Comparing Quantitative and Qualitative Methods for Detecting the In Vitro Activity of Colistin against Different Gram-Negative Bacilli

The surge in the prevalence of Multidrug-Resistant (MDR) Gram-negative bacterial infections with limited treatment led to colistin reusing treat MDR infections. This study aimed determine economical, simple, and reliable susceptibility testing methods as an alternative microdilution technique. We compared seven methods, including quantitative qualitative, namely: Disk diffusion, E-test, ComASPTM SensiTest Colistin, Colistin broth disk elution, agar test CHROMagarTM COL-APSE, BD Phoenix ID/AST automated identification system gold standard Broth Microdilution (BMD). Whole-genome sequencing was performed on all isolates if genetic resistant factors affect phenotypic profile resistance. Our results revealed that diffusion is still ineffective method for measuring Bacilli highest major error (31.75%), lowest Kappa 0 (0%), categorical agreement (68.25%) values. Phoenix, CompASPTM have remained superior reproducibility, sturdiness, simplicity use, similar currently recommended procedure; high sensitivity 95.56%, 97.73%, specificity 95.24, 100%, values 0.89 0.95, respectively. are routine microbiology laboratories a large workload.