We will focus on the intestinal flora structure, risk factors and clinical features of male elderly with SIBO in our study.

Our previous study had found that the prevalence rate of small intestinal bacterial overgrowth(SIBO) in male elderly was high up to 63.1%. In the recent years, SIBO has been found be associated not only with abdominal symptoms such as abdominal distention, pain and so on, but also with various diseases such as diabetes, Alzheimer's disease, joint pain, chronic prostatitis, fatty liver, liver cirrhosis etc. SIBO has significant impact on the health of elderly. Methane and hydrogen lactulose breath test(LBT) is effective and noninvasive for the diagnosis of SIBO. High throughput sequencing is a leading technique for the study of intestinal microflora.

Although more and more studies have focused their concern on the intestinal flora now, few SIBO-related studies are available in elderly patients. But we have found SIBO was very popular in the elderly. The conflict between high prevalence rate of SIBO in elderly and very few relevant studies is barrier to study of pathophysiology, early diagnosis and treatment of SIBO in elderly adults.

So in our study, we will apply LBT and high throughput sequencing technique to study the intestinal flora structure, risk factors and clinical features of male elderly patients with SIBO. And further, we will try to develop standard treatment for elderly patients with SIBO.

Inclusion Criteria:

• no use of antibiotics in the past 1 month, no use of prokinetic drugs and probiotics in the past 1 week

Exclusion Criteria:

• active inflammation, cardiac insufficiency, respiratory insufficiency, hepatic insufficiency, renal insufficiency, cirrhosis, thyroid diseases, Crohn disease, ulcerative colitis, hepatobiliary and pancreatic disease

male

male elderly outpatients at Department of Gastroenterology, Nanlou Division, Chinese PLA General Hospita, Beijing, China

the data of these male elederly enrolled in the study are secret on account of their status