Comparative evaluation of broth and agar dilution techniques for antimicrobial susceptibility testing against multidrug resistant pseudomonas aeruginosa

Valuation of mic is imperative and quite crucial for timely management of multiply drug resistant pathogens,surveillance epidemiology,comparative evaluation of novel drugs and their synergistic combinations. availability of such different methods makes it difficult to compare diverse data and also invoke certain inherent errors attributed to the choice of methodology. however,routine clinical diagnostics warrants a robust and reliable routine method equally good on efficiency and efficacy. in this study agar dilution (ad) methodology,being less time consuming has been compared to more conventional broth microdilution (bmd) method using multiply drug resistant (n=12) and susceptible (n=12) clinical strains of pseudomonas aeruginosa. the essential agreement (ea) in terms of plus minus one doubling dilution (±1 log2 dilution) was 92.3% for ceftazidime and 100% for ciprofloxacin. however,the ea with respect to all antimicrobials was equal to 90%. however,tazocin and meropenem each showed least ea of 84.6%. the correlation of bmd vs ad methodologies with respect to tested antimicrobials was statistically significant for all antimicrobials (p < 0.001). hence,ad has been found to be a more reliable,rapid and economical method for antimicrobial susceptibility testing against multi-drug resistant bacteria. © copyright 2016 zoological society of pakistan.