Emergence of Resistance to Novel Cephalosporin–β-Lactamase Inhibitor Combinations through the Modification of the Pseudomonas aeruginosa MexCD-OprJ Efflux Pump
María A. Gomis-Font, Cristina Pitart, Ester del Barrio-Tofiño, Yuliya Zboromyrska, Sara Cortés-Lara, Xavier Mulet, Francesc Marco, Jordi Vilà, Carla López-Causapé, Antonio Oliver
Abstract
A ceftolozane-tazobactam- and ceftazime-avibactam-resistant Pseudomonas aeruginosa isolate was recovered after treatment (including azithromycin, meropenem, and ceftolozane-tazobactam) from a patient that had developed ventilator-associated pneumonia after COVID-19 infection. Whole-genome sequencing revealed that the strain, belonging to ST274, had acquired a nonsense mutation leading to truncated carbapenem porin OprD (W277X), a 7-bp deletion (nt213Δ7) in NfxB (negative regulator of the efflux pump MexCD-OprJ), and two missense mutations (Q178R and S133G) located within the first large periplasmic loop of MexD.