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BackgroundWe investigated whether chemotherapy with the presence or absence of antibiotics against different kinds of cancer changed the gastrointestinal microbiota.Methodology/Principal FindingsFeces of 17 ambulant patients receiving chemotherapy with or without concomitant antibiotics were analyzed before and after the chemotherapy cycle at four time points in comparison to 17 gender-, age- and lifestyle-matched healthy controls. We targeted 16S rRNA genes of all bacteria, Bacteroides, bifidobacteria, Clostridium cluster IV and XIVa as well as C. difficile with TaqMan qPCR, denaturing gradient gel electrophoresis (DGGE) fingerprinting and high-throughput sequencing. After a significant drop in the abundance of microbiota (p = 0.037) following a single treatment the microbiota recovered within a few days. The chemotherapeutical treatment marginally affected the Bacteroides while the Clostridium cluster IV and XIVa were significantly more sensitive to chemotherapy and antibiotic treatment. DGGE fingerprinting showed decreased diversity of Clostridium cluster IV and XIVa in response to chemotherapy with cluster IV diversity being particularly affected by antibiotics. The occurrence of C. difficile in three out of seventeen subjects was accompanied by a decrease in the genera Bifidobacterium, Lactobacillus, Veillonella and Faecalibacterium prausnitzii. Enterococcus faecium increased following chemotherapy.Conclusions/SignificanceDespite high individual variations, these results suggest that the observed changes in the human gut microbiota may favor colonization with C.difficile and Enterococcus faecium. Perturbed microbiota may be a target for specific mitigation with safe pre- and probiotics.

Genetics, lifestyle, and dietary habits contribute to metabolic syndrome, but also an altered gut microbiota has been identified. Based on this knowledge it is suggested that host bacterial composition tends to change in response to dietary factors and weight loss. The aim of this study was to identify bacteria affecting host metabolism in obesity during weight loss and to correlate them with changes of the body composition obtained from bioelectrical impedance analysis (BIA). We recruited obese individuals receiving a dietary intervention according DACH (German, Austrian, and Swiss Society of Nutrition) reference values and guidelines for 'prevention and therapy of obesity' of DAG e.V., DDG, DGE e.V., and DGEM e.V. over three months. Faecal microbiota and BIA measurements were conducted at three time points, before, during, and after the intervention. Gut microbiota was analysed on the basis of 16S rDNA with quantitative real time PCR. Additionally, a food frequency questionnaire with questions to nutritional behaviour, lifestyle, and physical activity was administered before intervention. After weight reduction, obese individuals showed a significant increase of total bacterial abundance. The ratio of Firmicutes/Bacteroidetes significantly decreased during intervention. Lactobacilli significantly increased between the first and the second time point. These differences also correlated with differences in weight percentage. During the intervention period Clostridium cluster IV increased significantly between the second and the third time point. In contrast Clostridium cluster XIVa showed a decreased abundance. The dominant butyrate producer, Faecalibacterium prausnitzii, significantly increased as did the abundance of the butyryl-CoA: acetate CoA-transferase gene. Archaea and Akkermansia were significantly more prevalent after weight reduction. Our results show a clear difference in the gut bacterial composition before and after dietary intervention with a rapid change in gut microbial composition after a few weeks, but also indicate that a major shift requires long term dietary treatment.

Our results clearly show a difference in the gut bacterial composition in type 2 diabetics compared to lean controls or obesity. Therefore, the ratio of Fimicutes/Bacteroidetes might only be an indicator, but a detailed view at species level is even more important in regard to distinction of their functions.

SummaryBackgroundAn impaired gut microbiota has been reported as an important factor in the pathogenesis of obesity. Weight reduction has already been mentioned to improve gut microbial subpopulations involved in inflammatory processes, though other subpopulations still need further investigation. Thus, weight reduction in the context of a fasting program together with a probiotic intervention may improve the abundance and diversity of gut microbiota.MethodsIn this pilot study, overweight people underwent a fasting program with laxative treatment for 1 week followed by a 6 week intervention with a probiotic formula. Gut microbiota were analyzed on the basis of 16s rDNA with a quantitative real time polymerase chain reaction. Additionally, a food frequency questionnaire with questions about nutritional behavior, lifestyle, and physical activity was administered before and after the intervention.ResultsWe observed an increase in microbial diversity over the study period. No significant changes in abundance of total bacteria, or of Bacteroidetes, Prevotella, Clostridium cluster XIVa, or Clostridium cluster IV were found, although Faecalibacterium prausnitzii showed an increase over the study period. In addition, Akkermanisa and Bifidobacteria increased in abundance due to intervention. The inflammation-associated gut microbes Enterobacteria and Lactobacilli increased during the first week and then declined by the end of the intervention. Two-thirds of the study participants harbored Archaea. No significant improvements of eating habits were reported, although physical activity improved due to the intervention.ConclusionsOur results show that caloric restriction affects gut microbiota by proliferating mucin-degrading microbial subpopulations. An additional intervention with a probiotic formula increased probiotic-administered gut microbial populations.