Evaluation of sensitivity and specificity of Hodge Test in diagnosis of carbapenem resistance in Klebsiella pneumoniae isolates

Abstract

Introduction: Carbapenem is the last defensive line against gram negative bacterial infections that are resistant to extended spectrum antibiotics. Hence, using a proper method for determining the production of carbapenemase enzyme which controls the infection factors resistant to carbapenem antibiotic seemed to be essential. The aim of this study was qualitative analysis of Hodge test for finding a suitable method in determining carbapenemase.Materials and methods: Thirty six samples of Klebsiella pneumoniae with multiple antibiotic resistances capable of producing carbapenemase enzyme were collected from medical centers and laboratories, and approved through CHROMagar method. All the samples were analyzed with regards to the form of sensitive zone as clover shape in Hodge test, according to CLSI instruction.Results: All collected samples were identified for carbapenemase producing with CHROMagar KPC method. Thirty samples were reported positive with Hodge test, respectively. The sensitivity of Hodge test was calculated to be 83.3%. Also, all the negative control isolations were accompanied by negative result and its sensitivity was reported to be 100%. On the other hand, it was observed that all the positive cases were resistant to antibiotics including Ampicillin, Amikacin, Gentamicin, Tetracycline, Ceftazidime, Ciprofloxacin and Imipenem.Discussion and conclusion: According to the obtained results from Hodge test on the collected samples, using this method was determined to be appropriate in primary diagnosis and under the conditions where preparation of specific culture media or using molecular methods was not possible.

Keywords

• Klebsiella pneumoniae
• Extended spectrum β-lactamase
• Carbapenemase
• Modified Hodge test