Use of broad-spectrum antibiotics and the development of irritable bowel syndrome.

BACKGROUND: Irritable bowel syndrome (IBS) is a functional bowel disorder with an estimated prevalence of 9% to 22% in the United States. It is responsible for 28% of gastroenterology visits, with associated health care costs of $8 billion annually. Yet, IBS etiology is the subject of much debate. OBJECTIVES: Our study examines a possible relationship between IBS and exposure to broad-spectrum antibiotics. It is known that antibiotics alter the colonic flora; we hypothesize that this can create the manifestations seen in IBS patients. METHODS: Following approval by the Gundersen Clinic, Ltd Human Subjects Committee/IRB, the medical records of adults who were started on a broad-spectrum antibiotic at Gundersen Lutheran Health System between January 1, 2008, and December 31, 2008, were reviewed retrospectively. From this population, we identified those who developed IBS within 12 months and compared their demographic and clinical characteristics with the characteristics of those who did not. RESULTS: Of the 26,107 adult patients exposed to broad-spectrum antibiotics during the study period, 115 received an IBS diagnosis within 12 months. Most were women (84%; n = 97), and they had a higher prevalence of associated comorbidities than those who did not develop IBS. Patients indicated for macrolide or tetracycline use had a higher proportion of IBS development within 12 months; indication for tetracycline use maintained significance even after controlling for sex and comorbid conditions (odds ratio; 1.48; P = .046). CONCLUSION: Use of broad-spectrum antibiotics--particularly macrolides or tetracyclines--may be associated with IBS development. To date, we know of no other study that has associated these antibiotics with IBS development. Further studies are necessary.

The hibernating 13-lined ground squirrel as a model organism for potential cold storage of platelets.

Hibernating mammals have developed many physiological adaptations to extreme environments. During hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) must suppress hemostasis to survive prolonged body temperatures of 4-8°C and 3-5 heartbeats per minute without forming lethal clots. Upon arousal in the spring, these ground squirrels must be able to quickly restore normal clotting activity to avoid bleeding. Here we show that ground squirrel platelets stored in vivo at 4-8°C were released back into the blood within 2 h of arousal in the spring with a body temperature of 37°C but were not rapidly cleared from circulation. These released platelets were capable of forming stable clots and remained in circulation for at least 2 days before newly synthesized platelets were detected. Transfusion of autologous platelets stored at 4°C or 37°C showed the same clearance rates in ground squirrels, whereas rat platelets stored in the cold had a 140-fold increase in clearance rate. Our results demonstrate that ground squirrel platelets appear to be resistant to the platelet cold storage lesions observed in other mammals, allowing prolonged storage in cold stasis and preventing rapid clearance upon spring arousal. Elucidating these adaptations could lead to the development of methods to store human platelets in the cold, extending their shelf life.