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Bacterial Gastroenteritis Differential Diagnoses

  • Author: Jennifer Lynn Bonheur, MD; Chief Editor: BS Anand, MD  more...
Updated: Oct 13, 2015

Diagnostic Considerations

Conditions to consider in the differential diagnosis of bacterial gastroenteritis include the following:

  • Colovesical fistula
  • Cholera
  • Diverticulitis
  • Food allergies
  • Food poisoning
  • Gardnerella
  • Viral gastroenteritis
  • Giardiasis
  • Isosporiasis
  • Lower gastrointestinal bleeding
  • Meckel diverticulum
  • Microsporidiosis
  • Salmonellosis
  • Shigellosis
  • Short-bowel syndrome
  • Ulcerative colitis

Differential Diagnoses

Contributor Information and Disclosures

Jennifer Lynn Bonheur, MD Attending Physician, Division of Gastroenterology, Lenox Hill Hospital

Jennifer Lynn Bonheur, MD is a member of the following medical societies: American Gastroenterological Association, American Society for Gastrointestinal Endoscopy, New York Society for Gastrointestinal Endoscopy, New York Academy of Sciences, Sigma Xi

Disclosure: Nothing to disclose.


M Akram Tamer, MD Professor, Program Director, Department of Pediatrics, University of Miami, Leonard M Miller School of Medicine

M Akram Tamer, MD is a member of the following medical societies: American Medical Association, Florida Medical Association

Disclosure: Nothing to disclose.

Mukul Arya, MD Associate Professor of Internal Medicine, Weill Cornell Medical College; Assistant Director of Therapeutic Endoscopy, Department of Gastroenterology and Internal Medicine, Wyckoff Heights Medical Center

Mukul Arya, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Medical Association, American Society for Gastrointestinal Endoscopy

Disclosure: Nothing to disclose.

Chief Editor

BS Anand, MD Professor, Department of Internal Medicine, Division of Gastroenterology, Baylor College of Medicine

BS Anand, MD is a member of the following medical societies: American Association for the Study of Liver Diseases, American College of Gastroenterology, American Gastroenterological Association, American Society for Gastrointestinal Endoscopy

Disclosure: Nothing to disclose.


Simmy Bank, MD Chair, Professor, Department of Internal Medicine, Division of Gastroenterology, Long Island Jewish Hospital, Albert Einstein College of Medicine

Disclosure: Nothing to disclose.

Richard E Frye, MD, PhD Assistant Professor, Departments of Pediatrics and Neurology, University of Texas Medical School at Houston

Richard E Frye, MD, PhD is a member of the following medical societies: American Academy of Neurology, American Academy of Pediatrics, Child Neurology Society, and International Neuropsychological Society

Disclosure: Nothing to disclose.

John Gunn Lee, MD Director of Pancreaticobiliary Service, Associate Professor, Department of Internal Medicine, Division of Gastroenterology, University of California at Irvine School of Medicine

John Gunn Lee, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, and American Society for Gastrointestinal Endoscopy

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

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Table 1. Stool Characteristics and Sources
Stool Characteristics Small Bowel Large Bowel
AppearanceWateryMucus and/or blood
BloodPossibly heme-positive but never gross bloodPossibly grossly bloody
pHPossibly < 5.5>5.5
Reducing substancesPossibly positiveNegative
White blood cell (WBC) count< 5/high-power field (HPF)Possibly >10/HPF
Serum WBC countNormalPossible leukocytosis, bandemia
OrganismsPreformed toxins:

Bacillus species, Staphylococcus aureus

Invasive bacteria:

E coli and Shigella, Salmonella, Campylobacter, Yersinia, Aeromonas, and Plesiomonas species

Toxic bacteria:

E coli, cholera, C perfringens, Vibrio species, Listeria monocytogenes

Toxic bacteria:

C difficile

Other causes:

rotavirus, adenovirus, calicivirus, astrovirus, Norwalk virus, and Giardia and Cryptosporidium species

Other causes:

Entamoeba species

Table 2. Symptoms and Their Characteristics
Organism Incubation Duration Vomiting Fever Abdominal Pain
Aeromonas speciesNone0-2 weeks+/-+/-No
Bacillus species1-16 hours1-2 daysYesNoYes
Campylobacter species2-4 days5-7 daysNoYesYes
C difficileVariableVariableNoFewFew
C perfringens0-11 dayMildNoYes
Enterohemorrhagic E coli1-8 days3-6 daysNo+/-Yes
Enterotoxigenic E coli1-3 days3-5 daysYesLowYes
Listeria species20 hours2 daysFewYes+/-
Plesiomonas speciesNone0-2 weeks+/-+/-+/-
Salmonella species0-3 days2-7 daysYesYesYes
Shigella species0-2 days2-7 daysNoHighYes
S aureus2-6 hours1 dayYesNoYes
Vibrio species0-1 days5-7 daysYesNoYes
Y enterocolitica0-61-46 daysYesYesYes
Table 3. Common Bacteria and Optimum Culture Media
Organism Detection Method Microbiologic Characteristics
Aeromonas speciesBlood agarOxidase-positive, flagellated GNB
Bacillus speciesBlood agarFacultatively aerobic, spore-forming GPR; beta hemolytic; reduces nitrates; ferments carbohydrates
Campylobacter speciesSkirrow agarRapidly motile, curved GNR; Campylobacter jejuni 90% of infections, Campylobacter coli 5% of infections
C difficileCCFE agar, EIA for toxin, LA for proteinAnaerobic, spore-forming GPR; toxin-mediated diarrhea; produces pseudomembranous colitis
C perfringensNone availableAnaerobic, spore-forming GPR; toxin-mediated diarrhea
E coliMacConkey, EMB, or SM agarLactose-producing GNR
Listeria speciesBlood agarFlagellated GPB
Plesiomonas speciesBlood agarOxidase-positive GNR
Salmonella speciesBlood, MacConkey, EMB, XLD, or HE agarNonlactose, non–H2S-producing GNR
Shigella speciesBlood, MacConkey, EMB, XLD, or HE agarNonlactose and H2S-producing GNR; verotoxin (neurotoxin)
Staphylococcus speciesBlood agarHeat-stable, preformed toxin-mediated GPC
Vibrio speciesBlood or TCBS agarOxidase-positive, motile, curved GNB
Y enterocoliticaCIN agarNonlactose-producing, oval GNR
CCFE = cycloserine-cefoxitin-fructose-egg; CIN = cefsulodin-irgasan-novobiocin; EIA= enzyme immunoassay; EMB = e-methylene blue; GNB = gram-negative bacillus; GNR = gram-negative rod; GPB = gram-positive bacillus; GPC = gram-positive cocci; GPR = gram-positive rod; H2S = hydrogen sulfide; HE = Hektoen enteric; LA = latex agglutination; SM = Sorbitol-MacConkey; TCBS = thiosulfate-citrate-bile-sucrose; XLD = xylose-lysine-deoxycholate.
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