A study on prevalence of KPC producing from Klebsiella pneumoniae using Modified Hodge Test and CHROMagar in Iran

Carbapenems are the last defense resort against Gram-negative bacterial infections that are resistant to extended spectrum antibiotics. Thus the utilization of an appropriate method in order to determine the production of carbapenemase enzyme in infections caused by these organisms is one of the important responsibilities of Microbiology laboratories. The aim of this study was to compare the phenotypic method including CHROMagar KPC and Hodge Test for detection of KPC isolates in Iranian hospitals. Two hundreds and twenty four multiple antibiotic resistant strains of Klebsiella pneumoniae were collected from hospitals located in Tehran and other major cities of Iran. These strains were tested for production of KPC using by Hodge Test and CHROMagar. The results were analyzed to determine the frequency of carbapenemase enzyme. Interpretation of the Hodge Test was achieved according to CLSI recommendations. Chromagar method was applied based on the direction of the manufacture. Thirty six positive strains were identified by Hodge Test and CHROMagar methods respectively. CHROMagar confirmed all the positive strains which were positive by Hodge test method. The sensitivity of the Hodge Test was calculated to be 83.3% in comparison with CHROMagar method. In addition, it was observed that all the positive KPC strains were resistant to other antibiotics including Ampicillin, Amikacin, Gentemycin, Tetracycline, Ceftazidime, Ciprofloxacin and Imipenem Given the findings from the CHROMagar medium in comparison to Hodge Test, the utilization of chromogenic medium seems safe and appropriate. However, gold standard methods is recommended to identify the resistance genes such as blaKPC, blaIMP, blaNDM coding carbapenemase.