Escherichia coli O157:H7 Antibody Detection by Immunoassay (Serum/Plasma)

Why This Test Might Be Ordered

Your healthcare provider may order this test if you’ve had symptoms like stomach cramps, bloody diarrhea, or vomiting—common signs of E. coli infection. It’s also used to check if you’ve been exposed to this bacteria, especially after outbreaks or contaminated food/water events. Rarely, it helps confirm a diagnosis when other tests are inconclusive.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample (serum or plasma) via a simple venipuncture. If you’re unsure about recent food exposures or travel, mention it to your provider, as it may affect results.

What the Test Results Mean

Positive results indicate your immune system has likely encountered E. coli O157:H7 before, meaning you’ve had an infection at some point. Negative results suggest no detectable antibodies, so you may not have been exposed recently. Results alone don’t confirm current infection—your provider will consider symptoms and other tests.

Common Causes of False Results

Antibody levels can vary based on when you were infected (acute vs. recovered) or how strong your immune response was. Rarely, medications (like steroids) or other infections might affect results. If you’re unsure about your test timing, discuss it with your provider.