Clash of the microbes: let's bring back the good guys.

A 38-year-old man with a history of HIV infection virologically suppressed on antiretroviral therapy presents to his gastroenterologist for evaluation of iron deficiency anemia and weight loss. A diagnostic colonoscopy demonstrates a two-centimeter ulcerated mass in the cecum. Biopsies of the lesion return moderately differentiated adenocarcinoma that is wild type for the KRAS mutation by real-time PCR.