Author/Authors :
Abdeta ، Abera National Clinical Bacteriology and Mycology Reference Laboratory - Ethiopian Public Health Institute , Bitew ، Adane Department of Medical Laboratory Sciences - College of Health Sciences - Addis Ababa University , Fentaw ، Surafel National Clinical Bacteriology and Mycology Reference Laboratory - Ethiopian Public Health Institute , Tsige ، Estifanos National Clinical Bacteriology and Mycology Reference Laboratory - Ethiopian Public Health Institute , Assefa ، Dawit National Clinical Bacteriology and Mycology Reference Laboratory - Ethiopian Public Health Institute , Tigabu ، Eyasu East African Regional Office - Ohio State University , Lejisa ، Tadesse National Clinical Chemistry Reference Laboratory - Ethiopian Public Health Institute , Kefyalew ، Yordanos Department of Applied Biology - School of Applied Natural Science - Adama Science and Technology University , Fekede ، Ebisa National Clinical Bacteriology and Mycology Reference Laboratory - Ethiopian Public Health Institute
Abstract :
Background: Early detection of extended-spectrum β-lactamases (ESBLs) producing bacteria is critical for infection prevention and control. Numerous phenotypic approaches and automated systems have been developed for detecting ESBL bacteria. However, there is a scarcity of data in Ethiopia regarding the most reliable, simple, and cost-effective methods for detecting ESBL-producing bacteria. This study, therefore, aimed to evaluate the diagnostic performance of three phenotypic approaches for detecting ESBL-producing bacteria. Methods: In this study, 117 isolates of Klebsiella pneumoniae, Escherichia coli, Klebsiella oxytoca, and Proteus mirabilis were examined. Cefotaxime (30 μg) and ceftazidime (30 μg) were used for screening ESBL enzymes. A screening breakpoints of ≤ 27 mm and ≤ 22 mm were used for cefotaxime (30 μg) and ceftazidime (30 μg), respectively, as per the Clinical and Laboratory Standards Institute (CLSI) guidelines. All 117 strains were further confirmed by the Vitek 2 compact, double disk synergy, ESBL Epsilometer test, and combined disk method. The combined disk method was adopted as the reference method. Results: Out of 117 isolates, 90 (86%) had zone diameters of ≤ 27 mm and ≤ 22 mm for cefotaxime (30 μg) and ceftazidime (30 μg), respectively. The reference method detected 76 (65%) ESBL isolates out of 117 ones. From among the three techniques (i.e., double disk synergy, Vitek 2 compact, and ESBL Epsilometer test), the double disk synergy method demonstrated overall sensitivity and specificity of 97.4% and 97.6%, respectively. Vitek-2, cefotaxime, and ceftazidime Epsilometer test indicated indeterminate results of 6.8%, 6.8%, and 5.1% respectively. Conclusion: Double disk synergy was found to have the highest sensitivity and specificity for detecting ESBL isolates with no indeterminate results.
Keywords :
Double disk synergy , Combined disk , Gradient strip , Vitek 2 compact
