The present invention provides, inter alia, methods for treating or ameliorating an effect of a solid tumor present in a human. These methods include administering intratumorally to the human a unit dose of C. novyi, preferably C. novyi NT, colony forming units (CFUs), which contains about 1 x 10 3 -1 x 10 7 CFUs suspended in a pharmaceutically acceptable carrier or solution. Methods for debulking a solid tumor present in a human, methods for ablating a solid tumor present in a human, a method for microscopically precise excision of tumor cells in a human, methods for treating or ameliorating an effect of a solid tumor that has metastasized to one or more sites in a human, unit doses of C. novyi, preferably C. novyi NT, CFUs, and kits for treating or ameliorating an effect of a solid tumor present in a human are also provided.