The intriguing role of Rifaximin in gut barrier chronic inflammation and in the treatment of Crohn's disease.

INTRODUCTION: The gastrointestinal tract acts as a functional unit organized as a semipermeable multilayer system, in which commensal gut microbiota represents the anatomical barrier. Recently, several studies have highlighted the involvement of gut microbiota in inflammatory bowel diseases (IBD) pathogenesis, in sustaining gut barrier chronic inflammation, and in conditioning disease course and therapeutical response. This evidence provides a rationale for treating patients with gut microbiota modifiers. Among these, Rifaximin represents a non-traditional antibiotic able to act as a 'eubiotic' on intestinal barrier. AREAS COVERED: The purpose of this narrative review is to explore the impact of Rifaximin on gut barrier and gut microbiota in IBD, in particular in Crohn's disease (CD), and to analyze its potential therapeutic applications. EXPERT OPINION: The possibility of a beneficial activity of Rifaximin in chronic intestinal inflammation and CD has been debated and evaluated with different studies having obtained promising but still preliminary data. Larger trials are therefore needed. This gut-specific antibiotic could represent an alternative to systemic antibiotics thanks to its favorable safety profile and promising efficacy data. Rifaximin could exert, when appropriate, a synergic effect with immunomodulators in IBD, acting on both the microbial and the immunological sides of gut barrier impairment.

The use of rifaximin in pre-operative period of patients with tumors of the gastrointestinal tract - a retrospective study (2013-2016).

ntroduction: One of the most important goals of preparing a patient for elective gastrointestinal cancer surgery is prevention of postoperative complications. The literature gives many ways to prepare for surgery, but only a few suggests that pre-operative use of rifaximin provides benefits in the form of fewer perioperative complications and reduces the severity of pain during this period. O bjective: The presented project is a retrospective analysis of the effectiveness of rifaximin in the prevention of perioperative complications in patients treated in the Unit of General Surgery with the Orthopedic and Urology in the Hospital of the Ministry of the Interior and Administration in Lublin, and a review of international literature in this subject. MATERIALS AND METHODS: A retrospective analysis of the results of pre-operative use of rifaximin was performed in 181 patients scheduled for rectal and colorectal cancer between 2013 and 2016 in the General Surgery Unit with the Orthopedic and Urology in the Hospital of the Ministry of Interior and Administration in Lublin. Patients undergoing urgent surgery were excluded from the study. Patients were divided into 2 groups. The first group of 139 patients - patients operated on for rectal and colorectal cancer in 2013 until 2015, in whom rifaximine was not used in the preoperative period. The second group is 42 patients, operated on in 2016, in which the rifaximin was used in the pre-operative period at a dose of 2x2 tablets (400 mg) per day, 12-hour interval, for 7 days before the planned operation. Additionally, a probiotic was administered for 7 days. Drugs were ordained at the Oncological Outpatient Clinic as part of the pre-hospitalization check. R esults: The use of rifaximin in the preoperative period in patients with colorectal cancer had an effect on shortening the time of post-operative hospitalization and reduced post-surgical pain in comparison with the control group. The analysis of the cynumber and intensity of surgical complications in both groups did not differ. C onclusions: Large studies on the influence of rifaximin on the development of colorectal cancer have not been published so far. Only single reports suggest that its use has a positive effect on the perioperative period of patients treated for colorectal cancer including rectum and our retrospective analysis confirms these observations.

Rifaximin has minor effects on bacterial composition, inflammation, and bacterial translocation in cirrhosis: A randomized trial.

BACKGROUND AND AIM: Decompensated cirrhosis is characterized by disturbed hemodynamics, immune dysfunction, and high risk of infections. Translocation of viable bacteria and bacterial products from the gut to the blood is considered a key driver in this process. Intestinal decontamination with rifaximin may reduce bacterial translocation (BT) and decrease inflammation. A randomized, placebo-controlled trial investigated the effects of rifaximin on inflammation and BT in decompensated cirrhosis. METHODS: Fifty-four out-patients with cirrhosis and ascites were randomized, mean age 56 years (± 8.4), and model for end-stage liver disease score 12 (± 3.9). Patients received rifaximin 550-mg BD (n = 36) or placebo BD (n = 18). Blood and fecal (n = 15) sampling were conducted at baseline and after 4 weeks. Bacterial DNA in blood was determined by real-time qPCR 16S rRNA gene quantification. Bacterial composition in feces was analyzed by 16S rRNA gene sequencing. RESULTS: Circulating markers of inflammation, including tumor necrosis factor alpha, interleukins 6, 10, and 18, stromal cell-derived factor 1-α, transforming growth factor ß-1, and high sensitivity C-reactive protein, were unaltered by rifaximin treatment. Rifaximin altered abundance of bacterial taxa in blood marginally, only a decrease in Pseudomonadales was observed. In feces, rifaximin decreased bacterial richness, but effect on particular species was not observed. Subgroup analyses on patients with severely disturbed hemodynamics (n = 34) or activated lipopolysaccharide binding protein (n = 37) revealed no effect of rifaximin. CONCLUSION: Four weeks of treatment with rifaximin had no impact on the inflammatory state and only minor effects on BT and intestinal bacterial composition in stable, decompensated cirrhosis (NCT01769040).

Metronidazole or Rifaximin for Treatment of Clostridium difficile in Pediatric Patients with Inflammatory Bowel Disease: A Randomized Clinical Trial.

BACKGROUND: Interestingly, Clostridium difficile infection (CDI) worsens the course of inflammatory bowel disease (IBD); however, there is a paucity of data regarding the treatment of CDI in this group of patients. METHODS: This was a prospective, single-blind trial. Children with flare of IBD and CDI were randomly assigned to receive metronidazole or rifaximin orally for 14 days. CDI was diagnosed based on a positive well-type enzyme immunoassay (EIA) toxins A/B stool test for C. difficile toxins A and/or B. The cure rate was defined as the percentage of patients with a negative EIA stool test for C. difficile toxins A/B measured 4 weeks after the end of treatment. Recurrence was defined as a repeat CDI within 2 to 8 weeks. RESULTS: In total, we included 31 patients with IBD including 12 patients with Crohn's disease and 19 with ulcerative colitis. Of them, 17 received metronidazole and 14 received rifaximin. There were no statistically significant differences between the 2 study groups including age, type of treatment, and disease activity. There was no statistically significant difference in the cure rate between patients treated with metronidazole and rifaximin (70.6% versus 78.6%, respectively, P = 0.5). We found no difference in recurrence rate between the 2 study treatment types (17% versus 0%, respectively, P = 0.3). We did not find an association between immunosuppressive therapy and CDI cure rate or CDI recurrence rate. CONCLUSIONS: Metronidazole and rifaximin were similarly effective treatments for CDI in pediatric patients with IBD.

Rifaximin and Propranolol Combination Therapy Is More Effective than Propranolol Monotherapy for the Reduction of Portal Pressure: An Open Randomized Controlled Pilot Study.

BACKGROUND/AIMS: Non-selective beta blockers (NSBBs) are currently the only accepted regimen for preventing portal hypertension (PHT)-related complications. However, the effect of NSBBs is insufficient in many cases. Bacterial translocation (BT) is one of the aggravating factors of PHT in cirrhosis; therefore, selective intestinal decontamination by rifaximin is a possible therapeutic option for improving PHT. We investigated whether the addition of rifaximin to propranolol therapy can improve hepatic venous pressure gradient (HVPG) response. METHODS: Sixty-four cirrhosis patients were randomly assigned to propranolol monotherapy (n=48) versus rifaximin and propranolol combination therapy (n=16). Baseline and post-treatment HVPG values, BT-related markers (lipopolysaccharide [LPS], LPS-binding protein [LBP], interleukin-6 [IL-6], and tumor necrosis factor α [TNF-α]), serological data, and adverse event data were collected. HVPG response rate was the primary endpoint. RESULTS: Combination therapy was associated with better HVPG response rates than monotherapy (56.2% vs 87.5%, p=0.034). In combination therapy, posttreatment BT-related markers were significantly decreased (LPS, p=0.005; LBP, p=0.005; IL-6, p=0.005; TNF-α, p=0.047). CONCLUSIONS: Rifaximin combination therapy showed an additive effect in improving PHT compared to propranolol monotherapy. These pilot data suggest that the addition of rifaximin to NSBBs could be a good therapeutic option for overcoming the limited effectiveness of NSBBs.

Minimal Hepatic Encephalopathy in Cirrhosis- How Long to Treat?

Abstract: Introduction. Minimal hepatic encephalopathy (MHE) can reverse after short-term treatment. However, relapse rate of MHE after stopping treatment has not been studied so far. We aimed to evaluate long-term (9 months) efficacy of a short-term (3 months) treatment of MHE with lactulose/rifaximin, for maintenance of remission from MHE. Material and methods. In this prospective study, consecutive patients with cirrhosis and MHE were treated with lactulose/rifaximin for 3 months. After treatment, they were followed up for 6 months. Psychometric testing for diagnosis of MHE was performed at baseline, 3 months and 9 months. Results. Of the 527 patients screened, 351 were found eligible and tested for MHE. Out of these, 112 (31.9%) patients had MHE (mean age 55.3 years; 75% males). They were randomized to receive Rifaximin (n = 57; 1,200 mg/day) or Lactulose (n = 55; 30-120 mL/day) for three months. At 3 months, 73.7% (42/57) patients in Rifaximin group experienced MHE reversal compared to 69.1% (38/55) in Lactulose group (p = 0.677). Six months after stopping treatment, 47.6% (20/42) in rifaximin group and 42.1% (16/38) patients in lactulose group experienced MHE relapse (p = 0.274). The overt hepatic encephalopathy development rate (7.1% vs. 7.9%) and mortality rate (0.23% vs. 0%) were similar in both groups. The Child-Turcotte-Pugh score and model for end stage liver disease (MELD) scores of patients who had MHE relapse were higher compared to those who didn’t. On multivariate regression analysis, MELD score was an independent predictor of MHE relapse. Conclusion. Of the patients who became MHE negative after short-term (3 months) treatment with rifaximin/lactulose, almost 50% had a relapse of MHE at 6 months follow-up.

Improvement of abnormal vaginal flora in Ugandan women by self-testing and short use of intravaginal antimicrobials.

The vaginal composition of African women is more often lactobacillus-deficient compared to that of women from other areas around the world. Lactobacillus-deficient microflora is a known risk factor for serious health problems, such as preterm birth, cervix cancer, and entrapment of human immunodeficiency virus (HIV) and other sexually transmitted infections (STIs). The aim of this study was to assess the effect of local vaginal antibiotic or antiseptic treatment on abnormal vaginal flora (AVF), aerobic vaginitis (AV), and bacterial vaginosis (BV) among women in rural, semi-urban, and urban areas in Uganda, as compared to placebo. In a double-blind, placebo-controlled, randomized trial, 300 women presenting for outpatient routine, follow-up, or medical care at Mulago Hospital in Kampala, Uganda, were enrolled to receive 6 days of treatment with vaginal rifaximin (RFX), dequalinium chloride (DQC), or placebo if they had an increased vaginal pH of >4.5 as determined by self-testing. At initial visit and at control visit after 4 weeks, a smear was taken for blinded wet mount microscopy to determine AVF, BV, AV, and Candida severity scores. As compared to placebo, both RFX or DQC treatments dramatically diminished BV prevalence and severity from the initial to follow-up visit: the BV score declined from 2.5 to 1.6 (p < 0.0001) and from 2.5 to 1.9 (p < 0.0001), respectively. Similarly, strong improvements in the AV score were seen in both treatment regimens: moderate and severe AV declined from AV scores of 6.3 to 3.6 (p = 0.003) and from 6.6 to 4.1 (p < 0.004), respectively. Also, women with AVF (deceased or absent lactobacilli) showed similar improvements when compared with placebo. Women with normal flora and Candida at the initial visit showed less Candida after 4 weeks in the group treated with DQC (p = 0.014). Even after a short duration of intravaginal treatment with local non-absorbable antiseptics or antibiotics produced significant, lasting improvements in the vaginal microbiome composition of women with disturbed vaginal microflora. As African women have high prevalences of BV, AV, and AVF, this approach could improve their odds to prevent health-compromising complications. Further studies assessing direct health outcomes are needed to substantiate this.

Rifaximin, a non-absorbable antibiotic, inhibits the release of pro-angiogenic mediators in colon cancer cells through a pregnane X receptor-dependent pathway.

Activation of intestinal human pregnane X receptor (PXR) has recently been proposed as a promising strategy for the chemoprevention of inflammation-induced colon cancer. The present study was aimed at evaluating the effect of rifaximin, a non-absorbable antibiotic, in inhibiting angiogenesis in a model of human colorectal epithelium and investigating the role of PXR in its mechanism of action. Caco-2 cells were treated with rifaximin (0.1, 1.0 and 10.0 µM) in the presence or absence of ketoconazole (10 µM) and assessed for cell proliferation, migration and expression of proliferating cell nuclear antigen (PCNA). The release of vascular endothelial growth factor (VEGF) and nitric oxide (NO), expression of Akt, mechanistic target of rapamycin (mTOR), p38 mitogen activated protein kinases (MAPK), nuclear factor κB (NF-κB) and metalloproteinase-2 and -9 (MMP-2 and -9) were also evaluated. Treatment with rifaximin 0.1, 1.0 and 10.0 µM caused significant and concentration-dependent reduction of cell proliferation, cell migration and PCNA expression in the Caco-2 cells vs. untreated cells. Treatment downregulated VEGF secretion, NO release, VEGFR-2 expression, MMP-2 and MMP-9 expression vs. untreated cells. Rifaximin treatment also resulted in a concentration-dependent decrease in the phosphorylation of Akt, mTOR, p38MAPK and inhibition of hypoxia-inducible factor 1-α (HIF-1α), p70S6K and NF-κB. Ketoconazole (PXR antagonist) treatment inhibited these effects. These findings demonstrated that rifaximin causes PXR-mediated inhibition of angiogenic factors in Caco-2 cell line and may be a promising anticancer tool.

Rifaximin preserves intestinal microbiota balance in patients undergoing allogeneic stem cell transplantation.

Intestinal dysbiosis has been associated with acute gastrointestinal GvHD and poor outcome following allogeneic stem cell transplantation (ASCT). To assess the effect of a switch in 2012 from ciprofloxacin/metronidazole to rifaximin for gut decontamination on intestinal microbiota composition and ASCT outcome, we retrospectively analyzed 394 patients receiving ASCT from September 2008 through June 2015. In 131 and 90 patients, respectively, urinary 3-indoxyl sulfate levels and intestinal enterococcal load were measured before conditioning and weekly within the first 28 days after ASCT. The use of rifaximin correlated with lower enterococcal positivity (6.9 vs 21.9%, P=0.05) and higher urinary 3-indoxyl sulfate concentrations (10.5 vs 4.6 µmoL/mmoL crea, P<0.001) after ASCT. Patients on rifaximin showed lower 1-year transplant-related mortality (P=0.04) and higher overall survival (P=0.008). Treatment of infectious complications with systemic antibiotics did not abrogate the beneficial effects of rifaximin on intestinal microbiota composition in the early course of ASCT and outcome. The data underscore the importance of maintaining a diverse population of symbiotic and mutualistic bacteria in the gut on ASCT outcome.

The efficacy and the immunomodulatory effect of rifaximin in prophylaxis of spontaneous bacterial peritonitis in cirrhotic Egyptian patients.

BACKGROUND/AIMS: This study aimed to evaluate the efficacy and the immunomodulatory effect of rifaximin as another promising prophylactic therapy against spontaneous bacterial peritonitis (SBP) in cirrhotics. MATERIALS AND METHODS: Seventy cirrhotic patients with ascites were included in the study. Patients were divided into two groups in a randomized single-blind fashion. Group one (n=40) received rifaximin and group two (n=30) received norfloxacin (control group). The treatment duration was 6 months. Serum levels of tumor necrosis factor alpha (TNF-α), interleukin-6 ( IL-6), and interleukin-10 (IL-10) were the primary inflammatory markers of the study to evaluate the effect of the medications used. RESULTS: Three months after treatment, five cases on norfloxacin therapy showed SBP, whereas all cases on rifaxmine therapy were free from SBP. In addition, there was no significant difference between patients on rifaximin and norfloxacin therapy with respect to TNF-α, IL-6, and IL-10 serum levels (p>0.05). Furthermore, patients on both rifaximin and norfloxacin therapies showed a statistically significant decrease in TNF-α and IL-6 serum levels compared with their baseline levels (p=0.000 and p=0.000, respectively). In contrast, serum IL-10 showed a statistically significant increase in both groups in comparison with its baseline level (p>0.00). Six-month after treatment, patients on rifaximin therapy showed more effective remission from SBP than those on norfloxacin therapy. CONCLUSION: In conclusion, the use of rifaximin not only prevents bacterial translocation but also modulates the immune response of the inflammatory and the anti-inflammatory cytokines in SBP patients. However, the efficacy and the immunomodulatory effect of rifaximin in the prophylaxis of SBP in cirrhotics needs further prospective large-scale, double-blind studies.

Treatment optimization in patients co-infected with HIV and Mycobacterium tuberculosis infections: focus on drug-drug interactions with rifamycins.

Tuberculosis (TB) and HIV continue to be two of the major causes of morbidity and mortality in the world, and together are responsible for the death of millions of people every year. There is overwhelming evidence to recommend that patients with TB and HIV co-infection should receive concomitant therapy of both conditions regardless of the CD4 cell count level. The principles for treatment of active TB disease in HIV-infected patients are the same as in HIV-uninfected patients. However, concomitant treatment of both conditions is complex, mainly due to significant drug-drug interactions between TB and HIV drugs. Rifamycins are potent inducers of the cytochrome P450 (CYP) pathway, leading to reduced (frequently sub-therapeutic) plasma concentrations of some classes of antiretrovirals. Rifampicin is also an inducer of the uridine diphosphate glucuronosyltransferase (UGT) 1A1 enzymes and interferes with drugs, such as integrase inhibitors, that are metabolized by this metabolic pathway. Rifampicin is also an inducer of the adenosine triphosphate (ATP) binding cassette transporter P-glycoprotein, which may also lead to decreased bioavailability of concomitantly administered antiretrovirals. On the other side, rifabutin concentrations are affected by the antiretrovirals that induce or inhibit CYP enzymes. In this review, the pharmacokinetic interactions, and the relevant clinical consequences, of the rifamycins-rifampicin, rifabutin, and rifapentine-with antiretroviral drugs are reviewed and discussed. A rifampicin-based antitubercular regimen and an efavirenz-based antiretroviral regimen is the first choice for treatment of TB/HIV co-infected patients. Rifabutin is the preferred rifamycin to use in HIV-infected patients on a protease inhibitor-based regimen; however, the dose of rifabutin needs to be reduced to 150 mg daily. More information is required to select optimal treatment regimens for TB/HIV co-infected patients whenever efavirenz cannot be used and rifabutin is not available. Despite significant pharmacokinetic interactions between antiretrovirals and antitubercular drugs, adequate clinical response of both infections can be achieved with an acceptable safety profile when the pharmacological characteristics of drugs are known, and appropriate combination regimens, dosing, and timing of initiation are used. However, more clinical research is needed for newer drugs, such as rifapentine and the recently introduced integrase inhibitor antiretrovirals, and for specific population groups, such as children, pregnant women, and patients affected by multidrug-resistant TB.

[The role of neutrophils in the formation of peritoneal adhesions]. / Rôle des polynucléaires neutrophiles dans la formation des adhérences post opératoires.

BACKGROUND: The use of antibiotics during peritonitis appears to decrease the formation of postoperative intra peritoneal adhesions and reduce their severity. The effect of this antibiotic is still controversial. AIM: To study the relationship between the decrease postoperative adhesions induced by rifamycin, and the number of neutrophils and the number of intraperitoneal bacteria. METHODS: This is an experimental prospective, randomized singleblind study performed on adult male rats. The product used for the peritoneal lavage was rifamycin s. The animals were randomized into three groups: Group S: intra peritoneal lavage with saline to 9%, R25 Group: intra peritoneal lavage with rifamycin at a dose of 25 mg / kg group and 12.5 R: intra peritoneal lavage with rifamycin at a dose of 12.5 mg / kg. Adhesions score was evaluated according to Zulkhé by the same operator. RESULTS: The adhesion score was significantly lower between groups S and R12.5 (p = 0.000) and group S and group R25 (P = 0.01). However, the difference was not significant between the two groups R 25 and R12.5 compared to S group (p = 0.655). The number of bacteria between the time of caecal resection (before peritoneal lavage) and the time of death or sacrifice was significantly decreased significantly in the groups R25, comparing the group S (p = 0.003). However, there is no significant difference between groups S and R12, 5 (p = 0.106). The number of neutrophils between the time of cecal resection (before peritoneal lavage) and the time of death or sacrifice decreased significantly in the groups R25 and R12, 5 in comparison to the group S. Between the group R25 and the S group, the difference is significant (p = 0.037) as well between the group R12, 5 and S (p = 0.026). However, there is no significant difference between the two groups R 25 and R12, 5 (p = 0.712). CONCLUSION: The action of rifamycin sodium on neutrophils seems to be independent of its antibacterial action. These findings deserve to be explored at the end to clarify the mechanism of neutropenia by intra peritoneal washing with rifamycin and the relationship between neutropenia and post-operative adhesions.

Rifaximin improves systemic hemodynamics and renal function in patients with alcohol-related cirrhosis and ascites.

Circulating levels of endotoxin, interleukin (IL)-6, and tumor necrosis factor (TNF)-α increase with intestinal bacterial overgrowth and translocation, and are believed to be involved in the pathogenesis of hyperdynamic circulatory syndrome and functional renal failure in patients with advanced cirrhosis. We investigated the effects of the antibiotic rifaximin on systemic hemodynamics and renal function in patients with alcohol-related cirrhosis and ascites. We measured mean arterial pressure, cardiac output (CO) by Doppler ultrasound, systemic vascular resistance (as the ratio of mean arterial pressure:CO), plasma renin activity, levels of plasma aldosterone, the glomerular filtration rate by plasma clearance of technetium-99m-DTPA, natriuresis, levels of plasma endotoxin, and serum levels of IL-6 and TNF-α in 13 patients at baseline and after 4 weeks of treatment with rifaximin. Rifaximin treatment significantly reduced CO and significantly increased systemic vascular resistance, in association with a significant decrease in plasma rennin activity. The therapy also significantly increased the glomerular filtration rate and natriuresis while reducing levels of endotoxin, IL-6, and TNF-α. Intestinal decontamination with rifaximin improved systemic hemodynamics and renal function in patients with advanced cirrhosis.

Rifaximin-extended intestinal release induces remission in patients with moderately active Crohn's disease.

BACKGROUND & AIMS: Bacteria might be involved in the development and persistence of inflammation in patients with Crohn's disease (CD), and antibiotics could be used in therapy. We performed a clinical phase 2 trial to determine whether a gastroresistant formulation of rifaximin (extended intestinal release [EIR]) induced remission in patients with moderately active CD. METHODS: We performed a multicenter, randomized, double-blind trial of the efficacy and safety of 400, 800, and 1200 mg rifaximin-EIR, given twice daily to 402 patients with moderately active CD for 12 weeks. Data from patients given rifaximin-EIR were compared with those from individuals given placebo, and collected during a 12-week follow-up period. The primary end point was remission (Crohn's Disease Activity Index <150) at the end of the treatment period. RESULTS: At the end of the 12-week treatment period, 62% of patients who received the 800-mg dosage of rifaximin-EIR (61 of 98) were in remission, compared with 43% of patients who received placebo (43 of 101) (P = .005). A difference was maintained throughout the 12-week follow-up period (45% [40 of 89] vs 29% [28 of 98]; P = .02). Remission was achieved by 54% (56 of 104) and 47% (47 of 99) of the patients given the 400-mg and 1200-mg dosages of rifaximin-EIR, respectively; these rates did not differ from those of placebo. Patients given the 400-mg and 800-mg dosages of rifaximin-EIR had low rates of withdrawal from the study because of adverse events; rates were significantly higher among patients given the 1200-mg dosage (16% [16 of 99]). CONCLUSIONS: Administration of 800 mg rifaximin-EIR twice daily for 12 weeks induced remission with few adverse events in patients with moderately active CD.

Efficacy of rifaximin in prevention of travelers' diarrhea: a meta-analysis of randomized, double-blind, placebo-controlled trials.

BACKGROUND: Rifaximin has been used successfully for the prevention of travelers' diarrhea (TD), the most general cause of disability among international travelers to developing tropical and semitropical regions. METHODS: We sought to better evaluate the efficacy of rifaximin in the prevention of TD. Randomized controlled trials (RCTs) of rifaximin for the prevention of TD published in Pubmed, the Cochrane Central Register of Controlled Trials, Embase, and the Science Citation Index were searched. [Correction added on 3 October 2012, after first online publication: the phrase "protection of TD" was replaced with "prevention of TD".] The primary efficacy outcome was occurrence of TD over a 2-week treatment period. Secondary outcomes were requirement for antibiotic treatment, occurrence of mild diarrhea (MD), occurrence of TD in the third week after drug withdrawal, incidence of TD associated with isolation of diarrheagenic Escherichia coli (ie, ETEC, EAEC), and adverse events. RESULTS: Four RCTs with 502 participants were included in the systematic review. Rifaximin treatment showed a significant protection against TD (risk ratios, RR: 0.41, 95% CI: 0.30-0.56, p < 0.00001) and needed antibiotic-treated TD (relative risk [RR]: 0.30, 95% confidence interval [CI]: 0.18-0.49, p < 0.00001). There was no significant difference between rifaximin and placebo in the occurrence of MD (RR: 1.11, 95% CI: 0.78-1.59, p = 0.55) and the occurrence of TD in the third week after drug withdrawal (RR: 0.73, 95% CI: 0.30-1.73, p = 0.47). Enterotoxigenic E. coli was the major cause of TD, and all trials reported no differences in adverse events between rifaximin and placebo. CONCLUSIONS: Rifaximin can prevent TD caused by non-invasive enteric pathogens. Further research is needed for the treatment of invasive enteric pathogens. [Correction added on 3 October 2012, after first online publication: the phrase "Rifaximin can protect TD" was replaced with "Rifaximin can prevent TD".].

Double pathological fracture of mandibula caused by actinomycotic osteomyelitis: a case report.

Actinomycosis is an uncommon chronic granulomatous infection that cause formation of abscesses and cutaneous fistula. In mandibular actinomycosis the alveolar bone and mandibular body are usually not involved and the pathogenetic mechanisms of the actinomycotic infiltration is unknown. The patients usually report pain at the alveolar arch with development of a purplish-red swelling firmly attached to the mandibula; the fibrous tissue produces the continued development of new cutaneous fistulas with oncoming pus-secretion. An uncommon case of actinomycotic osteomyelitis with a double pathological fracture of mandibula is reported. Ortopanoramic X-ray and computed tomography scan of the mandibula are effective and relevant diagnostic procedures to quantify the entity and site of the osteolitic areas and to define the precise position of fractures. In association with the intravenous infusion of benzilpenicillina, daily local irrigations of rifamicina have been performed. Moreover, the patient underwent surgical drainage of abscesses with accurate curettage of osteomyelitic lesions and several biopsies of the trabecolar bone and fistulas were taken. It has been also necessary to perform a mandibular blockage using a resinal plaque anchored on premolars. To reach a precise diagnosis, an histopathological examination togheter with batterioscopic-coltural examination is needed. Antibiotic therapy alone is not a sufficient therapeutic approach and surgical treatment must be quickly performed with clean up of the osteomyelitic lesions and contention of fractures by alveolar blockage for at least 40 days.

Prevention of travelers' diarrhea with rifaximin in US travelers to Mexico.

BACKGROUND: Because bacterial pathogens are the primary cause of travelers' diarrhea (TD), antibiotic prophylaxis is effective in TD prevention. This study assessed the efficacy and safety of the nonsystemic antibiotic rifaximin in preventing TD in US travelers to Mexico. METHODS: Healthy adult students traveling to Mexico received rifaximin 600 mg/d or placebo for 14 days and were followed for 7 days post-treatment. Stool pattern and gastrointestinal symptoms were recorded in daily diary entries. The primary end point was prevention of TD during 14 days of treatment measured by time to first unformed stool. RESULTS: A total of 210 individuals received rifaximin (n = 106) or placebo (n = 104) and were included in the safety population. Median age was 21 years (range, 18-75 y), and the majority of participants were female (65%). Efficacy analyses were conducted in a modified intent-to-treat population of 201 patients who received rifaximin (n = 99) or placebo (n = 102). Rifaximin prophylaxis reduced risk of developing TD versus placebo (p < 0.0001). A smaller percentage of individuals who received rifaximin versus placebo developed all-cause TD (20% vs 48%, respectively; p < 0.0001) or TD requiring antibiotic therapy (14% vs 32%, respectively; p = 0.003). More individuals in the rifaximin group (76%) completed treatment without developing TD versus those in the placebo group (51%; p = 0.0004). Rifaximin provided a 58% protection rate against TD and was associated with fewer adverse events than placebo. CONCLUSIONS: Prophylactic treatment with rifaximin 600 mg/d for 14 days safely and effectively reduced the risk of developing TD in US travelers to Mexico. Rifaximin chemoprevention should be considered for TD in appropriate individuals traveling to high-risk regions.

Involvement of intestinal uptake transporters in the absorption of azithromycin and clarithromycin in the rat.

Macrolide antibiotics azithromycin (AZI) and clarithromycin (CLARI) are large molecular weight compounds and are substrates for apically polarized efflux transporters such as P-glycoprotein, which can potentially restrict intestinal absorption. However, despite these undesired physicochemical and biopharmaceutical properties, AZI and CLARI exhibit moderate to excellent p.o. bioavailability in preclinical species and humans. Intestinal uptake transporters, such as organic anion transporting polypeptides (OATPs), can facilitate the uptake of drugs that are substrates and hence increase p.o. absorption. The present study was designed to determine whether the intestinal Oatps are involved in absorption of these macrolides. AZI or CLARI was dosed p.o. to Sprague-Dawley rats after p.o. administration with vehicle or rifamycin SV (RIF), an OATP inhibitor. The p.o. exposures of AZI and CLARI were reduced 65 and 45%, respectively, when coadministered with an optimized RIF regimen. The p.o. RIF had no affect on the total blood clearance of these macrolides and most likely did not cause induction of metabolizing enzymes and/or transporters. Therefore, the results suggest that inhibition of an RIF-sensitive uptake transporter such as Oatp along the rat gastrointestinal tract was responsible for reduced p.o. exposure of AZI and CLARI. In addition, AZI and CLARI caused inhibition of taurocholate uptake in rat Oatp1a5-transfected Madin-Darby canine kidney cell monolayers. The in vitro and in vivo results suggest that the intestinal Oatps are involved in the p.o. absorption of AZI and CLARI in the rat.