EN
INTRODUCTION: The ketogenic diet (KD) is used to manage drug‑resistant epilepsy in children. The KD directs the metabolism towards fat consumption as an alternative source of caloric demand, thus a state similar to starvation is created. The gut‑brain axis is associated with biochemical signaling between the large intestine and the nervous system via gut microbiota. It seems that, for an efficient functioning of the brain, a well-developed gut‑brain axis is required. Growing evidence supports the participation of gut microbiota in the regulation of cognitive functions, mood, anxiety, and pain. The probability of the KD affecting the composition of gut microbiota has been shown. One of the important aspects is the right choice of animal model for research. Animal models are not equal in metabolic, biochemical, physiological, and behavioral conditions. It is important to know the microbiota diversity in animal models. AIM(S): The aim of this study was a quantitative and comparative analysis of Enterococcus faecalis bacteria in the faeces of Wistar and Long Evans rats fed with KD of two different compositions. METHOD(S): Ten male Wistar rats and ten male Long Evans rats were divided into two groups. Animals were fed the KD based on animal or plant fat for 28 days. Subsequently, real‑time PCR was performed to assess the number of Enterococcus faecalis. Body mass and β‑hydroxybutyrate levels were measured as well. RESULTS: It has been observed that, after 28 days, the number of Enterococcus faecalis in faeces of rats fed with the KD was increased. Furthermore, results showed an increase in body mass and β‑hydroxybutyrate levels in both Wistar and Long Evans rats. CONCLUSIONS: In conclusion, analysis of changes in the number of bacteria Enterococcus faecalis has shown that the KD may alter gut microbiota composition in Long Evans and Wistar rats fed with the KD.