MecA

mecA is a gene found in bacterial cells which allows them to be resistant to antibiotics such as methicillin, penicillin and other penicillin-like antibiotics.^[1]

The bacteria strain most commonly known to carry mecA is methicillin-resistant Staphylococcus aureus (MRSA). In Staphylococcus species, mecA is spread through the staphylococcal chromosome cassette SCCmec genetic element.^[2] Resistant strains cause many hospital-acquired infections.^[3]

mecA encodes the protein PBP2A (penicillin-binding protein 2A), a transpeptidase that helps form the bacterial cell wall. PBP2A has a lower affinity for beta-lactam antibiotics such as methicillin and penicillin than DD-transpeptidase does, so it does not bind to the ringlike structure of penicillin-like antibiotics. This enables transpeptidase activity in the presence of beta-lactams, preventing them from inhibiting cell wall synthesis.^[4] The bacteria can then replicate as normal.