Typing of methicillin-resistant Staphylococcus aureus with IS256.

A simple one-step procedure is described for specifically amplifying and labelling insertion element IS256 which is associated with the gentamicin-resistance transposon Tn4001. The product has been used to probe DNA digests of methicillin-resistant Staphylococcus aureus. The resulting restriction fragment length polymorphisms were found to be able to distinguish isolates which were indistinguishable by other typing methods. The probe also hybridised with methicillin-resistant Staphylococcus aureus which were isolated before the emergence of gentamicin resistance, demonstrating its usefulness in typing species other than those that are gentamicin-resistant.