Discovery of Cephalosporin-3′-Diazeniumdiolates That Show Dual Antibacterial and Antibiofilm Effects against <i>Pseudomonas aeruginosa</i> Clinical Cystic Fibrosis Isolates and Efficacy in a Murine Respiratory Infection Model

Abstract

The formation of biofilms provides a formidable defense for many bacteria against antibiotics and host immune responses. As a consequence, biofilms are thought to be the root cause of most chronic infections, including those occurring on medical indwelling devices, endocarditis, urinary tract infections, diabetic and burn wounds, and bone and joint infections. In cystic fibrosis (CF), chronic <i>Pseudomonas aeruginosa</i> (<i>P. aeruginosa</i>) respiratory infections are the leading cause of morbidity and mortality in adults. Previous studies have shown that many bacteria can undergo a coordinated dispersal event in the presence of low concentrations of nitric oxide (NO), suggesting that NO could be used to initiate biofilm dispersal in chronic infections, enabling clearance of the more vulnerable planktonic cells. In this study, we describe efforts to create "all-in-one" cephalosporin-based NO donor prodrugs (cephalosporin-3'-diazeniumdiolates, C3Ds) that show both direct β-lactam mediated antibacterial activity and antibiofilm effects. Twelve novel C3Ds were synthesized and screened against a panel of <i>P. aeruginosa</i> CF clinical isolates and other human pathogens. The most active compound, AMINOPIP2 ((<i>Z</i>)-1-(4-(2-aminoethyl)piperidin-1-yl)-2-(((6<i>R</i>,7<i>R</i>)-7-((<i>Z</i>)-2-(2-aminothiazol-4-yl)-2-(((2-carboxypropan-2-yl)oxy)imino)acetamido)-2-carboxy-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl)methoxy)diazene 1-oxide)-ceftazidime <b>12</b>, showed higher antibacterial potency than its parent cephalosporin and front-line antipseudomonal antibiotic ceftazidime, good stability against β-lactamases, activity against ceftazidime-resistant <i>P. aeruginosa in vitro</i> biofilms, and efficacy equivalent to ceftazidime in a murine <i>P. aeruginosa</i> respiratory infection model. The results support further evaluation of AMINOPIP2-ceftazidime <b>12</b> for <i>P. aeruginosa</i> lung infections in CF and a broader study of "all-in-one" C3Ds for other chronic infections.