Sequence-selective recognition of extended-spectrum beta-lactamase GES-2 by a competitive, peptide nucleic acid-based multiplex PCR assay.

Extended-spectrum beta-lactamases (ESBLs) in Pseudomonas aeruginosa, such as GES-2, which compromises the efficacy of imipenem, tend to be geographically restricted. The CC-to-AA base pair substitution at positions 493 and 494 of the bla(GES-2)-coding region distinguishes this ESBL from bla(GES-1) and the bla(IBC)-type genes, making it an ideal target for the development of a novel sequence-specific, peptide nucleic acid (PNA)-based multiplex PCR detection method. By using two primer pairs in conjunction with a PNA probe, this method provided an accurate means of identification of bla(GES-2) compared to standard PCR and gene sequencing techniques when it was used to test 100 P. aeruginosa clinical isolates as well as previously published, well-described control strains encompassing all presently known genes in the bla(GES-IBC) ESBL family. This novel method has the potential to be used in large-scale, cost-effective screening programs for specific or geographically restricted ESBLs.