A colored electron microscopy image of methicillin-resistant staphylococcus aureus (MRSA), a bacterium commonly targeted by<unk> s A<unk>  is an antibiotic that acts on the two major bacterial groups, Gram-positive and Gram-negative, or any antibiotic that acts against a wide range of disease-causing bacteria. These medications are used when a bacterial infection is suspected but the group of bacteria is unknown (also called empiric therapy) or when infection with multiple groups of bacteria is suspected. This is in contrast to a narrow-spectrum antibiotic, which is effective against only a specific group of bacteria. Although powerful,<unk> s pose specific risks, particularly the disruption of native, normal bacteria and the development of antimicrobial resistance. An example of a commonly used<unk>  is ampicillin.
Broad-spectrum antibiotic
Antibiotic
Steroid
Beta-lactam antibiotics
Combination antibiotic
Antimicrobial
Neuromuscular blocking agents
Antiseptic