Comparison of disk diffusion agar method and E-test for determination of sensitivity and resistance of Klebsiella and Acinetobacter strains to Cefepime in patients with ventilator-associated pneumonia in intensive care unit

Abstract

Background: Ventilator-associated pneumonia (VAP) is one of the common causes of death in intensive care unit (ICU), and microorganisms such as Acinetobacter and Klebsiella are the main contributing factors. The aim of this study was to compare disk diffusion agar method with E-test for determination of sensitivity of Klebsiella and Acinetobacter strains isolated from pulmonary sputum of patients with VAP in ICU to Cefepime antibiotic. Methods: In this descriptive cross-sectional study, 100 patients with VAP, that had 55 cases for Acinetobacter and 45 cases for Klebsiella as the causing microorganisms according to antibiogram, were included in the study. Sensitivity and resistance of the species to Cefepime antibiotic were assessed using two methods: disk diffusion agar and E-test. Results: Sensitivity and specificity of disk diffusion test were respectively calculated 100 and 25%, and on the other side, positive predictive value was 87.5% and negative predictive value was 100%. According to kappa test, kappa coefficient was 0.35 (P<0.0001) which demonstrated the agreement between two tests. Conclusion: Comparing to E-test, disk diffusion agar method had high sensitivity and low specificity for determination of resistance and sensitivity of Acinetobacter and Klebsiella microorganisms to Cefepime in patients with VAP in ICU.