penicillin-resistant bacteria(n = noun.animal) - bacteria that are unaffected by penicillin;
is a kind of bacteria, bacterium

bacteria, bacteria bed, bacteria family, bacteria genus, bacteria order, bacteria species, endospore-forming bacteria, enteric bacteria, gliding bacteria, nitric bacteria, nitrous bacteria, penicillin-resistant, phototrophic bacteria, phototropic bacteria, potato scab bacteria, purple bacteria, pus-forming bacteria, ring rot bacteria, slime bacteria, sulfur bacteria, sulphur bacteria, true bacteria