Can beneficial bacteria protect us from pathological bacteria? According to a recent medical study, the answer seems to be yes.
Over the past few years, there have been multiple instances of bacterial infection of food. Most recently, in Germany, over 1,500 people have become ill and at least 17 have died as a result of food being infected with a specific strain of the bacteria, Escherichia coli (E. coli). Most strains of E coli are harmless, and some are actually beneficial. However, some can cause life-threatening illnesses usually as a result of eating contaminated food. The outbreak in Germany is particularly serious since this specific strain seems to be resistant to antibiotics.
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Pathogenic E. coli bacteria cause problems because they are able to colonize the intestine and produce toxins. There are many different kinds of pathogenic bacteria and toxins. Some toxins are so deadly that, in susceptible individuals, they can cause the kidneys and heart to fail. The bacteria are found in the intestines of cattle. They become increasingly antibiotic resistant because antibiotics are liberally used in the cattle industry. Ultimately, these bacteria can make their way into our food and have the potential to cause serious illness.
All bacteria are not pathogenic. There are many good bacteria (probiotics) living in our intestines that play a crucial role in our health. We live with them in a mutually beneficial, symbiotic relationship. We provide them a warm place to live, food and protection from the environment. In return, they provide us with vitamins and other compounds essential for our well-being. They also prevent pathogenic bacteria from setting up shop and some even prevent pathogenic bacteria from producing toxins.
In a recent study, done at the University of Michigan medical school, the good bacteria Lactobacillus reuteri was able to protect mice infected with a particularly pathogenic strain of E. coli. In this study, the lactobacillus prevented colonization of the bowel by E. coli. In addition, those mice fed lactobacillus twice per day did not develop any the symptoms associated with the toxins made by the E. coli. This suggests that probiotics may have an important role in the prevention (and treatment) of food-borne infections.
There are no similar studies in humans because it would be unethical to purposely infect someone with pathogenic bacteria so we have to extrapolate from animal studies. Many probiotic bacteria may confer similar protection as Lactobacillus reuteri and research in this area is progressing quickly. Probiotics may also reduce allergies and asthma as well as proving to be beneficial for inflammatory bowel conditions like ulcerative colitis and Crohn's disease. I enthusiastically endorse the use of probiotics and are generally safe.
• Patrick B. Massey, M.D., Ph.D is medical director for complementary and alternative medicine for the Alexian Brothers Hospital Network.