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Discussions
False negative?
Has anyone had a negative culture for MAC in between 2 positive cultures. Makes me wonder if there are false negatives.
Replies
Yes, there are false negatives and false positives and contamination in testing situations, but read on.
Yes, I have had negatives mixed in with positives for pulmonary MAC. Your lung has five lobes and most of us have scaring, nodules, mucous plugs, and inflamed bronchial tubes so our lungs are weakened. Maybe MAC is not growing in all of your lung's lobes or it is growing behind some of the mucous plugs. Maybe you just could not cough up a good sample (remember those weak lungs). I have had positive and negative results from samples taken 3 days in a row, as well as a month apart. This is partly why the standard is you must go 12 months without having a positive sputum sample.
Comments
KC,
We are here to assist one another to get the information we need.
Here are some of the things I do to help me cough up sputum.
I first use nebulized saline (a pulmonologist can prescribe this - I use 7% saline). You would need to get a nebulizer machine as well as the prescribed saline. I actually use the saline DAILY as it does help keep things looser in my lungs. At the same time I use the RespirTech InCourage therapy vest which performs percussion on my lungs (expensive and insurance may not approve). I also use this vest daily (I use a flutter valve when traveling). On days that I need a sputum sample (which should be at least monthly), after I have done the nebulized saline while using the vest, I get on our inclined bed (head on lowest end and I am on my stomach). In this position I get my husband to do percussion on my back and sides for a few minutes to again help loosen up the mucous. We have also found that using an electric vibrating body massager on my back irritates and loosens mucous my lungs. Then I work hard for 20 to 30 minutes while standing to cough up mucous for my sample. I try to forceably make the hard "K" sound. Yes, it is hard and is hard work. It is no fun, but I want to try to get the best sputum sample I can. Even without the nebulized saline and therapy clearance vest, you can do the other steps. I am usually hoarser than usual for the rest of the day AND my lungs usually feel a little clearer for the rest of my sputum sample days.
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