## **Core Concept**
Lysozymes are enzymes found in various bodily secretions, such as tears, saliva, and mucus, that have antimicrobial properties. They work by breaking down the peptidoglycan layer in bacterial cell walls. Gram-negative bacteria have an outer lipopolysaccharide membrane in addition to their peptidoglycan layer.

## **Why the Correct Answer is Right**
The correct answer, , indicates that lysozymes are less effective against gram-negative bacteria. This is because the outer membrane of gram-negative bacteria, composed of lipopolysaccharides, acts as a barrier that prevents lysozyme from accessing and hydrolyzing the peptidoglycan layer underneath. For lysozymes to be effective, they need direct access to the peptidoglycan layer.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option suggests lysozymes are highly effective against gram-negative bacteria by directly hydrolyzing their cell walls, which is incorrect due to the protective outer membrane.
- **Option B:** This option implies a partial effect, which might be misleading as it suggests lysozymes have some level of action on gram-negative bacteria, but in reality, their effect is significantly hindered by the outer membrane.
- **Option C:** This option suggests an indirect effect through complement activation, which is not the primary mechanism by which lysozymes act on bacteria.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that lysozymes are more effective against gram-positive bacteria because they lack the outer membrane that protects gram-negative bacteria. This is a critical distinction in understanding the innate immune response.

## **Correct Answer:** . Lysozymes have little to no direct effect.