Molecular epidemiology of orf513-bearing class 1 integrons in multiresistant clinical isolates from Argentinean hospitals

The spread of orf513-bearing class 1 integrons is associated with bla(CTX-M-2) in gram-negative clinical isolates in Argentina, with In35 being the most frequently found integron (74%). Among 65 isolates without bla(CTX-M-2), only one harbored a novel orf513-bearing class 1 integron with the dfrA3b gene. The finding of orf513 not associated with class 1 integrons in two gram-positive strains indicates the widespread occurrence of this putative site-specific recombinase.