LEILA AZIMI¹, ABDOLAZIZ RASTEGAE LARI¹, PARVIS OWLIA², MOHAMMAD-R POURSHAFIE ³, FATEMEH FALLAH<sup>1

1</sup>1. Pediatric Infectious Research Center, Mofid Children Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran, ²2. Molecular Microbiology Research Center, Shahed University, Tehran, Iran, ³3. Department of Bacteriology, Pasteur Institute of Iran, Tehran, Iran

Carbapenemases production can cause multi antibiotics resistance in Gram-negative bacteria. A simple phenotypic rapid and accurate test for detection of Gram-negative bacteria - carbapenemase-producer can be useful for treatment of infection that cause with them. The aim of this study was to detected carbapenemases and some specific type of that phenotypic and genotypic. In this study, 150 imipenem resistant Gram-negative bacteria were surveyed. Modified Hodge test, boronic acid, ethylenediaminetetraacetic acid and dipicolinic acid were used for detection of carbapenemase, KPC and Metallo-Beta-Lactamases as phenotypic methods, respectively. PCR was performed for detection of carbapenemases genes. Our results indicated that 52.7%, 31.6% and 69.5% Modified Hodge Test, boronic acid and dipicolinic acid positive tests respectively. Non synergism affect was observed between imipnem and ethylenediaminetetraacetic acid. Sixty-nine of strains was confirmed as carbapenemases-producer according to results of molecular tests. Comparison between results of phenotypic and genotypic methods, we can purpose that phenotypic methods just can use for primary screening of carbapenemases and PCR based methods remains as a gold standard for detection of them.

Table. Sensitivity and specificity of MHT for detection of carbapenemases
NPV PPV Specificity Sensitivity
51% 69% 60% 61% MHT for carbapenemases