How Do You Contract Morganella Morgagni? My Father Has Been

How do you contract Morganella Morgagni? My father has been in the hospital for a week. His knee swelled up and he was originally diagnosed with cellulitis, but after a week of IV antibiotics it hasn’t worked out. They had to go in today and clean it out and put in a drain. But now they say it’s Morganella Morgagni. I’m confused