EM guidemap - Acute diarrhea

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Introduction

General principles

History and examination

Diagnostic workup

Medical decision-making Appendix
Introduction

- this guidemap only deals with the problem of acute diarrhea (diarrhea of < 4 weeks duration) and it does not deal with the problem of chronic diarrhea

- the guidemap is primarily focused on the ED evaluation and management of acute diarrhea due to an "apparent" infectious agent, and it does not address the issue of other, less common, causes of diarrhea (eg, secretory diarrhea, osmotic diarrhea, drug-induced diarrhea, malabsorption syndromes)

- the diagnostic workup of acute diarrhea is an ED setting is often very limited, and an empirical approach is often used with no/minimal diagnostic testing

(* many textbooks contain considerable detail on the different infectious organisms causing diarrhea and their common patterns of clinical presentation, but there is too much variability to correlate the type of clinical presentation to a particular infectious organism => ED managment is usually based on very simple empirical principles)
 
General principles

- acute diarrhea is defined as the passage of an increased number of stools, of decreased form from the normal, lasting less than 14 days

- acute diarrhea is often associated with other gastro-intestinal symptoms - nausea, vomiting, abdominal cramps or pain, bloating and tenesmus (constant urge-sensation to move the bowels)

- most causes of acute diarrhea are due to infectious agents and less frequently due to other causes (eg. osmotic agents, laxative abuse, secretory diarrhea)

- most infectious causes of diarrhea produce a self-limited illness, and don't require specific antibiotic therapy; the main focus of the clinical evaluation is usually centered on determining the degree of dehydration that is secondary to the diarrhea

- clinical evaluation is specifically warranted if there is reason to suspect an infectious agent that requires targeted antibacterial or antiparasitic therapy, or if one suspects an inflammatory diarrhea that is non-infectious in origin (eg. Crohn's disease, ulcerative colitis, ischemic colitis)

- reasons for recommending a clinical evaluation include:-

- the presence of rectal pain and tenesmus and the passage of small amounts of stool with blood and mucus suggests proctitis (inflammation confined to the distal 15 cm of colon) => consider the possibility of recipient anal intercourse and the presence of sexually transmitted infectious agents

- prominent vomiting and a lesser degree of diarrhea suggests the possibility of food poisoning or the syndrome of gastro-enteritis

- gastro-enteritis usually presents with vomiting, abdominal cramps and watery diarrhea, while dysentery (severe inflammatory enterocolitis) usually presents with bloody diarrhea, a febrile illness and no/minimnal vomiting

- suspect food-borne or water-borne food poisoning due to a pre-formed toxin if vomiting +/- diarrhea occurs within 6 hours of exposure to a food item, especially if multiple victims are afflicted and if vomiting and abdominal cramps (rather than diarrhea) are the main symptoms; Bacillus cereus and Staphylococcal aureus pre-formed toxins are the most common causes of early onset food poisoning

- suspect Clostridium perfringens if the incubation period of suspected food poisoning is 8 - 14 hours and diarrhea is the main symptom

- suspect a viral gastro-enteritis if the incubation period of a food poisoning-type illness is > 14 hours, especially if there are associated URI symptoms

(* fever and/or bloody stools are not usually seen in food poisoning, and their presence suggests an invasive pathogen)

- the presence of voluminous stools with minimal vomiting suggests an enterocolitis

- most causes of an acute enterocolitis are due to infectious agents; less likely causes include inflammatory or ischemic colitis, partial bowel obstruction and pelvic abscesses in the area of the rectosigmoid colon

- the incubation period of the most common viral-bacterial causes of diarrhea vary from hours-few days, and it is unlikely that a specific etiological cause can be established based solely on the "apparent" incubation period -- especially if the patient has consumed many meals containing food products frequently associated with diarrhea (contaminated water, dairy products, eggs, poultry, undercooked fish and meats)

- a few common food-bacterial disease associations include:-

- some causes of persistent diarrhea (diarrhea lasting > 14 days) include giardiasis or other parasitic infections (cryptosporidium, cyclospora, microsporidium), small bowel overgrowth syndrome, secondary lactase deficiency or malabsorption syndrome

(* the diagnostic workup of chronic diarrhea is complex and requires special expertise => referral to a gastro-enterologist is appropriate)

- enterocolitis is an uncommon cause of diarrhea in the neonatal period, and systemic infection or UTI should be suspected as the likely cause of diarrhea in neonates

- clostridium difficile toxin can be found in the stool of 10% of healthy neonates, and its presence does not imply pathogenicity

- rotavirus is the most common diarrheal pathogen in infants and young children

- diarrhea lasting longer than 10 days in a healthy adolescent suggests a parasite such as giardia or cryptosporidium, or certain bacteria such as C. difficile, plesiomonas or yersinia

- sexually active adolescents are prone to proctocolitis infection secondary to campylobacter, shigella, chlamydia and E. histolytica
 

Common and uncommon diarrheal pathogens in children
  Infants and toddlers Children 5-12 years old Adolescents
 Common
  • rotavirus
  • enteric adenovirus
  • salmonella
  • shigella
  • campylobacter
  • yersinia
  • giardia
  • Norwalk virus
  • Giardia
  • EPEC
  • EHEC
  • ETEC
  • salmonella
  • campylobacter
  • Norwalk virus
  • campylobacter
  • ETEC
  • EHEC
  • salmonella
  • shigella
 Uncommon
  • ETEC
  • aeromonas
  • plesiomonas
  • C. difficile
  • cryptosporidium
  • yersinia
  • aeromonas
  • C. difficile
  • rotavirus
  • B. cereus
  • C. difficile
  • yersinia
  • V. cholerae
  • E. histolytica

- most enterotoxins produce a secretory diarrhea via various mechanisms; damage to the enterocyte can also lead to loss of brushborder hydrolase activity and carbohydrate malabsorption, which produces a secondary osmotic diarrhea

- certain bacteria produce cytotoxins which damages the enterocytes, producing an inflammatory diarrhea with mucosal ulcerations and hemorrhage

- the non-inflammatory diarrheas usually result in large volumes of watery diarrhea without pus or blood, and the patient is usually afebrile and has no significant abdominal pain

(* common causes include rotavirus, Norwalk agent, enterotoxigenic E Coli, staphylococcal and clostridial food poisoning, giardia lambia, cryptosporidium and cholera)

- the inflammatory diarrheas usually result in the frequent pasage of small volume stools that are variably bloody; fever and abdominal discomfort +/- tenesmus are frequently present

(* common causes include salmonella, shigella, campylobacter, enterohemorrhagic or enteroinvasive E. Coli, clostridum difficile and yersinia)
 
History and examination

- the history should focus on determining the duration and extent of any diarrhea, and the presence of associated symptoms (nausea, vomiting, abdominal cramps or pain, tenesmus, dysentery, fever, myalgia or other systemic symptoms); on the pattern of evolution of the illness and whether diarrhea was the initial, and/or most prominent, symptom

(* the presence of prominent vomiting, bile-stained vomiting, hematemesis, marked abdominal pain, and/or abdominal distension suggest other serious pathology)

- the color and consistency of the stools, and the presence of blood or mucus in the stools should be determined

- a history of dehydration symptoms (postural weakness or dizziness, extreme thirst, oliguria) should be sought

- a recent history of fluid and food intake, and urinary output should be obtained (especially in children - including the most recent body weight)

- an epidemiologic history is occasionally useful  in selected cases => a basic history should focus on a history of:-

Clinical clue table suggesting a likely cause of acute diarrhea
Epidemiologic consideration Etiologic agent to consider
Travel to a mountainous area, or recreational body of water in North America or Russia Giardia, cryptosporidium
Recent travel to a developing area Travelers diarrhea due to bacterial agents (enterotoxigenic E. Coli mainly)
Recent antimicrobial therapy, recent hospitalization, chronic institutionalization Clostridium difficile
Day care center contact Any infectious agent spread by fecal-oral route, especially Shigella, giardia and cryptosporidium
Consumption of marine fish Ciguatera or other marine fish envenomation (especially if dyesthesias and other bizarre neurological symptoms are present); vibrios (inadequately cooked seafood - sushi, cerviche); clostridium perfringens, Norwalk virus (raw seafood eg. oysters and shellfish); plesiomonas
Consumption of wild plants or mushrooms Plant or mushroom poisoning
Explosive onset of vomiting and cramps +/- diarrhea, multiple victims, recent (< 6 hours) consumption of un-refrigerated food capable of harboring staphylocccus bacteria Staphylococcal food poisoning (heat-stable toxin)
Recreational water venues eg. community swimming pools, water fountains, hot tubs, spas Norwalk virus, cryptosporidium
Sick animal pets Yersinia enterocolitica, salmenollosis, cryptosporidium
Male homosexual All enteric pathogens spread by fecal-oral route; sexually transmitted pathogens -  Neisseria gonorrhea, chlamydia trachomatis, herpes simplex
Diarrhea longer than 10 days Giardia, Cryptosporidium, Yersinia, Clostridium difficle, Plesiomonas

- giardiasis is suggested by the presence of foul-smelling stools, flatulence and abdominal bloating in a patient who attends a day care center, camps in mountainous areas or travels to foreign countries; or if steatorrheic-type diarrhea is interspersed between periods of normal stooling

- the examination should be mainly focused on determining whether the patient has signs of dehydration -- physical signs include alterations in pulse and blood pressure, decreased capillary refill, decreased skin turgor, mucosal dryness and absence of tears, fontanelle sunkeness, eye sunkeness, altered mental status and decreased urinary output

- there is no absolute correlation between individual abnormal signs (eg. decreased lacrimation, depressed fontanelle, sunken eyes and dry mucous membranes) and the degree of dehydration => the abnormal signs should be considered in toto

- one physician's description of the clinical signs of dehydration in children follows:-

Mild dehydration (3-5% body weight loss)

Moderate dehydration (6-9% of body weight) Severe dehydration (> 10% of body weight) Another physician's description of the signs of dehydration in table form
 
Signs of dehydration in children
Degree of dehydration General condition Eyes Tears Mouth/tongue Thirst Skin
None or mild (<3-5%) Well, alert Normal Present Moist Drinks normally, not thirst or slightly thirsty Pinch retracts immediately
Mild-moderate (5-10%) Restless, irritable Sunken  Absent Dry Drinks thirstly Pinch retracts slowly (1-2 secs)
Severe (>10%) Lethargic and/or floppy Very sunken and dry Absent Very dry Drinks poorly or not at all Pinch retracts very slowly

- some clinicians think that a delay in capillary refill can be very reflective of the degree of dehydration in children => however, it is also affected by age, ambient temperature and the presence of a fever

- the abdomen should be examined for signs of tenderness/guarding which can suggest a secondary complication (eg. intestinal perforation) or a non-infectious inflammatory diarrhea (eg. Crohn's disease) or a diarrhea-mimic (eg. appendicitis); the combination of physical signs of an abdominal hernia and abdominal distension and hyperactive bowel sounds suggest a partial bowel obstruction and secondary diarrheal leakage

- a rectal examination can demonstrate the presence of blood or mucus in the stool, and help differentiate inflammatory from non-inflammatory diarrhea
 
Diagnostic testing

- diagnostic testing rarely affects treatment or the outcome, and it should be used selectively

- diagnostic testing is not indicated in previously healthy patients with watery, non-inflammatory diarrhea

- reserve diagnostic testing for very young/elderly patients, immunocompromized patients, severely dehydrated patients, patients with inflammatory diarrhea and bloody stools, or if the clinical presentation is atypical

Stool examination for occult blood

- the presence of occult blood suggests an invasive bacterial enterocolitis or inflammatory colitis

- the presence of occult blood is usually equivalent (from an emergency physician's medical decision-making perspective) to a positive lactoferrin test or positive fecal leucocyte test

- however, the combination of positive occult blood testing and the absence of fecal leucocytes suggests amebiasis (the most common cause of dysentery in developing countries), heavy metal poisoning or an underlying malignancy

Stool examination for fecal leucocytes

- two drops of fresh stool suspension (or mucus strand) is stained with two drops of methylene blue => greater than 5 leucocytes per high power field (in 4 or more fields) is a positive result and suggests an inflammatory colitis warranting stool culture for common organisms (eg. salmonella, shigella, and campylobacter)

- a fecal lactoferrin test has a higher sensitivity (60-75%) for an inflammatory diarrheal infection than a positive fecal leucocyte test (40%)

(* there is apparently a high incidence of false-positive fecal lactoferrin tests in breast fed infants, precluding the use of the test in that age group)

Stool culture

- stool cultures should not routinely be performed because of the very low yield and consequent unnecessary expense (> $1,000 per positive culture result)

- indications for routine stool culture include:-

- stools are usually only routinely cultured for certain bacteria eg. salmonella, shigella and campylobacter

- in children with bloody diarrhea suspected to be due to enterohemorrhagic E coli (diarrhea epidemics associated with hamburger or apple cider consumption, or diarrhea associated with hemolytic uremic syndrome) => stools should also be cultured on sorbitol-MacConkey agar to detect entero-hemorrhagic E Coli (shigatoxin producing and E Coli 0157:H7)

- specific stool culturing for vibrios and plesiomonas may be indicated if the patient has recently eaten oysters or if the patient has travelled along the gulf of Mexico

Serum electrolytes

- are not routinely indicated unless the patient has severe dehydration, or an altered mental status

- a low serum bicarb (<15 mEq/L) in children suggests a metabolic acidosis due to moderate-severe dehydration and the likely need for hospital admission, although there is widespread disagreement regarding the correlation between the degree of hypocarbotinemia and the need for hospital admission => the serum bicarbonate level should not be considered in isolation

Laboratory evaluation for ova and parasites

- not cost effective and rarely indicated

- traditionally requires the examination of three stool specimens from three separate occasions

- may be indicated if the diarrhea is persistent (entamoeba histolytica, cryptosporidium, giardia); if there is a history of travel to Nepal or Russia (cryptosporidium, giardia, Cyclospora); in adults with a history of contact with infants in day care centers (cryptosporidium, giardia); and if HIV infection is strongly suspected (E. histolytica, cryptosporidium, giardia and others)

- stools for amebiasis should be considered if the stools are strongly occult blood positive, but fecal leucocytes are absent + there is an exposure risk for amebiasis (travel to undeveloped countries)

- stool examination for giardiasis and cryptosporidium is indicated if giardiasis or cryptosporidiasis is clinically suspected -- homosexuals, day care center exposures, history of travel to mountainous areas or recreational fresh water areas of North America or Russia, or if the diarrhea is persistent (>14 days)

- special staining and EIA techniques are required to detect parasites that are likely to cause diarrhea in AIDS patients eg. coccidians (Cryptosporidium parvum and Cyclospora cayatensis),  isospora belli, and microsporidians (E. beineusi, E. intestinalis)

- newer EIA and immunoflouresence techniques are available for detection of giardia, E. histolytica and C. parvum, but they are not routinely used

Stool assay for clostridium difficile toxin

- may be indicated if the patient is currently taking antibiotics or has taken antibiotics within the past 2 weeks

- direct detection of C. difficile toxins is the most popular test, although the cytotoxin B tissue culture assay is the most specific test

- many EIA kits area available to detect toxins, and they have varying sensitivity (34-100%) and specificity (88-100%)

Endoscopy

- flexible sigmoidoscopy +/- upper endoscopy may be indicated for patients with persistent diarrhea that has not responded to empiric therapy, especially homosexual male patients who have a higher likelihood of undiagnosed infection due to Giardia, Cyclospora, Cryptosporidium, Microsporidium, CMV or Mycobacterium avium intracellulare

- colonoscopy is also indicated if ulcerative colitis or ischemic colitis is suspected

- proctosigmoidoscopy should be considered if anal manipulation or a rectal foreign body is the likely cause of the acute diarrhea
 
Medical decision-making in an ED setting

- the major focus of the clinical evaluation is targeted at determining the presence of dehydration, and the need for ED rehydration therapy or hospital admission for IV hydration

- most cases of acute diarrhea are self-limited, and empirical treatment is often indicated

- there are no "fixed" criteria for hospital admission and the threshold should be low in the following circumstances:

Rehydration therapy

- oral fluid therapy is often adequate for the majority of patients with mild/moderate diarrhea +/- mild/moderate dehydration, while IV hydration therapy is more suitable for patients with moderate/severe diarrhea + moderate/severe dehydration, especially if the patients are persistently vomiting or disinclined to drink fluids (or if social factors warrant rapid IV hydration in the ED setting)

- sport drinks, diluted fruit juices, other flavored soft drinks or watery soups augmented with saltine crackers are acceptable therapy in non-dehydrated adults, or in adults with mild dehydration

- however, the presence of 'cholera-like' diarrhea, or signs of moderate dehydration, warrant the use of specially-constituted oral rehydration solutions (ORS) containing about 45-90 mEq/L of sodium, 20 mEq/L of potassium, 80 mEq/L of chloride and 20g/L of glucose

(* a homemade form of this solution is to prepare two separate glasses that are consumed alternately - the first contains 8 ounces (240cc) of orange, apple or other fruit juice (supplying potassium) + 1/2 teaspoon of honey or corn syrup + 1 pinch of salt; the second contains 8 ounces (240cc) of water  + 1/4 teaspoon of baking soda)

Homemade ORS should not be used in children because of the frequency of serious misformulations

- generally, oral replacement solution (ORS) containing 45-60 mEq/L of sodium may be preferable for children, rather than 90 mEq/L of sodium (WHO replacement formula) which is more likely to result in hypernatremia; the WHO replacement formula may be more suitable for cholera-like diarrhea in developing countries

- in children who are not dehydrated, maintenance amounts of approximately 100 ml/kg of ORS should be given ad libitum over 24 hours if the child can tolerate their slightly salty taste (ORS can be flavored +/- frozen into ice-pops form, which may appeal to some children); in children who are mildly dehydrated (3-5%) 50 ml/kg of ORS should be given over 4 hours (~10ml/kg/hour) in the supervised setting of the ED in addition to the replacement of ongoing losses (10 ml/kg for each loose stool); in children with moderate dehydration (6-9%) 100 ml/kg of ORS can be given over 4-6 hours (~15-20ml/kg/hour) in the supervised setting of the ED in addition to replacement of ongoing losses (10 ml/kg for each loose stool) => the child should be clinically re-evaluated for hydration status and fluid replacement progress at least every 2 hours

- small amounts of recurrent emesis are not a contradication to continued oral fluid replacement therapy by spoon, cup or bottle => a syringe can be used to administer small aliquotes of fluid (5cc) every 1-2 minutes directly into the child's mouth if the child is disinclined to drink voluntarily (significant vomiting rarely occurs if small amounts of fluid are administered in this manner and the thirsty child usually swallows any fluid squirted into the mouth)

(* the syringe technique, although labour-intensive, can allow for the administration of 150-300ml of ORS/hour)

- ORS can be given by naso-gastric tube if the child is disinclined to drink or vomits frequently; alternatively, 20-40 ml/kg of IV replacement fluid can be given over the first hour to initiate replacement fluid therapy => oral replacement therapy can then commence if the child is more alert and more inclined to drink

Antiemetic drugs should not be used in young children

- additional amounts of replacement fluid may be needed to replace any fluid lost in the vomitus if the volume of vomitus is significant

- the standard ORS usually contains glucose, which is suitable for non-cholera diarrhea; while rice-based ORS may be better for patients with cholera, or 'cholera-like', diarrhea

- children who have severe dehydration (> 10%), moderate dehydration + unable to tolerate oral fluid replacement, or who have an associated ileus and abdominal distention usually require treatment with IV fluids in hospital

- a 20ml/kg bolus of normal saline should be administered IV over 20 minutes if the child is severely dehydrated + hemodynamically unstable => repeat boluses of 10-20 ml/kg N/S IV should be administered until hemodynamic stability is achieved => 0.45 N/S in 2.5% dextrose (+ 20 meq/L potassium) is often used for replacement therapy (50% over the first 8 hours and 50% over the next 16 hours), and 0.45 N/S or 0.2 N/S is used for maintenance therapy

- use of "clear fluids" alone is not recommended because it is too hypotonic and it predisposes to hyponatremia; fruit juices or sugar-containing cola juices are not recommended because their high sugar content can worsen the diarrhea as a result of their high osmolar load and because they are deficient in sodium
 

Brand pH Osmolality (mOsm/kg) Sodium concentration (mmol/L) Potassium concentration
(mmol/L)
Coca Cola 2.8 469 3.0 0.1
Pepsi Cola 2.7 576 1.0 0.1
Seven-up 3.5 388 4.0 0.0
Orange juice 4.0 587 1.0 46.0
Apple juice 3.6 694 0.0 27.4

- if ORS therapy is successful in the ED, the child can be discharged for continued oral replacement/maintenance therapy at home

See this online website for the "Canadian pediatric society guidelines on oral replacement therapy and early re-feeding in the managment of childhood gastro-enteritis" for more details about oral replacement therapy

Dietary therapy

- patients should consume eating as soon as rehydration is accomplished and conditions allow

- suitable dietary agents for adults include boiled starches/cereals (potatos, noodles, rice, wheat, oats), crackers, bananas, yogurt and boiled vegetables

- some authorities suggest avoiding milk products in adults because of the possibility of a secondary lactose intolerance, but this is uncommon in most cases of acute diarrhea (? medical myth)

- milk and full-strength formula can be used from the start in children, and there is no need to start feeding with diluted or half-strength formula; continued breast-feeding from the onset probably hastens recovery

- an age-appropriate diet should be initiated in children after the 3-4 hour period of ORS therapy is complete; it may shorten the duration of diarrhea and it results in more rapid weight gain; complex carbohydrates (rice, wheat, potatos, cereals) lean meats, yoghurt, fruit and vegatables are preferred; the BRAT diet (bananas, rice, apple sauce, toast) is low in energy density, protein and fat; fatty foods should be avoided

Symptomatic therapy with anti-motility drugs

- loperamide is commonly recommended for adults with non-febrile, non-dysentery cases of acute diarrhea => 2 tablets (4 mg) initially, then 2mg after each loose stool to a maximum of 8-16mg/day

- diphenoxylate and atropine (lomotil) is less preferable because of the higher incidence of side-effects

- lomotil (+/- immodium) is dangerous in children because it's central opiate effects can cause severe respiratory depression => lomotil should not be used in children

- bismuth subsalicylate (Pepto-bismol) - 30 ml or two tablets q 30 minutes x 8 doses - can be used for traveler's diarrhea; however, it is less effective than loperamide and it is contraindicated in HIV positive patients because the deliberate taking of excessive doses can produce bismuth encephalopathy; bismuth subsalicylate should not be used concurrently with certain antibiotics because it affects their absorption; bismuth subsalicylate may be most effective in improving the symptom of vomiting in patients with gastro-enteritis and prominent vomiting

- the use of agents such as kaolin-pectin and fiber make the stool firmer but do not decrease stool output, which leads to an underestimation of the severity of the diarrhea

- antimotility drugs are contra-indicated in antibiotic-induced colitis (suspected clostridium difficile) and febrile dysenteric patients

The American Academy of Pediatrics recommends that pharmacologic agents should not be used routinely in the management of vomiting and diarrhea in children

Antimicrobial therapy

- antibiotic therapy is not usually recommended for "garden-variety" watery diarrhea for the following reasons:-

- empiric therapy for presumed bacterial diarrhea is often recommended for acute diarrhea patients with:- - some suggested antimicrobial regimens include:- - antibiotic therapy is routinely indicated for shigellosis (because it is spread rapidly by human-to-human contact and because it may produce a life-threatening illness), but antibiotic therapy is not routinely recommended for salmonellosis because it increases the carrier rate and the persistent excretion of salmonella organisms

- TMP/SMX is often recommended for USA-acquired shigellosis, and quinolones for internationally-acquired shigellosis; there is considerable resistance of shigella to sulfonamides, TMP, amoxicillin and tetracyclines; azithromycin or a short quinolone course (severe cases only or if non-quinolone therapy has been unsuccessful) has been recommended for shigellosis in children

- salmonella infection is usually secondary to consumption of poultry, eggs, meat or dairy products; pets (turtles and lizards) have also been implicated

- most salmonella gastro-enteritis infections are self-limited, and antibiotics are not indicated

- indications for using antibiotics in salmonellosis include:-

- campylobacteriosis is commonly secondary to the consumption of contaminated poultry, especially in the late summer and early fall => antibiotics are not recommended for mild-moderate diarrhea, which usually resolves spontaneously within one week; antibiotics are usually reserved for elderly patients, immunocompromized or pregnant patients, patients with presumed septicemia, patients with moderate-severe dysentery or infants in day-care centers (to rapidly increase the eradication rate); erythromicin stearate or azithromycin antibiotics can shorten the duration of campylobacter diarrhea if given within the first 3 days of the diarrheal illness (which is 2x more common than intestinal salmonellosis and 7x more common than shigellosis in developed countries); quinolones may have a therapeutic advantage because they are effective even if started > 4 days after the onset of diarrhea, although quinolone resistance should be suspected in recent foreign travelers (especially to Thailand) or in patients who have a history of recent quinolone use; antibiotics may decrease the relapse rate, which occurs in 20-30% of cases of campylobacteriosis

- yersiniosis is suspected in patients who have consumed pork chitterlings (pork intestines) or milk products, or who have a pseudoappendicular syndrome with terminal ileitis and marked mesenteric lymphadenitis (a more common presentation in school-age children) => most cases of yersinia enteritis resolve spontaneously => antibiotic therapy is indicated if the diarrhea is prolonged, if there is extra-intestinal involvement or if septicemia is likely (iron overload conditions like hemochromatosis, multiple blood transfusions or desferrioxamine therapy) => an aminoglycoside + fluroquinolone is frequently  used for yersinia sepsis

- some suggested antibiotic regimens in AIDS-immunocompromized patients

- patients with chronic diarrhea lasting > 14 days and an exposure history compatible with giardia are often treated empirically for giardiasis because ~50% of the stool specimens will be negative (false-negative) for giardia => definitive workup for giardia may be indicated if the patient does not respond to appropriate metronidazole therapy

(* metronidazole may also be effective for small bowel bacterial overgrowth syndrome, which can also cause persistent diarrhea; some gastro-enterologists prefer to avoid empirical therapy and prefer to perform further diagnostic studies in all patients with persistent diarrhea)

- patients previously treated with antibiotics should be presumed to have clostridium difficile infection => mild cases only require symptomatic therapy while moderate-severe cases require antibiotic therapy => start empirical metronidazole therapy (vancomycin is a second choice and equally efficacious) while awaiting stool assay test for clostridium difficle toxin and stool cultures  for other organisms; antimotility agents are absolutely contraindicated; IV metronidazole is clearly less effective than oral metronidazole therapy and IV vancomycin is ineffective; C difficile colitis relapses within 1-6 weeks in 20% of cases and relapses are usually due to a re-infection rather than a failure of initial antibiotic therapy; asymptomatic recolonization with C. difficile does not require antibiotic therapy

- antibiotic therapy in childhood diarrhea

Probiotics

- probiotics, such as Lactobacillus casei GG and Saccharomyces boulardii, may reduce the frequency and/or duration of diarrhea in acute infantile gastroenteritis but their role is still undefined

Useful health education messages for parents of children with diarrhea

Appendix

- this section contains brief capsules of background information on infectious organisms, that may unfamiliar to the average emergency physician

Less frequent causes of infectious diarrhea

Aeromonas

- most commonly due to consumption of freshwater and marine-associated food products

- spectrum of disease from mild to severe; chronic diarrhea is more common in adults, whereas children < 12 years old are more likely to have an acute, severe diarrheal illness

- complications include hemolytic-uremic syndrome, meningitis, septicemia, peritonitis and URIs

- septicemia is more common in infants < 2 years old with underlying diseases, immunocompromised adults, patients with traumatic wound infections

- underlying medical conditions can predispose to extra-intestinal disease eg. Laennec's cirrhosis, blood dyscrasias, diabetes and biliary disease

- the role of antibiotics is not clear; many intestinal illnesses are self-limited; effective antibiotics include tetracyclines, TMP-SMX, and quinolones

Plesiomonas

- found in freshwater ecosystems and marine estuaries

- infection is strongly associated with consumption of uncooked shellfish within the past 48 hours; oysters are a major source of infection and sushi, scallops, shrimp and poultry are also sometimes involved

- causes acute inflammatory diarrheas in both adults and children

- sickle cell disease, primary hemachromatosis, leukemia predisposes to extra-intestinal disease (meningitis, cholecystitis, pancreatic abscesses, septic arthritis and osteomyelitis)

- antibiotics (quinolones or TMP-SMX) are recommended for severe disease

Some infectious causes of diarrhea in HIV-positive patients

- using a comprehensive diagnostic approach, a responsible cause of the diarrheal illness can be found in 50-80% of HIV-positive patients

- 20-25% of HIV patients have multiple intestinal infections

- cryptosporidium and CMV are the two most common causes of diarrhea

- acute dysentry and fever is usually due to shigella, campylobacter or salmonella

- profuse watery diarrhea is usually due to one of the coccidial organisms eg. cryptosporidium, isospora or cyclospora

- C. difficile infection is also frequent due to the common long term usage of antibiotics, and it may present as a severe diarrheal illness, pseudomembranous colitis or toxic megacolon

- large volume-, or infrequent-, or nocturnal diarrhea suggests small bowel involvement; while frequent, small-volume bloody stools with abdominal discomfort and tenderness and tenesmus suggests colonic involvement

- a fulminating course suggests a disseminated infection eg. CMV or mycobacterium avium intracellulare

- diarrhea is rarely self-limited and all patients require a diagnostic workup

- the routine diagnostic workup usually starts with stool C&S, stool examination for ova and parasites and stool assay for C. difficile

- blood cultures are also routinely indicated (especially if the patient is febrile) because they may be positive when the stool C&S is negative

- proctosigmoidoscopy is routinely indicated for lower bowel involvement

- upper endoscopy/colonoscopy and multiple biopsies are indicated if stool cultures and stool staining techniques are negative or the patient fails to respond to therapy of an identified organism; multiple biopsy specimens are cultured for CMV, adenovirus, mycobacterium, fungi and herpes simplex virus

- if all diagnostic tests are negative, the patient is often treated symptomatically and the diagnostic testing cycle repeated in 6-8 weeks if the diarrhea persists

Brief information on some organisms causing diarrhea in HIV-positive patients

Cryptosporidiosis

- due to the cryptosporidium parasite

- spread zoonotically, person-to-person and via contaminated water

- produces a self-limiting diarrheal illness in healthy patients, but can cause a chronic, debilitating diarrheal illness in HIV-positive patients

- profuse watery diarrhea, which may be exacerbated by eating, +/- cramping abdominal pain, anorexia, nausea and vomiting

- most HIV-positive patients have a chronic illness with many exacerbations and remissions

- diagnosed by examining the stool using an acid fast stain or ELISA testing

- supportive rehydration is the mainstay of treatment as there is no effective treatment; the disease is self-limited in immunocompetent patients

- paromomycin can produce a temporary decrease in stool frequency and decreased oocyte shedding in immunocompromized patients, but relapse is common despite continued treatment

Microsporidiosis

- obligate intracellular spore-producing parasite; most common species is Enterocytozoon bieneusi

- commonly produces chronic diarrhea, malabsorption and wasting

- patients usually have very low CD4 counts

- diarrhea is watery +/- abdominal discomfort

- the organism cannot be cultured; diagnosis requires special staining or indirect immunofluorescence antibody assays

- no known effective treatment for E. bieneusi, while albendazole is effective for S. intestinalis

Isospora belli

- a coccidian protozoan that is far more common in developing countries; uncommon in the USA

- produces a prolonged, watery diarrheal illness (similar to cryptosporidiosis)

- peripheral eosinophilia occurs; Charcot-Leyden crytals are found in the stools

- intestinal biopsy is the preferred method of diagnosis if multiple stool examinations are negative (because the oocysts are infrequently found in the stools)

- sensitive to many antibiotics, including TMP-SMX and pyrimethamine

Cyclospora cayetanensis

- produces diarrhea that lasts 2-6 weeks in travellers to Nepal and the tropics, and causes intermittent prolonged diarrhea in HIV-positive patients

- often spread by contaminated berries or leafy vegetables, spring-summer outbreaks

- diagnosis is by stool examination and staining (resembles cryptosporidium oocysts and requires expert laboratory technician to differentiate the two two types of oocyts)

- good response to TMP-SMX antibiotics, but relapses are common requiring prophylactic antibiotic therapy

Entameba histolytica

- patients who acquire the disease sexually are more likely to develop extra-intestinal illness

- wide spectrum of disease from a self-limited diarrheal illness to a fulminating invasive colitis

- diagnosed by a wet mount of a stool specimen

- treated with metronidazole for invasive disease followed by a luminalcidal agent eg. paromomycin or iodioquinol

Giardia lambia

- spread by oro-anal contact in male homosexuals and is part of the "gay bowel syndrome"

- diagnosed by stool examination, ELISA testing or an enterotest/duodenal aspirate

- responds to treatment with quinacrine or metronidazole

Cytomegalovirus

- the most common and serious viral infection affecting the GI tract in HIV-positive patients

- no characteristic symptoms; patchy colitis is most common producing intermittent or persistent diarrhea, crampy lower abdominal pain, tenesmus and weight loss

- fever and abdominal tenderness is common; full thickness bowel ulceration can occur followed by perforation

- can also produce bowel obstruction and lower GI bleeding

- colonic involvement can be patchy and localised, or diffuse

- diagnosis requires colonoscopy and multiple biopsies and special staining

- treated initially with ganciclovir followed by foscarnet if needed

Herpes simplex virus

- frequently asociated with a distal colitis or proctitis in HIV-positive patients

- can produce anorectal pain, tenesmus, hematochezia and painful perianal ulcers

- diagnosis is by biopsy and staining, +/- immunochemistry or viral culture

- treated with high-dose oral or IV acyclovir +/- foscarnet

Mycobacterium avium complex

- the most common systemic bacterial infection in HIV-positive patients

-  produces protracted diarrhea, abdominal discomfort, fever, weight loss, anemia and night sweats

- intestinal complications include obstruction, strictures, bleeding and perforation

- definitive diagnosis is made by intestinal biopsy

- requires a prolonged course of treatment with a combination of antituberculous drugs (eg. clofazimine, ethambutol, ciprofloxacin, rifampin, rifabutin, amikacin and azithrmycin) and life-long suppressive therapy

Some useful emedicine.com chapters for more detailed information

Campylobacter infections
Clostridium difficile
Cryptosporidiosis
Gastroenteritis,bacterial
Gastroenteritis- viral
Giardiasis
Isosporiasis
Microsporidiosis
Salmanellosis
Shigellosis
Vibrios
Yersinia

Disclaimer: My EM guidemaps reflect my personal approach to problem-solving/managing clinical cases in an ED setting and they should not be regarded as the standard of care. They merely represent the personal opinions of the author and they should only be used in clinical practice if the reader-user has substantial reason to believe that the clinical advice contained in the guidemaps is valid and accurate. The guidemaps are not meant to be "authoritative" and the reader-user should consult standard medical textbooks and expert opinion articles/guidelines for more authoritative advice. The reader-user should particularly confirm all drug doses, their indications and contra-indications, prior to their use.