[Microbiology] Hygromycin marker for Non tuberculous mycobacteria

[Mvenge, Nyasha]

I am writting to ask about what concentrations you have found to be
effective when selecting for transformants of Non tuberculous
mycobacteria such as M.avium,abscessus and chelonae.
 
Currently we have been using 50 and 100 ucl/ml but we keep getting
colonies growing effectively rendering selection a complete waste of
time.Apparently selection should work at 50ucl/ml.Do you have any
suggestions for any other antibiotic apart from kanamycin?
 
Thank you 
 
Grace.