Real-time sequencing to decipher the molecular mechanism of resistance of a clinical pan-drug-resistant Acinetobacter baumannii isolate from Marseille, France.

We compare the whole-genome sequences of two multidrug-resistant clinical Acinetobacter baumannii isolates recovered in the same patient before (ABIsac_ColiS susceptible to colistin and rifampin only) and after (ABIsac_ColiR resistant to colistin and rifampin) treatment with colistin and rifampin. We decipher all the molecular mechanisms of antibiotic resistance, and we found mutations in the rpoB gene and in the PmrAB two-component system explaining resistance to rifampin and colistin in ABIsac_ColiR, respectively.