Human hemoglobin, the oxygen carrying protein in red blood cells, is the most efficient fuel for Staphylococcus aureus infections, according to a study that may help clarify how the bacteria homes in on certain patients with deadly consequences.

Hemoglobin also contains the iron needed for bacteria to develop and spread. Researchers led by Gleb Pishchany from Vanderbilt University Medical School’s microbiology department showed in laboratory testing how Staph aureus latches on more simply to hemoglobin from humans than other mammals to cause invasive infections.