GASTROENTERITIS

• Epidemiology

• Definition

• Etiology

• Diagnosis

• Approach

• Treatment

• Prevention

Acute diarrheal infections are a common health problem globally and among both individuals in the United States and traveling to developing world countries

EPIDEMIOLOGY

• Acute diarrheal infection is a leading cause of outpatient visits, hospitalizations, and lost quality of life occurring in both domestic settings and among those traveling abroad.

• The CDC has estimated 47.8 million cases occurring annually in the United States, at an estimated cost upwards of US$150 million to the health care economy

DEFINITION

• Acute diarrhea can be defined as the passage of a greater number of stools of decreased from the normal lasting <14 days.

• Some definitions require an individual to present with an abrupt onset 3 or more loose or liquid stools above baseline in a 24 h period to meet the criteria of acute diarrhea.

TYPES

• On the basis of its duration, diarrhea can be classified as:

• Acute: <14 days

• Persistent: 14 to 29 days

• Chronic: ≥30 days

• Acute diarrhea of infectious etiology is generally associated with other clinical features suggesting enteric involvement including:

• Vomiting and Nausea

• Abdominal pain and cramps

• Bloating

• Flatulence

• Fever

• Passage of bloody stools, tenesmus, and fecal urgency

Acute diarrheal infection is also often referred to as gastroenteritis, and some acute gastrointestinal infections may cause a vomiting predominant illness with little or no diarrhea.

ETIOLOGY

• Bacterial

• Viral

• Parasites

• Poisoning by microbial toxins: food borne intoxication

Non-inflammatory vs. inflammatory diarrhea

ETIOLOGY

• Non-inflammatory

• Enterotoxin production

• Destruction of villi

• Adherence to GI tract

• Inflammatory

• Intestinal invasion

• Cytotoxins

INFLAMMATORY DIARRHEA, BACTERIAL

• Aeromonas

• Campylobacter jejuni

• Clostridium dificile

• E. coli: enteroinvasive, O157:H7

• Plesiomonas shigelloides

• Salmonella

• Shigella

• Vibrio parahaemolyticus

• Yersinia enterocolitica

NON-INFLAMMATORY, BACTERIAL

• E. coli: enteropathogenic, enterotoxigenic• Vibrio cholera

MECHANISM OF DIARRHEA

Mechanism Non-inflammatory Enterotoxin/Adherence

InflammatoryInvasion/cytotoxin

Penetration

Location Proximal Small Bowel Colon Distal Small Bowel

Illness Watery Diarrhea Dysentery Enteric Fever

Stool Examination No fecal leukocytesMild or no lactoferrin

Fecal Neutrophillactoferrin

Fecal mononuclear leukocyte

ExampleV.cholera,E.coli

(ETEC,EPEC,EAEC),Norwalk,Giardia,Staphaure

us,Cl.perfringes.

Shigella,E.coli(EIEC,EHEC) Salmonella

enteritidis,Cl.defficile,E.histolytica.

Salmonella typhiYersina

Enterocolitica

12

HOST FACTORS

Higher rates of infectious diarrhea occur among:

Persons at extremes of age

Altered immunity because of disease or drugs

Physiological features of the gut that are altered by medications, including acid-reducing agents such as proton-pump inhibitors and antibiotics that alter intestinal flora and gut homeostasis

DOSE AND INFECTIVITY

• infections with shigella, Shiga toxin–producing E. coli, noroviruses, rotaviruses, giardia, and cryptosporidium are easily spread by low inoculums of agents that often cause secondary spread of illness.

• Shigella and noroviruses, the most communicable pathogens, have a high potential for person-to-person spread

• Secondary spread occasionally occurs with salmonella strains, and the infection rate among infants is high, suggesting transmission at lower amounts of inoculum.

FACTORS THAT ARE RELEVANT TO THE CAUSE OF DIARRHEA

• Previous international travel

• Treatment with antibiotics

• Chemotherapy

• Proton pump inhibitors

• Unsafe sexual practices

• Work at a day-care center

• Immunosuppressive disorder

DIAGNOSIS

History

Stool examination• Mucus

• Blood

• Leukocytes

• Stool culture

PCR

DIAGNOSTIC TESTS AND PROCEDURES

Blood Studies

• Levels of electrolytes and serum creatinine should be measured in cases of systemic toxicity or dehydration, especially in elderly or infirm patients.

• Severe diarrhea accompanied by fever or toxicity, in whom leukocytosis or a shift to the left in neutrophils: CBC

• In parasitic infections with an extraintestinal migration phase (e.g., strongyloidiasis): Eosinophilia

STOOL EXAMINATION

• Acute diarrhea that is sever or associated with fever (≥38.5°C)

• Severe coexisting condition in a hospitalized patient who is receiving antibiotics (with testing only for C. difficile toxins)

• Symptoms lasting >7 days

• Profuse cholera- like watery diarrhea, dehydration, and dysentery

• Elderly

• Immunocompromised patients

• Persons employed as food handlers

• Nursing home, and Day-care center. Identification

• In an outbreak of diarrhea

STOOL CULTURE

Diagnostic evaluation using stool culture and culture independent methods if available should be used in situations where the individual patient is at high risk of spreading disease to others, and during known or suspected outbreaks

Antibiotic sensitivity testing for management of the individual with acute diarrheal infection is currently not recommended

• In patients with inflammatory bowel disease and possible C. difficile–associated diarrhea, multiple samples may be needed for diagnosis

• In patients with persistent diarrhea due to a potential parasitic infection, three separate stool samples may be needed to detect the causative organism

• PCR assays for the detection of norovirus are available in local public health laboratories in the case of outbreaks

ENDOSCOPY AND ABDOMINAL COMPUTEDTOMOGRAPHY

Flexible sigmoidoscopy or colonoscopy has limited value in the routine evaluation of patients with acute diarrhea

FLEXIBLE SIGMOIDOSCOPY

• Persistent diarrhea

• Selected cases of acute diarrhea with clinical colitis in which the diagnosis is not clear, such as cases of suspected C. difficileassociated diarrhea with toxin-negative stool

ENDOSCOPY

Suspected C. difficile– associated diarrhea and dysenteric diarrhea with negative results of stool toxin and microbiologic tests

MANAGEMENT

• Maintain electrolyte and fluid balance

• Antimotility drug loperamide

• Empirical antibiotic therapy

• Probiotic

REHYDRATION

• The usage of balanced electrolyte rehydration over other oral rehydration options in the elderly with severe diarrhea or any traveler with cholera-like watery diarrhea is recommended.

• Most individuals with acute diarrhea or gastroenteritis can keep up with fluids and salt by consumption of water, juices, sports drinks, soups, and saltine crackers.

For patients with moderate to severe diarrhea, the first goal of treatment is to correct and maintain electrolyte and fluid balance, which can be lifesaving in the elderly, patients with coexisting conditions, and infants

NON-ANTIBIOTIC THERAPIES

• Bismuth subsalicylates (BSSs) can be administered to control rates of passage of stool and may help travelers function better during bouts of mild to moderate illness

• In patients receiving antibiotics for TD, adjunctive loperamide therapy can be administered to decrease duration of diarrhea and increase chance for a cure

• The major antimotility drugs used for therapy of acute diarrhea are loperamide and diphenoxylate.

• Of these, the most useful drug is loperamide, which has less central opiate effects.

• Another limitation of diphenoxylate is that it contains atropine, which has no antidiarrheal effectiveness and may produce objectionable side effects.

ANTIBIOTIC THERAPY

• The evidence does not support empiric anti-microbial therapy for routine acute diarrheal infection, except in cases of TD where the likelihood of bacterial pathogens is high enough to justify the potential side effects of antibiotics

• Use of antibiotics for community-acquired diarrhea should be discouraged as epidemiological studies suggest that most community-acquired diarrhea is viral in origin (norovirus, rotavirus, and adenovirus) and is not shortened by the use of antibiotics.

PROBIOTICS

Probiotics are defined as live microorganisms, which, when administered in adequate amounts, confer health benefits on the host.

For a microorganism to be considered a probiotic, it must exhibit non-pathogenic properties, be viable in delivery vehicles, be stable in acid and bile, adhere to target epithelial tissue, persist within the gastrointestinal tract, produce anti-microbial substances, modulate the immune system, and influence metabolic activities

PROBIOTICS

The use of probiotics or prebiotics for treatment of acute diarrhea in adults is not recommended, except in cases of postantibiotic associated illness

TREATMENT OF ACUTE DIARRHEA

• Some probiotic strains are useful in reducing the severity and duration of acute infectious diarrhea in children

• The microbiota is maintained in a stable ecology, and it appears that probiotics are very helpful in shortening the course of acute gastroenteritis diarrhea in children

• Starting Saccharomyces boulardii, LGG, or strains of Lactobacillus reuteri are extremely helpful in shortening the course of the diarrhea

PREVENTION OF ANTIBIOTIC-ASSOCIATED DIARRHEA

In the prevention of antibiotic-associated diarrhea, there is strong evidence of efficacy in adults or children who are receiving antibiotic therapy

PREVENTION OF CLOSTRIDIUM DIFFICILE DIARRHEA

• Although there is moderate evidence that two probiotics ( Lactobacillus rhamnosus GG and Saccharomyces boulardii ) decrease the incidence of antibiotic associated diarrhea, there is insufficient evidence that probiotics prevent C. difficile infection

• There is limited evidence for the use of adjunct probiotics to decrease recurrences in patients with RCDI.

• At present, probiotics have an uncertain effect on the prevention of C. difficile infection, and their routine use for the prevention or treatment of active infection is not recommended

PREVENTION OF RADIATION-INDUCED DIARRHEA

• The gut microbiota may play an important role in radiation-induced diarrhea by reinforcing intestinal barrier function, improving innate immunity, and stimulating intestinal repair mechanisms

• Probiotics may be beneficial in the prevention and possibly in the treatment of radiation-induced diarrhea

PREVENTION

• Patient level counseling on prevention of acute enteric infection is not routinely recommended but may be considered in the individual or close-contacts of the individual who is at high risk for complications.

• Individuals should undergo pre travel counseling regarding high risk food/beverage avoidance to prevent TD

HAND WASHING

Frequent and effective hand washing and alcohol-based hand sanitizers are of limited value in preventing most forms of traveler’s diarrhea but may be useful where low dose pathogens are responsible for the illness as for an example during a cruise ship outbreak of norovirus infection, institutional outbreak, or in endemic diarrhea prevention.

PROPHYLAXIS

• Bismuth subsalicylates have moderate effectiveness and may be considered for travelers who do not have any contraindications to use and can adhere to the frequent dosing requirements

• Probiotics, prebiotics, and synbiotics for prevention of traveler’s diarrhea are not recommended

• Antibiotic chemoprophylaxis has moderate to good effectiveness and may be considered in high risk groups for short term use.

CHRONIC DIARRHEA

Chronic diarrhea is defined by a duration of >4 weeks

• It is estimated that 1%–5% of adults suffer from chronic diarrhea.

• In immunocompetent patients in developed countries, chronic diarrhea is generally not infectious. The challenge in managing these patients is the fact that the differential diagnosis is vast.

• However, a careful history and thorough physical examination with judicious use of selected tests often lead to a specific diagnosis and an appropriate treatment plan.

CATEGORIZATION

• Watery diarrhea: osmotic, secretory, and functional

• Fatty diarrhea

• Inflammatory diarrhea :IBD or Infectious diseases: TB, CMV, HSV, Amebiasis/other invasive parasites, Radiation or ischemic colitis, neoplasia

HISTORY

• The characteristics of the onset of diarrhea: Whether it was congenital, abrupt, or gradual in onset.

• The pattern of diarrhea : continuous or intermittent?

• The duration of symptoms should be identified clearly.

HISTORY

• Travel before the onset of illness

• Exposure to potentially contaminated food or water

• Illness in other family members should be elicited

• Stool characteristics: watery, bloody, or fatty.

HISTORY

• Risk factors for HIV infection

• Weight loss

• Occurrence of diarrhea during fasting or at night (suggesting a secretory diarrhea)

• Family history of IBD

CAUSES OF CHRONIC DIARRHEA IN LESS DEVELOPED CONTRIES

The most common causes of chronic diarrhea:

• Chronic bacterial

• Mycobacterial

• Parasitic infections

Functional disorders, inflammatory bowel disease, and malabsorption are also common in this setting

DIAGNOSIS

• History: age, duration, food, family history, pattern, timing, travel

• Physical examination: general, eye, skin, abdomen, anorectal

• Laboratory tests

• Blood (albumin and thyroid-stimulating hormone levels; complete blood count; erythrocyte sedimentation rate; liver function testing)

• Stool (bacteria, blood, fat, leukocytes, ova and parasites, pH test, Giardia and Cryptosporidium antigen tests)

• Celiac panel

• Clostridium difficile toxin, if indicated

• Laxative screen, if indicated

OTHERS

• Hydrogen breath test

• Abdominal ultrasonography

• Abdominal CT-scan, endoscopic biopsy (esogastroduodenoscopy, sigmoidoscopy, colonoscopy),

• Small-bowel conventional follow through/enteroclysis, ERCP, MRCP, endoscopic capsules

DRUGS

CHRONIC INFECTIONS (PRIMARILY INFLAMMATORY)

Most microbial gastrointestinal infections cause acute self-limited diarrhea, but others persist, resulting in inflammation (invasive bacteria and parasites) or occasionally malabsorption (giardiasis).

• A history of travel and antibiotic use is important.

• Bacterial causes include Aeromonas, Campylobacter, C. difficile, Plesiomonas, and Yersinia. Parasitic diarrhea may be caused by Cryptosporidium, Cyclospora, Entamoeba, Giardia, Microsporida, and Strongyloides. Giardia, the most common of these, is best diagnosed with fecal antigen testing.

C. DIFFICILE

• The cause of pseudomembranous colitis, has emerged as a major infection in U.S. hospitals.

• This gram-positive anaerobic bacillus is easily spread through ingestion of spores, rapidly colonizing the colon following antibiotic therapy.

• A history of using fluoroquinolones, clindamycin, penicillins, or cephalosporins in the past three months is often associated.

• Approximately 3 percent of healthy adults may be asymptomatic carriers, but this increases to at least 40 percent in hospitalized patients.

MANAGEMENT

• Hydration

• Empirical Therapy

• Probiotics

HYDRATION

Essential part in the management of chronic diarrhea, for example by administering oral rehydration solutions. Intravenous fluid administration is provided when oral rehydration is not possible

EMPIRICAL THERAPY

Ideally, a work-up for chronic diarrhea will lead to a specific diagnosis and treatment. However, that is not always the case.

Empiric therapy in three conditions:

• (1) as an initial or temporary therapy prior to diagnostic testing

• (2) when the diagnostic testing has failed to confirm a diagnosis

• (3) when a diagnosis has been established, but no specific treatment is available or it fails to provide any therapeutic effect

EMPIRIC THERAPY

• Opiate anti diarrheals are a mainstay of symptomatic management when specific treatment is not possible.

• Dosing should be scheduled rather than as needed

PROBIOTICS

Ulcerative colitis:

• Certain probiotics have been found to be safe and as effective as conventional therapy in achieving higher response and remission rates in mild to moderately active ulcerative colitis in both adult and pediatric populations

Crohn’s disease:

• Studies of probiotics in Crohn’s disease have indicated that there is no evidence to suggest that probiotics are beneficial for maintenance of remission of Crohn’s disease.

PROBIOTICS AND IBS

• Reduction in abdominal bloating and flatulence as a result of probiotic treatments is a consistent finding in published studies; some strains may ameliorate pain and provide global relief.

• The literature suggests that certain probiotics may alleviate symptoms and improve the quality of life in patients with functional abdominal pain.

PROBIOTICS AND LACTOSE MALABSORPTION

• Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus improve lactose digestion and reduce symptoms related to lactose intolerance.

• This was confirmed in a number of controlled studies with individuals consuming yogurt with live cultures

DEFINITION

• Brain abscess is a focal, intracerebral infection that begins as a localized area of cerebritis and develops into a collection of pus surrounded by a well-vascularized capsule

EPIDEMIOLOGY

• Before the advent of human immunodeficiency virus (HIV) infection, brain abscess accounted for 1500 to 2500 cases treated in the United States each year; the incidence was estimated at 0.3 to 1.3 cases per 100,000 people per year

• In most pediatric and adult series, a male predominance exists (a ratio of 2 : 1 to 3 : 1) with a median age of 30 to 40 years