The disclosure relates generally to molecular diagnostic devices configured to amplifying a single nucleotide polymorphism (SNP) locus and discriminate between two or more allelic variants of the SNP, indicating presence or absence of a target allele. In some embodiments, the molecular diagnostic devices are capable of detecting, at point-of-care, SNPs associated with resistance or susceptibility to antibiotic treatment of organism infections. In other aspects, the disclosure provides methods of treatment for disease or disorders (e.g. organism infections) where treatment is guided by presence or absence of an allele at a SNP locus as determined by such molecular diagnostic devices.