I want to further investigate samples from herds of diseased animals. In the infected herds, some animals tested positive for a bacterial infection and the remaining of the animals tested negative. I want to investigate the effect of the infection on the faecal microbiome; I was planning to pick 3 infected animals and a corresponding 3 animals negative , however only few herds have more than one infected animals. Could I pick the available (1 OR 2) samples that tested positive and the SAME number of samples from those tested negative?