Human flora‐associated rodents – does the data support the assumptions?

There is little direct literature detailing exhaustive bacteriological studies comparing human donor faecal flora, human flora-associated (HFA) mouse models and conventional rodent faecal flora. While there is a premise that the implanted donor faecal flora from humans is established in the rodent model the evidence is incomplete and indeed for groups such as Bifidobacterium spp. it is lacking. The reviewed bacteriology studies are generally lacking in detail with the exception of one study from which the data have mostly been overlooked when cited by other workers. While there are studies that suggest that the HFA rodent model is more relevant to man than studies with conventional rodents, the hypothesis remains to be proven. This review concludes that the established microbial flora in the HFA rodent model is different to that of donor human faecal flora, and this clearly raises the question as to whether this matters, after all a model is a model and as such models can be useful even should they fail to be a true representation of, in this case, the gastrointestinal tract. What matters is that there is a proper understanding of the limitations of the model as we attempt to unravel the significance of the components of the gastrointestinal flora in health and disease; examples of why such an analysis is important are provided with regard to obesity and nutritional studies. The data do unsurprisingly suggest that diet is an extremely influential variable when interpreting HFA and conventional rodent data. The microbiology data from direct bacteriology and indirect enzyme studies show that the established microbial flora in the HFA rodent model is different to that of donor human faecal flora. The significance of this conclusion remains to be established.