Publications

MRSA is defined by the presence of staphylococcal cassette chromosome mec(SCCmec); which is a large mobile genetic element that carries the mecA genewhich codes for an alternative form of penicillin binding protein (PBP2a).Staphylococcus aureus developed resistance to this type of β-lactam antibiotics byacquiring the mecA gene which is carried on the SCCmec element describedearlier. Strains which carry this mecA gene are known as methicillin resistantStaphylococcus aureus (MRSA), even though they are actually resistant to all β-lactam based antibiotics. Historically, Staphylococcus aureus has been known todevelop antimicrobial resistance to most antimicrobials rapidly. The bacteriadeveloped resistance to penicillin only a year after the introduction of penicillin intoclinical use. It is now estimated that 90%–95% of Staphylococcus aureus strainsworldwide are resistant to penicillin. The resistance exhibited by MRSA to mostantibiotics imply that treatment for suspected or verified severe Staphylococcusaureus infections, including common skin and wound infections, must rely onsecond line drugs.