In Some Cases, Even Bad Bacteria May Be Good
And for our last guest post of the Fall 2011 BIO230 course, Lindsay Kavchok (5 PM Micro) found this article from the New York Times about antibiotics and obesity.
Dr. Martin Blaser, a professor of microbiology at New York University Langone Medical Center has come up with the hypothesis that the overuse of antibiotics can increase the risk of obesity. There has been a significant overuse of antibiotics which has led to the creation of drug- resistant bacteria or superbugs, like methicillin- resistant Staphylococcus aureus. Researchers are now discovering that there is a troubling possibility that the abuse of antibiotics may also be connected to the escalating occurrence of obesity, as well as allergies, inflammatory bowel disease, asthma and gastroesophageal reflux.
In a commentary published in August in the journal Nature, he asserted that antibiotics are permanently altering microbial flora of the human body, also known as the microbiome or microbiota, with serious health consequences.
The stomach is home to billions of bacteria and doctors are very quick to prescribe antibiotics to a patient even when they don’t have any signs or symptoms of a bacterial infection. Dr. Blaser and his lab have formed a lot of data supporting his suspicion of antibiotics relating to obesity. The normal stomach contains H. pylori which is found to be present in patients with chronic gastritis and gastric ulcers, but is not believed to have a microbial cause. H. pylori is also linked to development of duodenal ulcers and stomach cancer. On the other hand over 80 percent of those who are infected with the bacterium are asymptomatic and it plays an important role in the natural stomach ecology. Dr. Blaser and his colleagues discovered that the stomach behaves in a different way after a course of antibiotics is ingested and destroys the resident H. pylori.
After a meal, levels of ghrelin, a hunger hormone secreted in the stomach, are supposed to fall, but in subjects without H. pylori, the amount of ghrelin in the bloodstream held steady, in essence telling the brain to keep eating.
This would eventually lead to over eating and then to obesity. In tests done on other animals such as mice, where they were fed antibiotics in similar dosages to children treated for such things as an ear or throat infection had marked various increases in body fat even if their diets remained the same. Another fact that would add to this argument is that farmers have for a long time given antibiotics to livestock to promote weight gain without increasing calorie intake. If we are aware of this problem now and take the steps to cut back on the over distribution of antibiotics for the wrong reasons we could possibly decrease the obesity and asthma population in the United States and maybe one day Dr. Blaser believes that a detoxified strain of H. pylori could be administered as a treatment for these conditions.