Resumen

AGUAYO-REYES, Alejandro et al. Molecular basis of methicillin-resistance in Staphylococcus aureus. Rev. chil. infectol. [online]. 2018, vol.35, n.1, pp.7-14. ISSN 0716-1018.  http://dx.doi.org/10.4067/s0716-10182018000100007.

Staphylococcus aureus isolates resistant to several antimicrobials have been gradually emerged since the beginning of the antibiotic era. Consequently, the first isolation of methicillin-resistant S. aureus occurred in 1960, which was described a few years later in Chile. Currently, S. aureus resistant to antistaphylococcal penicillins is endemic in Chilean hospitals and worldwide, being responsible for a high burden of morbidity and mortality. This resistance is mediated by the expression of a new transpeptidase, named PBP2a or PBP2’, which possesses lower affinity for the β-lactam antibiotics, allowing the synthesis of peptidoglycan even in presence of these antimicrobial agents. This new enzyme is encoded by the mecA gene, itself embedded in a chromosomal cassette displaying a genomic island structure, of which there are several types and subtypes. Methicillin resistance is mainly regulated by an induction mechanism activated in the presence of β-lactams, through a membrane receptor and a repressor of the gene expression. Although mec-independent methicillin resistance mechanisms have been described, they are clearly infrequent.

Palabras clave : Staphylococcus aureus; methicillin-resistance; methicillin-resistant Staphylococcus aureus (MRSA); antibiotic resistance.

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