Antibacterial Chemoprophylaxis in the Prevention of Traveler's Diarrhea: Evaluation of Poorly Absorbed Oral Rifaximin

Exploring the Prevalence, Predictors, and Impact of Bacterial Infections to Guide Empiric Antimicrobial Decisions in Cirrhosis (EPIC-AD)

Background/Aims

This study delved into cirrhosis-related infections to unveil their epidemiology, risk factors, and implications for antimicrobial decisions.

Methods

We analyzed acutely decompensated cirrhosis patients (n = 971) from North India between 2013-2023 at a tertiary center. Microbiological and clinical features based on infection sites (EASL criteria) and patient outcomes were assessed.

Results

Median age was 45 years; 87% were males with 47% having alcoholic hepatitis. Of these, 675 (69.5%) had infections; 305 (45%) were culture-confirmed. Notably, 71% of confirmed cases were multi-drug resistant organisms (MDRO)-related, chiefly carbapenem-resistant (48%). MDRO prevalence was highest in pulmonary (80.5%) and skin-soft-tissue infections (76.5%). Site-specific distribution and antimicrobials were suggested. Predictive models identified prior hospitalization [OR:2.23 (CI:1.58-3.14)], norfloxacin prophylaxis [OR:2.26 (CI:1.44-3.55)], prior broad-spectrum antibiotic exposure [OR:1.61 (CI:1.12-2.30)], presence of systemic inflammatory response-SIRS [OR:1.75 (CI: 1.23-2.47)], procalcitonin [OR:4.64 (CI:3.36-6.40)], and HE grade [OR:1.41 (CI:1.04-1.90)], with an area under curve; AUC of 0.891 for infection prediction. For MDRO infection prediction, second infection [OR: 7.19 (CI: 4.11-12.56)], norfloxacin prophylaxis [OR: 2.76 (CI: 1.84-4.13)], CLIF-C OF [OR: 1.10 (CI: 1.01-1.20)], prior broad-spectrum antibiotic exposure [OR: 1.66 (CI: 1.07-2.55)], rifaximin [OR: 040 (0.22-0.74)] multisite [OR: 3.67 (CI: 1.07-12.56)], and polymicrobial infection [OR: 4.55 (CI: 1.45-14.17)] yielded an AUC of 0.779 and 93% specificity. Norfloxacin prophylaxis, multisite infection, mechanical ventilation, prior broad-spectrum antibiotic exposure, and infection as acute precipitant predicted carbapenem-resistant infection (AUC: 0.821). Infections (culture-proven or probable), MDROs, carbapenem/pan-drug resistance, and second infections independently linked with mortality (P < 0.001), adjusted for age, leucocytosis, and organ failures. A model incorporating age [HR:1.02 (CI: 1.01-1.03), infection [HR:1.52 (CI: 1.05-2.20)], prior hospitalization [HR:5.33 (CI: 3.75-7.57)], norfloxacin [HR:1.29 (CI: 1.01-1.65)], multisite infection [HR:1.47 (CI:1.06-2.04)], and chronic liver failure consortium-organ failure score; CLIF-C OF [HR:1.17 (CI: 1.11-1.23)] predicted mortality with C-statistics of 0.782 (P < 0.05).

Conclusion

High MDRO burden, especially carbapenem-resistant, necessitates urgent control measures in cirrhosis. Site-specific epidemiology and risk models can guide empirical antimicrobial choices in cirrhosis management.

Evaluation of a Dual-Acting Antibacterial Agent, TNP-2092, on Gut Microbiota and Potential Application in the Treatment of Gastrointestinal and Liver Disorders

TNP-2092 is a unique multitargeting drug conjugate with extremely low propensity for development of resistance. The in vitro activity of TNP-2092 against a panel of urease-producing bacteria was similar to that of rifaximin, a locally acting antibiotic approved for the treatment of hepatic encephalopathy, irritable bowel syndrome with diarrhea, and traveler's diarrhea. When given orally, TNP-2092 exhibited low absorption and the majority of compound was recovered in feces as parent. The impact of oral TNP-2092 on gut microbiota was investigated in rats. TNP-2092 was administered to rats by oral gavage for 7 days. Feces samples were collected and analyzed by 16S rRNA sequencing. Although the total amount of bacterial load appeared relatively unchanged before, during, and after treatment, significant changes in the relative abundance of certain gut bacteria at family and genus levels were observed. Some of the changes are known to be associated with improvement of symptoms associated with liver cirrhosis and hepatic encephalopathy. The observed effects of TNP-2092 on gut microbiota in rats were similar to those of rifaximin. In vivo, TNP-2092 demonstrated potent efficacy in a mouse Clostridium difficile infection model, superior to metronidazole and vancomycin, with no relapse observed after treatment. TNP-2092 is currently in clinical development for the treatment of symptoms associated with gastrointestinal and liver disorders.

Review article: the antimicrobial effects of rifaximin on the gut microbiota

BACKGROUND

Disruption of the gut microbiota through use of systemic antimicrobials or activation of the mucosal inflammatory response by pathogens can cause dysregulation of the intestinal mucosa.

AIM

To explore the mechanisms of action of rifaximin that may underlie its clinical benefits in travellers' diarrhoea (TD).

METHODS

A literature search was performed using the terms 'rifaximin' and 'L/105' in combination with the terms 'in vitro activity', 'diarrhea', 'microbiota' and 'gut flora'.

RESULTS

Rifaximin has been traditionally identified as a nonsystemic, broad-spectrum, bactericidal antibiotic. Evidence shows that the activity of rifaximin against enteropathogens in this setting is likely enhanced by its increased solubility in the presence of bile acids in the small intestine. Results of clinical studies show that although rifaximin is efficacious in TD, a clinical cure often occurs without apparent bacterial eradication and with minimal effect on the gut microbiota, suggesting an effect of rifaximin other than direct antibiotic activity.

CONCLUSIONS

Although definitive studies on the effect of rifaximin on the gut microbiota in large cohorts of healthy volunteers or patients have not been published, pre-clinical studies provide some insight. These studies have shown that rifaximin may have effects on both the pathogen and host, including direct effects on pathogenic bacteria (such as reducing the expression of bacterial virulence factors) and indirect effects on the host (such as inhibiting bacterial attachment and internalisation at the intestinal mucosa and reducing mucosal inflammation).

Single nucleotide polymorphisms in the promoter of the gene encoding the lipopolysaccharide receptor CD14 are associated with bacterial diarrhea in US and Canadian travelers to Mexico

BACKGROUND

Under normal conditions, the expression of CD14, which is the principal receptor for bacterial lipopolysaccharide, is down-regulated in the intestinal mucosa but increases in response to inflammatory stimuli. The aim of the present study was to investigate whether fecal CD14 levels increased in response to infection with diarrheagenic Escherichia coli and whether single nucleotide polymorphisms (SNPs) in the CD14 gene were associated with an increased susceptibility to traveler's diarrhea (TD) in US visitors to Mexico.

METHODS

Six SNPs located at the promoter, exon, and untranslated regions of CD14 were typed in a prospective cohort study of 1360 visitors to Mexico at risk for TD. Stools from visitors with TD were studied for enteric pathogens by culture, colony hybridization, and polymerase chain reaction. Fecal soluble CD14 (sCD14) was measured in a subgroup of 203 adults with diarrhea and 66 healthy controls by enzyme-linked immunosorbent assay.

RESULTS

The minor allele frequencies for CD14 SNPs were significantly different among the various racial and ethnic groups studied. Two SNPs in the promoter region of CD14 (-159 C > T; rs2569190 and -4191 C > T; rs5744441) were found to be associated with TD in White visitors. The -159 TT genotype was associated with a higher risk for TD (Relative risk [RR], 1.21; 95% confidence interval [CI], 1.05-1.38; P = .008), whereas individuals with the -4191 TT genotype were protected from infection (RR, 0.82; 95% CI, 0.71-0.92; P = .006). Subjects with TD excreted higher levels of fecal CD14 than did healthy controls (33,480 pg/mL vs 6178 pg/mL; P < .02). Fecal sCD14 levels were higher in stool samples from visitors with TD and the -159 TT genotype than they were in visitors with the CC/CT genotypes (P = .02), and stool samples from subjects with the -4191 CC genotype had higher fecal sCD14 levels than did stool samples from visitors with the CT/TT (P = .005) genotype. In a multivariate analysis with haplotypes constructed with the 6 SNPs studied, subjects with the haplotype containing the -159 C and the -4191 T allele were less likely to acquire TD (P = .015).

CONCLUSIONS

Our study suggests that CD14 levels increase in response to bacterial diarrhea and that polymorphisms in the CD14 gene influence susceptibility to TD. Intestinal CD14 plays an important role in the innate immune response to enteric pathogens.

Rifaximin-induced alteration of virulence of diarrhoea-producing Escherichia coli and Shigella sonnei

Rifaximin shortens the duration of travellers' diarrhoea without important alteration of colonic flora. This study investigated the expression of virulence factors [heat-stable (ST) and heat-labile (LT) enterotoxins, surface adhesion factors (CS2/CS3, CS6) and matrix metalloproteinase-9 (MMP-9)] as well as the interleukin (IL)-8 induction potential of diarrhoeagenic Escherichia coli and Shigella sonnei strains exposed to rifaximin (8, 32 and 64mg/L) for 4, 8, 18 and 24h. Following exposure to rifaximin, enterotoxigenic E. coli (ETEC) isolates did not express ST/LT, CS2/CS3 or CS6, whereas enteroaggregative E. coli (EAEC) and S. sonnei isolates did not produce detectable amounts of MMP-9. Moreover, induction of IL-8 was undetectable. At subinhibitory concentrations, rifaximin alters the virulence of ETEC, EAEC and S. sonnei isolates. These findings help explain the efficacy of rifaximin despite minimal alteration of colonic flora.

Diarrhea A to Z: America to Zimbabwe

PURPOSE

To review international statistics on the morbidity and mortality of diarrhea, pathophysiology, global incidence, and implications for the clinical practice of nurse practitioners (NPs).

DATA SOURCES

Selective review of literature.

CONCLUSIONS

Because of ever-increasing international travel, immigration, and rising awareness of global health issues, NPs must be current on the prevention, diagnosis, and treatment of diarrhea.

IMPLICATIONS FOR PRACTICE

Increased awareness of diarrhea as a significant international health issue mandates that NPs counsel clients who travel to high-risk areas about preventive measures to avoid exposure or manage symptoms while traveling. Guidelines for evidence-based treatments of diarrheal illness are widely available and should be followed.

Traveler's diarrhea: updates for pediatricians

Children who travel are at risk of developing the same illnesses that affect adult travelers. Treatment, etiology and actual risk of TD in children are not well defined. Prevention and self-treatment of TD should be discussed in great detail during pre-travel counseling. This includes information and instructions on various preventive measures as well as when to use medications and the potential adverse effects associated with these medications. A TD that is mild can be managed effectively by appropriate use of oral rehydration solutions. Families should be advised to carry ORS packets and start treatment in children as soon as the diarrhea begins. Self treatment with antibiotics such as azithromycin may be considered in children if diarrhea is moderate to severe. Caregivers should contact local health authorities if there is no improvement especially after self treatment with antibiotics.

Antimicrobial prevention and therapy for travelers' infection

International journeys are increasing and more than 70 million people from industrialized countries cross the borders of tropical countries every year. More than 50% of them will suffer from some form of infectious illness, ranging from mild travelers' diarrhea to severe dengue fever to fatal malaria, with a wide spectrum of microbiological entities. Travel-related respiratory infections, including TB, and sexually transmitted infections are also increasingly reported. Awareness of travel-related risk is not always adequate among international travelers. Specific training on travel medicine-related issues, as well as better diagnostic facilities for imported diseases, is crucial for physicians and nurses in industrialized countries.

[The management of travellers' diarrhoea]

Travellers' diarrhoea represents the most frequent health problem when travelling in developing countries. In most cases it is a self-limited disease. Nonetheless it can cause incapacitation and significant morbidity. It can become persistent in up to 3% of travellers who have suffered from acute diarrhoea in regions at high risk. This article discusses the investigations and the management of diarrhoea in returning travellers, preventive measures and its management during travel.

[Infectious aetiologies of travelers' diarrhoea]

Traveler's diarrhoea (TD) occurs in 20 to 60% of European or North-American travelers in intertropical areas. Following return from endemic zone, malaria must always be evocated in front of febrile diarrhoea. Many causative infectious agents are involved in TD and their frequency may vary according to destination and seasons. The main agents involved in TD are Escherichia coli pathovars (especially enterotoxigenic and enteroaggregative E. coli) followed by enteroinvasive bacteria (Campylobacter spp., Shigella spp., Salmonella enterica), enteric viruses (norovirus, rotavirus) and protozoa (Gardia intestinalis, Cryptosporidium parvum et Entamoeba histolytica). The development of molecular biology methods as PCR may allow us to evaluate the relative frequency of these agents and especially of viral agents in TD. Protozoa and microsporidia are more frequently isolated in persistent and chronic TD, especially in compromised patients. A complete etiological research in routine microbiology laboratories is difficult and time-consuming, related to the high diversity of causative agents and the need for specific methods. Implementation of laboratory diagnosis is highly recommended when diarrhoea is associated with fever or presence of blood in stools, immunosuppression, antibiotic treatment (Clostridium difficile toxins) or in case of persistent/chronic diarrhoea. According to the high frequency of acquired antibiotic-resistance in enteric bacteria, an antibiogram must be performed for all causative bacterial agents.

Postinfectious irritable bowel syndrome--a meta-analysis

OBJECTIVES

Irritable bowel syndrome (IBS) is a heterogeneous disorder affecting 12% of the population worldwide. Several studies identify IBS as a sequela of infectious gastroenteritis (IGE) with reported prevalence ranging from 4% to 31% and relative risk from 2.5 to 11.9. This meta-analysis was conducted to explore the differences between reported rates and provide a pooled estimate of risk for postinfectious irritable bowel syndrome (PI-IBS).

DATA SOURCES

Electronic databases (MEDLINE, OLDMEDLINE, EMBASE, Cochrane database of clinical trials) and pertinent reference lists (including other review articles).

REVIEW METHODS

Data were abstracted from included studies by two independent investigators; study quality, heterogeneity, and publication bias were assessed; sensitivity analysis was performed; and a summative effect estimate was calculated for risk of PI-IBS.

RESULTS

Eight studies were included for analysis and all reported elevated risk of IBS following IGE. Median prevalence of IBS in the IGE groups was 9.8% (IQR 4.0-13.3) and 1.2% in control groups (IQR 0.4-1.8) (sign-rank test, p= 0.01). The pooled odds ratio was 7.3 (95% CI, 4.7-11.1) without significant heterogeneity (chi2 heterogeneity statistic, p= 0.41). Subgroup analysis revealed an association between PI-IBS risk and IGE definition used.

CONCLUSIONS

This study provides supporting evidence for PI-IBS as a sequela of IGE and a pooled risk estimate revealing a sevenfold increase in the odds of developing IBS following IGE. The results suggest that the long-term benefit of reduced PI-IBS may be gained from primary prevention of IGE.

Prevention and self-treatment of traveler's diarrhea

Of the millions who travel from the industrialized world to developing countries every year, between 20% and 50% will develop at least one episode of diarrhea, making it the most common medical ailment afflicting travelers. Although usually a mild illness, traveler's diarrhea can result in significant morbidity and hardship overseas. Precautions can be taken to minimize the risk of developing traveler's diarrhea, either through avoidance of potentially contaminated food or drink or through various prophylactic measures, including both nonpharmacological and antimicrobial strategies. If diarrhea does develop despite the precautions taken, effective treatment-usually a combination of an antibiotic and an antimotility agent-can be brought by the traveler and initiated as soon as symptoms develop. In the future, vaccines-several of which are in the advanced stages of clinical testing-may be added to the list of prophylactic measures.

Poorly Absorbed Antibiotics for the Treatment of Traveler' Diarrhea

This article describes the use of poorly absorbed antibiotics for the treatment of traveler's diarrhea. Poorly absorbed oral antibiotics can deliver high concentrations of drug to the site of enteric infection with minimal risk of systemic adverse effects, toxicity, and drug interactions. Compared with systemically absorbed oral antibiotics, poorly absorbed oral antibiotics may be less associated with the pressure that leads to the development of bacterial resistance, because they do not affect bacteria outside the gastrointestinal tract. In clinical studies, poorly absorbed oral antibiotics, including aztreonam, bicozamycin, and rifaximin, were more effective than and as well tolerated as placebo; in particular, rifaximin was as effective as oral ciprofloxacin in reducing the duration of illness in traveler's diarrhea. More research is warranted to delineate the effects of poorly absorbed antibiotics in invasive infection and to assess the potential for the development of bacterial resistance.