Urine culture are reliable std test? mine came back negative but now have a black small blister on labia majora. labia is burning! candida albicans +!

Not always: Urine testing is a good means by which infections and some stds such as chlamydia and gonorrhea can be detected however a lot of other infections and stds are also missed this way. You will need to be seen by a gynecologist for a pelvic exam and more detail testing to detect all infections. Herpes may present with blisters and burning as well.