In vitro and in vivo activity of ceftazidime/avibactam and aztreonam alone or in combination against mcr-9, serine- and metallo-β-lactamases-co-producing carbapenem-resistant Enterobacter cloacae complex.

Purpose: Enterobacteriaceae carrying mcr-9, in particularly those also co-containing metallo-β-lactamase (MBL) and TEM type β-lactamase, present potential transmission risks and lack adequate clinical response methods, thereby posing a major threat to global public health. The aim of this study was to assess the antimicrobial efficacy of a combined ceftazidime/avibactam (CZA) and aztreonam (ATM) regimen against carbapenem-resistant Enterobacter cloacae complex (CRECC) co-producing mcr-9, MBL and TEM.

Methods: The in vitro antibacterial activity of CZA plus ATM was evaluated using a time-kill curve assay.

Activities of aztreonam in combination with several novel β-lactam-β-lactamase inhibitor combinations against carbapenem-resistant strains coproducing KPC and NDM.

Isolates coproducing serine/metallo-carbapenems are a serious emerging public health threat, given their rapid dissemination and the limited number of treatment options. The purposes of this study were to evaluate the antibacterial activity of novel β-lactam-β-lactamase inhibitor combinations (BLBLIs) against carbapenem-resistant (CRKP) coproducing metallo-β-lactamase and serine-β-lactamase, and to explore their effects in combination with aztreonam, meropenem, or polymyxin in order to identify the best therapeutic options. Four CRKP isolates coproducing carbapenemase (KPC) and New Delhi metallo-β-lactamase (NDM) were selected, and a microdilution broth method was used to determine their susceptibility to antibiotics.

Molecular characterization of NDM-1-producing carbapenem-resistant complex from a tertiary hospital in Chongqing, China.

Background: The aim of this study was to clarify the molecular characterization of NDM-1-producing carbapenem-resistant complex (CREL) at a teaching hospital in Chongqing, China.

Methods: Antimicrobial susceptibility and resistance genes were analyzed. Epidemiological relationship was analyzed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

Increased Expression and Amplification of Contributes to Resistance to Ceftazidime/Avibactam in a Sequence Type 11 Carbapenem-Resistant Klebsiella pneumoniae Strain.

Ceftazidime/avibactam (CAZ/AVI) is regarded as an effective alternative antibiotic for the clinical treatment of Klebsiella pneumoniae carbapenemase (KPC)-producing isolates. As resistance has been reported in some strains, it is critical to understand the key mechanisms contributing to the acquired resistance to CAZ/AVI. From January 2018 to April 2020, 127 KPC-producing carbapenem-resistant Klebsiella pneumoniae strains (CRKPs) were isolated at a university hospital in Chongqing, China, and 25 strains showed reduced susceptibility to CAZ/AVI.