Modified CIM test as a useful tool to detect carbapenemase activity among extensively drug-resistant Klebsiella pneumoniae, Escherichia coli and Acinetobacter baumannii

Abstract

Purpose Timely detection of carbapenemases is essential for developing strategies to control the spread of infections by carbapenem-resistant isolates. The purpose of this study was to determine the epidemiology of carbapenemase genes among carbapenem-resistant isolates of Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli. In addition, the efficacy of the modified Hodge test (MHT), Carba NP test, and modified carbapenem inactivation method (mCIM) were compared. Methods A total of 122 carbapenem-resistant clinical isolates including 77 K. pneumoniae, 39 A. baumannii, and six E. coli were collected from hospitalized patients. Three phenotypic methods, including the MHT, Carba NP test, and mCIM were used for investigation of carbapenemase production. In addition, polymerase chain reaction (PCR) was performed to detect carbapenemase-encoding genes. Result The sensitivity and specificity of the MHT were 75.0% and 100%, respectively. In addition, Carba NP displayed 80.8% sensitivity and 100% specificity, whereas the sensitivity and specificity were 90.4% and 100% for the mCIM test, respectively. Among carbapenem-resistant isolates, 70, 84, and 87 isolates exhibited positive results according to the MHT, Carba NP test, and mCIM, respectively. PCR indicated the presence of one or more carbapenemase genes in 119 of carbapenem-resistant isolates, with blaKPC and blaVIM being the most commonly encountered. Co-production of ‘KPC and OXA-48’, ‘KPC and VIM’, and ‘KPC and IMP’ was detected in three, nine, and seven isolates, respectively. Conclusion Our results confirm that the mCIM test is a useful tool for the reliable detection of carbapenemase activity in enterobacterial isolates, especially in clinical microbiological laboratories with limited resources.

Molecular characterization and epidemiological investigation of colistin resistance in carbapenem-resistant Klebsiella pneumoniae in a tertiary care hospital in Tehran, Iran

“…CRKP stands out as the most frequently implicated microorganism causing nosocomial infections. The global increase in multidrug-resistant K. pneumoniae strains has led to increase the use of colistin to treat these infections, resulting in the emergence of colistin resistance worldwide [ 21 , 22 ]. An important consideration in the management of nosocomial infections caused by K. pneumoniae are periodic surveillance to identify the resistant strains, optimizing available infection control policies, and treatment options in different areas of hospitals [ 23 ].…”

Prevalence and epidemiological investigation of mgrB-dependent colistin resistance in extensively drug resistant Klebsiella pneumoniae in Iran

“…The global increase in multidrug-resistant K. pneumoniae strains has increased the use of colistin to treat these infections, resulting in the emergence of colistin resistance worldwide 26 , 27 . The important concern that must be considered in the management of nosocomial infections caused by K. pneumoniae are periodic surveillance to identify the resistant strains for optimizing available infection control policies and treatment options in different parts of the hospitals 28 .…”

Search for carbapenem-resistant bacteria and carbapenem resistance genes along swine food chains in Central Italy

“…Parallelly, the same aliquot of each homogenate was inoculated in 10 mL of Luria-Bertani (LB) broth supplemented with 0.12 μg/mL ertapenem (Merck KGaA, Darmstadt, Germany) and incubated at 37˚C for 24 h. Tubes showing turbidity were ten-fold serially diluted and 100 μL of the appropriate dilutions were spread on MacConkey agar containing ertapenem (0.12 μg/mL). After incubation at 37˚C for 24 h, presumptive carbapenem-resistant colonies were selected and analysed for their carbapenemase activity using a modified Hodge test (MHT) [37] and for their resistance to carbapenems by minimum inhibitory concentration (MIC) determination, following the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines (https://www.eucast.org/ast_of_bacteria). MIC 50 and MIC 90 were defined as the MIC values able to inhibit the growth of 50% or 90% of isolates, respectively.…”