Emergence of ceftazidime-avibactam resistance due to a novel blaKPC-2 mutation during treatment of carbapenem-resistant Klebsiella pneumoniae infections

OBJECTIVE: Klebsiella pneumoniae carbapenemase (KPC)-producing K.pneumoniae has represented a serious health problem in worldwide. The resistance to ceftazidime-avibactam (CAZ-AVI) began to emerge since its approval in 2015. We aim to explore the resistance mechanism of CAZ-AVI. METHODS: Phenotypic test and whole-genome sequencing (WGS) analysis were performed in KP-HX0917 and KP-HX1016 Klebsiella pneumoniae isolates, collected from the same patient following treatment with CAZ-AVI. RESULTS: We report a case of emergence of CAZ-AVI resistance in ST 11 KPC-2-producing K. pneumoniae (KP-HX1016) during 14 days of exposure with CZA-AVI. Molecular analysis highlighted the A533C mutation in the blaKPC-2 gene, resulting a D179A substitution in protein sequence, which restored the hydrolysis ability of imipenem and meropenem, but not for ertapenem, and the result of phenotypic test was negative. However, KP-HX0917 produced serine-carbapenemase by phenotypic detection and lost its capacity of hydrolyzing carbapenems. CONCLUSION: The emergence of CAZ-AVI resistance should arouse our attention, the susceptibility testing should be followed by a combination of phenotypic and molecular methods, to make sure that no potential carbapenemase-producing bacteria are missed.