What are substances called that inhibit other microorganisms in very small amounts?

Antibiotics are substances that can inhibit the growth or kill other microorganisms, particularly bacteria, at very low concentrations. They work by targeting specific components or functions of bacterial cells, such as cell wall synthesis, protein synthesis, or metabolic pathways, which are essential for the bacteria's survival. Their effectiveness at low doses is a defining characteristic, allowing for selective suppression of harmful bacteria without necessarily harming the host organism.

In contrast, antigens refer to substances that evoke an immune response, vaccines are biological preparations that provide immunity to specific diseases, and probiotics are live microorganisms that confer health benefits, mainly by enhancing or re-establishing the gut flora. None of these substances primarily focus on inhibiting other microorganisms in the same way antibiotics do, which highlights the specific role antibiotics play in managing bacterial infections.