Susceptibility test - can't get answer from my doctor

Hello, I'm not sure this will help you, but I also have MAC, bronchiectasis and Pseudomonas. When initially diagnosed with Pseudos, the test showed the bacteria (Pseudo) as well as most of the antibiotics used for treatment with the susceptibility of the bacteria to each drug...Susceptible, Intermediate and Resistant. I have not seen that evalution for my MAC but have not wanted to have MAC treated in the past. This was a simple sputum for Culture, Aerobic Bacteria done by Quest Labs. It seems that you have requested beyond what would be a reasonable ask. I wonder if you asked your GP to request your lab results, if that might be the most expeditious route?? Or you might consider telling them you want them to re-run the sputum test with susceptiblity and make sure you are copied into the results before they send it to the lab. It is truly irritating that you have to continually ask for results...And important results!! Sorry that you are stressed over this...it should be simple. Doctors forget who they work for. Good luck,
Kate

I only know that susceptibility testing is not routinely done unless a doctor requests it, usually within a few weeks of the final results for the sputum sample being posted. It can take a while to get the results of susceptibility testing, especially with a slow growing NTM. In a recent case it took nearly six weeks to obtain the results of susceptibility testing. Good luck.

In my case, 6 years ago now, the culture was done at our state health dept lab (still standard procedure here). If it is positive for NTM the doc can request sensitivity testing within 14 days. My first pulmonologist didn't request, just treated.

A year later when I didn't clear, the ID doc had a positive culture sent to NJH for testing, it took 4 more weeks and confirmed I was on the correct antibiotics.

Our clinics might now use Quest labs, I haven't asked - they didn't have a big presence here until recently.

Is susceptibility testing necessary only for certain strains? The big 3 are standard for MAC but for other NTM like m abscessus wouldn't you be in danger of using resistant drugs if you did not test?

According to my ID doc, it is the doctor's call, but if you don't convert within 6 months, sensitivity testing is definitely warranted.

Thanks to everyone for their helpful and kind replies. I did more research, which included listening to one of the sessions from the recent NTMir Patient Conference and it seems, broadly, the susceptibility test provides just these two pieces of information for someone with MAC avium or intracellulare (as opposed to abscessus) :
1. if the MAC is susceptible to two macrolides, azithromycin and clarithromycin
2. if the MAC is susceptible to Amikacin
That's it - I believe. Susceptibility testing for ethambutol, rifampin, and moxifloxacin in MAC is not routinely used to guide therapy due to poor correlation with clinical efficacy. But please don't rely on what I've sussed out.

What I think happened is that although my doctor ordered the susceptibility test (it's in my clinical notes), he forgot to execute, and so now he and the care team won't respond to my messages asking if the test is actually underway and if so , what sputum sample of mine it is being performed on. With my research today, it seems the results of the test aren't super-relevant (I guess that's why the vast majority of us are on the same regimen, i.e. the Big Three) but just to say: I wish I could have gotten a clear answer from my doc on this and didn't have to figure it out with the help of this great community and off my own research. Don't mind being my own advocate etc but I also am hesitant to going too deep into things when I'm not a health professional.

It is very important sputum or bronch sample be tested for susceptibility for those with MAC as well. I know people that have MACs that are macrolide resistant. In these cases, azithromycin and clarithromycin cannot be used. I have M. Abscessus and there is no standard treatment, so quite a few antibiotics were tested for "S". To complicate things, one of the antibiotics tested showed resistant but I later learned at NJH, that particular antibiotic does not stay active in the testing medium, so it will show a false "R". It has a half-life of 1 hour. Another test that is valuable is the bacterial "count". This will tell you if your infection is mild, moderate, or severe. This will help determine (with CT scans) is treatment should be initiated or "watch and wait". or is it "wait and watch":).