Which antibiotic is primarily used for treating methicillin-resistant Staphylococcus aureus (MRSA)?

Daptomycin is an effective antibiotic primarily used for treating infections caused by methicillin-resistant Staphylococcus aureus (MRSA). It belongs to the class of cyclic lipopeptides and works by disrupting the bacterial cell membrane, leading to cell death. Daptomycin is particularly useful in cases of complicated skin and skin structure infections, bacteremia, and infective endocarditis caused by MRSA.

Other antibiotics traditionally used to treat MRSA include vancomycin and linezolid. However, daptomycin is preferred in certain scenarios, especially when resistance to other agents is a concern or in cases where other agents are not sufficiently effective.

The other options listed are not suitable for the treatment of MRSA: penicillin and amoxicillin are ineffective against MRSA due to the presence of beta-lactamase enzymes that confer resistance. Ciprofloxacin, while it can treat a variety of infections, is not typically the first choice for MRSA due to the potential for resistance and the better alternatives available.