A lab-on-a-chip (LOC) device for detecting pathogens in a biological sample, the LOC device having an inlet for receiving the sample, a supporting substrate, a dialysis section for separating pathogens from larger constituents in the sample, a plurality of reagent reservoirs, a lysis section downstream of the dialysis section for lysing the pathogens to release genetic material therein, the lysis section being in fluid communication with one of the reagent reservoirs containing a lysis reagent for lysing the cells in the lysis section, a first nucleic acid amplification section downstream of the lysis section for amplifying first nucleic acid sequences in the genetic material, and, a second nucleic acid amplification section downstream of the first nucleic acid amplification section for amplifying second nucleic acid sequences in the amplicon from the first nucleic acid amplification section, wherein, the dialysis section, the lysis section, the first nucleic acid amplification section and the second nucleic acid amplification section are all supported on the supporting substrate.