Serum/plasma *Substance concentration* for *Escherichia coli* (bacterial) antibodies (immunoassay)

What This Test Measures

This test looks for antibodies in your blood that target *Escherichia coli*, a type of bacteria commonly linked to infections. Antibodies are proteins your immune system makes to fight infections. If you’ve been exposed to E. coli (even without symptoms), your body may have produced these antibodies. This test helps determine whether your immune system has recognized and responded to this bacteria.

Why It’s Done

Your healthcare provider may order this test if you’ve had symptoms of an infection (like fever, pain, or nausea) that could be caused by E. coli, or if you’ve been exposed to contaminated food/water. It can also be part of routine screening in certain high-risk groups (e.g., travelers to areas with poor sanitation).

How It Works

A small blood sample is taken from your arm and sent to a lab. The lab uses an immunoassay method to detect specific antibodies that bind to *Escherichia coli* antigens. If antibodies are present, they’ll react with the test reagents, producing a measurable signal (e.g., color change or light detection).

What the Results Mean

A positive result means your blood contains antibodies against *Escherichia coli*, suggesting past exposure or infection. A negative result means no detectable antibodies were found in this sample. Results alone don’t confirm current infection—other tests (like urine cultures) may be needed for diagnosis.