The Role of Small Intestinal Bacterial Overgrowth in the IBS

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小肠细菌过度生长与肠易激综合征

小肠细菌过度生长与肠易激综合征陈坚* 邱志兵张会禄汤子慧杨冬琴（复旦大学附属华山医院消化内科上海 200040）摘要本文概要介绍小肠细菌过度生长（small intestinal bacterial overgrowth, SIBO）和低度炎症在肠易激综合征患者中的发生率、SIBO的致病作用、利福昔明治疗伴有SIBO的肠易激综合征患者的疗效以及对利福昔明治疗失败的患者的补救治疗方法。

关键词肠易激综合征小肠细菌过度生长乳果糖呼气试验低度炎症利福昔明中图分类号：R574.4; R363.21文献标志码：A文章编号：1006-1533(2019)15-0007-04Small intestinal bacteria overgrowth and irritable bowel syndromeCHEN Jian*, QIU Zhibing, ZHANG Huilu, TANG Zihui, YANG Dongqin(Department of Digestive Disease, Huashan Hospital, Fudan University, Shanghai 200040, China)ABSTRACT The incidence and pathogenesis of small intestinal bacterial overgrowth (SIBO) and low-grade inflammatory response in irritable bowel syndrome (IBS) patients are introduced. The effects of rifaximin on IBS patients with SIBO and the remedial treatment for rifaximin-resistant IBS patients are also discussed.KEy WORDS irritable bowel syndrome; small intestinal bacterial overgrowth; lactulose breath test; low-grade inflammation; rifaximin肠易激综合征（irritable bowel syndrome, IBS）是一种常见的功能性胃肠病，临床上主要表现为腹痛、腹胀以及腹泻或便秘等，全球人口的患病率为3% ~ 25%[1]，亚洲地区人口的患病率为4% ~ 10%[2]。

Small Intestinal Bacterial Overgrowth Syndrome

457C.S. Pitchumoni and T.S. Dharmarajan (eds.), Geriatric Gastroenterology ,DOI 10.1007/978-1-4419-1623-5_46, © Springer Science+Business Media, LLC 2012B ackgroundT he aging population has resulted in a geriatric group rang-ing from the healthy to the frail, characteristically manifest-ing comorbid illness. While several chronic disorders in theaged can be diagnosed easily, some escape early diagnosis. Small intestinal bacterial overgrowth (SIBO) is de ﬁ n ed as any condition in which part of the small bowel harbors for along time bacterial counts over 10 5Colony Forming Units/ml (CFU/ml) in the intestinal juice. SIBO is an entity that the aged are prone to, but often escapes diagnosis, partly due to its vague and nonspeci ﬁ c presentation. Also referred to as small bowel bacterial overgrowth (SBBO), it is an unrecog-nized, but common cause of malnutrition in the geriatric age group, resulting from the proliferation of bacteria in the oth-erwise normally sterile small intestine lumen [ 1, 2].The bac-terial proliferation deprives the host of macro- and micronutrients. The term SIBO refers to an increase or an alteration of the normal ﬂ o ra of the upper gastrointestinal (GI) tract and an overgrowth of colonic-type bacteria in the small intestine [ 3].N ormal Gut FloraIn the healthy state, several defense mechanisms play a role in keeping gut bacterial counts close to normal; mecha-nisms include gastric acid secretion, normal intestinal motility, intestinal secretions with their bacteriostatic prop-erties, and immunoglobulins in the intestinal mucosa. These defense mechanisms can be altered by systemic disease, surgery, ﬁ s tulas or diverticuli, and medications. On the other hand, gut microbiota also contribute to useful func-tions such as trophic effects for the gut epithelium, immune function, fermentation of carbohydrates and prevention of growth of oppressive ﬂ o ra, amongst others.B acterial counts have become possible through a process of DNA sequencing; based on the technique used, the num-ber of bacteria and variety change signi ﬁ c antly. The epithe-lial surface of the small intestine is not colonized in health. As many as 500 or more different species of bacteria reside in the gut, but the majority are compromised of a few spe-cies. In healthy states, the upper gastrointestinal tract barring the oral cavity is low in bacterial activity, while at the lower end the colon is loaded with bacteria, the huge number alsocontributing to more than half the fecal mass [ 4,5].The oral cavity houses bacteria of several species that line the tongue, ﬂ o or of mouth, cheek, and teeth; the bacteria are diverse even in good health, and predominantly anerobes. In the healthy state, protozoa and fungi contribute small numbers in the gut. The bacterial count is low in the duodenum and proxi-mal jejunum, counts typically below 10 4CFU/mL; here,counts above 10 5CFU/mL are diagnostic of SIBO. While most bacteria in the small intestine are anerobes, there is a signi ﬁ c ant increase in aerobes at the cecal site. The large intestine lumen carries the highest load of bacteria, 99% of them anerobes, contributing to fecal mass. Table 46.1pro-vides an idea of bacterial ﬂ o ra and counts at different gut sites [4– 6].S mall Intestinal Bacterial Overgrowth Syndrome T.S.Dharmarajan and C.S.Pitchumoni46T . S . D harmarajan, MD, FACP, AGSF (*) P rofessor of Medicine ,A ssociate Dean , N ew York Medical College, Valhalla ,N Y ,U SA V ice Chairman, Department of Medicine , C linical Director, Division of Geriatrics, Program Director, Geriatric Medicine Fellowship Program, Monte ﬁo re Medical Center (North Division) ,B ronx ,N Y ,U SA e-mail: d harmarajants@ C . S . P itchumoni, MD, MPH, FRCP(C), MACP, MACG, AGAF C linical Professor of Medicine , R obert Wood Johnson School of Medicine, Drexel University School of Medicine ,A djunct Professor of Medicine, New York Medical College, Valhalla ,N Y ,U SA C hief, Gastroenterology ,H epatology and Nutrition , S aint Peter’s University Hospital, New Brunswick ,N J ,U SA458T.S. Dharmarajan and C.S. PitchumoniP revalence of Bacterial OvergrowthT he precise prevalence is not clear as the entity of SIBO islargely unsuspected and underdiagnosed. In most situationsan alternate diagnosis is considered to be the explanation for the patient’s manifestations. Ranges for SIBO in studies vary considerably from as low as 2.5% to as high as 90% in older adults with lactose intolerance [7].Bacterial overgrowth does not spare persons of any body weight, with high preva-lence in morbid obesity as noted in a recent study [8].Based on speci ﬁc risk factors in the individual, the prevalence of SIBO varies; its greater prevalence in older adults correlates well with age being a predisposition in association with the high frequency of comorbid disorders in the aged that are linked to SIBO.R isk Factors and Predisposition to SIBOA ge predisposes to SIBO for several reasons. Older adults are more likely to have a decline in gastric acid due to gastric disease or use of acid neutralizing agents; we are in an era where the use of proton pump inhibitors ranges from estab-lished indications to redundancy; immune dysfunction from disease or use of medications such as steroids is common in the older adult; disease processes (Tables 46.2and 46.3) which predispose to bacterial overgrowth are common in the elderly [9]. When healthy aged were compared to physically disabled older adults, with measures of physical activity and food intake, interestingly, not a single SBBO positive subject was detected by hydrogen breath test in the healthy group, in contrast to a fourth of the disabled elderly being SBBO posi-tive [10]. Comparing the physically disabled and healthy older group further, there is no signi ﬁc ant inﬂ uence of SBBO on rice absorption [11].I ntestinal stasis irrespective of cause is a predisposition; stasis results from strictures, adhesions, blind loops, postop-erative states (including Billroth II, gastric bypass surgery), ﬁs tulae, in ﬂa mmatory bowel disease (Crohn’s disease), diverticular disease of the small bowel, and motility disorders such as scleroderma and autonomic neuropathy of diabetes or Parkinson’s disease. “Short bowel” syndrome allows tran-sit of chime and undigested food, a substrate for bacterial growth. Type 1 diabetics with autonomic neuropathy have a higher prevalence of SIBO; further, SIBO positive diabetics also require higher daily insulin doses [12].SIBO occurs more frequently is systemic sclerosis, present in 30 of 54 patients in a study; eradication of bacteria improved clinical features; orocecal transit time was slower in those with scle-roderma (vs. controls), suggesting impaired motility as a basis for SIBO [13]. Gastroparetics with abdominal pain and bloating have a high likelihood of SIBO; in fact, 60% may have SIBO with pareisis of 5 years duration, irrespective of gender or etiology of paresis [14].Gastropareisis is well known to occur in longstanding diabetics, but does not result solely from aging.T able 46.1 M icrobiota in the human gastrointestinal tract [4–6]L ocation B acterial counts T ype of bacteriaO ral cavity H igh bacterial counts O ver 200 species.S treptococcus, Actinomyces,Fusospirochetes, Neisseria,Lactobacillus, VeilonellaS tomach B elow 10 3CFU/mL H elicobacter pylori,acid-tolerant lactobacilliD uodenum B elow 10 4CFU/mL L actobacilli, enterocci,anerobes both gram positiveand facultativeJ ejunum S terile to below10 4CFU/mL L actobacilli, enterococci, anerobes both gram positive and facultativeI leum L ow counts increaseto10 5–8CFU/mL D istal ileum shows marked increase in anerobes and coliformsC olon O ver 10 12/content.Huge numbers,comprise half thefecal mass O ver 500 species, 99% areanerobes. B acteroides,E nterobacter, Clostridium,Enterococcus, Lactobacillus,Fusobacterium, StaphylococcusT able 46.2 S IBO: risk factors and predispositionA ging is a predisposing factorD isease states predisposing to SIBOG astroparesis and achlorhydria, if long standingS tasis, any cause: blind loops, gastrocolic or enterocolic ﬁs tulae,strictureS hort bowel syndrome (e.g., ileocolic or jejunocolic anastamoses)P ostoperative: Billroth II, gastric bypass and other bariatric surgicalproceduresD iverticular disease of duodenum or jejunumD iabetes mellitus, Parkinson’s disease (autonomic neuropathy)C eliac diseaseC rohn’s diseaseS clerodermaI rritable bowel syndromeR adiation enteritisC irrhosis liver and nonalcoholic steatohepatitisC ancer of pancreasC hronic pancreatitisC hronic renal failureR heumatoid arthritisI mmune suppressed statesM edications and SIBO: bene ﬁc ial or worsenU se of immunosuppressive agents, a predispositionL ong-term use of PPIs, a predispositionW arfarin requirements increase, because of vitamin K1 absorptionA ntibiotics produce temporary relief in manifestations459 46 Small Intestinal Bacterial Overgrowth SyndromeI mmune de ﬁc ient states are common with age. Although age is associated with blunting of immune function, it is more likely that SIBO results from disease processes or immune suppressed states resulting from the medications used to treat disease. The presence of SIBO has been noted in pancreatic cancer treated with chemotherapy; the patient improved dramatically following administration of antibiotics [15].I n senior resident sites at Germany, SBBO was prevalent (by hydrogen breath test) in 15.6% of older adults compared to the 5.9% in the below 59 age group; those with SBBO consumed much less ﬁb er and B vitamins, and manifested reduced body weight [16].T he relationship of SIBO with irritable bowel syndrome (IBS) deserves mention, for consideration as an association and in differential diagnosis. SIBO is present in a sizable propor-tion of patients with IBS, with older age and female gender predictors of SIBO [17]. The symptoms of constipation, diar-rhea, and alternating patterns in IBS may be due to fermenta-tion of methane in the gut and slow transit time causing constipation [18]. On the other hand, a large meta-analysis con-cluded that the prevalence of SIBO in IBS varied with criteria used to de ﬁn e a positive test, and was highest with breath test-ing [19]. SIBO is more likely to be present in diarrhea domi-nant IBS compared to the constipation dominant IBS [20].M edication use has been associated with SIBO. The use of immunosuppressive agents has received attention. Often, PPI use meant to be short term, not uncommonly becomes long term in the treatment of gastroesophageal re ﬂu x disease (GERD) or nonerosive re ﬂu x disease (NERD); PPI therapy for 3 years in GERD was associated with SIBO in 50% of cases; this was eradicated by use of rifaximin in the majority who continued PPI therapy [21].The ﬁn dings prompt PPI use for a shorter term, or as step-down, or as on demand therapy. Interestingly, SIBO increases warfarin dose require-ments through an increase in the dietary vitamin K1 absorp-tion through damaged intestinal mucosa, rather than by increased intestinal vitamin K2 biosynthesis [22].W hile the association of SIBO with cirrhosis of the liver is recognized, the pathophysiology is not clear [23].SIBO has been associated with and implicated in the pathogenesis of nonalcoholic steatohepatits. As many as half the patients with celiac disease may have SIBO [24].Chronic exocrine disorders of the pancreas have been linked to SIBO. Finally, it is likely that more than one predisposing factor may be present in an individual with SIBO.M anifestationsP resentations in SIBO vary from the asymptomatic, presence of only nutrient de ﬁc iencies and the extreme of weight loss with failure to thrive. Classic manifestations include anorexia, bloating or ﬂa tulence, abdominal discomfort, pain, and diar-rhea. Complaints in the old may not be typical and may even resemble gradual deterioration in health attributed falsely to aging; the patient may report improvement in the abdominal complaints following a recent antibiotic course prescribed for a respiratory or urinary infection.B acterial overgrowth leads to carbohydrate malabsorp-tion by decreasing the disaccharidase enzymes in the brush border of the villi. Protein malabsorption, though not often clinically overt, is caused by decreased absorption of aminoT able 46.3 S tudies on SIBOS ymptomatic elders [9]168 Patients, teaching hospital, UKM edian age 65, 106 femalesP ositive glucose breath test correlated with increasing age, low serum albumin, low serum B12, partial gastrectomy or right hemicolectomy, small bowel diverticulae and PPI useH ealthy vs. disabled adults [10]P hysical Fitness and Sports University Center, Japan41 Healthy, mean age 74.6 years, vs. 42 disabled, mean age 78.8 yearsS IBO not seen in healthy old, but present in 25% of disabled;no difference in food intakeR ice ingestion [11]P hysical Fitness and Sports University Center, Japan15 disabled older adults, vs. 11 healthy older adults5 of 15 disabled had SBBO; rice malabsorption seen in 1 of 11 healthy and 2 of 14 disabled, not signi ﬁc antS BBO has no in ﬂu ence on rice absorptionD iabetics and autonomic neuropathy [12]25 type I diabetics with normal autonomic tests vs. 25 type 1 diabetics with abnormal autonomic function2 of 25 with normal autonomic had SIBO vs. 11 of 25 with abnormal autonomic functionD iabetics with autonomic dysfunction require more insulinN utrition [16]E ight senior resident sites, Germany294 subjects >61 years compared to ages 24–59S IBO 15.6% in 61+ years vs. 5.9% in 24–59 yearsS IBO associated with lower ﬁb er, folic acid, B2 and B6 intake and weight lossI BS and SIBO [18]M edline and EMBASE search; Universities in the USA, Canada 1,921 subjects who met criteria for IBSP ooled prevalence of +ve lactulose or glucose hydrogen breath test, and positive jejuna aspirate and cultureP ooled odds for +ve test for SIBO was 3.45 vs. prokinetic drugs may be bene ﬁc ial in conditions such as scleroderma. Search controlsC irrhosis liver and association [23]40 patients with cirrhosis, GermanyC ulture of jejuna aspirates provided diagnosis in 73#G lucose breath hydrogen test sensitivity 27–52%, speci ﬁc ity36–80%B one mineral density [26]P hysical Fitness and Sports University Center, Japan33 disabled older adults vs. 17 healthy older adultsZ scores were not statistically different in the groupsa pproximately 80 years old460T.S. Dharmarajan and C.S. Pitchumoniacids and peptides probably secondary to mucosal damage. Steatorrhea, the major manifestation of SIBO, results from a decrease in primary bile acids which are deconjugated by the bacteria. Malabsorption of fat and fat-soluble vitamins results from bile acid de ﬁc iency. After lipolysis by pancreatic lipase and bicarbonate, the products of lipolysis normally undergo micelle formation in the presence of adequate bile acids. In SIBO, the concentration of bile acids (referred to as “crtical micellar concentration”) in the jejunal lumen declines, with resultant steatorrhea.D e ﬁc iencies of vitamins A, D, andE occur, while vitamin K de ﬁc iency is rare because of production of vitamin K by intestinal bacteria. While intestinal bacteria compete with the host and consume vitamin B12 resulting in low blood B12 levels, they synthesize folate, resulting in the unusual combination of low blood B12 levels but elevated folate [1].T he features of the predisposing condition such as sys-temic sclerosis or diabetes may be evident; on the other hand nutrient de ﬁc iencies (e.g., vitamin D or B12, calcium or iron) may be the basis for symptoms or signs unique to the nutri-ent. Lactose intolerance is common and may contribute to diarrhea.W hile the differential diagnosis of SIBO includes several disorders, coexisting irritable colon may provide dilemmas in diagnosis or treatment. When diarrhea is of short duration, an infectious cause or an adverse drug effect may be the eti-ology in any age group; following their exclusion, differen-tial diagnosis includes malabsorption of any etiology; SIBO and anatomic abnormalities predisposing to SIBO must be considered in any unexplained weight loss with or without malnutrition [25].S tudies demonstrate that malabsorption of rice does not necessarily occur in SIBO [11]nor is the bone mineral den-sity affected [26]; these studies were from one center and compared small groups of healthy and disabled older adults.D iagnosisT he gold standard with regard to diagnosis for SIBO remains poorly de ﬁn ed [3]. Although duodenal or jejunal aspirates and a variety of breath tests are available, they suffer varia-tions in their performance and interpretation, leading to differing prevalence data for bacterial overgrowth [3].There is also a lack of consensus with regard to optimal diagnostic criteria (“gold standard”) for diagnosis of bacterial over-growth [27].T he gold standard, though technically dif ﬁc ult, is culture of the upper small bowel aspirate which normally reveals concentrations of bacteria below 10 4CFU/mL; concentra-tions of duodenal aspirate over 10 5CFU/mL are diagnostic; similarity to colonic bacteria is even more con ﬁr matory of SIBO. This method is time-consuming, invasive, and costly.B reath tests vary, including in their sensitivity and are in ﬂu enced by patient factors (capacity to produce methane and hydrogen), and life style (diet and smoking). Breath tests provide a noninvasive in vivo means to assess bacterial enzyme activities, organ functions, and transport processes [27–29]. The glucose hydrogen breath test is widely used; other tests are 14C-glycocholic acid (produces 14C-glycine) and 13C-glycine hydrolase breath tests [28, 29].Hydrogen breath tests assess carbohydrate malassimilation in SIBO, besides measuring orocecal transit time which is useful in diagnosis of motility disorders of the small intestine; g lycine breath tests measure CO2in breath and substrate metabolism to assess gastric bacterial activity with H elicobacter pylori infection [28]; the test lacks sensitivity as some bacterial species lack cholylglycine hydrolase required to deconjugate glycine. The 14C and 13C-xylose breath tests involve radiation and measure labeled CO2in expired air. Xylose is a sugar that is absorbed without metabolism in the intestine.T he hydrogen breath test is safe and easy to perform in 2–3 h in the outpatient setting; it evaluates carbohydrate mal-absorption. Breath samples analyze hydrogen concentration at baseline and every 30 min for 2 h; an earlier-than-expected rise of 20 parts per million (ppm) in breath over baseline at approximately 90 min is diagnostic of SIBO. The test is non-radioactive and has reasonable sensitivity and speci ﬁc ity, more so than the methane breath test. In the human, hydro-gen and methane are produced in the large intestine only, but also in the small intestine in SIBO. Most of the hydrogen and methane is expelled by ﬂa tus and the rest in the breath [2].In SIBO, the early increase in breath hydrogen within 90 min is due to metabolism by bacteria in small bowel. Glucose and lactulose are the sugars utilized for the test; lactulose is nor-mally metabolized in the colon, giving it a peak hydrogen release in 3 h; but in SIBO, bacteria metabolize lactulose in the small bowel with hydrogen release in 90 min or less. Gut ﬂo ra of some individuals produce methane and not hydro-gen, while not all individuals produce methane; hence, it is better to measure both gases [1, 2].I n patients with cirrhosis, microbiological cultures of jejunal secretions are better for diagnosis than the glucose breath hydrogen test which correlates poorly with the gold standard for SIBO [23].D uodenal biopsies in patients with SIBO con ﬁr med by cultures and CFU counts demonstrate villous blunting as the only histopathology common to SIBO, compared to controls; as over half the biopsies in SIBO are unremarkable, one must consider SIBO as the explanation for GI manifestations even with normal duodenal biopsies [30].O lder adults tolerate the breath tests well; for reliable test-ing, the patient should not ingest high- ﬁb er or carbohydrate-rich foods for a day prior to the test. Antibiotics in the recent past may negatively impact on the testing as the bacterial counts fall to low levels [1].461 46 Small Intestinal Bacterial Overgrowth SyndromeA test that once enjoyed popularity in the evaluation of patients with steatorrhea is the D-Xylose test; D-Xylose (normally not metabolized in the gut) excretion in the urine is marginally reduced because the sugar is consumed by the bacteria.A dditional tests to evaluate anemia or nutrient de ﬁc iencies and their cause may be warranted; fecal fat collection help con ﬁr m steatorrhea; radiological tests may help diagnose anatomic abnormalities such as diverticulae or ﬁs tulae.M anagementT reatment is supported by scant evidence, with most com-monly used antibiotic regimens based on custom than from data derived from clinical trials [3].Management of SIBO remains in large part primarily empiric, comprising antibi-otic therapy and correction of nutritional de ﬁc iencies [31]. Nutritional support is essential to correct malnutrition.T he impact of probiotic yogurt administration for 4 weeks was studied in healthy older community subjects; normaliza-tion of the various cytokine responses and modulation of activation markers in blood phagocytes became more appar-ent in the group with positive breath test [32].Although pro-biotics have been ascribed barrier-enhancing, antibacterial, and immune-modulator roles, their role in SIBO in humans requires further study [32].P rokinetic drugs may be bene ﬁc ial in motility disorders, such as scleroderma. Examples of these agents include oct-reotide, cisapride (withdrawn in the USA due to cardiac arrhythmias), metoclopramide, domperidone, and erythro-mycin; data is limited over their long-term ef ﬁc acy.B road-spectrum antibiotics are the mainstay to help reduce bacterial overgrowth. Empirical use is often resorted to, with-out common agreement on choice. Quinolones such as nor ﬂo xacin (800 mg/day), cipro ﬂo xacin (1,000 mg/day), amoxicillin/cavulinic acid (1,500 mg/day), metronidazole (750 mg/day), and tetracycline (1,000 mg/day) are options. More recently, rifaximin (600–1,200 mg/day), a nonsystemic, nonabsorbable antibiotic, has gained favor. The duration of therapy is about a week, though the initial course may be for 2 weeks, and repeated as required; improvement in manifes-tations is usually evident within days of therapy. Rotation of antibiotics may minimize resistance. The combination of rifampin with partially hydrolyzed guar gum appears more effective than rifampin alone in eradicating SIBO [33].R ecurrence after successful antibiotic therapy as shown by glucose breath test was 12.6, 27.5, and 43% and after 3, 6, and 9 months, respectively; recurrence was positively in ﬂu enced by older age, prior appendectomy, and chronic use of PPIs [34]. Long-term use of antibiotic therapy is associated with its own problems: resistance, costs, and C lostridium dif ﬁc ile infectionA ddressing the predisposing factors for SIBO would be ideal, but is not always practical. Conditions amenable for surgical correction include mechanical causes such as stric-tures, blind loops, or ﬁs tulae.S pecial Considerations in the ElderlyA s older adults high have a high prevalence for malnutrition and tend to suffer from chronic disorders, SIBO as the possible explanation is often lost in the myriad of alternate diagnostic possibilities. In any cause of malnutrition or weight loss that is not fully explained, it may be worthwhile entertaining and excluding the diagnosis of SIBO. Treatment not only has the potential to improve patient’s well-being and quality of life but also avoids unnecessary costs and treatment for alternate erroneous diagnoses. Further, it is the geriatric age population that carries the background to develop unwanted gut bacterial overgrowth; they are the group subjected to courses of antibiotics, at times with ques-tionable indications. The long-term use of PPIs is another area that continues to demonstrate a relationship to increased incidence of bacterial overgrowth [35], in fact suggesting the need to consider a step down or on-demand PPI therapy for an entirely different disorder, GERD [36].Recent data sug-gest that SIBO and irritable bowel syndrome are common in chronic prostatitis (a disorder common in the old); and that patients with chronic prostatitis and SIBO may beneﬁ t from rifaximin therapy [37].K ey PointsS IBO is an underrecognized cause of malabsorption in •the geriatric population, commonly mistaken for other disorders.A ge is a predisposing factor; however, additional comor-•bidity such as diabetes, systemic sclerosis, and stasis syn-dromes such as blind loops, diverticulae, and ﬁs tulae are more likely to be contributory.M edications that affect immune function and excessive •use of PPIs are recognized causes.D iagnosis is based on linking manifestations to causative •factors, utilizing duodenal or jejunal aspirate cultures, and breath tests.M anagement typically involves a short course of antibiot-•ics; the use of probiotics needs further study.R ecurrences follow months following antibiotic therapy, •hastened and in ﬂu enced by predisposing factors.462T.S. 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Small intestinal bacterial over-growth in patients suffering from scleroderma: clinical effectivenessof its eradication. Am J Gastroenterol. 2008;103(5):1257–62.14. R eddymasu SC, McCallum RW. Small intestinal bacterial over-growth in gastroparesis: are there any predictors ?J Clin Gastroenterol. 2010;44(1):e8–13. 15. B ustillo I, Larson H, Saif MW. Small intestinal bacterial over-growth: an undiagnosed cause of diarrhea in patients with pancre-atic cancer. JOP. 2009;10(5):576–8. 16. P arlesak A, Klein B, Schecher K, et al. Prevalence of small bowelbacterial overgrowth and its association with nutrition intake in non-hospitalized older adults. J Am Geriatr Soc. 2003;51(6):768–73. 17. R eddymasu SC, Sostarich S, McCallum RW. Small intestinal bac-terial overgrowth in irritable bowel syndrome: are there any predic-tors? BMC Gastroenterol. 2010;10:23. 18. L ee HR, Pimental M. Bacteria and irritable bowel syndrome: theevidence for small intestinal bacterial overgrowth. Curr Gastroenterol Rep. 2006;8(4):305–11. 19. F ord AC, Spiegel BM, Talley NJ, et al. Small intestinal bacterialovergrowth in irritable bowel syndrome: systematic review and meta-analysis. Clin Gastroenterol Hepatol. 2009;7(12):1279–86.20. M ann NS, Limoges-Gonzales M. The prevalence of small intestinalbacterial overgrowth in irritable bowel syndrome. Hepatogastroen-terology. 2009;56(91–2):718–21. 21. L ombardo L, Foti M, Ruggia O, et al. Increased incidence of smallintestinal bacterial overgrowth during proton pump inhibitor ther-apy. Clin Gastrenterol Hepatol. 2010;8(6):504–9. 22. G iuliano V , Bassotti G, Mourvaki E, et al. Small intestinal bacterialovergrowth and warfarin dose requirement variability. Thromb Res. 2010;126(1):12–7. 23. B auer TM, Schwacha H, Steinbruckner B, et al. Diagnosis of smallintestinal bacterial overgrowth in patients with cirrhosis of the liver: performance of the glucose breath hydrogen test. J Hepatol. 2000;33(3):382–6. 24. R ubio-Tapia A, Barton SH, Rosenblatt JE, et al. Prevalence of smallintestinal bacterial overgrowth diagnosed by quantitative culture of intestinal aspirate in celiac disease. J Clin Gastroenterol. 2009;43:157–61. 25. H olt PR. Diarrhea and malabsorption in the elderly. GastroenterolClin North Am. 2001;30(2):427–44. 26. M itsui T, Shimaoka K, Takagi C, et al. Small bowel bacterial over-growth may not affect bone mineral density in older people. ClinNutr. 2005;24(6):920–4. 27. A bu-Shanab A, Quigley EM. Diagnosis of small intestinal bacterialovergrowth: the challenges persist. Expert Rev Gastroenterol Hepatol. 2009;3(1):77–87. 28. B raden B. Methods and functions: Breath tests. Best Pract Res ClinGastroenterol. 2009;23(3):337–52. 29. B raden B, Lembcke B, Kuker W, et al. 13C-breath tests: currentstate of the art and future directions. Dig Liver Dis. 2007;39(9):795–805. 30. L appinga PJ, Abraham SC, Murray JA, et al. Small intestinal bacte-rial overgrowth; histopathological features and clinical correlatesin an underrecognized entity. Arch Pathol Lab Med. 2010;134:264–70. 31. Q uigley EM, Querra R. Small intestinal bacterial overgrowth: rolesof antibiotics, prebiotics and probiotics. Gastroenterology. 2006;130(2 Suppl 1):S67–9. 32. S chiffrin EJ, Parlesak A, Bode C. Probiotic yogurt in the elderlywith intestinal bacterial overgrowth: endotoxaemia and innate immune functions. Br J Nutr. 2009;101(7):961–6. 33. F urnari M, Parodi A, Gemignani L, et al. Clinical trial: the combi-nation of rifampin with partially hydrolyzed guar gum is moreeffective than rifaximin alone in eradicating small intestinal bacte-rial overgrowth. Aliment Pharmacol Ther. 2010;32(8):1000–6. 34. L auritano EC, Gabrielli M, Scarpellini E, et al. Small intestinalbacterial overgrowth recurrence after antibiotic therapy. Am J Gastroenterol. 2008;103(8):2031–5. 35. L ombardo L, Foti M, Ruggia O, Chiecchio A. Increased incidenceof small intestinal bacterial overgrowth during proton pump inhibi-tor therapy. Clin Gastroenterol Hepatol. 2010;8(6):504–8. 36. C ompare D, Pica L, Rocca A, et al. Effects of longterm PPI treat-ment on producing bowel symptoms and SIBO. Eur J Clin Invest.2011;41(4):380–6. 37. W einstock LB, Geng B, Brandes SB. Chronic prostatits and smallintestinal bacerial overgrowth: effect of rifaximin. Can J Urol. 2011;18(4):5826–30.。

脸上的微生物英文演讲稿

脸上的微生物英文演讲稿以下是一篇关于“脸上的微生物”的英文演讲稿，供您参考：Ladies and gentlemen,Today, I am going to talk about the microorganisms on our faces. Our faces are constantly covered by a variety of microorganisms, some of which are beneficial while others may cause harm. Understanding the composition and function of these microorganisms is crucial for maintaining our health and skin well-being.Firstly, let’s take a look at the types of microorganisms found on our faces. There are over 100 species of bacteria, fungi, and viruses that call our faces their home. The distribution of these microorganisms varies from person to person and depends on a range of factors such as genetics, environment, and personal hygiene habits.One of the most common types of bacteria found on the face is Propionibacterium acnes. This bacteria is known to play a role in the development of acne vulgaris, commonly known as “acne”. However, Propionibacterium acnes is not the only bacteria that can cause acne. Other species such as Staphylococcus aureus and Streptococcus pyogenes can also be involved in the development of this skin condition.On the other hand, there are also beneficial microorganisms on our faces. One example is the yeast strain known as Malassezia globosa. This yeast is believed to have anti-inflammatory properties and can help protect the skin from harmful microorganisms.Now that we have a better understanding of the types of microorganisms on our faces, let’s move on to discuss their function and how they impact our health. Microorganisms on our faces can influence our skin in a number of ways. For example, some bacteria can help to protect our skin from harmful external factors such as UV rays and environmental toxins. In addition, some species can also help to maintain the acidity of the skin surface, which helps to keep the skin healthy and hydrated.Moreover, the presence of certain microorganisms can also trigger an immune response in our bodies, helping us to fight off harmful invaders. However, if the balance of these microorganisms is disturbed, it can lead to various skin problems such as acne, rosacea, or psoriasis.To maintain a healthy balance of microorganisms on our faces, it is important to practice good hygiene habits. Regularly washing your face with warm water and mild soap can help to remove excess oil, dirt, and dead skin cells that can clog pores and lead to the development of acne.In conclusion, our faces are home to a diverse community of microorganisms that play both harmful and beneficial roles in our health. Understanding the types and functions of these microorganisms is crucial for maintaining a healthy complexion. By practicing good hygiene habits and adopting an anti-inflammatory diet, we can help to support the balance of microorganisms on our faces and promote healthy, glowing skin. Thank！。

壳脂胶囊治疗非酒精性脂肪肝临床分析

壳脂胶囊治疗非酒精性脂肪肝临床分析【关键词】非酒精性脂肪肝；壳脂胶囊；中医药疗法非酒精性脂肪肝(nonalcoholic fatty liver disease， NAFLD)是以无过量饮酒史(酒精摄入量＜20 g/d)以及肝细胞脂肪变性、气球样变、弥散性小叶轻度炎症和(或)肝中央静脉、肝窦周围胶原沉积等为临床病理特点的慢性肝脏疾病。

随着我国人们物质生活的不断改善，NAFLD的发病率也逐年升高，已成为仅次于病毒性肝炎的常见肝病。

由于缺乏明确有效的治疗药物，NAFLD的治疗成为临床上比较棘手的问题。

笔者采用壳脂胶囊治疗NAFLD取得了较好的疗效，现报道如下。

1 资料与方法1.1 诊断标准诊断参照2002年10月中华医学会肝脏病学会脂肪肝和酒精性肝病学组制订的非酒精性脂肪肝诊断标准[1]：①无饮酒史或饮酒折合乙醇量每周40 g；②除外病毒性肝炎、全胃肠营养等可导致脂肪肝的特定疾病；③除原发病临床表现外，可出现乏力、腹胀、肝区隐痛等症状，可伴有肝脾肿大；④血清转氨酶升高，并以丙氨酸氨基转移酶(ALT)增加为主，常伴有谷氨酰氨基转肽酶(GGT)、三酰甘油(TG)水平增高；⑤肝脏B超符合弥漫性脂肪肝的影像学特点。

1.2 排除标准免疫性、遗传性、药物性肝病及胆道梗阻，怀疑肝细胞癌，ALT大于正常参考值上限10倍以上或总胆红素(TBil)＞50 μmol/L；伴有其他严重疾病，如恶性肿瘤、严重的心肺疾病、不稳定的糖尿病、酗酒；服药前30 d接受过降脂或护肝治疗；未避孕的生育期妇女，怀孕或哺乳期妇女。

1.3 一般资料108例NAFLD病例均为本院消化内科2005年10月－2008年3月的门诊及住院患者。

男性68例，女性40例，年龄18～62岁，平均33.4岁，病程1～30个月。

按入选顺序随机将患者分为治疗组与对照组各54例，2组病例在性别、年龄、病程、临床表现及检验指标等方面具有可比性。

1.4 治疗方法治疗组予壳脂胶囊(内蒙古福瑞中蒙药科技股份有限公司生产，国药准字：Z20050665，0.25 g/粒)，1.25 g，3次/d，口服，疗程6个月。

肠道菌群与酒精性肝病

宣墅痘堂塑匪痘堂盘查！Ｑ！鱼生！旦箜！！鲞箜！塑ｄｏｉ：１０．３９６９／ｊ．ｉｓｓｎ．１００６—５７０９．２０１６．０９．０２５
曼！！里！堡型翌塑！！翌！里！塑型！曼望！璺！鱼！Ｙ型：箜！墅．竺
肠道茵群与酒精性肝病
熊燕鹃，罗和生武汉大学人民医院消化内科【摘要】酒精性肝病（ａｌｃｏｈｏｌｉｃ
消化系统疾病湖北省重点实验室，湖北武汉４３００６０
ａｎ
ｈｅａｖｙｄｒｉｎｋｅｒ，ｆｏｒｅｘａｍｐｌｅ，ｔｈｅｃｏｍｐｏｓｉｔｉｏｎｏｆｔｈｅｇｕｔｍｉｃｒｏｂｉｏｔａｉｓａｌｔｅｒｅｄｗｉｔｈ
ｎｅｇａｔｉｖｅｂａｃｔｅｒｉａｔｈａｔｗｉｌｌｌｅａｄｔｏｅｎｄｏｔｏｘｅｍｉａａｎｄｏｖｅｒａｃｔｉｖｅｉｍｍｕｎｅ
３．１
抗生素饮酒所致的肠道菌群改变主要与胃肠
道细菌大量繁殖有关。抗生素疗法通过控制大肠细菌过度繁殖来改善ＡＬＤ的预后。但是，此疗法虽可以改善肝功能，长期
万方数据
宣墅痘堂塑壁痘堂銎查兰Ｑ！垒生竺旦筮兰！鲞筮２塑使用又会引起肠道菌群再次失衡，引发病原菌的增长。抗生素的具体选择又需要根据药敏实验的结果，这将要求过多地使用细胞培养。所以，抗生素疗法应该针对那些引起ＳＩＢＯ的肠道菌群。目前认为，利福昔明、羟氨苄青霉素、克拉维酸、甲硝唑、环丙沙星、诺氟沙星和头孢氨苄这几种抗生素，在对抗革兰氏阴性需氧菌和产芽孢厌氧菌的过度生长方面，疗效肯定。近期已有研究‘１引表明，利福昔明在肝性脑病的治疗中同样有着非常重要的作用，且对于ＡＬＤ的治疗效果可观。利福昔明最大的优点就是它不被胃肠道吸收，副作用很少，且耐药发生率极低‘２０’２２Ｉ。
ｉｎｃｒｅａｓｅｉｎｔｈｅｐｒｏｐｏｒｔｉｏｎｏｆＧｒａｍ—

小肠细菌过度增长病因、诊断、治疗及饮食健康教育-附示意图

小肠细菌过度增长病因、诊断、治疗及饮食健康教育肠道菌群是一个复杂的微生物系统，人体各部分肠道微生物的分布和数量都不相同。

与结肠中大量细菌定植不同，小肠液中的微生物数量＜104/mL。

小肠细菌过度增长（small intestine bacterial overgrowth, SIBO）是肠道菌群失调的后果。

SIBO以营养吸收障碍为主要特点，发病率随年龄增长而上升，总人群发生率约为8~20%，在75岁以上人群中可达50%，女性多于男性，是一种可严重影响患者健康和生活质量的疾患。

本文将介绍小肠细菌过度生长的病因，症状、诊断、治疗和饮食干预。

病因正常情况下，由于肠粘膜屏障、胃酸、胰酶、小肠蠕动和回盲瓣的作用，小肠菌群保持稳定。

先天性消化道畸形、高龄、麻醉性止痛药、肝硬化、免疫力低下、慢性胰腺炎、胆囊疾病、胃肠道手术等均能影响上述保护性机制，小肠细菌数量增多或出现原先在定植结肠的细菌，发生SIBO。

肠易激综合征（IBS）、憩室病、乳糜泻、炎症性肠病患者常伴有SIBO，其中IBS患者中63~85%SIBO为阳性。

临床表现及对机体的影响SIBO多表现为肠易激综合征的症状，包括腹痛、腹胀、产气增多、腹泻、恶心、便秘等，长时间伴有体重减轻。

SIBO可导致碳水化合物、脂质及脂溶性维生素吸收不良、蛋白质丢失及产氨增多和维生素B12缺乏，造成营养不良。

诊断方法通过内镜抽取小肠液培养(small bowel aspirate culture)被认为是最准确的诊断方法。

微生物定量培养的阳性标准还无定论，临床上常以十二指肠液检出＞103/mL或空肠液检出>105/mL视为SIBO阳性。

此法的缺点是价格昂贵，耗时长，可能污染样本，难以检测小肠远端SIBO的状况。

呼气试验(Breath testing, BT)是一种更为常用的诊断方法。

BT属于无创性检查，操作简单，但诊断准确性较差。

方法：给受检者口服一定量的糖类，通过检测呼出气中氢气(H2)、甲烷(CH4)等浓度。

SIBO and IBS

SIDDS 2009 Seoul International Digestive Disease Symposium 2009S5-3 Irritable Bowel Syndrome and SmallIntestinal Bacterial Overgrowth (SIBO)Oh Young Lee, M.D., Ph.D.Irritable bowel syndrome (IBS) is characterized by bowel habit change and abdominal pain relieved with defecation.1 Although the exact mechanisms of IBS are unclear, the pathogenesis is known to be due to multifactorial factors which include visceral hypersensitivity, altered brain-gut axis, dysmotilities, and genetic influence. Therefore, IBS is diagnosed and managed based on the clinical criteria with exclusion of organic causes. Recently the relatively objective factor of small intestinal bacterial overgrowth (SIBO) sharing similar symptoms with IBS has been suggested as a pathogenetic factor of IBS.SIBO is a condition defined by the presence of abnormally high number of bacteria or the growth of colon-type bacteria in the small intestine.2 As anatomical or functional impairment of the small intestine as well as systemic conditions could develop SIBO, there are many conditions predisposing to SIBO such as resection of an ileocecal valve which would normally prevent colonic bacteria from entering the ileum, intestinal stasis caused by small bowel dysmotility, reduced secretion of gastric acid which inhibits bacterial overgrowth, and systemic diseases like liver cirrhosis or scleroderma. By fermenting undigested carbohydrates within the small intestine, SIBO could impair the digestion and absorption of nutrients resulting similar symptoms of IBS, such as diarrhea, abdominal pain, bloating, and flatulence.Many studies have reported the higher prevalence of SIBO in patients with IBS than healthy controls (HC). About 80% of IBS patients were reported to have SIBO compared with only 20% of HC,3 and their IBS symptoms improved after antibiotic treatment with normalization of SIBO test.4 However, other studies concluded that IBS patients had low prevalence of SIBO and the prevalence of SIBO in IBS was not significantly different from HC.5 These discrepancies might be influenced by variable methods and different criteria used to diagnose SIBO. Currently lactulose breath test (LBT) is most commonly used to diagnose SIBO, but actually it was a method measuring colon transit time at first. LBT detects hydrogen or methane gas in expired air which is produced from fermentation of lactulose by intestinal bacteria and then absorbed through the intestinal mucosa. There are three different criteria for SIBO by LBT; when expired air was collected every 15 to 20 min for 3 h after ingestion of 10 g of lactulose, double peaks during LBT can be considered as a positive result, or increase of hydrogen within 90 min, or increase ＞20 particles per million (ppm) within 180 min can also be regarded as positive. In addition, glucose has been used as a substrate for breath test substitute for lactulose, and direct culture of aspirates from proximal small bowel has been also used to diagnose SIBO. However, glucose breath test has a high false negative result when glucose is absorbed from the proximal small bowel and direct culture methods can underestimate bacterial overgrowth in the distal small intestine. Even LBT has a false positive result when subjects34 | Seoul International Digestive Disease Symposium 2009Symposium 5: Irritable Bowel Syndrome and Small Intestinal Bacterial Overgrowth (SIBO)have a rapid intestinal transit time. Therefore, it can be said that there is no gold standard to diagnose SIBO yet and it is controversial that SIBO plays a definite role in the pathogenesis of IBS. However, fecal DNA fingerprinting could be used as an objective and direct method to qualify intestinal bacteria but the difficulty of anaerobes culture may elucidate the association between bacterial overgrowth and gastrointestinal symptoms.6 One of the main physiologic functions of gastric acid is inactivation of ingested micro-organism. Majority of ingested micro-biological pathogens never reach the intestine due to gastric barrier. PPIs may lead to gastrointestinal bacterial overgrowth. As we know, overlaps between IBS and GERD are common in the general population. Therefore, possible link among SIBO, IBS and PPI should be investigated, based on the following facts that IBS patients take PPI more likely than controls, PPI may contribute to SIBO by inhibiting gastric acid secretion, and studies exhibiting the association between IBS and SIBO did not exclude the PPI users.7In spite of all these uncertainties, it is still intriguing and worthwhile to study the quality and quantity of variable intestinal bacteria that could alter the intestinal function and develop gastrointestinal symptoms associated with functional alterations. The manipulation of these intestinal bacteria might improve the gastrointestinal symptoms and furthermore the general health of human being.References1.Longstreth GF, et al. Functional bowel disorders. Gastroenterology 2006;130:1480-1491.2.Donaldson RM Jr. Normal Bacterial Populations of the Intestine and Their Relation to Intestinal Function. NewEngland Journal of Medicine 1964;270:1050-1056 CONCL.3.Pimentel M, Chow EJ, Lin HC. Normalization of lactulose breath testing correlates with symptom improvement inirritable bowel syndrome. a double-blind, randomized, placebo-controlled study. American Journal of Gastroenterology 2003;98: 412-419.4.Pimentel M, Chow EJ, Lin HC. Eradication of small intestinal bacterial overgrowth reduces symptoms of irritable bowelsyndrome. American Journal of Gastroenterology 2000;95:3503-3506.5.Walters B, Vanner SJ. Detection of bacterial overgrowth in IBS using the lactulose H2 breath test: Comparisonwith14C-D-xylose and healthy controls. American Journal of Gastroenterology 2005;100:1566-1570.6.Kassinen A, et al. The fecal microbiota of irritable bowel syndrome patients differs significantly from that of healthysubjects. Gastroenterology 2007;133:24-33.7.Spiegel BM, Chey WD, Chang L. Bacterial overgrowth and irritable bowel syndrome: unifying hypothesis or aspurious consequence of proton pump inhibitors? American Journal of Gastroenterology 2008;103:2972-2976.Towards New Horizons in Gastroenterology: Focused on Translational Research| 35。

211256960_小肠细菌过度生长的检测及其在肠易激综合征诊治中的临床意义

小肠细菌过度生长的检测及其在肠易激综合征诊治中的临床意义陈坚张会禄邱志兵（复旦大学附属华山医院消化内科上海 200040）摘要小肠细菌过度生长（small intestinal bacterial overgrowth, SIBO）是肠道菌群失调的一种特殊表现，可引起肠道局部炎症和免疫变化，进而引发多种消化系统症状，如腹泻、腹痛、腹胀和营养吸收障碍等。

目前，SIBO在肠易激综合征发病中的作用已越来越受到关注。

本文就SIBO的健康危害、SIBO检测方法和SIBO检测在肠易激综合征诊治中的临床意义作一综述。

关键词小肠细菌过度生长肠易激综合征呼气试验中图分类号：R574.5; R574.4 文献标志码：A 文章编号：1006-1533(2023)09-0020-06引用本文陈坚, 张会禄, 邱志兵. 小肠细菌过度生长的检测及其在肠易激综合征诊治中的临床意义[J]. 上海医药, 2023, 44(9): 20-25.Detection of small intestinal bacterial overgrowth and its clinical significance in diagnosis and treatment of irritable bowel syndromeCHEN Jian, ZHANG Huilu, QIU Zhibing(Department of Gastroenterology, Huashan Hospital, Fudan University, Shanghai 200040, China) ABSTRACT Small intestinal bacterial overgrowth (SIBO) is a specific form of intestinal microbiome disorder that can cause local inflammatory-immune response in the intestinal tract, resulting in a variety of digestive symptoms (such as diarrhea, abdominal pain, bloating and nutrition malabsorption). The role of SIBO in the pathogenesis of irritable bowel syndrome (IBS) is a highlight in the recent years. The present review will focus on the hazards of SIBO in human, various methods for the detection of SIBO, the clinical significance of SIBO in the diagnosis and treatment of IBS.KEY WORDS small intestinal bacterial overgrowth; irritable bowel syndrome; breath test小肠细菌过度生长（small intestinal bacterial over-growth, SIBO）又称小肠淤积综合征、小肠污染综合征或盲袢综合征，是指小肠内菌群数量和（或）种类改变已达到一定程度并引起一系列症状这样一种临床综合征[1]。

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JNMJournal of Neurogastroenterology and MotilityEditorial3J Neurogastroenterol Motil, Vol. 16 No. 1 January, 2010 DOI: 10.5056/jnm.2010.16.1.3ⓒ2010 The Korean Society of Neurogastroenterology andMotilityJ Neurogastroenterol Motil, Vol. 16 No. 1 January, 2010The Role of Small Intestinal Bacterial Overgrowth in the Pathophysiology of Irritable Bowel SyndromeHyojin Park, M.D., Ph.D.Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, KoreaArticle :Frequency of small intestinal bacterial overgrowth in patients with irritable bowel syndrome and chronicnon-specific diarrhea(J Neurogastroenterol Motil 2010;16:40-46)Small intestinal bacterial overgrowth (SIBO) is a clinical condition caused by excessive number of bacteria in the small bowel. SIBO is characterized by symptoms of diarrhea, abdomi-nal pain, or bloating which may be associated with excessive gas of small intestine due to increased production by bacterial fer-mentation in the gut. In the last decade, SIBO has been occupied as a hot topic of interests by a group of researchers because of its potential role in the development of irritable bowel syndrome(IBS).1In the diagnosis of SIBO, a bacterial count greater than 105colony-forming units/mL by small bowel culture is believed to bethe gold standard.2But small bowel culture through jejunal aspi-rate is time-consuming, invasive, and potential for contamination. Due to several flaws of small bowel culture, a number of non-invasive and indirect tests for diagnosing SIBO have been developed. Breath test, the most common indirect method for evaluating SIBO, utilizes the metabolism of carbohydrates by bacterial enzymes, in turn indirectly measures bacterial activity of small bowel. Different carbohydrates have different properties. As lactulose is a non-absorbable carbohydrate, it easily reaches the site of potential overgrowth in the small bowel, although non-absorbed carbohydrate has limitations by the intestinal transit time. In patients with rapid transit, lactulose may produce an ear-ly hydrogen peak which makes it difficult to discriminate the true SIBO from a phenomenon by rapid intestinal transit, therefore specificity of lactulose hydrogen breath test (LHBT) is relatively low.3Pimentel and colleagues 4suggested a concept that SIBO is a major pathogenic mechanism underlying IBS in 2000. They have found 78% of 202 IBS subjects to be positive for LHBT which is suggestive of SIBO. They also demonstrated a significant im-provement in symptoms including abdominal pain, bloating, and diarrhea by treating SIBO with antibiotics and converted many IBS patients from Rome criteria positive to negative.Since then, SIBO has been proposed as an etiologic factor in IBS, but also the potential role of SIBO in IBS has been strongly debated about the methods used in diagnosing SIBO. A prevalence of SIBO in subjects meeting diagnostic criteria forHyojin Park4Journal of Neurogastroenterology and MotilityIBS varies from 4% to 64%, depending on the kind of test andcriteria used to define a positive result.5In addition, a recentwell-designed study from the US 6using LHBT to diagnose SIBO could not discriminate patients with IBS from healthy subjects, which was a consistent finding the authors de-monstrated previously.7Therefore, the proposed etiologic role of SIBO diagnosed by LHBT in IBS patients is controversial and the correlation between the normalization of the LHBT following antibiotic treatment and symptom improvement has become less clear.Glucose, on the other hand, is rapidly absorbed in the prox-imal small bowel. Thereby detecting hydrogen in this test means SIBO in a proximal location. Glucose hydrogen breath test (GHBT) is the most commonly used test in the diagnosis of SIBO, although GHBT may be less sensitive for the diagnosis of SIBO since it is absorbed in the proximal small bowel. GHBT has been reported to have a overall sensitivity between 25% to93% and a specificity from 34% to 96% in detecting SIBO.3,5In this issue of the Journal of Neurogastroenterology and Motility, Ghoshal et al. reported the frequency of SIBO in pa-tients with IBS and chronic non-specific diarrhea (CNSD) with comparison to healthy controls by using GHBT. The authors found that SIBO was more common in patients with CNSD (21.9%) than those with IBS (8.5%) and healthy controls (2%). Since CNSD including diarrhea predominant IBS (D-IBS) had higher frequency of SIBO, the authors suggested clinicians toconsider testing for SIBO among them. However, since false positive GHBT could result from rapid intestinal transit in pa-tients with diarrhea, the frequency of SIBO in patients with CNSD and D-IBS demonstrated in the author’s study might have been overestimated in part.References1.Lin HC. Small intestinal bacterial overgrowth: a framework for un-derstanding irritable bowel syndrome. JAMA 2004;292;852-858.2.Vanner S. The small intestinal bacterial overgrowth. Irritable bowel syndrome hypothesis: implications for treatment. Gut 2008;57:1315- 1321.3.Abu-Shanab A, Quigley EM. Diagnosis of small intestinal bacterial overgrowth: the challenges persist! Expert Rev Gastroenterol Hepatol 2009;3:77-87.4.Pimentel M, Chow EJ, Lin HC. Eradication of small intestinal bac-terial overgrowth reduces symptoms of irritable bowel syndrome. Am J Gastroenterol 2000;95:3503-3506.5.Ford AC, Spiegel BM, Talley NJ, Moayyedi P. Small intestinal bac-terial overgrowth in irritable bowel syndrome: systemic review and meta-analysis. Clin Gastroenterol Hepatol 2009;7:1279-1286.6.Bratten JR, Spanier J, Jones MP. Lactulose breath testing does not discriminate patients with irritable bowel syndrome from healthy controls. Am J Gastroenterol 2008;103;958-963.7.Gupta D, Ghoshal UC, Misra A, Misra A, Choudhuri G, Singh K. Lactose intolerance in patients with irritable bowel syndrome from northern India: a case-control study. J Gastroenterol Hepatol 2007;22:2261-2265.。