Pan-drug resistant Acinetobacter baumannii (A.baumannii) (PDRAB) is resistant to all currentlyavailable antimicrobials (including carbapenems),with the exception of colistin (polymyxin).Recently,PDRAB infection has become a serious medical problem.The mechanisms of A.baumannii drug resistance include low permeability of the outer membrane to antibiotics,an antibiotic effiux pump,and an extended-spectrum β-lactamase,etc.In addition,drug resistance can be easily acquired by incorporating genetic elements such as plasmids,transposons,and integrons.Multidrug-resistant A.baumannii (MDRAB;ie,strains with resistance to ≥3 classes of drugs) strains are being increasingly reported worldwide.Infections due to such resistant microbes are associated with increased morbidity and mortality.Carbapenems,which used to be the antimicrobials of choice,have become increasingly ineffective against such multi-resistant strains and no longer constitute salvage therapy for A.baumannii infections.In the last few years,PDRAB infections have been encountered several times during the treatment of patients with extensive bs.A.baumannii is susceptible to polymyxin B,which is not available in China.Therefore,the nine PDRAB infected patients were successfully treated with high doses of meropenem,cefoperazone-sulbactam and minocycline.