Analysis of Susceptibility Patterns and MIC Distributions of Five Gram-negative Bacterial Species Against Aminoglycosides in Intensive Care Units at 108 Military Central Hospital

Abstract

Objectives: To investigate five common Gram-negative bacteria in the ICU and to analyze the antibiotic susceptibility and MIC distribution of the aminoglycoside group for the isolated strains. Materials and Methods: A cross-sectional descriptive study was conducted. Microbiological data were extracted from the laboratory management software between June 1, 2025, and December 31, 2025. We screened for the five most common Gram-negative bacteria: A. baumannii, K. pneumoniae, E. coli, P. aeruginosa, and K. aerogenes, then collected and analyzed the data. Results: Analysis of 443 microbiological samples showed that A. baumannii and K. pneumoniae were the two most common Gram-negative strains. E. coli remained highly sensitive to aminoglycosides, specifically 91.7% to amikacin and 60-70% to gentamicin and tobramycin. Similarly, K. pneumoniae was sensitive to gentamicin (71.2%), amikacin (54.8%), and tobramycin (36.3%). In contrast, a critical resistance situation was observed in A. baumannii and K. aerogenes, with sensitivity rates dropping to approximately 10%. MIC distribution data showed that amikacin maintains good efficacy against E. coli (90%) and K. pneumoniae (55%) at MIC ≤4 mg/L, ensuring that therapeutic targets can be reached with the standard dose of 15 mg/kg. Conclusion: Aminoglycosides maintain high efficacy against E. coli and K. pneumoniae, yet face significant challenges due to high resistance rates in P. aeruginosa and A. baumannii. MIC distribution data serves as a critical foundation for empirical antibiotic selection and TDM protocols to optimize dosing for critically ill patients.