In Vitro Activity of Cefiderocol against Clinical Gram-Negative Isolates Originating from Germany in 2016/17

Antimicrobial resistance poses a global threat to public health. Of great concern are Acinetobacter baumannii , Pseudomonas aeruginosa and Enterobacterales with resistance to carbapenems or third-generation cephalosporins. The aim of the present study was to investigate the in vitro activity of the novel siderophore cephaloporin cefiderocol (CID) and four comparator β-lactam-β-lactamase-inhibitor combinations and to give insights into the genetic background of CID-resistant isolates. In total, 301 clinical Enterobacterales and non-fermenting bacterial isolates were selected for this study, including randomly chosen isolates (set I, n = 195) and challenge isolates (set II, n = 106; enriched with ESBL and carbapenemase producers, as well as colistin-resistant isolates). Isolates displayed CID MIC 50/90 values of 0.12/0.5 mg/L (set I) and 0.5/1 mg/L (set II). Overall, the CID activity was superior to the comparators against A. baumannii , Stenotrophomonas maltophilia and set II isolates of P. aeruginosa . There were eight CID-resistant isolates detected (MIC > 2 mg/L): A. baumannii (n = 1), E. cloacae complex (n = 5) and P. aeruginosa (n = 2). Sequencing analyses of these isolates detected the acquired β-lactamase ( bla ) genes bla NDM-1,   bla SHV-12 and naturally occurring bla OXA-396 , bla ACT- type and bla CMH-3 . In conclusion, CID revealed potent activity against clinically relevant organisms of multidrug-resistant Enterobacterales and non-fermenters.