Abstract: A method of detecting a target organism in a sample mixture comprising preparing at least one complex sample mixture, performing primer directed nucleic acid amplification of the complex sample mixture; and examining the primer directed nucleic acid amplification result to detect for presence or absence of amplification product of the target organism, wherein the presence or absence of the amplification product is indicative of the presence or absence of the target organism in the sample mixture. Preparing the complex sample mixture comprises adding to a container at least one sachet containing at least a nutrient concentrate and a sample mixture suspected of containing the target organism.