Serum or plasma concentration of immunoglobulin G (IgG) antibodies against *Escherichia coli* O157:H7 (E. coli O157:H7 IgG antibody)

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you’ve had symptoms like bloody diarrhea, abdominal pain, or fever that could suggest an E. coli infection. It may also be used in cases of suspected food poisoning or after exposure to contaminated food or water. Rarely, it could be part of monitoring for recurrent infections or research studies.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. If you’re concerned about needles, let your lab technician know so they can help make it more comfortable.

What the Test Results Mean

Positive results indicate your body has produced antibodies against E. coli O157:H7, suggesting past exposure. Negative results mean no detectable antibodies were found at this time. Results alone don’t confirm current infection—symptoms and clinical context are also considered.

Common Causes and Risks

E. coli O157:H7 infections often spread through contaminated food (like undercooked meat or unpasteurized dairy), water, or person-to-person contact. Risk factors include eating at high-risk restaurants, traveling to areas with poor sanitation, or handling raw meat without proper hygiene.