I do not beleive that a breathalyzer will detect acetaldehyde. There are two other tests for candida which I think may have some scientific merit. A blood sample is taken from the patient. The patient is then given a measured amount of glucose to drink. After a period of time another blood sample is taken from the patient. The two samples are analyzed for alcohol content. If the patient has candidasis, the second blood sample should contain alcohol. The candida eats the glucose, swiftly converts it into alcohol, then the alcohol is rapidly absorbed into the patient's bloodstream. The second test is known as the "hydrogen breath test".