mycobacterium, chelonae/abscessus group, in lungs

My mother (65) has been diagnosed w/ mycobacterium, chelonae/abscessus group in both her lungs. The doctors are merely prescribing 1 Antibiotic for 21 days. However from what I've read this won't knock out the infection. A CAT scan also showed she has seriously infected sinuses What would your treatment advice be?

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