Evaluation of Fosfomycin Susceptibility Testing Methods in Clinical Isolates in a Tertiary Care Hospital.

Fosfomycin has received attention in recent years as an alternative for management of infection by drug resistance bugs. However, method of Invitro Susceptibility methods for Fosfomycin is cumbersome and not being standardized for all organisms. The present study aims to compare the E strip Test & Disk Diffusion Test(DDT) for Fosfomycin susceptibility taking Agar dilution Test as the reference method. Statistical analysis was performed using 95% Condence Interval. ROC curve & Bland Altman analysis wasperformed too A total of 102 isolates obtained from urine & miscellaneous samples were tested by the three methods using standard guidelines .Most common organism was Eschrichia coli and overall MIC90 was 512µg/ml and MIC50 was 216µg/ml. In urinary isolates, Categorial Agreement for DDT was 43.9 % & 70.2 % for E strip. Essential Agreement for E strip was 28.4%. In non-urinary isolates,Categorial agreement for DDT was 52.8% & 75% for E strip,while Essential Agreement for E strip was 22.2%. Sensitivity & specicity were higher for E strip . Overall,E strip had lower error rates than DDT. In non-urinary isolates,there were no Major error & minor error for both the test methods. E strip had good correlation with Agar Dilution Test while DDT showed poor agreement