Is Dicloxacillin effective against MRSA?

Dicloxacillin is a penicillinase-resistant penicillin that is typically used to treat infections caused by penicillin-resistant staphylococci, specifically those that are methicillin-sensitive (MSSA). However, Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to all beta-lactam antibiotics, including dicloxacillin. Therefore, dicloxacillin is ineffective against MRSA.

The key concept to understand here is that MRSA has acquired mechanisms that allow it to resist the actions of methicillin and related antibiotics. This highlights the importance of distinguishing between MSSA and MRSA when considering treatment options for staphylococcal infections. In clinical practice, alternative antibiotics such as vancomycin or linezolid are typically used to treat infections caused by MRSA. Understanding the resistance patterns of staphylococci is crucial for effective treatment selection.