Escherichia coli enteritis laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Yazan Daaboul, M.D.; Serge Korjian M.D.

Identification of the causative strain is usually not necessary for diagnosis and treatment. Diagnostic laboratory tests for E. coli enteritis usually include either stool culture, ELISA, or polymerase chain reaction (PCR). Other laboratory findings in E. coli enteritis are usually non-specific and may include increased white blood cell count and elevated inflammatory markers. Laboratory findings suggestive of dehydration may include relative polycythemia, metabolic alkalosis, elevated BUN and serum creatinine (suggestive of pre-renal acute kidney injury). When hospitalized, patients should also be monitored for laboratory findings that may suggest the development of hemolytic uremic syndrome, such as hemolytic anemia, elevated serum creatinine, and thrombocytopenia.

• Stool cultures

• Usually considered a reliable diagnostic test with good sensitivity since E. coli organisms typically shed continuously
• Diagnosis of E. coli O157:H7 usually requires sorbitol-MacConkey agar

• Serotyping

• ELISA detects Shiga-like toxins 1 and 2 in stools
• ELISA may detect anti-LPS IgM antibodies against some E. coli strains

• Polymerase chain reaction (PCR)

• Detection of E. coli pathogens and Shiga-like toxin

• Laboratory findings of E. coli enteritis are usually related to the degree of dehydration or development of complications. Laboratory findings include:

• WBC count may be normal or elevated
• Elevated concentration of inflammatory markers (e.g. CRP or ESR)
• Chloride-sensitive metabolic alkalosis and electrolyte derangement (commonly hypokalemia)
• Relative polycythemia in cases of dehydration or hemolytic anemia in cases of hemolytic uremic syndrome
• Elevated concentration of BUN
• Elevated creatinine is suggestive of pre-renal acute kidney injury in severe dehydration or onset of hemolytic uremic syndrome
  
  

To learn more about laboratory findings associated with hemolytic uremic syndrome (such as prolonged PT and PTT, hemolytic anemia, and thrombocytopenia) click here.