We present the rapid and sensitive detection of amplified DNA on a giant magneto-resistance sensor using superparamagnetic particles as a detection label. The one-step assay is performed on an integrated and miniaturized detection platform suitable for application into point-of-care devices. A double-tagged PCR amplification product of the LamB gene of the Escherichia coli bacterium was used to investigate binding kinetics of the assay. We applied magnetic actuation to concentrate the target-particle complexes at the sensor surface and to remove unbound particles from the sensor surface. We achieved biological dose-response curves detecting 4-250pM amplicon concentrations in a one-step format in total assay times of less than 3min. Using various tag-antibody combinations specific for one of the individual genes, multi-analyte detection is shown of several antibiotic resistance genes of the food pathogen Salmonella.