i checked colistin resistivity through broth micro dilution method and tube dilution method. Phenotypically isolates were colistin resistant with mics> 4 ug/ml.. PCR was done but isolates don`t show presence of mcr 1 gene?
Dear Marwa Kidwany
Could you tell us what bacterial species did you find colistin resistant?
Until now, 8 variants of mcr-gene were published. See: https://www.nature.com/articles/s41426-018-0124-z#MOESM1
Beside of them, mutation in chromosome can also cause colistin resistance in Gram-negatives. See: Article Polymyxins: Antibacterial Activity, Susceptibility Testing, ...
Regards,
Marcela
Acording to the latest literature, the mutations and/or insertions/deletions in the mgrB gene are the most common cause of the colistin resistance in K. pneumoniae.
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