An SHV-derived extended-spectrum beta-lactamase in Pseudomonas aeruginosa.

A clinical isolate of Pseudomonas aeruginosa RP-1 produced the extended-spectrum beta-lactamase (ESBL) SHV-2a. Its gene was expressed from a composite promoter made of the -35 region derived from the left inverted repeat of IS26 and the -10 region from the blaSHV-2a promoter itself. The DNA sequences immediately surrounding blaSHV-2a were homologous to plasmid pMPA2a from Klebsiella pneumoniae KpZU-3, while further away and 3' to the blaSHV-2a gene, a sequence corresponding to the left end of Tn1721 was detected, thus indicating a likely enterobacterial origin of this ESBL gene.