Extensively drug-resistant and pan-drug resistant Gram-negative bacteria in a tertiary-care hospital in Eastern India: a 4 year retrospective study.

•High burden of extensively drug-resistant (XDR) (41.3%) and pandrug-resistant (PDR) (8.1%) bacteria in a single centre.•Colistin and tigecycline resistance rates were 16% and 51.9%, respectively.•Elderly patients admitted to hospital are at high risk from these resistant bacteria.•First report of XDR and PDR rare pathogens belonging to different genera isolated from a single centre.