Ceftazidime/avibactam-resistant meropenem-susceptible KPC-producing Klebsiella pneumoniae: Analysis of cases and evaluation of in vitro activity of fosfomycin-containing combinations

•Clinical characteristics and fosfomycin synergism of KPC-variants were investigated.•KPC-variant detection follows a previous CZA-susceptible KPC-Kp in the same patient.•Treatment with meropenem achieved clinical cure in all the patients.•Fosfomycin plus meropenem resulted in full synergism in 40% of cases.•FOS plus MEM may be an option for KPC-variant infections at low risk of mortality.