Did Lister test his assumption that mold could kill bacteria on human subjects? No, that would have been illegal.

No, he could not find any willing test subjects.

Yes, a nurse with whom he worked had a bacterial infection on her arm; when he applied a salve containing the mold spores, the infection became much worse

Yes, a nurse with whom he worked had a bacterial infection on her arm; when he applied a salve containing the mold spores, the infection resolved.