Original Research Article
Year: 2017 | Month: April | Volume: 7 | Issue: 4 | Pages: 113-118
Evaluation of Two Phenotypic Methods for the Confirmatory Testing of Extended Spectrum Beta Lactamases Producing Strains of Klebsiella Pneumoniae
Mohammed Yahaya1, Galadima Gadzama Bala2, Zailani Sambo Bello3, Manga Mohammed Mohammed4, Ibrahim Baffa Sule5, Kaoje Aminu Umar6, Adamu Habibullah6, Dalhat Muazu Mahmoud7, Ibrahim Mohammed Taofeek Olalekan8
1Lecturer, Department of Medical Microbiology and Parasitology, Faculty of Basic Medical Sciences, College of Health Sciences, Usmanu Danfodiyo University, Sokoto State, Nigeria
Department of Medical Microbiology and Parasitology, College of Medical Sciences, University of Maiduguri, Borno State, Nigeria.
4Senior Lecturer, Department of Medical Microbiology and Immunology, Gombe State University.
5Senior Registrar, Department of Medical Microbiology and Parasitology, Aminu Kano Teaching Hospital, Kano, Nigeria.
6Lecturer, Department of Community Health, Faculty of Clinical Sciences, College of Health Sciences, Usmanu Danfodiyo University, Sokoto State, Nigeria.
7HIV Surveillance Advisors, Nigerian Field Epidemiology and Laboratory Training Program.
8Professor and Vice Chancellor, Al-Hikmah University, Ilorin, Kwara State.
Corresponding Author: Mohammed Yahaya
Background: The resistance to antimicrobials has become a serious global health concern with negative consequences on treatment strategies and increasing health-care costs. The extended spectrum beta lactamases producing bacteria stands outs as bacteria of great concern among Gram negative bacilli. Lack of capacity to effectively diagnose these organisms in developing countries result in sub-optimal treatment. We compared two phenotypic methods for the confirmatory testing of ESBL in Klebsiella pneumoniae to identify an easy and efficient method for their laboratory diagnosis.
Materials and Methods: We screened all patients admitted into various units of University of Maiduguri Teaching Hospital between from the 01/01/2014 to 31/06/2014 to isolate Klebsiella pneumoniae.
All confirmed isolates were screened for ESBL enzyme using CLSI breakpoints. Suspected ESBLs producers were subjected to confirmation using two phenotypic methods. The double disk synergy method (with ceftazidime; 30 µg, cefotaxime;30 µg, and amoxicillin;20 µg, plus clavulanate;10µg,:[augmentin;30 µg].) and Etest method for MIC determination (using cefotaxime and cefotaxime + amoxicillin-clavulanic acid).
Multiplex polymerase chain reaction (PCR) method was considered as a gold standard for confirmation. We compared the two methods with the gold standard to determine their sensitivity, specificity and predictive value positive.
Results: We detected 178 isolates of Klebsiella pneumoniae among of hospitalized patients. The DDST method revealed 59 out of the 178 isolates resistant with a sensitivity of 100%, specificity of 97%, positive predictive value of 93% and negative predictive value of 100%.
Using the Etest MIC, 56 resistant isolates were identified with a sensitivity of 100%, specificity of 99%, positive predictive value of 98% and negative predictive value of 100%.
Only 55resistant organisms were found based on the multiplex Polymerase chain reaction method.
Conclusion: The two methods of DDST and Etest MIC used shows high validity with Etest MIC MIC having a relatively higher specificity. However, in view of cost, the DDST is recommended for use in our clinical laboratories.
Key words: Resistance, Cefotaxime, Cephalosporins, Methods, Klebsiella pneumoniae, Double disk synergy.