Acute Diarrhea Evaluation in Primary Care Acute Diarrhea luation in ...

Acute Diarrhea 

Evaluation in Primary Care 

Robert F. Miller, M.D. 

28 November, 2007

Definition— —”diarrhea” 

• Patient: stools too frequent or too soft 

• Caregiver: stools have too much water 

• Patient consideration lead to visit and 

• is addressed in treatment 

• Caregiver definition leads to decision for 

• evaluation and treatment

Definition— —”Acute” 

• Patient: change in bowel frequency or 

consistency 

Caregiver: new disease 

requires careful consideration of prior 

bowel pattern

Developed vs. undeveloped 

countries 

• High prevalence of serious infectious 

• disease in underdeveloped areas 

• In developed countries, pain, fear, 

• explanations, & missed work 

• Most diarrhea in developed world 

• unexplained

Initial Evaluation 

• Evaluation primarily clinical 

– Low yield of diagnostic tests 

– Most illnesses selflimited limited 

– Deal with reason(s) for patient visit 

– Exclude chronic diarrhea, with flare 

– Consider causes not directly gastrointestinal 

– runner’s diarrhea; medication; colon 

– ischaemia

Initial Evaluation 

• Degree of illness of patient: 

• hydration 

• septic or toxic 

• systemic disease 

• consider therapeutic dilemmas: 

• antibiotics; antidiarrheal agents 

• how best to rehydrate—oral vs IV 

• duration of diarrhea

Initial evaluationdiagnostic 

possibilities 

• Exposure history—epidemics; others 

• who are ill 

• Outdoor or unclean water exposure 

• Food exposure; time since exposure; 

• others who became ill 

• Enclosed space/nursing home/nursery 

• Nutrition 

• travel

Types of diarrhea 

• Watery 

• secretory 

• malabsorption 

• periumbilical pain 

• Inflammatory (colitis implied) 

• blood 

• pain(hypogastric) 

• tenesmus 

• Motility 

• urgency 

• pain (associated with passage of stool)

Food Poisoning Syndromes 

• Preformed toxin 

• emesis, with or without diarrhea 

• immediate (26 hr) symptoms 

• Staph aureus 

• Bacillus cereus (type I) 

• Containerrelated related syndromes (esp. copper) 

• Anisakiasis (raw herring)(larvae are toxic)

Food Poisoning Syndromes 

• Toxin formed in GI tract 

• delay in symptoms (c. 24 hr) 

• Clostridium perfringens 

• Bacillus cereus (type II) 

• Foodacquired bacterial infections 

• Salmonella 

• Viral 

• E.coli

GI disease not related to food 

• Waterborn pathogens 

• giardia; cryptosporidium; cyclosporosis 

• enterotoxic E.coli (traveller’s diarrhea) 

• cholera 

• 

• Amoeba 

• Sexually transmitted colon disease 

• gonorrhea; HSVII; LGV

Testing in acute diarrhea 

• “expensive, uncomfortable, low yield; 

• labor intensive” 

• for acute diarrhea, yield

Gastroenteritis syndromes 

• Emesis and diarrhea 

• 80% food related or oralfecal (infants) 

• Secondary transmission; carrier of 

• infective particles for 2 weeks 

• Prognosis worse in infants and elderly 

• Cultures if publichealth concerns 

• (E coli; salmonella; shigella, plus 

• hepatitis A) 

• testing for research or epidemiology 

• Serology for persons with asymptomatic disease

Major causes of viral gastroenteritis 

• Calicivirus group 

• 90% of epidemic gastroenteritis) 

• includes Norwalk agent, sapovirus 

• (children), norovirus 

• Rotavirus—primarily infants 

• Adenovirus types 40 & 41 

• Astrovirus 

• (CMV in immunosuppressed)

Calicivirus 

• 90% of epidemic gastroenteritis 

• Norwalk, Saporo, etc virus 

• =norovirus 

• Cannot grow virus in cell culturestudy by 

• EIA for antibody and stool antigen, 

• or more recently by RTPCR 

• Immunity shortterm term and genotype 

• specific—repeat infections; vaccine 

• will be problematic (attempts underway) 

• Prolonged excretion of virus; secondary cases

Calicivirus (continued) 

• Highly infectious—fecal fecaloral, 

approxomately 20% may be respiratory 

• Epidemicsàhumanà àseafood/shellfishà 

• multiple humans 

• Incubation 2448 hr 

• Little immunity, multiple strains 

• Difficult to remove from (clean) surfaces

Rotavirus 

• Major illness in very young. Nevertheless, 

• about 1/5 in older patients, with 

• mortality in very old 

• Multiple strains, partial immunity after 

• infection. Vaccine reduced incidence 

• but was withdrawn 

• Villus injury not related to severity of 

• diarrhea 

• DiagnosisEIA or RT PCR 

• Treatment:rehydration,?YGlobulin,?probiotics

Pathogenesis of viralinduced 

diarrhea 

• Inflammation minimal, or patchy 

• Involves upper 2/3 of villus membrane 

• (brush border) 

• Rotavirus best studied; 

• NSP4 protein—viral plus enterocyte 

• contribution—viruscell cell interaction. Increase in intra 

• cellular calcium promotes chloride secretion. 

• disaccharidases inhibited 

• SCLT1 inhibited (=malabsorption of CHO) 

• epithelial cell cytoskeleton altered (distortion of 

• chemical and osmotic gradients) 

• cytokinelike peptides (from host as well as virus)

Traveller’s diarrhea 

• Usually 36 days after arrival in new 

• country 

• Central America>Africa>SE Asia>Asia 

• Most from entertoxigenic E.coli 

• Rotavirus accounts for 10% 

• Clostridium difficile also common 

• Parasites (except giardia) rare 

• 5 days – 3 weeks is usual course 

• High incidence of postinfectious FBDz

Functional gastrointestinal 

disorders 

• May be induced by otherwise mild 

gastroenteritis. Most resolve eventually 

• Rome criterion 

• Most prevalent explanations: change in 

• Flora; mild E.coli; different foods; different 

daily routines, including different 

bathrooms 

• Most common cause of prolonged 

diarrhea after travel(&after a mission)

Foodrelated gastrointestinal 

infections 

• Gastroenteritis syndrome be a minor or 

• major manifestation of infection 

• Inoculum size (degree of infectivity) 

• variable: low for viral illness, shigella, 

• and E.coli 

• high for salmonella, probably high for 

• campylobacter 

• Many bacterial illnesses waterborn 

• Most parasitic illnesses waterborn

Types of infectious (nonviral) 

• Secretory 

• toxin related 

diarrhea 

• Inflammatory 

• locally active toxin (shiga);direct invasion 

• may have systemic toxin as well 

• (motilityrelated factors)

salmonella 

• Most common foodborn infection 

• Attack rates highest in those 75 

• Predisposing conditions: hemolytic anemia 

• (esp sickle cell disease; achlorhydria 

• (esp after gastric surgery);prior antibiotics 

• immunosuppression; schistosomaisis 

• Food source often from farm workers 

• Domestic animals & pets as carriers

Salmonella (continued) 

• Distinct clinical syndromes: 

• gastroenteritis: incubation ½1 day 

• duration 34 days; N&V; RLQ pain 

• colitis: bloody diarrhea; fever. May 

• have sepsis or toxic megacolon. 

• 1 week – 3 mo illness 

• bacteremia (esp in AIDS pts) 

• (typhoid fever) S. typhimurium 

• focal infection/abscess 

• carrier state (0.20.6%) 0.6%)

Salmonella (continued) 

• Treatment: 

• for acute gastroenteritis syndrome 

• (antibiotics debated) 

• for colitisantibiotics usually suggested 

• for sepsis—ampicillin if sensitive 

• for focal infection—ampicillin or TMS 

• for AIDS, sickle, etc—ampicillin, etc 

• for carrier?cholecystectomy; ?nothing 

• if schistosomaisis?praziquantl

E.Coli alphabet 

• Enteropathogenic (EPEC) 

• newbornsàAsians; 

• localized adherence(eaeA gene cluster) 

• Enterotoxigenic(ETEC) 

• traveller’s diarrhea; heatlabile &stable 

• toxin 

• Enteroinvasive(EIEC)— —colitis (Asia) 

• Enterohemorrhagic(EHEC)O157:H7 

• Enteroaggregative(EAggEC)?any dz from it? 

• Diffusely adhering E. coli(DAEC) (France)

E.coli O157:H7 

(Enterohemorrhargic E.coli) 

• 35 days incubation; diarrhea>blood in 

• 1à2 days. Pain in 1/3, usually after 

• blood appears. Diarrhea lasts 38 days 

• Multiple food can carry organism; food works, wild 

• animal also (water may be a source) 

• Low infective doseà10% secondary 

• spread; ?isolation; identify others exposed 

• HUS usually if

shigella 

• Ubiquitous organism; invasive (colon and 

• terminal ileum; food and personto 

• person spread; moderate attack rate 

• 13 week illness; pain and diarrhea may 

• preceed blood 

• Extraintestinal complications 

• Hydration; systemic antibiotics (ampicillin) 

• Avoid antimotlity drugs

Campylobacter jejuni 

• Common; rarely asymptomatic but disease 

• may be mild 

• Infected food; animals as source 

• 13 day usual incubation period 

• Antibiotics do not shorten illness

Other infectious 

diarrheas 

• Vibrio – usually secretory darrhea 

• cholera 

• biotype 01: classic & El Tor 

• toxins: activate CAMP; ZOT 

• parahaemolyticus”Kanagawa +” 

• cholera Non01 – (esp V. vulnificus) 

• vaccines only partially and briefly 

• effective 

• Yersinia enterocolitica

Clostridium difficile 

• No longer “just” a nosocomal infection 

• Inflammatory diarrhea 

• A small but significant number have no 

• antibiotic exposure 

• Humantohuman spread (hand washing) 

• One of he causes of traveller’s diarrhea 

• Usually requires treatment (metronidazole 

• if mild disease)

summary 

• Acute diarrhea syndrome usually defined 

• by the patient 

• Multiple causes—most diagnosed clinically 

• at time of initial evaluation 

• Most are foodrelated 

• Most selflimited; limited; supportive rx only 

• Care with antibiotics and opiates 

• Epidemiological considerations 

• Secondary cases not infrequent

Acute Diarrhea Evaluation in Primary Care Acute Diarrhea luation in ...

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