A positive H. pylori test means that an H. pylori infection may be present. Clinical testing for H. pylori may indicate the presence of a current infection, i.e., the patient is currently infected with H. pylori; it may also indicate a previous H. pylori infection. The carbon 13 or carbon 14 breath test is commonly used in clinical practice, and a positive test for H. pylori reflects that the patient is now infected with H. pylori. If the stool is positive for H. pylori antigen, it suggests that H. pylori infection is present. In the case of a positive blood test for serum antibodies to H. pylori, it is difficult to determine whether it is a current or previous infection. If the patient has not been tested or treated for H. pylori before, a positive blood test for H. pylori antibodies may reflect the presence of H. pylori infection. If the blood is positive for H. pylori, the patient should consult a doctor for a complete examination to determine whether H. pylori infection is present, and follow the doctor’s instructions for treatment.