A comparative study of VITEK-2, Double Disc Synergy and Combined Disc Methods for detection of ESBL (Extended Spectrum Beta-Lactamase) production in Escherichia coli and Klebsiella pneumoniae strains

Abstract

Aim: In this prospective study we aimed to compare the effectiveness of VITEK-2 (bioMérieux, France) automated system, double-disc synergy (DDST) versus combined disc test (CDT) in detecting the Extended-Spectrum Beta-Lactamase (ESBL) positivity in Escherichia coli and Klebsiella pneumoniae strains isolated from various clinical samples. Material and Method: E.coli and K. pneumoniae strains inoculated on Mueller Hinton Agar plate. Susceptibility tests were performed with the VITEK 2 (BioMérieux, France) system before. Afterward, EBSL positivity was investigated manually DDST and CDT. Minimal inhibitor concentration (MIC) results of three tests were compared with each other according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. Results: 184 E. coli and K.pneumoniae strains, elevated. 92.9% of 98 patients with VITEK 2 positive results were positive with combined disc and DDS method, 100% of the 86 patients with negative results of VITEK 2 were negative with combined disc and MDC. Conclusion: VITEK 2 was found to have a sensitivity of 100%, a specificity of 92.4%, a positive predictive value of 92.8% and a negative predictive value of 100%. VITEK 2 was found to be compatible with validation tests for ESBL positivity.

Keywords

• escherichia coli
• klebsiella pneumoniae
• vitek-2
• double disk synergy (dds) test
• extended-spectrum beta-lactamase
• combined disc test