Efficacy of Cefiderocol Against Endophthalmitis Isolates

<b>Background/Objectives:</b> Endophthalmitis is an intraocular microbial infection that can lead to permanent blindness, even with prompt anti-microbial therapy. Multi-drug-resistant organisms are on the rise, potentially limiting the efficacy of current empiric antibiotic therapies of intravitreal ceftazidime and vancomycin. Cefiderocol is a recent FDA- and EMA-approved antibiotic for multi-drug-resistant Gram-negative bacteria. <b>Methods:</b> To better understand its potential utility in the treatment of ocular infections, the MIC of cefiderocol was compared to ceftazidime and amikacin in endophthalmitis bacterial isolates using Epsilometer testing. Because vancomycin is commonly given concomitantly as part of empiric endophthalmitis treatment, possible synergistic and antagonistic effects of concomitant vancomycin and cefiderocol were also evaluated. <b>Results:</b> Cefiderocol was found to have lower MIC values compared to ceftazidime for <i>Pseudomonadales</i> or <i>Enterobacterales</i> species. When comparing the MICs of cefiderocol and vancomycin, there appeared to be no antagonism between the two antibiotics. <b>Conclusions:</b> This is the first report exploring the use of cefiderocol in endophthalmitis strains. The results of this study show this is a promising antibiotic for multi-drug-resistant Gram-negative organisms but further research is needed to investigate its intraocular safety profile.