IS1999 Increases Expression of the Extended-Spectrum β-Lactamase VEB-1 in Pseudomonas aeruginosa

ABSTRACT The integron-borne bla VEB-1 gene encodes an extended-spectrum β-lactamase. This gene was associated mostly with IS1999 and rarely with an additional IS2000 element in Pseudomonas aeruginosa isolates from Thailand, whereas IS1999 was only very rarely associated with bla VEB-1 in Enterobacteriaceae. Expression experiments and promoter study identified promoter sequences in IS1999 that increased the expression of VEB-1 in P. aeruginosa.