Multiplex PCR amplification assay for the detection of blaSHV, blaTEM and blaCTX-M genes in Enterobacteriaceae

Extended-spectrum β-lactamases (ESBLs) are often mediated by bla-SHV, blaTEM and blaCTX-M genes in Enterobacteriaceae and other Gram-negative bacteria. Numerous molecular typing methods, including PCR-based assays, have been developed for their identification. To reduce the number of PCR amplifications needed we have developed a multiplex PCR assay which detects and discriminates between bla-SHV, blaTEM and blaCTX-M PCR amplicons of 747, 445 and 593 bp, respectively. This multiplex PCR assay allowed the identification of bla-SHV, blaTEM and blaCTX-M genes in a series of clinical isolates of Enterobacteriaceae with previously characterised ESBL phenotype. The presence of blaSHV, blaTEM and blaCTX-M genes was confirmed by partial DNA sequence analysis. Apparently, the universal well-established CTX-M primer pair used here to reveal plasmid-encoded blaCTX-M genes would also amplify the chromosomally located K-1 enzyme gene in all Klebsiella oxytoca strains included in the study.