@ann0616 Hi. If you go to the main group page 'Mac and Bronchiectasis' you will see a blue highlighted box labled 'Discussions'. Click on that and you can schroll down continuously to find various topics. I will go there now and copy a few that you may find helpful.

@ann0616 Here is more: Possible Causes of MAC/NTM re-Infection

One cause is that we do not fully get ‘cured’ of these infections; but rather they get beat down to a manageable level by antibiotics. When we get run down or sick, that gives it the opportunity to rear it’s ugly head again and grow colonies that make us very sick.

The second known cause is that we most likely caught this somewhere in our daily routine, whether it be in the home, job, outdoors, or at the gym. Most likely, we caught this in our own homes.

Most of the mycobacteriums that typically infect those with bronchiecstasis and cystic fibrosis form a bio-film. Bio-film is the sticky stuff the bacteria surrounds itself with to shield it from our immune system, antibiotics, and other mycobacteriums. It also uses it to attach itself to plumbing pipes and tubes, sides of swimming pools and hot tubs, inside of water filters, inside of water tanks of your refrigerator (ice-maker & water in the door), tanks inside medical equipment for surgeries, and dental rinsing tools.

Some people get re-infected by environmental means as well. For example a person who works in a nursery/garden center may catch it from the potting soils and misting water. Because they work around that day after day; they build up a bacterial load where the body can no longer defend against it. This is only one example of many on how it can be contracted again from outside sources.