Stenotrophomonas Maltophilia

I was just diagnosed with Stenotrophomonas Maltophilia today after having had severe congestion, breathing problems, a horrible headache on top and back of head, intense sinus pain, since my trans-sphenoidal surgery in April of 2009. A culture was taken on 9/1/09 and an MRI on 9/3/09 showed a massive infection in the sphenoid sinus area close to the brainstem, but not in the brain yet. I have many allergies to many antibiotics and other medications and have been on one antibiotic or another since my surgery. Right now I am doing the Sinus Rinse with Pulmicort and my doctor has called in a script for Gentimycin to use in my Sinus Rinse.

How is Steno formed? How is it caused? How did I catch it? Is it like a Staph infection? Are there any precautions I can take in the future to not get infected with this nasty infection?

Thank you.