Evaluation of sulbactam-durlobactam disk diffusion and broth microdilution methods for Acinetobacter baumannii

Area of Science:

• Microbiology
• Antimicrobial Susceptibility Testing
• Clinical Diagnostics

Background:

• Acinetobacter baumannii is a significant opportunistic pathogen, frequently exhibiting multidrug resistance.
• Accurate and efficient methods for determining antimicrobial susceptibility are crucial for effective treatment of A. baumannii infections.

Purpose of the Study:

• To evaluate the accuracy of the sulbactam-durlobactam disk diffusion method compared to the broth microdilution reference method for A. baumannii.

Main Methods:

• 504 non-duplicated A. baumannii isolates were tested using broth microdilution and disk diffusion (10/10 µg) according to CLSI M100 Ed34.
• Categorical agreement (CA), minor error (mE), major error (ME), and very major error (VME) were calculated to assess accuracy.

Main Results:

• The disk diffusion method demonstrated high accuracy, with an overall categorical agreement of 99.6% and no major or very major errors.
• Excellent agreement was observed across various resistance phenotypes, including carbapenem-susceptible, carbapenem-resistant, difficult-to-treat resistant, and colistin-resistant A. baumannii.

Conclusions:

• The sulbactam-durlobactam disk diffusion method (10/10 µg) is a reliable and accurate tool for assessing A. baumannii susceptibility.
• Its simplicity, cost-effectiveness, and ease of interpretation make it ideal for routine clinical microbiology laboratories.