Surveillance of In Vitro Activity of Cefiderocol Against Carbapenem-Resistant Gram-Negative Clinical Isolates in a Tertiary Care Hospital

Of the total 101 isolates, the majority (75, 74.25%) were Enterobacterales which included <i>Klebsiella pneumonia</i> (42, 41.58%) and <i>Escherichia coli</i> (33, 32.67%), followed by <i>Pseudomonas aeruginosa</i> (13, 12.87%) and <i>Acinetobacter baumannii</i> (10, 9.9%). Only three (2.97%) of the isolates were <i>Stenotrophomonas maltophilia</i>. Most of the isolates were susceptible to cefiderocol, with only four (3.96%) isolates showing resistance. Colistin resistance was observed in six (6.12%) of the isolates. There was a good correlation between disc diffusion testing and broth microdilution testing for the detection of cefiderocol-resistant isolates. No cross-resistance with colistin was observed, as all colistin-resistant isolates were uniformly susceptible to cefiderocol Conclusion: Cefiderocol is highly effective with good in vitro activity against the majority of carbapenem-resistant pathogens. While some isolates do show resistance, it is relatively uncommon. Given its safety profile compared to colistin, cefiderocol can serve as an alternative to colistin to treat carbapenem-resistant infections and it may be considered even for the management of colistin-resistant cases. Disc diffusion testing is a reliable method for identifying cefiderocol-resistant isolates in routine clinical and diagnostic laboratories, especially in resource-limited settings.