The present invention provides methods for obtaining information regarding nucleic acid from an individual and nucleic acid associated with a disease of the individual, in particular when the disease is associated with a pathogenic microorganism present within the individual. The present invention also provide probe-immobilized substrates, such as probe-immobilized chips, for use in the methods. In particular, the present invention provides methods and probe-immobilized substrates for obtaining information regarding responsiveness to a treatment for a disease of an individual.