İn vitro effectiveness of new antibiotics against carbapenem-resistant enteric bacteria

INTRODUCTION AND PURPOSE: New and effective antibiotics are needed for the treatment of carbapenem-resistant Enterobacterales. In this study, the in vitro activity of cefiderocol, a new siderophore cephalosporin, against Klebsiella pneumoniae (K.pneumoniae) and Escherichia coli (E.coli) strains was investigated. MATERIALS AND METHODS: Previously isolated from clinical samples, carbapenemases OXA-48, NMD, KPC, VIM, IMP, extended spectrum beta lactamase (ESBL) CTX-M-1, CTX-M2, CTX-M9, CTX-M8/25, TEM, SHV, OXA-1-like, PER, VEB, GES enzymes from and AmpCs FOX, MOX, DHA, CIT, EBC, DHA 50 E. coli and 50 K. pneumoniae isolates whose presence was determined by multiplex and monoplex PCR-based methods and flow-mediated resistance was determined by the carbonyl cyanide m-chlorophenyl hydrazone (CCCP) method and carbapenem resistance genes (VIM, NDM, OXA-48). , KPC, IMP) were examined with Gene-Xpert and a total of 121 strains were included in the study, including 21 K. pneumoniae strains. Cefiderocol antimicrobial susceptibility test was performed according to EUCAST recommendations. Iron-free cation-adjusted Mueller Hinton Broth medium, in which the antimicrobial susceptibility test was performed, was prepared by incubating with chelating resin in a magnetic stirrer for 6 hours in accordance with CLSI recommendations. RESULTS: Carbapenemase genes are present in all isolates. Resistance to cefiderocol was determined in 51 of the 121 isolates included in the study (42.14%), and 25 (50%) of the carbapenem resistance (KD) E. coli isolates and 26 (36.61%) of the KD K. pneumoniae isolates were found to be resistant to cefiderocol. Cefiderocol resistance was found to be higher in E. coli isolates than in K. pneumoniae isolates. CONCLUSION: Cefiderocol is effective against K. pneumoniae and E. coli with a total effectiveness of 57% (121/70) for all strains. However, when evaluated according to the CLSI guideline, this rate increases to 74%. The strains found in our study also carry many β-lactamase genes. Therefore, CR ıt has been commented that cefiderocol may be an important antimicrobial treatment in cases of serious infection caused by strains. Key Words: Cefiderocol, K. pneumoniae, E. coli, Antibiotic resistance, Siderophore