Question

You run an ELISA for the presence of Bacillus anthracis, the causative agent of anthrax, in a patient's blood sample. Other than the different molecule of interest, this ELISA works exactly like the one you saw in the video. You run the sample, a negative control, and a positive control, all in duplicate. How would you interpret the following results? Result Laboratory Notebook: ELISA - E. coli Observation at 15 Well Contents min Patient's blood Patient's blood Negative control Negative control Positive control Positive control Empty well Empty well

Answer 1

Answer: You cannot interpret the patient data, because the negative control didn't work.

Development of color indicates positive ELISA test, which means presence of anthrax. Positive controls (wells 5 and 6) have developed positive color, but the negative control (wells 3 and 4) has also developed the blue color. The negative control should not have developed any color, that is why it's called 'negative' control; it should have remained colorless. In this case it cannot be understood if the patient is positive for this test or negative.