First observation of excision and integration in Class 1 integron in staphylococci

Abstract

Class 1 integron had been well-known as a mobile genetic element involved in the antibiotic resistance of various bacteria. Up to date, most of the relevant publications concentrated on gram-negative bacteria, with limited exceptions. However, in recent studies, class 1 integron had been detected in methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase negative staphylococci (MRCNS). So in this study, we tested in S. aureus, the class 1 integron mediated excision and integration. We first asked 8 plasmids from previous studies, then established some transformants and perform the excision and integration reaction. As the results revealed, we observed positive excision assay, which had been confirmed by further integration assays. This observation may raise the public attention of integron as a novel antibiotic resistance determinant in gram-positive bacteria, especially in staphylococci.

Key words: Staphylococcus aureus, class 1 integron, mobile genetic element, excision and integration, antibiotic resistance.