Comparison of four phenotypic assays for the detection of ESBL producing gram negative bacilli and Assessment of the magnitude of carbapenemase-producing gramnegative bacilli isolated from specimens referred to Ethiopian Public health Institute.
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Date
2020-07
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Addis Abeba University
Abstract
Background: The detection of extended-spectrum β-lactamase producing (ESBL)Enterobacteriaceae
and carbapenemase-producing gram-negative bacilli are of importance for infection control and
epidemiological purposes. The common mechanism of resistance to extended spectrum cephalosporins
and carbapenem antibiotics is through the production of ESBL and carbapenemase enzymes. Thus, this
study was designed to compare four phenotypic assays to detect ESBLs in clinical isolates of
Enterobacteriaceae and determine the magnitude of carbapenemase-producing gram-negative bacilli.
Objective:To compare four phenotypic assays for the detection of ESBL production and to determine the
magnitude of carbapenemase-producing gram-negative bacilli.
Methods:The study was conducted from June 30, 2019, to May 30, 2020. Modified and simplified
carbapenem inactivation methods were used to screen for carbapenemase. The MICand combination disk
methods were used to confirm Klebsiella pneumonia carbapenemase (KPC)and Metallo β-lactamases
(MBL)respectively. ESBL detectionassays (Vitek2 Compact, ESBL Etests, combination disks, DDS
methods on Mueller-Hinton [MHA]) were compared. Initially, data were entered on WHOnet 2019 and
analyzed using both WHOnet 2019 and SPSS 23 version.
Results:Out of 117 clinical isolates, CAZ/CAL disk, CTX/CTL disk, DDS, Vitek 2 compact, MIC
CAZ/CAL, and MIC CTX/CTL detected, 65% (76/117), 64.1% (75/117),64.1% (75/117), 63.2% (74/117),
60.7% (71/117), and 59.8% (70/117)ESBL producers respectively.Out of 429 clinical isolates, 15.4%
(66/429), 5.4% (23/429), and 23.77% (102/429 isolates were non-susceptible to carbapenems, carbapenem
ase positive, and MDR respectively.0.7% (3/429)and 2.3% (10/429)were positivefor KPC and MBL
respectively. The highest and lowest resistance was observed against Ampicillin (92%) and Amikacin
(11.2%) respectively.
Conclusions: The prevalence of MDR, carbapenem non susceptible and carbapenemase producing gram
negative bacilli was found to be high in this study. In this study, a combination disk method was found to
be superior to other methods for ESBL detection. Metallo β-lactamase was found to be the most prevalent
carbapenemase among clinical isolates. For prevention infection control and regular surveillance must be
enhanced.
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Keywords
Extended-spectrum β-lactamase, Carbapenemase,Modified carbapenem inactivation method,Combination disk method, Ethiopia