Pseudomonas is another bug which invades compromised lungs and can cause pneumonia. May occur alone or in combination with MAC/MAI. It is (generally) easier to treat than MAC/MAI, the course of treatment is usually much shorter, and it (generally) responds to levaquin, doxycycline, and/or inhaled trobamycin. It can also reoccur, and like Terri says, is also often found in yard and garden. Just another one of those things to be aware of if you have bronchiectasis. I wear long sleeves, gloves and an N-95 mask when working in the yard to minimize exposure to both bugs. I can't leave it to my husband, because he also has bronchiectasis, has had pseudomonas (but not MAC) and has really bad allergies. Another commonly-cited source for both bugs is wood mulch (which can also harbor mold spores) so I leave the handling of that to a hired teenager, who also does some of the heavy work in our yard and a lot of the trimming and hauling of brush.