Comparison of results of rapid diagnostic test kits and pcr results for the detection of carbapenemases in bacterial cultures

Carbapenems are antimicrobial agents that exhibit high levels of effectiveness against Gram negative bacteria and are used as a last resort in the treatment of infections caused by these pathogens. However, due to the misuse and overuse of these antibiotics, strains resistant to carbapenems have emerged. In recent years, carbapenem-resistant strains have been increasing globally, including in Turkey. This resistance complicates treatment. It is critical to rapidly and accurately identify carbapenemases, particularly since carbapenemase-resistant Klebsiella pneumoniae is associated with a 40-50% mortality rate. Monitoring and preventing the spread of carbapenemase-producing Enterobacterales species is crucial for effective treatment. Various phenotypic and genotypic methods are available for the detection of carbapenemases, such as the Modified Hodge test, carbapenem inactivation method (CIM) and its modified version (mCIM), CarbaNP test, MALDI-TOF MS, immunochromatographic lateral flow test, and PCR. CIM and mCIM require overnight incubation and can only detect carbapenem hydrolysis but cannot determine the type of enzyme. PCR is considered the gold standard for carbapenemase detection; however, the need for additional equipment and personnel limits its routine use in laboratories. In recent years, rapid diagnostic tests capable of identifying carbapenemase-producing Enterobacterales species have been developed. In this study, 54 K. pneumoniae isolates which were isolated in the laboratory between December 2021 and December 2023 and identified as meropenem-resistant (R) and susceptible at high doses (I) according to EUCAST (European Committee on Antimicrobial Susceptibility Testing) criteria using an automated system were evaluated for the presence of carbapenemases using conventional PCR and lateral flow rapid test methods and the results of the two methods were compared. In our study, the in vitro rapid diagnostic test lateral flow (Coris BioConcept O.K.N.V.I. RESIST-5, Belgium) showed high sensitivity and specificity in detecting OXA-48, KPC, NDM and VIM-type carbapenemases. However, it should be kept in mind that false-negative results can occasionally occur with NDM.