Acquisition of extended-spectrum ss-lactamase GES-6 leading to resistance to ceftolozane-tazobactam combination in Pseudomonas aeruginosa [Mechanisms of Resistance]

A clinical Pseudomonas aeruginosa isolate resistant to all β-lactams including ceftolozane-tazobactam and carbapenems was recovered. It belonged to the Sequence Type ST235 and produced the extended-spectrum β-lactamase (ESBL) GES-6 differing from GES-1 by two amino-acid substitutions (E104K and G170S). GES-6 possessed an increased hydrolytic activity toward carbapenems and to ceftolozane, and a decreased susceptibility to β-lactamase inhibitors as compared to GES-1, except for avibactam. We showed here that resistance to ceftolozane-tazobactam may occur through acquisition of a specific ESBL in P. aeruginosa, but that ceftazidime-avibactam combination remained an effective alternative.

https://ift.tt/2P3kQA4