Infectious diarrhea

Rifaximin Rifamycin Antibiotic Gut bacteria Enteric infection Diarrhea, infectious Hepatic encephalopathy Small intestine bacterial overgrowth Inflammatory bowel disease Colonic diverticular disease Irritable bowel syndrome Constipation Clostridium difficile infection Helicobacter pylori infection Colorectal surgery Bowel decontamination, selective Pancreatitis, acute Bacterial peritonitis, spontaneous Nonsteroidal anti-inflammatory drug enteropathy... 

Because patients often present with nonspecific GI symptoms, initial diagnostic evaluation includes methods to characterize the disease and rule out other potential etiologies. This may include stool cultures to examine for infectious causes of diarrhea. 

Compare and contrast diarrhea caused by different infectious agents. 

There are many possible causes of acute diarrhea, but infection is the most common cause. Infectious diarrhea occurs because of food and water contamination via the fecal-oral route. Viruses are the cause in a large proportion of cases. Likely viral suspects include Rotavirus, Norwalk, and adenovirus. Patients usually exhibit sudden low-grade fever, vomiting, and watery stools. 

Bacteria are likely precipitants in many other cases including Escherichia coli, Salmonella species, Shigella species, Vibrio cholerae, and Clostridium difficile. The term dysentery has often been used to describe some of these bacterial infections when associated with serious occurrences of bloody diarrhea. Additionally, acute diarrheal conditions can be prompted by parasites-protozoa such as Entamoeba histolytica, Microsporidium, Giardia lamblia, and Cryptosporidium parvum. Most of these infectious agents can be causes of traveler s diarrhea, a common malady alflicting travelers worldwide. It usually occurs during or just after travel subsequent to the ingestion of fecally-contaminated food or water. It has an abrupt onset but usually subsides within 2 to 3 days. 

Patients with acute infectious diarrhea from invasive organisms also have bloody stools and severe abdominal pain. 

Guerrant RL, Van Gilder T, Steiner TS, et al. Practice guidelines for the management of infectious diarrhea. Clin Infect Dis 2001 32 331-351. 

V. cholerae is a gram-negative bacillus. Vibrios pass through the stomach to colonize the upper small intestine. Vibrios have filamentous protein extensions that attach to receptors on the intestinal mucosa, and their motility assists with penetration of the mucus layer.2 The cholera enterotoxin consists of two subunits, one of which (subunit A) is transported into the cells and causes an increase in cyclic AMP, which leads to a deluge of fluid into the small intestine.20 This large volume of fluid results in the watery diarrhea that is characteristic of cholera. The stools are an electrolyte-rich isotonic fluid, the loss of which results in blood volume depletion followed by low blood pressure and shock.2 Of note, the diarrheal fluid is highly infectious. 

Diarrhea may occur from effects of chemotherapy on the lower portion of the GI tract. Diarrhea can be severe and may need to be treated with intravenous fluids and electrolytes. Infectious causes, such as C. difficile, should be ruled out. Pharmacologic therapy of diarrhea can range from loperamide or cholestyramine to octreotide for severe cases of diarrhea that are refractory to usual treatments. 

Travelers diarrhea An acute infectious diarrhea that afflicts travelers. The disease is characterized by the presence of at least three loose stools within 24 hours that is associated with nausea, vomiting, abdominal pain, fecal urgency, or dysentery. 

Many of these organisms are easily transmitted through food and water or by human contact. Thus, prevention by avoiding the ingestion of raw or undercooked meat, seafood or unpasteurized milk products, and the selective use of available vaccines are the key to the control of infectious diarrhea. 

Among functional alterations in patients with infectious diarrhea are increased secretion, failure of barrier function and reduction of absorptive function causing dehydration and nutritional deficiency. An understanding of the molecular pathogenesis with regard to each enteric pathogen will likely lead to a quicker diagnosis, more effective treatment and prevention of enteric infections. 

Fig. 1. Recommendations for the diagnosis and management of enteric infections. Adapted from Guerrant et al. [113], Infectious Diseases Society of America Practice Guidelines for the Management of Infectious Diarrhea.

Black RE, Brown KH, Becker S, Yunus M Longitudinal studies of infectious diseases and physical growth of children in rural Bangladesh. II. Incidence of diarrhea and association with known pathogens. Am J Epidemiol 1982 115 315-324. 

Cameiro-Filho BA, Bushen OY, Brito GA, Lima AA, Guerrant RL Glutamine analogues as adjunctive therapy for infectious diarrhea. Curr Infect Dis Rep 2003 5 114-119. 

A large number of human studies [71, 77-80] performed in patients with infectious diarrhea or other GI diseases (e.g. hepatic encephalopathy, small bowel bacterial overgrowth, IBD, colonic diverticular disease) have confirmed the antibacterial activity of rifaximin demonstrated in vitro and in laboratory animals. 

In approximately 50% of patients with infectious diarrhea enrolled in clinical trials the most common organism isolated and presumed causative was E. coli. Treatment with the antibiotic led to clearance of the bacterium in... 

As shown in table 7, there are established and potential clinical indications for this peculiar drug. In all these conditions, many of which share SIBO as a common feature, gut bacteria represent the specific target of rifaximin. The drug can be used alone (like, for instance, in the treatment of infectious diarrhea) or as add-on medication (as in the management of IBD) and given short-term (single course of treatment) or long-term (repeated courses of therapy, i.e. cyclically). 

Ericsson CD, DuPont HL Rifaximin in the treatment of infectious diarrhea. Chemotherapy 2005 51(suppl l) 73-80. 

Interestingly, in a small study on patients with AIDS, rifaximin was found to be effective against infectious diarrhea with stool cultures positive for protozoal pathogens, such as Cryptosporidium parvum and Blastocystis hominis [34], The favorable effects of rifaximin on protozoal diarrhea have been also reported in a recent multicenter study on patients with travelers diarrhea [33], In fact, patients with pretreatment stools positive for Cryptosporidium infections obtained a clinical improvement with rifaximin significantly superior to the placebo-treated subjects. 

Rifaximin Diarrhea Treatment - Infectious diarrhea Bacterial diarrhea - Travelers diarrhea... 

As proposed in earlier publications, an ideal antimicrobial agent for the treatment of bacterial causes of infectious diarrhea would have the following features [1, 2] (1) excellent activity against a broad range of bacterial enteropathogens (2) nonabsorbable (3) favorable side effect profile (4) efficacious in the treatment of infectious diarrhea (5) major indication is enteric disease, and (6) does not easily develop resistance or promote cross-resistance. 

Finally, one report of diarrhea in HIV-positive patients indicated that rifaximin might well prove useful in the treatment of protozoal causes of infectious diarrhea [4], Thirteen patients had infections with Cryptosporidium parvum. 

Table 2A. Summary of clinical studies of the efficacy of rifaximin in the treatment of acute infectious diarrhea study design...

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