Intestinal Coating Replaces Antibiotics After Surgery

By injecting a protective coating into the intestines to pacify bacteria, researchers were able to protect mice from infection with Pseudomonas aeruginosa after major surgery without the need for antibiotics. Their experiment was reported in the February 2004 issue of Gastroenterology.

Pseudomonas is a frequent cause of hospital-acquired infections, especially after major surgery. It can detect an ill host's vulnerability by sensing chemicals that indicate stress, and it has tools that allow it to evade and even disable the host's immune system. Pseudomonas resists antibiotics and secretes toxins similar to those used by diphtheria or anthrax. However, the researchers found that a coating with a high molecular-weight polymer can form a surrogate bioshield and stop the process before it begins by preventing the stress signals from reaching bacteria and triggering the virulent response.

The researchers tested the approach by performing major surgery on mice, then introducing Pseudomonas into the bowel, a model that kills all the mice within two days. One treatment with PEG 15-20, injected into the bowel at the time of infection, however, completely protected the mice. A solution taken by mouth four to eight hours after infection also protected treated mice. A lighter weight PEG did not protect the mice.

"An unhappy parasite is programmed to kill the host and move on. So we decided to look for ways to gratify them, to please these powerful microbes and keep them content,” explained John Alverdy, M.D., associate professor of surgery at the University of Chicago (IL, USA) and the director of the study.





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