peptidoglycan in bacterial cell walls, especially affecting Gram-positive bacteria, leading to cell disruption. Lactoferrin binds ferric iron, removing a vital nutrient and slowing or halting bacterial growth; it can also have direct antimicrobial effects. The peroxidase system, primarily lactoperoxidase, uses hydrogen peroxide and thiocyanate to produce reactive hypothiocyanite, which inhibits bacterial enzymes and metabolism. This combination—lysozyme disrupting cell walls, lactoferrin sequestering iron, and peroxidase-generated oxidants—constitutes the classic salivary antimicrobial activity described here. The other options either include components not primarily responsible for salivary antimicrobial action or contain incorrect statements (for example, lysozyme does have antimicrobial effects).

Saliva contains several immediate defense proteins that act together to limit microbial growth, including enzymes that damage cells, metal-binding proteins that starve microbes of nutrients, and oxidizing systems that inactivate microbial enzymes. Lysozyme is a muramidase that cleaves the peptidoglycan in bacterial cell walls, especially affecting Gram-positive bacteria, leading to cell disruption. Lactoferrin binds ferric iron, removing a vital nutrient and slowing or halting bacterial growth; it can also have direct antimicrobial effects. The peroxidase system, primarily lactoperoxidase, uses hydrogen peroxide and thiocyanate to produce reactive hypothiocyanite, which inhibits bacterial enzymes and metabolism. This combination—lysozyme disrupting cell walls, lactoferrin sequestering iron, and peroxidase-generated oxidants—constitutes the classic salivary antimicrobial activity described here. The other options either include components not primarily responsible for salivary antimicrobial action or contain incorrect statements (for example, lysozyme does have antimicrobial effects).