Smartphone detection of antibiotic resistance using convective PCR and a lateral flow assay

Rapid and simple nucleic acid tests are critical for the emerging field of personalised medicine. In particular, rapid detection of antibiotic resistance in Staphylococcus aureus is crucial in initiating appropriate antibiotic treatment that can be used in routine clinical situations. Our aim was to develop a rapid detection method based on convective PCR (cPCR) in combination with a nucleic acid lateral flow assay. cPCR offers an alternative rapid amplification of nucleic acids in less than 30 min without the need for complex equipment. A low-cost cPCR device was developed with off-the shelf electronic components that allows amplification of nucleic acids without the need for electrical power. The multiplex cPCR was performed using fluorescein- and digoxigenin-modified primers targeting the femA and mecA genes to differentiate methicillin-sensitive and -resistant S. aureus in a single tube. The mecA gene is responsible for methicillin-resistance while the femA gene allows identification of the causative organism. The modified amplicons were analysed with a duplex lateral flow assay using quantum dot-labelled reporter probes and the fluorescent signal was acquired via a smartphone camera. The utility of our diagnostic system was demonstrated by detecting clinical samples of MRSA with a detection limit of 4.7 x 10(3) copies of DNA. The smartphone system developed may find facile applications outside centralised laboratories, such as in doctor's offices and at the bed-side of patients.