Antibiotics Disrupt Gut Ecology, Metabolism

Antibiotics Disrupt Gut Ecology, Metabolism

ScienceDaily (Apr. 20, 2011) — Humans carry several pounds of microbes in our gastro-intestinal tracts. Recent research suggests that this microbial ecosystem plays a variety of critical roles in our health. Now, working in a mouse model, researchers from Canada describe many of the interactions between the intestinal microbiota and host, and show that antibiotics profoundly disrupt intestinal homeostasis. The research is published in the April 2011 issue of the journal Antimicrobial Agents and Chemotherapy .

“Intestinal microbes help us digest our food, provide us with vitamins that we cannot make on our own, and protect us from microbes that make us sick, amongst other things,” says L Caetano M. Antunes of the University of British Columbia, a researcher on the study. In this study, the investigators used powerful mass spectrometry techniques to detect, identify, and quantify more than two thousand molecules which they extracted from mouse feces. They then administered antibiotics to the mice, to kill off most of their gut microbiota, and analyzed the feces anew.

The second round of mass spectroscopy revealed a very different metabolic landscape. The levels of 87 percent of the molecules detected had been shifted up or down by factors ranging from 2-fold to 10,000-fold.

The most profoundly altered pathways involved steroid hormones, eicosanoid hormones, sugar, fatty acid, and bile acid. “These hormones have very important functions in our health,” says Antunes. “They control our immune system, reproductive functions, mineral balance, sugar metabolism, and many other important aspects of human metabolism.”

The findings have two important implications, says Antunes. “First, our work shows that the unnecessary use of antibiotics has deleterious effects on human health that were previously unappreciated. Also, the fact that our gut microbes control these important molecules raises the possibility that manipulating these microbes could be used to modulate diseases that have hormonal or metabolic origins (such as inmmunodeficiency, depression, diabetes and others). However, further studies will be required to understand exactly how our microbial partners function to modulate human physiology, and to devise ways of using this information to improve human health.”

(L.C.M. Antunes, J. Han, R.B.R. Ferreira, P. Lolic, C.H. Borchers, and B.B. Finlay, 2011. Effect of antibiotic treatment on the intestinal metabolome. Antim. Agents Chemother. 55:1494-1503. )

Journal Reference :


L. C. M. Antunes, J. Han, R. B. R. Ferreira, P. Lolic, C. H. Borchers, B. B. Finlay. Effect of Antibiotic Treatment on the Intestinal Metabolome . Antimicrobial Agents and Chemotherapy , 2011; 55 (4): 1494 DOI: 10.1128/AAC. 01664-10
Probiotics Reduce Rate of Recurrent Urinary Tract Infections in Women, Study Suggests

ScienceDaily (Apr. 18, 2011) — Urinary tract infections are common in women, costing an estimated $2.5 billion per year to treat in 2000 in the United States alone. These infections frequently recur, affecting 2 to 3 percent of all women. A depletion of vaginal lactobacilli, a type of bacteria, is associated with urinary tract infection risk, which suggests that replenishing these bacteria may be beneficial.

Researchers conducted a double-blind placebo-controlled trial to investigate this theory. Their results are published in Clinical Infectious Diseases .

In the study, young women with a history of recurrent urinary tract infections received antibiotics for acute urinary tract infections. They were then randomized to receive either a Lactobacillus crispatus intravaginal suppository probiotic, called LACTIN-V, or a placebo for five days, then once a week for 10 weeks.

The results suggest that the probiotic may reduce the rate of recurrent urinary tract infections in women prone to these infections. Of the 100 women who participated in the study, 50 received LACTIN-V, and 50 received the placebo. Seven of the women who received LACTIN-V had at least one urinary tract infection, compared to 13 in the placebo group.

According to study author Ann Stapleton, MD, of the University of Washington in Seattle, “Larger efficacy trials of this novel preventive method for recurrent urinary tract infections are warranted to determine if use of vaginal Lactobacillus could replace long-term antimicrobial preventive treatments.”