Table 3.
Differential diagnosis of diarrhea in patients with suspected STEC
| Pathogen | Incubation Period | Blood in Stool | Abdominal Cramping and Pain | Nausea or Vomiting | Fever | Other Signs and Diagnostic Aids | Diagnostic Laboratory Testing |
|---|---|---|---|---|---|---|---|
| Bacillus anthracis (gastrointestinal anthrax) | 2 d to wk | + | + | + | + | Patient history: exposure may be accidental from consumption of infected meat | Culture of food, any lesions, blood; CDC select agent; culture hazard |
| Brucella spp | 7–21 d | + | − | − | + | Patient history: bacteremia and fever; unpasteurized dairy product consumption; travel to endemic area; muscle and joint pain; headache | Blood cultures with special incubation request; CDC select agent; culture hazard |
| Campylobacter spp | 2–5 d | +/− | + | + | + | Consumption of or contact with raw or undercooked poultry | Stool culture (special request) |
| Clostridium difficile (C difficile associated disease); Community-associated C difficile associated disease | Variable (d to mo) | +/− | + | +/− | + | May occur in patients with or without prior antibiotic use | Stool toxin EIA; anaerobic stool culture and toxin EIA of isolates |
| Cryptosporidium spp | 2–28 d | − | + | + | + | May be chronic in ICH | Microscopic stool examination; DFA; EIA |
| Cyclospora spp | 1–11 d | − | + | + | − | Fatigue; may be chronic if unrecognized | Microscopic stool examination |
| EIEC | 10–18 h | − early; <10% + late | + | − | + | Fecal leukocytes late, as seen with Shigella spp | Stool culture for other pathogens |
| Entamoeba histolytica | 2 d–4 wk | + | + | − | + | Invasive; liver abscess if chronic; may be confused with STEC; patient food and exposure history very important | Microscopic stool examination; serology for chronic or invasive disease; stool EIA or PCR |
| EPEC | 9–12 h | +/− | + | + | + | Infant diarrhea; mucus in stool; dehydration severe; prolonged infections | Stool culture for other pathogens |
| ETEC | 1–3 d | − | + | − | − | Patient history useful (travel, infant weaning) | Stool culture for other pathogens |
| Giardia spp | 1–4 wk | − | + | − | − | Flatulence, bloating; may be chronic if unrecognized | O&P stool examination; stool DFA or EIA |
| Norovirus | 24–48 h | − | − | + | − | Outbreak settings common; most common viral cause of gastroenteritis | PCR testing of stool |
| Rotavirus | 1–3 d | − | − | + | +/− | Common in children; outbreak settings | Stool EIA for rotavirus |
| Salmonella enterica subsp. enterica; 2500 serovars; nontyphoidal | 1–3 d | − | +/− | + | + | May be chronic if not recognized or untreated | Stool culture |
| Shigella spp | 1–2 d | + | + | + | + | S dysenteriae serotype 1 especially severe due to Shiga toxin; all Shigella are invasive of intestinal epithelium | Stool culture (special request for S dysenteriae serotype 1) |
| STEC, O157 or non-O157 (EHEC, VTEC) | 1–8 d | +/− | + | + | +/− | Nonbloody diarrhea may precede blood in stool; oliguria, renal failure, hemolytic uremic syndrome; history of undercooked beef consumption | Stool culture to include SMAC agar for O157 STEC (special request); Shiga toxin EIA; O157 EIA; PCR testing of stool for Stx genes |
| Toxins, bacterial, preformed: Bacillus cereus, Clostridium botulinum, Clostridium perfringens, Staphylococcus aureus | 1–16 h Bc; 12–72 h Cb; 8–16 h Cp; 1–6 h Sa | − | + | + | −/+ | Sudden onset vomiting with Sa; diplopia and muscle paralysis with Cb; Cb is life-threatening | Toxin testing of food |
| Toxins: fish, shellfish, and mushrooms | <30 min to 8 h | − | + | + | +/− | Visual disturbance, confusion, numbness, altered sensations; may be life-threatening | Toxin testing of food |
| Toxins, chemical: organic compounds, metals (As, Sn, Tl, Zn), nitrite, fluoride | 5 min to 8 h | − | + | + | − | Headache, nervousness, twitching movements, visual disturbance | Toxin testing of food |
| Trichinella spp | 1 d–8 wk | − | + | + | + | Myalgias, periorbital edema; cardiac and neurological involvement possible | Larval cysts detectable in muscle tissue by microscopy |
| Vibrio cholerae, serogroup 01 or 0139 | 1–3 d | − | − | + | − | Profuse watery diarrhea; dehydration life-threatening | Stool culture (special request) |
| Vibrio para-hemolyticus, V mimicus, V fluvialis, V furnissii, V hollisae | 2–48 h | +/− | + | + | + | Patient history of seafood consumption | Stool culture (special request) |
| Yersinia enterocolitica and pseudotuberculosis | 24–48 h | +/− | +/− | + | + | Mesenteric lymphadenitis mimicking appendicitis | Stool culture (special request) |
Symbols used: + usually present; +/− may be present; − rarely present.
Abbreviations: DFA, direct fluorescent antibody staining; EIA, enzyme immunoassay; ICH, immunocompromised host; Bc Cb Cp Sa (for toxins, bacterial, preformed) are Bacillus cereus, Clostridium botulinum, Clostridium perfringens, and Staphylococcus aureus, respectively; O&P, ova and parasite; PCR, polymerase chain reaction; SMAC, sorbitol-Mac Conkey.