- ORIGINAL ARTICLE - Characterization of Plasmid-Mediated AmpC and Carbapenemases among Iranain Nosocomial Isolates of Klebsiella pneumoniae Using Phenotyping and Genotyping Methods Alireza Japoni-Nejad a, *, Ehsanollah Ghaznavi-Rad b , Alex van Belkum c,d a Department of Mycobacteriology, Pasteur Institute of Iran, Tehran, Iran. b Department of Medical Microbiology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran. c Erasmus MC, Department of Medical Microbiology and Infectious Diseases, Rotterdam, The Netherlands. d bioMe´rieux, La Balme-les-Grottes, Ise`re, France. Received: August 6, 2014 Revised: September 17, 2014 Accepted: September 23, 2014 KEYWORDS: AmpC b-lactamase genes, carbapenemase, Iran, Klebsiella pneumoniae, phenotypic tests Abstract Objectives: Plasmid-mediated AmpC b-lactamases (PMABLs) and carbapene- mases are emerging groups of antimicrobial-resistance determinants. The aims of the study were to evaluate the occurrence of PMABLs and carbapenemases in clinical isolates of Klebsiella pneumoniae and compare the test performance of various phenotypic methods for detection of these enzymes in Iran. Methods: A total of 100 K. pneumoniae isolates were collected from clinical specimens obtained in Valiasr Hospital. AmpC production in all isolates was determined using the AmpC disk test, the cephamycin Hodge test, the AmpC Etest, and the boronic acid combined-disk test. In addition, carbapenemase production was determined using the modified Hodge test, the EDTA disk synergy test, and the boronic acid combined-disk test. The performances of various phenotypic methods were evaluated by the comparison of their results with polymerase chain reaction (PCR) method as the gold standard. Results: Of the 100 isolates, 19 (19%) were demonstrated to harbor the PMABL- resistance gene by the multiplex PCR method. The PCR result indicated the presence of carbapenemase genes in 12 isolates. The performance of various phenotypic tests carried out for detection of carbapenemase-producing isolates varied widely, ranging in sensitivity from 30% to 100% and in specificity from 90.8% to 100%. Conclusion: This is the first report of MOX-type AmpC b-lactamase and bla GES in K. pneumoniae in Iran. A comparison of the phenotypic methods showed that a combination of cefoxitin plus boronic acid is optimal for detecting plasmid- *Corresponding author. E-mail: alizh63@yahoo.com This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Osong Public Health Res Perspect 2014 5(6), 333e338 http://dx.doi.org/10.1016/j.phrp.2014.09.003 pISSN 2210-9099 eISSN 2233-6052 Copyright ª 2014 Korea Centers for Disease Control and Prevention. Published by Elsevier Korea LLC. All rights reserved.