Dot-blot amperometric genosensor for detecting a novel determinant of β-lactamase resistance in Staphylococcus aureus

A new electrochemical hybridisation genosensor for the detection of resistant bacteria has been developed. This device relies on the immobilisation of a 50-mer oligonucleotide target, unique to a novel determinant of beta-lactamase resistance in Staphylococcus aureus, onto an electrochemical transducer. This genosensor is based on a concept adapted from classical dot-blot DNA analysis, but implemented in an electrochemical biosensor configuration. Amperometric transduction and an enzyme label method, that increases the genosensor sensitivity, are the main features of this new approach. In addition to the adapted dot-blot format, a double hybridisation assay, in which two different labelled probes were used, is reported. This procedure, if combined with polymerase chain reaction (PCR), allows determination of the genotype of an antibiotic-resistant organism in a shorter time than that required to perform traditional phenotypic susceptibility testing. Its characteristics are ideal for implementation in a kit form.