Determination of MIC distribution of colistin, fosfomycin, and tigecyclin antibiotics against carbapenem resistant enterobacteriaceae

Introduction: There are limited treatments options for carbapenem resistant Enterobacteriaceae (CRE) species and especially colistin, fosfomycin and tigecyclin are used for treatment. Therefore, in this study, we aimed for determining the rates of antibiotic susceptibility against colisting, fosfomycin and tigecyclin in CRE isolates with microdilution method. Material method: In our study, a total of 63 isolates, which were isolated from blood, urine and tracheal aspirate samples. Bacteria identification of the isolates was made with MALDI-TOF MS (Bruker Biotyper; Germany) device. Imipenem, meropenem and ertapenem susceptibilities were determined with the gradient strip test (Liofilchem, Italy) method and genotypic properties were determined with the PCR method. Colistin (0.06-32 μg/ml), fosfomycin (0.06-32 μg/ml) and tigecyclin (0.25-256 μg/ml) MİK values were determined with the microdilution method. Results: Of the isolates included in the study, 60 isolates (95.24%) were defined as Klebsiella pneumoniae, 2 (3.17%) as Escherichia coli and 1 (1.59%) as Enterobacter cloacae. 57 isolates (90.48%) had OXA-48, 4 (6.35%) had NDM and 2 (3.17%) had OXA-48 and NDM resistant genotypes. MİK50 values for colistin, fosfomycin and tigecyclin were 0.50, 4 and 0.25 MİK90 values were 1, 16 and 1, respectively. Two isolates (3.17%) had resistance to colistin, 23 (63.51%) to fosfomycin and 18 (28.57%)