Worldwide efficacy of bismuth subsalicylate in the treatment of travelers' diarrhea

The Role of Purported Mucoprotectants in Dealing with Irritable Bowel Syndrome, Functional Diarrhea, and Other Chronic Diarrheal Disorders in Adults

Chronic diarrhea is a frequent presenting symptom, both in primary care medicine and in specialized gastroenterology units. It is estimated that more than 5% of the global population suffers from chronic diarrhea. and that about 40% of these subjects are older than 60 years. The clinician is frequently faced with the need to decide which is the best therapeutic approach for these patients. While the origin of chronic diarrhea is diverse, impairment of intestinal barrier function, dysbiosis. and mucosal micro-inflammation are being increasingly recognized as underlying phenomena characterizing a variety of chronic diarrheal diseases. In addition to current pharmacological therapies, there is growing interest in alternative products such as mucoprotectants, which form a mucoadhesive film over the epithelium to reduce and protect against the development of altered intestinal permeability, dysbiosis, and mucosal micro-inflammation. This manuscript focuses on chronic diarrhea in adults, and we will review recent evidence on the ability of these natural compounds to improve symptoms associated with chronic diarrhea and to exert protective effects for the intestinal barrier.

Designing a multi-epitope vaccine for cross-protection against Shigella spp: An immunoinformatics and structural vaccinology study

Shigellosis is a severe diarrheal disease with high mortality and morbidity rate. Until now, there is no approved vaccine against the disease. Therefore, the present study was planned to design a novel multi-epitope vaccine against Shigella spp., the causative agents of the disease based on the immunoinformatic tools. For this end, firstly seven conserved antigens of the bacteria, including IpaA, IpaB, IpaC, IpaD, OmpC, OmpF and VirG were selected. Then, linear B-cell epitope mapping of these proteins was carried out and top-ranked and shared epitopes were selected based on antigenicity, allergenicity, stability, toxicity and physicochemical properties for further analysis. In next step, B-cell derived T-cell epitopes were determined and appropriate epitopes were selected for incorporation into the final construct. Moreover, the selected epitopes and two mucosal adjuvants including ctxB and LT-IIc were joined using appropriate linkers. The three dimensional structure of the final construct was modeled and evaluated in term of structural quality and presence of conformational B-cell epitopes. Furthermore, binding affinity of the proposed vaccine to MHC I and II molecules were evaluated through molecular docking method using Hex 8.0. as well as the stability of the vaccine-MHC complexes was monitored by molecular dynamics method using the NAMD graphical user interface embedded in visual molecular dynamics. Finally, to evaluate the immunogenicity of the designed protein, the protein was administered to BALB/c mice and the serum IgG was determined by ELISA. The results indicated that the proposed vaccine has high structural quality and binding affinity to both MHC I and II molecules. Moreover, molecular dynamics studies confirmed that the vaccine-MHC docked complexes were stable during simulation time. Animal study showed that the proposed protein is able to evoke mice's humoral immune response. In sum, the results suggested that the proposed candidate vaccine could be considered as a promising anti-shigellosis vaccine.

Diarrhea: Initial Evaluation and Treatment in the Emergency Department

Diarrhea generates a wide range of diagnostic considerations and has profound individual and public health significance. The setting and circumstances under which a patient presents with diarrhea drastically influences the concern brought to the encounter. Nausea, vomiting, and diarrhea are often provisionally labeled "gastroenteritis" with appropriate expectant management. In resource-poor countries, the significance of diarrhea is even greater. This review focuses on diarrhea and its initial evaluation and management in the emergency department.

Traveler's Diarrhea

Travelers' diarrhea (TD) is the most important health issue among international travelers. In high risk areas, 50-90% of travelers may experience an episode of TD. The risk of acquiring TD is influenced by factors such as the destination, duration of stay, standard of accommodation, type of travel, age of the traveler, and also by individual risk factors. Most cases of TD are caused by bacteria; treatment for TD are loperamide and antibiotics. Preventive strategies such as hygiene measures have limited impact. Prophylactic intake of antibiotics or vaccines to prevent from TD can be considered in special situations.

Acute infectious pediatric gastroenteritis: beyond oral rehydration therapy

Worldwide diarrheal diseases are a leading cause of childhood morbidity and mortality. Improvements in gastroenteritis management have reduced the annual number of pediatric deaths attributable to gastroenteritis from 5 million in 1982 to 2 million over 20 years. Recent advances are likely to contribute further to a reduction in morbidity and mortality secondary to acute infectious gastroenteritis. A new generation of vaccines against rotavirus is entering into routine use. Research into antisecretory agents has demonstrated that this class of medications may play a significant role in the future management of acute infectious gastroenteritis. A significant body of literature has recently emerged supporting the use of the antiemetic agent ondansetron. In developing countries, the routine use of zinc is now recommended by many experts, while, in developed countries, the use of probiotic agents has been associated with significant benefits in acute infectious gastroenteritis. Finally, more aggressive intravenous rehydration strategies are being employed; however, at present, limited data from randomized clinical trials are available to support its routine use.

Nonantimicrobial Agents in the Prevention and Treatment of Traveler' Diarrhea

Among the nonantimicrobial agents that are available and useful for the prevention of traveler's diarrhea are bismuth subsalicylate-containing preparations, which can provide a rate of protection of up to 65% when taken 4 times daily. In one study, the probiotic Lactobacillus GG was found to provide 49% protection against traveler's diarrhea, but results with this agent and other probiotics have been highly variable and geographically inconsistent. Tannin albuminate plus ethacridine lactate provided 36% protection, but it is not widely available. Among the nonantimicrobial agents that are available and useful for the treatment of traveler's diarrhea are bismuth subsalicylate-containing preparations, which reduce the passage of loose stools by 16%-18%. The antisecretory and antimotility agent loperamide reduces the passage of loose stools by approximately 50% and has been especially useful, in combination with antimicrobial agents, in reducing the total duration of posttreatment diarrhea to a matter of hours.

Infectious diarrhea in developed and developing countries

Diarrhea from gastrointestinal infection remains a common problem. In industrialized countries, management is aimed at reducing morbidity and defining groups that may benefit from further investigation. Most infectious diarrhea is self-limiting and only requires supportive management. Viral agents are increasingly recognized as causative agents of epidemic and sporadic diarrhea. In developing countries, diarrhea is a major cause of mortality in children. Oral rehydration therapy, guided by a clinical assessment of the degree of dehydration, is cheap, simple, and effective and remains the mainstay of management of infant diarrhea. Controversies focus on the optimal formulation of oral rehydration solution. A vaccine against rotavirus has the potential to save millions of lives worldwide.

Acute diarrhea: a practical review

This review provides a practical, simple, and logical approach to the diagnosis and management of patients with acute infectious diarrhea, one of the most common diagnoses in clinical practice. Diarrhea in the immunocompromised host, traveler's diarrhea, and diarrhea in the hospitalized patient are also discussed. Most episodes of acute diarrhea are self-limited, and investigations should be performed only if the results will influence management and outcome. After an adequate history and physical examination, the clinician should be able to classify the acute diarrheal illness, assess the severity, and determine whether investigations are needed. Most patients do not require specific therapy. Therapy should mainly be directed at preventing dehydration. Various home remedies frequently suffice in mild, self-limited diarrhea. However, in large-volume, dehydrating diarrhea, oral rehydration solutions should be used, as they are formulated to stimulate sodium and water absorption. Antidiarrheal agents can be useful in reducing the number of bowel movements and diminishing the magnitude of fluid loss. The most useful agents are opiate derivatives and bismuth subsalicylate. Antibiotic therapy is not required in most patients with acute diarrheal disorders. Guidelines for their use are presented.

Antimicrobial activities of synthetic bismuth compounds against Clostridium difficile

Clostridium difficile is a major nosocomial pathogen responsible for pseudomembranous colitis and many cases of antibiotic-associated diarrhea. Because of potential relapse of disease with current antimicrobial therapy protocols, there is a need for additional and/or alternative antimicrobial agents for the treatment of disease caused by C. difficile. We have synthesized a systematic series of 14 structurally simple bismuth compounds and assessed their biological activities against C. difficile and four other gastrointestinal species, including Helicobacter pylori. Here, we report on the activities of six compounds that exhibit antibacterial activities against C. difficile, and some of the compounds have MICs of less than 1 microgram/ml. Also tested, for comparison, were the activities of bismuth subcitrate and ranitidine bismuth citrate obtained from commercial sources. C. difficile and H. pylori were more sensitive both to the synthetic bismuth compounds and to the commercial products than were Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis, and the last three species were markedly resistant to the commercial bismuth salts. Testing with human foreskin fibroblast cells revealed that some of the synthetic compounds were more cytotoxic than others. Killing curves for C. difficile treated with the more active compounds revealed rapid death, and electron microscopy showed that the bismuth of these compounds was rapidly incorporated by C. difficile. Energy dispersive spectroscopy X-ray microanalysis of C. difficile cells containing electron-dense material confirmed the presence of internalized bismuth. Internalized bismuth was not observed in C. difficile treated with synthetic bismuth compounds that lacked antimicrobial activity, which suggests that the uptake of the metal is required for killing activity. The nature of the carrier would seem to determine whether bismuth is transported into susceptible bacteria like C. difficile.

Travelers' diarrhea. Prevention and treatment

Travelers' diarrhea affects almost half of all travelers from developed to developing nations. Its occurrence frequently alters planned activities. Enterotoxigenic Escherichia coli and other bacterial pathogens endemic to the area visited account for the majority of pathogens isolated. Newer research technologies are assisting in defining virulence properties and epidemiologic characteristics. Prudence exercised during travel remains the preferred mode of prevention, reserving antimicrobial prophylaxis for specific situations. Oral rehydration and early pharmacologic intervention with antimicrobial and antimotility agents significantly decrease length of illness when diarrhea occurs.

Treatment of diarrhea of neonatal calves

Therapeutic strategies for the treatment of diarrhea of neonatal calves should be logical and should be targeted at correction of physiologic dysfunction. Appropriate, specific antimicrobial or antiprotozoal therapy should be instituted when colibacillosis, salmonellosis, or giardiasis is confirmed or suspected. All calves with diarrhea should be rehydrated if necessary, and proper nutritional support should be provided. Antisecretory agents such as flunixin meglumine and bismuth subsalicylate may be beneficial for treatment of calves with colibacillosis and salmonellosis. Adsorbants, such as attapulgite and bismuth subsalicylate, also may reduce loss of fluids. Perhaps loperamide or a similar drug will be proven effective in calves in the future. Potentially harmful drugs include several antimicrobial agents when they are administered orally, because they result in malabsorption; kaolin and pectin, which increase loss of ions during diarrhea; and motility modifiers that cause a decrease in all types of intestinal motor function. Finally, success should be measured by indicators of production such as survivability, days treated, weight gained, and net profit. Our goal should be to restore and maintain the health of the calf, not simply to alter the volume and consistency of the feces.

Bismuth therapy in gastrointestinal diseases

Bismuth therapy has shown efficacy against two major gastrointestinal disorders: peptic ulcer disease and diarrhea. In peptic ulcer disease it is as effective as the H2-receptor antagonists, costs considerably less, and offers a lower rate of relapse. When Helicobacter pylori is implicated, bismuth acts as an antimicrobial agent, suppressing the organism but not eliminating it. In recent studies, bismuth compounds have been used with conventional antibiotics, producing elimination of the organism, histological improvement, and amelioration of symptoms for periods longer than one year. Bismuth subsalicylate has shown modest efficacy in treating traveler's diarrhea and acute and chronic diarrhea in children, and it is effective prophylactically for traveler's diarrhea. An epidemic of neurological toxicity was reported in France in the 1970's with prolonged bismuth treatment, usually bismuth subgallate and subnitrate. Such toxicity has been rare with bismuth subsalicylate and colloidal bismuth subcitrate. However, recent studies have demonstrated intestinal absorption of bismuth (about 0.2% of the ingested dose) and sequestration of this heavy metal in multiple tissue sites, even occurring with conventional dosing over a 6-week period. These findings have inspired recommendations that treatment periods with any bismuth-containing compound should last no longer than 6-8 weeks, followed by 8-week bismuth-free intervals.