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SCCmec, or staphylococcal cassette chromosome mec, is a mobile genetic element of Staphylococcus bacterial species. This genetic sequence includes the mecA gene coding for resistance to the antibiotic methicillin and is the only known way for Staphylococcus strains to spread the gene in the wild by horizontal gene transfer. [1]
The mecA gene, which confers resistance to a number of antibiotics, is always present in MRSA and usually absent in MSSA; however, in some instances, the mecA gene is present in MSSA but is not expressed. Polymerase chain reaction (PCR) testing is the most precise method for identifying MRSA strains. Specialized culture media have been ...
Meca or MECA may refer to: Biology. mecA, responsible for methicillin resistance in MRSA; Meca, a snout moth genus in the subfamily Pyralinae; Places Meca ...
Resistance is conferred by the mecA gene, which codes for an altered penicillin-binding protein (PBP2a or PBP2') that has a lower affinity for binding β-lactams (penicillins, cephalosporins, and carbapenems). This allows for resistance to all β-lactam antibiotics, and obviates their clinical use during MRSA infections.
Molecular methods, like MALDI-TOF [24] and qPCR primers, [25] are the gold standard for accurately identifying the presence of the mecA gene, which confers resistance to beta-lactam drugs. However, methicillin resistance can still be identified reliably using biochemical or phenotypic methods, such as disc diffusion.
High-level vancomycin resistance in S. aureus has been rarely reported. [13] In vitro and in vivo experiments reported in 1992 demonstrated that vancomycin resistance genes from Enterococcus faecalis could be transferred by gene transfer to S. aureus, conferring high-level vancomycin resistance to S. aureus. [14]
Resistance to methicillin is conferred by activation of a new bacterial penicillin binding protein (PBP) mecA gene. This encodes protein PBP2a. This encodes protein PBP2a. PBP2a works in a similar manner to other PBPs, but it binds β-lactams with very low affinity, meaning they do not compete efficiently with the natural substrate of the ...
The mecA gene is carried by a mobile genetic element called the staphylococcal cassette chromosome mec (SCCmec) which is thought to promote spread between different species. [58] The presence of the mecA gene, expression of PBP2a, and methicillin resistance has been reported in S. schleiferi isolates. [13]