What mechanism of resistance is associated with nafcillin?

Nafcillin is a penicillin derivative that is particularly effective against certain strains of staphylococci, including those that produce β-lactamase, due to its resistance to this enzyme. The mechanism of resistance associated with nafcillin primarily involves the alteration of penicillin-binding proteins (PBPs).

Staphylococci can acquire mutations in these PBPs, which are essential for the synthesis of bacterial cell walls. When these proteins are modified, they have a reduced affinity for β-lactam antibiotics like nafcillin, allowing the bacteria to survive even in the presence of these drugs. This alteration of PBPs represents a key strategy used by bacteria to resist the action of β-lactam antibiotics, making it a significant mechanism of resistance, especially in methicillin-resistant Staphylococcus aureus (MRSA).

Other mechanisms listed, while valid resistance strategies for different antibiotics, do not specifically relate to how nafcillin is resisted in staphylococci. For example, the production of β-lactamase primarily affects other penicillins rather than nafcillin, which is specifically designed to be resistant to such enzymes. Alteration in ribosomal subunits and increased porin size are mechanisms relevant to antibiotics that target