Emergence of meropenem/vaborbactam resistance in KPC-producing Klebsiella pneumoniae causing bloodstream infections in northern Italy, 2018

Abstract We aimed to investigate the incidence of meropenem/vaborbactam-resistance among KPC-producing Klebsiella pneumoniae (KPC-Kp) bloodstream infection in a large Italian hospital. Meropenem/vaborbactam-resistance was found in 8% (n = 5) KPC-Kp, while 5% (n = 3) strains exhibited cross-resistance to ceftazidime/avibactam. Genomic analysis revealed that meropenem/vaborbactam-resistance was associated to non-functional OmpK35 and OmpK36 porins and no specific mutation was associated to cross-resistance. No specific antimicrobial treatment was related to favorable clinical outcome, while cross-resistance was not associated to higher clinical and/or microbiological failures. Our study indicated that resistance to meropenem/vaborbactam was due to porins deficiency and is associated to reduced susceptibility both to ceftazidime/avibactam and carbapenems.