01Approach to the Critical Patient/attcp65

Immediate priorities

›Airway and breathing assessment

›Vomiting with aspiration risk

›Depressed mental status or inability to protect airway

›Active or uncontrolled emesis

›If aspiration risk, position upright and prepare suction

›Head-of-bed 30 to 45 degrees

›Yankauer suction at bedside

›Respiratory compromise from severe dehydration or sepsis

›SpO2 target >94%

›Supplemental oxygen if below target

›Circulation and shock assessment

›Sepsis physiology

›SBP <90 mmHg or MAP <65 mmHg

›Tachycardia >100 beats/min with altered mental status

›Lactate >=2 mmol/l

›Dehydration severity

›Orthostatic hypotension (SBP drop >20 mmHg or HR rise >20 bpm on standing)

›Dry mucous membranes, poor skin turgor, sunken eyes

›Decreased urine output or anuria

›If septic shock, IV access and isotonic crystalloid 30 mL/kg bolus

›Class I recommendation

›Broad-spectrum antibiotics within 1 hour

›If severe dehydration without sepsis, IV fluid resuscitation with reassessment

›Lactated Ringer's or normal saline

›Reassess after each 500 mL bolus

›Critical red flag recognition

›Suspected STEC — bloody diarrhea without fever

02History/hx66

Presentation pattern

›Core diarrheal syndrome

›Stool frequency (>=3 loose/watery stools per day defines acute diarrhea)

›Onset and duration

›Watery vs. bloody or mucoid character

›Associated symptoms

›Fever, chills, tenesmus

›Nausea and vomiting

›Abdominal cramping

›Incubation period and timing

›1 to 6 hours: preformed toxin (S. aureus, B. cereus)

›8 to 16 hours: C. perfringens

›16 to 72 hours: invasive bacterial pathogens (Salmonella, Campylobacter, Shigella)

Alarm features

›High-risk symptoms requiring urgent evaluation

›Grossly bloody stools (dysentery)

›Suggests invasive organisms: Shigella, Salmonella, Campylobacter, STEC

›Bloody diarrhea without fever raises specific concern for STEC

›High fever >=38.5 degrees C

›Warning sign of complicated illness or bacteremia

›Symptoms >7 days without improvement

›Raises concern for parasitic infection, C. difficile, or IBD

›Signs of volume depletion

›Decreased urine output, dizziness, syncope, confusion

›Severe abdominal pain out of proportion to exam

›Raises concern for mesenteric ischemia or surgical abdomen

Exposure and risk factors

›Food and water exposures

03Physical Exam/exam41

Vital signs

›Hemodynamic status

›Temperature — fever >38.0 degrees C suggests bacterial or invasive pathogen

›Hypothermia may indicate sepsis in elderly

›Heart rate — tachycardia as dehydration and sepsis marker

›HR >120 suggests significant volume depletion or systemic toxicity

›Blood pressure with orthostatic assessment

›SBP drop >20 mmHg or HR rise >20 bpm on standing (most useful bedside indicator of significant volume depletion)

›Respiratory rate — tachypnea in sepsis or severe metabolic acidosis

Dehydration assessment

›Volume status examination

›Mucous membranes dryness

›Absent axillary sweating

›Sunken eyes

›Skin turgor assessment (less reliable in elderly)

›Delayed capillary refill >2 seconds

›Neurological manifestations of severe dehydration

›Confusion or altered mental status

›Weakness or presyncope

›Urinary output history at bedside

Abdominal exam

›Systematic abdominal assessment

›Bowel sounds character

›Hyperactive in acute gastroenteritis

›Absent or hypoactive suggests ileus or obstruction

›Tenderness distribution

›Diffuse — typical in gastroenteritis

›Focal RLQ — consider appendicitis (Yersinia can mimic)

04Differential Diagnosis/ddx45

Cannot-miss diagnoses

›Life-threatening conditions to exclude

›Mesenteric ischemia (ICD-10: K55.0)

›Severe abdominal pain out of proportion to exam

›Age >50, atrial fibrillation, or known atherosclerosis

›Lactic acidosis and elevated WBC as supporting features

›STEC-associated HUS (ICD-10: D59.3)

›Bloody diarrhea + thrombocytopenia + AKI + microangiopathic hemolytic anemia

›Primarily affects children and elderly

›Do not give antibiotics if STEC suspected

›Sepsis from invasive enteric pathogen (ICD-10: A02.1, A03.1)

›Salmonella bacteremia in immunocompromised, sickle cell, extremes of age

›Hemodynamic instability with febrile diarrhea

›Toxic megacolon (ICD-10: K59.31)

›Colonic dilation >6 cm with systemic toxicity

›C. difficile, severe IBD, or fulminant colitis

›Appendicitis (ICD-10: K35.80)

›Yersinia enterocolitica can mimic appendicitis

›RLQ tenderness, fever, leukocytosis

Infectious mimics

›Alternative infectious diagnoses

›Viral gastroenteritis (ICD-10: A08.4)

›Most common cause of acute diarrhea overall

›Vomiting-predominant, self-limited 2 to 3 days, afebrile or low-grade fever

›C. difficile colitis (ICD-10: A04.7)

›Recent antibiotic use or hospitalization

›Watery, foul-smelling diarrhea; rarely bloody in early disease

›Preformed toxin food poisoning

05Laboratory Tests/lt52

Initial workup

›Core laboratory panel

›Complete blood count

›Leukocytosis with left shift suggests bacterial or invasive pathogen

›Leukopenia may indicate severe sepsis or typhoid fever

›Thrombocytopenia raises concern for HUS or sepsis

›Comprehensive metabolic panel

›Sodium and potassium — electrolyte derangements from losses

›Bicarbonate — metabolic acidosis from diarrhea losses or lactic acidosis

›Creatinine and BUN — AKI from dehydration or HUS

›Glucose — hypoglycemia in pediatric severe dehydration

›Lactate

›Lactate >=2 mmol/l defines sepsis-associated organ dysfunction

›Elevation also seen in mesenteric ischemia

›Urinalysis

›Specific gravity as hydration marker

›Proteinuria and hematuria in HUS

Stool studies

›Microbiological evaluation

›Stool culture indications

›Bloody diarrhea (dysentery)

›Fever >=38.5 degrees C with diarrhea

›Symptoms >7 days

›Immunocompromised host

›Suspected outbreak or public health concern

›Hospitalized patients after >3 days admission (C. difficile more likely)

›C. difficile toxin PCR or GDH/toxin EIA

›Indicated with recent antibiotic use, hospitalization, or institutional exposure

06Diagnostic Tests/dt70

Scoring Systems

›Severity stratification framework

›Mild severity

›Tolerable diarrhea, no fever, no blood, maintaining oral intake

›Management: supportive care only, no antibiotics

›Moderate severity

›Distressing symptoms interfering with activities, mild dehydration

›Management: consider antidiarrheals, antibiotics if travel-related

›Severe severity

›Incapacitating illness, high fever (>=38.5 degrees C), bloody stools, sepsis signs, significant dehydration

›Management: IV fluids, stool studies, empiric antibiotics, possible admission

›Clinical Decision Tool — Stool Culture Trigger (IDSA 2017)

›Indications for stool culture

›Bloody or mucoid diarrhea

›Fever >=38.5 degrees C

›Duration >7 days

›Immunocompromised host

›Outbreak setting

›IDSA Level A recommendation

›Dehydration scoring (WHO classification)

›No dehydration: normal mental status, eyes, skin turgor, and drinking

›Management: ORS as maintenance

›Some dehydration (2 of 4 features): restless/irritable, sunken eyes, pinch goes back slowly, drinks eagerly

›Management: ORS 75 mL/kg over 4 hours

›Severe dehydration (2 of 4 features): lethargic/unconscious, very sunken eyes, pinch goes back very slowly, unable to drink

›Management: IV fluid resuscitation

MRI

›MRI abdomen and pelvis

›Role in bacterial gastroenteritis

›Not routinely indicated for uncomplicated bacterial gastroenteritis

›Limited utility in acute setting due to acquisition time

›Potential indications

›Suspected Crohn's disease complicating infection or IBD flare

›MR enterography for small bowel inflammatory assessment

›Mesenteric adenopathy characterization when CT inconclusive

›MRI bowel findings in severe infection

›Bowel wall thickening and edema

›Mesenteric hypervascularity (comb sign in IBD)

›Abscess or fistula complicating severe colitis

CT

›CT abdomen and pelvis with IV contrast

›Indications

›Concern for surgical pathology (appendicitis, diverticulitis, perforation)

›Suspected mesenteric ischemia

›Toxic megacolon assessment (colonic dilation >6 cm)

›Peritoneal signs or severe abdominal pain

›Failure to improve or diagnostic uncertainty

›Key CT findings in bacterial gastroenteritis

›Bowel wall thickening (>3 mm) with mural stratification

›Pericolonic fat stranding

›Mesenteric lymphadenopathy (especially Yersinia)

›Free air — perforation emergency

›Thumbprinting pattern — ischemic or inflammatory colitis

›CT angiography (CTA) mesentery

›Indicated if mesenteric ischemia suspected

›Age >50, pain out of proportion to exam, atrial fibrillation

›Superior and inferior mesenteric artery assessment

›CT limitations

›Radiation exposure — relevant in young patients

›Does not establish bacterial etiology

›Cannot differentiate bacterial from other infectious causes

Ultrasound

›Point-of-care ultrasound (POCUS)

›IVC collapsibility assessment

›IVC collapsibility index >50% suggests significant volume depletion

›Useful in tachycardic or hypotensive patients to guide IV fluid resuscitation

›Inferior vena cava diameter <1.5 cm with collapsibility suggests hypovolemia

›Abdominal POCUS indications

›RLQ assessment for appendicitis (graded compression technique)

›Free fluid detection (perforation or ascites)

›Gallbladder assessment (acalculous cholecystitis in ICU patients)

›Right lower quadrant ultrasound performance

›Sensitivity 86%, specificity 81% for appendicitis in adults

›CT preferred when US nondiagnostic

07Disposition/dispo43

Admission indications

›Criteria warranting inpatient admission

›Hemodynamic criteria

›Sepsis or septic shock

›Persistent hemodynamic instability after initial resuscitation

›Lactate >=4 mmol/l (septic shock)

›Clinical severity criteria

›Severe dehydration unresponsive to initial IV resuscitation

›Inability to tolerate oral intake despite antiemetics

›Suspected or confirmed HUS

›Toxic megacolon or peritoneal signs requiring surgery

›Significant electrolyte abnormalities requiring IV correction

›High-risk patient criteria

›Age >=65 years with moderate-severe illness

›Immunocompromised host

›Significant cardiac or renal comorbidity

›Inability to care for self or ensure adequate oral hydration at home

Observation and short-stay criteria

›Indications for observation period

›Moderate dehydration requiring IV fluids with expected rapid improvement

›Reassess tolerance of oral fluids after rehydration

›Elderly or comorbid patients needing monitoring

›Electrolyte and renal function reassessment in 4 to 6 hours

›Antiemetic trial for inability to tolerate PO

›Discharge once tolerating fluids and stable

Discharge criteria

›Criteria for safe discharge

›Clinical stability

08Treatment/t103

Fluid resuscitation

›Oral rehydration therapy (ORT)

›Preferred route for mild to moderate dehydration

›Low-osmolarity ORS preferred (200 to 250 mOsm/L)

›WHO/UNICEF ORS: 75 mEq/L sodium, 20 g/L glucose

›Commercial ORS (Pedialyte, Gastrolyte) acceptable

›Volume targets

›Mild dehydration: ORS 50 mL/kg over 4 hours plus maintenance

›Moderate dehydration: ORS 75 mL/kg over 4 hours then reassess

›Dietary advice alongside ORT

›Early refeeding shortens illness duration

›Age-appropriate normal diet as tolerated — no special diet required

›Avoid excessive sugary drinks (worsen osmotic diarrhea)

›Intravenous fluid resuscitation

›Indications for IV fluids

›Severe dehydration or shock

›Inability to tolerate oral intake

›Persistent vomiting despite antiemetics

›Altered mental status

›IV fluid selection

›Isotonic crystalloid (Lactated Ringer's preferred over normal saline in children per Cochrane 2023)

›Normal saline 0.9% as alternative

›IV fluid dosing

›Septic shock: 30 mL/kg isotonic crystalloid bolus over 3 hours

›Severe dehydration: 20 mL/kg boluses with reassessment

›Reassess after each bolus for response

Symptomatic therapy

›Antidiarrheal agents

›Loperamide

›Indication: watery, non-bloody, afebrile diarrhea only

›Adult dose: 4 mg initial, then 2 mg after each unformed stool

›Maximum: 8 mg/day for 48 hours (OTC label)

›Contraindicated in bloody or febrile diarrhea — risk of toxic megacolon and prolonged illness

›Bismuth subsalicylate

›Dose: 524 mg (30 mL) every 30 to 60 minutes as needed

›Maximum: 8 doses per day

›Safe alternative in inflammatory diarrhea with fever

›Mildly effective; turns stools black (benign)

›Avoid in aspirin allergy, children <12 years (Reye's syndrome risk)

›Antiemetic therapy

›Ondansetron

›Adult dose: 4 to 8 mg IV or PO every 6 to 8 hours as needed

›Pediatric dose: 0.1 to 0.15 mg/kg IV/PO (max 4 mg per dose)

›Baseline ECG or QTc assessment recommended before use

›Caution: QT prolongation risk — avoid with other QT-prolonging agents

›Use to facilitate oral rehydration when vomiting impairs intake

›Metoclopramide

›Adult dose: 10 mg IV or IM every 8 hours

›Alternative if ondansetron unavailable or QT concern

›Avoid in bowel obstruction; extrapyramidal side effects possible

›Prochlorperazine

›Adult dose: 5 to 10 mg IV/IM every 6 to 8 hours

›Extrapyramidal side effects — diphenhydramine 25 mg IV as premedication

Empiric antibiotic therapy

›Indications for empiric antibiotics

›Sepsis or signs of systemic toxicity

›Class I recommendation (IDSA 2017)

›Moderate-to-severe traveler's diarrhea

›Ciprofloxacin or azithromycin based on region

›Bacillary dysentery (bloody stool + fever + tenesmus)

›Presumptively Shigella — empiric treatment indicated

›Immunocompromised host with moderate-severe illness

›Lower threshold for antibiotic initiation

›NOT indicated for uncomplicated watery diarrhea in immunocompetent host

›IDSA Level A recommendation against routine empiric antibiotics

›Empiric antibiotic regimens (adults)

›Fluoroquinolone (first-line in most regions)

›Ciprofloxacin 500 mg PO twice daily for 3 days

›Alternative single dose: ciprofloxacin 750 mg PO once

›Levofloxacin 500 mg PO once daily for 3 days or single dose

›Not preferred in Southeast Asia or India (fluoroquinolone-resistant Campylobacter)

›Azithromycin (preferred for Campylobacter and resistant regions)

›Standard: 500 mg PO daily for 3 days

›Single-dose option: 1,000 mg PO once

›IDSA preferred agent for travel to Southeast Asia, India

›First-line for confirmed or suspected Campylobacter

›Rifaximin (non-invasive traveler's diarrhea only)

›Dose: 200 mg PO three times daily for 3 days

›Not appropriate for bloody diarrhea or febrile illness

›IDSA Level A recommendation for moderate non-invasive traveler's diarrhea

›Pathogen-specific antibiotic selection

›Salmonella non-typhoidal

›Antibiotics not recommended for uncomplicated illness in immunocompetent adults

›Treat if bacteremia, severe illness, immunocompromised: ciprofloxacin 500 mg BID x 5 to 7 days

›Alternative: azithromycin 500 mg daily x 7 days

›Shigella

›Ciprofloxacin 500 mg BID x 3 days (resistance increasing — culture-guided)

›Azithromycin 500 mg daily x 3 days if fluoroquinolone resistance

›Ceftriaxone 2 g IV daily if severe or resistance concerns

›Campylobacter

›Azithromycin 500 mg daily x 3 days (first-line)

›Fluoroquinolone resistance common (>50% in some regions)

›STEC (E. coli O157:H7 and other Shiga toxin producers)

›AVOID antibiotics — Class I contraindication

›Fluoroquinolones, beta-lactams, TMP-SMX, and metronidazole all increase HUS risk

›Supportive care with close monitoring for HUS development

›C. difficile

›Metronidazole 500 mg PO three times daily x 10 days (mild-moderate, fidaxomicin/vancomycin preferred per IDSA 2021)

›Vancomycin 125 mg PO four times daily x 10 days (first-line per IDSA 2021)

›Fidaxomicin 200 mg PO twice daily x 10 days (superior recurrence reduction)

›Discontinue offending antibiotic if possible

Probiotics

›Probiotic therapy considerations

›Lactobacillus and Saccharomyces boulardii

›Modest reduction in diarrhea duration (approximately 1 day shorter)

›ACG guideline: conditional recommendation for acute infectious diarrhea

›Safe in healthy adults; caution in severely immunocompromised hosts

09Special Populations/sp70

Pregnancy

›Physiologic and risk considerations

›Increased susceptibility to foodborne illness

›Listeria monocytogenes — disproportionately severe in pregnancy

›Risk of premature labor, fetal loss, neonatal sepsis

›Avoid unpasteurized dairy, deli meats, and soft cheeses

›Dehydration risk

›Volume depletion may trigger uterine contractions or preterm labor

›Aggressive ORT or IV hydration threshold lower than non-pregnant adults

›Fetal heart rate monitoring if >20 weeks gestation with severe dehydration

›Medication safety in pregnancy

›Safe options

›Oral rehydration salts — safe in all trimesters

›Ondansetron: use with caution (Category B); limited QT data; avoid in first trimester if possible

›Azithromycin (Category B) — preferred antibiotic if needed

›Avoid in pregnancy

›Fluoroquinolones (Category C) — cartilage toxicity concern; avoid unless no alternative

›Bismuth subsalicylate — salicylate component; avoid third trimester

›Loperamide — generally avoided, especially first trimester

›Listeria treatment if confirmed

›Ampicillin 2 g IV every 6 hours for 2 to 3 weeks

›Alternative: TMP-SMX (avoid near term — kernicterus risk)

Geriatric

›Age-related risk factors

›Increased mortality from bacterial gastroenteritis

›Age >=65 accounts for disproportionate share of ~1,500 annual deaths from bacterial diarrhea in US

›Impaired thirst response and decreased renal reserve increase dehydration severity

›Blunted febrile response

›Normal temperature does not exclude serious infection

›Hypothermia may indicate sepsis

›Comorbidity burden

›Cardiovascular disease makes electrolyte derangements (hypokalemia) poorly tolerated

›Chronic kidney disease at higher AKI risk

›Cognitive impairment may mask symptom severity

›Management modifications in elderly

›Lower threshold for IV fluid resuscitation

›Oral rehydration may be inadequate with impaired swallowing or cognition

›Antibiotic dosing adjustments

›Renally dose-adjust ciprofloxacin (GFR <30: 250 to 500 mg twice daily)

›Azithromycin: no renal adjustment required

›Lower admission threshold

›Moderate illness in geriatric patient may warrant observation or admission

›QTc monitoring if ondansetron administered

›Elderly have higher baseline QT prolongation risk

Pediatrics

›Age-specific considerations

›Pediatric dehydration assessment

›Clinical Dehydration Scale (CDS) or Gorelick scale

›Infants: sunken fontanelle, absent tears, decreased wet diapers

›Toddlers: sunken eyes, dry mucous membranes, decreased activity

›HUS risk in children

›STEC E. coli O157:H7 is leading cause of HUS in children

›Accounts for 90% of pediatric HUS cases

›Peak age 1 to 5 years; highest risk with Shiga toxin 2 producers

›Do not treat with antibiotics if STEC suspected

›Rotavirus vs. bacterial — peak age overlap

›Rotavirus: age 6 months to 2 years, often winter, vaccine-preventable

›Bacterial: higher fever, bloodier stools, older children more common

›Pediatric fluid management

›ORT preferred for mild-moderate dehydration

›Low-osmolarity ORS 75 mOsm/L (WHO formula preferred over sports drinks)

›Volume: 50 mL/kg for mild, 100 mL/kg for moderate over 3 to 4 hours

›Ondansetron 0.1 to 0.15 mg/kg PO/IV (max 4 mg) to facilitate ORT

›IV fluid resuscitation in pediatrics

›Isotonic crystalloid (Lactated Ringer's preferred per Cochrane 2023)

›Bolus: 10 to 20 mL/kg isotonic saline over 30 to 60 minutes; repeat as needed

›Avoid hypotonic solutions — risk of hyponatremia

›Pediatric antibiotic indications

›Shigella: azithromycin 12 mg/kg daily x 3 days (max 500 mg/day)

›Alternative: ceftriaxone 50 mg/kg IV daily if severe

›Campylobacter severe: azithromycin 10 mg/kg daily x 3 days

›Salmonella typhi: ceftriaxone 75 mg/kg IV daily x 10 to 14 days

›Neonates and infants <3 months: lower threshold for admission and IV antibiotics

10Background/b72

Epidemiology

›Disease burden and prevalence

›US burden

›Approximately 179 million outpatient visits for acute diarrheal disease annually in the United States

›Estimated 5.2 million cases of bacterial diarrhea per year

›Approximately 46,000 hospitalizations annually from bacterial diarrhea

›Approximately 1,500 deaths annually from bacterial diarrhea

›Pathogen distribution in North America

›Most common identified bacterial pathogens: Salmonella, Campylobacter, Shigella, and STEC

›Campylobacter: most common cause of bacterial foodborne illness in developed world

›ETEC: most common cause of traveler's diarrhea (80 to 90% of cases bacterial)

›High-risk groups

›Age extremes: infants (<1 year) and elderly (>=65 years)

›Immunocompromised individuals

›International travelers (developing world destinations)

›Food handlers and healthcare workers (occupational exposure + transmission risk)

Pathophysiology

›Mechanisms of bacterial diarrhea

›Secretory (toxin-mediated) mechanism

›Preformed toxins — ingested before bacterial colonization

›S. aureus enterotoxin: heat-stable, rapid onset 1 to 6 hours

›B. cereus emetic toxin: cereulide, rice dish association

›In vivo toxin production — ETEC LT and ST toxins, V. cholerae CT

›Stimulates adenylate or guanylate cyclase causing chloride and water secretion

›Results in profuse watery diarrhea without mucosal invasion

›Invasive mechanism

›Direct mucosal invasion and destruction

›Shigella: invades colonic epithelium, spreads laterally, causes dysentery

›Salmonella: invades M cells in Peyer's patches, may reach bloodstream

›Campylobacter: invades jejunal and ileal mucosa, triggers inflammatory response

›Results in bloody mucoid diarrhea with fever and tenesmus

›Cytotoxin mechanism

›STEC Shiga toxins (Stx1, Stx2)

›Stx2 has stronger association with HUS than Stx1

›Toxin inhibits ribosomal protein synthesis in endothelial cells

›Microangiopathic hemolytic anemia, thrombocytopenia, AKI (HUS triad)

›Dehydration pathophysiology

›Intestinal electrolyte and water losses

›Sodium and water depletion causing hypovolemia

›Potassium losses from diarrhea and vomiting causing hypokalemia

›Bicarbonate losses in diarrheal fluid causing non-anion gap metabolic acidosis

›Glucose-sodium cotransport preserved in bacterial gastroenteritis — basis for ORT efficacy

Therapeutic Considerations

›Antibiotic stewardship principles

›Most bacterial gastroenteritis is self-limited

›Inappropriate antibiotic use drives resistance (Campylobacter fluoroquinolone resistance >50% in SE Asia)

›Reserve antibiotics for high-risk features: sepsis, dysentery, immunocompromise, travel

›STEC avoidance principle

›Antibiotics significantly increase HUS risk by promoting Shiga toxin release

›Absolute contraindication to antibiotics if STEC suspected (bloody diarrhea without fever)

›IDSA and ACG Level A recommendation against antibiotic use in suspected STEC

›Rehydration therapy evidence base

›ORT mechanism

›Glucose-coupled sodium absorption remains intact despite diarrheal losses

›Low-osmolarity ORS (200 to 250 mOsm/L) reduces stool output and vomiting vs. standard ORS

›WHO endorses low-osmolarity ORS universally

›Early refeeding evidence

›Early enteral nutrition decreases intestinal permeability

›Reduces illness duration and normalizes intestinal function faster

›No evidence supporting "bowel rest" or BRAT diet

›Emerging diagnostics impact

›Multiplex PCR panels (BioFire FilmArray GI Panel)

›Detect 22 pathogens from single stool specimen within 1 hour

›Higher sensitivity for Campylobacter and Norovirus vs. conventional culture

›Risk of overdiagnosis of co-pathogens of uncertain significance

›IDSA/ASM 2024 recommends selective use with clinical correlation

›Complications to anticipate and prevent

›HUS prevention strategy

›Avoid antibiotics if STEC suspected

›Serial monitoring CBC and BMP for 7 to 10 days post-onset

›Eculizumab (anti-C5 complement inhibitor) considered in severe atypical HUS

›Post-infectious sequelae

›Reactive arthritis: occurs 1 to 4 weeks post-Salmonella, Shigella, Campylobacter, Yersinia

›Guillain-Barre syndrome: post-Campylobacter (most common preceding infection)

›Post-infectious IBS: bowel habit alterations persisting weeks to months

11Patient Discharge Instructions/pdi31

copy discharge instructions

›Discharge instructions for Bacterial Gastroenteritis

›What is bacterial gastroenteritis?

›Bacterial gastroenteritis is an infection of your stomach and intestines caused by bacteria, resulting in diarrhea, vomiting, nausea, and stomach cramps

›Most cases get better on their own within 3 to 7 days with proper rest and hydration

›The most important treatment is replacing fluids and electrolytes lost through diarrhea and vomiting

›Hydration instructions

›Drink small sips of oral rehydration solution (Pedialyte, Gastrolyte, or similar) frequently throughout the day

›Avoid large volumes at once if vomiting — try 5 to 10 mL every 5 minutes

›Avoid alcohol, caffeinated beverages, and very sweet drinks like juice or soda

›Resume normal eating as soon as you feel able — there is no need for a special diet

›Medications prescribed

›Take all antibiotics exactly as prescribed — complete the full course even if you feel better

›Anti-nausea medication may be taken as prescribed to help you keep fluids down

›Do not use anti-diarrheal medications (Imodium/loperamide) if you have bloody stools or fever — call us first

›Preventing spread to others

›Wash hands thoroughly with soap and water after every bathroom visit and before handling food

›Do not prepare food for others while you are symptomatic

›If you work as a food handler or healthcare worker, stay home from work until you have been symptom-free for at least 48 hours

›Disinfect bathroom surfaces with appropriate disinfectants

›Follow-up instructions

›See your family doctor in 2 to 3 days if symptoms are not improving

›If stool tests were ordered, your doctor will contact you when results are available — some results take 2 to 3 days

›Return to the emergency department immediately if you experience

›Bloody or black stools (new or worsening)

›High fever (temperature >=38.5 degrees C or 101.3 degrees F)

›Inability to keep fluids down for more than 24 hours

›Decreased urination, dizziness, or fainting

12References/r21

Guidelines and key sources

›Primary evidence sources

›Meisenheimer ES, Epstein C, Thiel D. Acute Diarrhea in Adults. American Family Physician. 2022. PMID 35839362

›AAFP clinical practice guideline: comprehensive evaluation and management framework

›Shane AL, Mody RK, Crump JA, et al. 2017 IDSA Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea. Clinical Infectious Diseases. 2017. PMC5850553

›Level A and B recommendations for antibiotic selection, stool testing indications, STEC management

›DuPont HL. Bacterial Diarrhea. New England Journal of Medicine. 2009

›Pathogen-specific features, alarm signs, antibiotic selection

›DuPont HL. Acute Infectious Diarrhea in Immunocompetent Adults. New England Journal of Medicine. 2014

›Supportive care evidence, ORT, traveler's diarrhea management

›Riddle MS, DuPont HL, Connor BA. ACG Clinical Guideline: Diagnosis, Treatment, and Prevention of Acute Diarrheal Infections in Adults. American Journal of Gastroenterology. 2016

›ACG recommendations for diagnostic testing including multiplex PCR

›Miller JM, Binnicker MJ, et al. Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update. IDSA and ASM. Clinical Infectious Diseases. 2024

›Stool culture and multiplex PCR panel indications and limitations

›Florez ID, Sierra J, Perez-Gaxiola G. Balanced Crystalloid Solutions Versus 0.9% Saline for Treating Acute Diarrhoea and Severe Dehydration in Children. Cochrane Database of Systematic Reviews. 2023

›Evidence supporting Lactated Ringer's over normal saline in pediatric dehydration

›McGee S, Abernethy WB, Simel DL. Is This Patient Hypovolemic? JAMA. 1999

›Orthostatic hypotension as most useful bedside indicator of volume depletion

›Connor BA, Leung DT. Travelers' Diarrhea. CDC Yellow Book. 2025

›Empiric antibiotic selection by region, rifaximin indications

›Lopez-Velez R, Lebens M, Bundy L, et al. Bacterial Travellers' Diarrhoea: Narrative Review. Travel Medicine and Infectious Disease. 2022

›Regional pathogen distribution and antibiotic resistance patterns

Evidence & Review

Evidence & Review