At the Memorial Sloan Kettering (USA), she discovered that there are certain bacteria normally present in the intestinal microbiota capable of keeping at bay the proliferation of enterococci and enterobacteria, two types of intestinal pathogens. "The problem is that these bacteria attack people with poor health, with the immune system depressed due to other infections or treatments to avoid rejection of a transplant, for example," explains the female Peruvian doctor.

In her experiments, Caballero has shown that the administration of a probiotic composed of these beneficial bacteria to people whose natural microbiota is altered helps them cope with the proliferation of enterococci and enterobacteria resistant to antibiotics.