and comparison of eravacycline- and tigecycline-based combination therapies for tigecycline-resistant .

Several antimicrobial combination therapies are used to treat multiple drug resistant (MDR) and extensively drug resistant (XDR) infections. A novel antibiotic, eravacycline, shows a higher potency than tigecycline. The efficacies of eravacycline-based therapies have not yet been evaluated. We demonstrated the effectiveness of eravacycline- and tigecycline-based combination therapies in XDR and especially tigecycline resistant . Thirteen eligible isolates were selected from 642 non-duplicate blood isolates from four medical centres in 2010-2014. Tigecycline/imipenem and eravacycline/imipenem combinations were simultaneously effective against some isolates with fractional inhibitory concentration index of 0.5. In contrast, eravacycline- and tigecycline-based combination therapies provided no additional benefits in mouse survival compared to those for monotherapy. In summary, colistin is still the final resort for XDR- treatment according to the sensitivities. Owning to rapid development of resistance in novel antibiotics are urgently needed.