What type of infections would macrocyclic lactones be primarily effective against?

Macrocyclic lactones are primarily effective against nematodes, which are a type of parasitic roundworm. These agents work by targeting specific pathways in nematode physiology, such as the glutamate-gated chloride channels. This mechanism leads to paralysis and death of the parasites, making them effective in treating infections caused by nematodes.

In contrast, bacterial infections are treated with antibiotics that specifically target bacterial cell wall synthesis or protein synthesis, not macrocyclic lactones. Flukes, which are flatworms, require different classes of drugs—such as praziquantel—for effective treatment. Fungal infections are addressed with antifungal agents that target the unique components of fungal cell membranes or cell walls. Therefore, the specificity of macrocyclic lactones to nematodes underscores their importance in the context of anthelmintic therapy.