In this article. Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that causes infections in different parts of the body. It's tougher to treat than most strains of staphylococcus aureus -- or staph -- because it's resistant to some commonly used antibiotics.n this article. Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that causes infections in different parts of the body. It's tougher to treat than most strains of staphylococcus aureus -- or staph -- because it's resistant to some commonly used antibiotics.
Although enterococci have been known to be intrinsically resistant to cephalosporins for decades, the mechanism of cephalosporin resistance remains incompletely understood. Three determinants for cephalosporin resistance in E. faecalis have been described.
Cephalosporins are bactericidal agents (which means that they kill bacteria) and have the same mode of action as other beta-lactam antibiotics (such as penicillins). All bacterial cells have a cell wall that protects them.