Multiplex detection of antibiotic resistance genes using padlock probes.

The elucidation of resistance mechanisms is of central importance to providing and maintaining efficient medical treatment. However, molecular detection methods covering the complete set of resistance genes with a single test are still missing. Here, we present a novel 100-plex assay based on padlock probes in combination with a microarray that allows the simultaneous large-scale identification of highly diverse β-lactamases. The specificity of the assay was performed using 70 clinical bacterial isolates, recovering 98% of the β-lactamase nucleotide sequences present. Additionally, the sensitivity was evaluated with PCR products and genomic bacterial DNA, revealing a detection limit of 10(4) DNA copies per reaction when using PCR products as the template. Pre-amplification of genomic DNA in a 25-multiplex PCR further facilitated the detection of β-lactamase genes in dilutions of 10(7) cells/mL. In summary, we present an efficient, highly specific, and highly sensitive multiplex detection method for any gene.