IS1999 increases expression of the extended-spectrum [beta]-lactamase VEB-1 in Pseudomonas aeruginosa

The integron-borne bl[a.sub.VEB-1] gene encodes an extended-spectrum [beta]-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 bl[a.sub.VEB.-1] in Enterobacteriaceae. Expression experiments and promoter study identified promoter sequences in IS1999 that increased the expression of VEB-1 in P.aeruginosa.