Investigation of colistin resistance and method comparison in Klebsiella pneumoniae strains
Project no. 22130 · Status: Kapanmış (Yayın bekleniyor) · 2020
Summary
<p><strong>Introduction and Aim:</strong> In recent years, multidrug-resistant gram-negative bacteria which causing nosocomial infections with high rates of morbidity and mortality have emerged in intensive care units (ICUs). This has led to the reintroduction of colistin, an old antibiotic, for clinical use in the past decade. However, as a consequence of its widespread use, resistance to colistin has also started to develop among the bacterial pathogens. Considering the potential side effects of the drug, determining the susceptibility of the pathogens to colistin becomes an important issue. The aim of this study is to determine the prevalence of colistin resistance in K. pneumoniae strains isolated from blood culture samples received in Medical Microbiology Laboratory, Ege University Faculty of Medicine Hospital, obtain epidemiological data, and evaluate alternative methods for determining colistin susceptibility by comparing them with the gold standard method, broth microdilution (BMD), which is a challenging method to implement but has been established as the gold standard. Additionally, the detection and evaluation of the prevalence of transferable plasmid-mediated <em>mobile colistin resistance </em>(<em>mcr</em>) genes using the polimerase chain reaction method are also targeted.</p><p><strong>Materials and Methods:</strong> The study included 151 <em>K. pneumoniae</em> strains, isolated from blood culture samples received at the Medical Microbiology Laboratory, Ege University Faculty of Medicine Hospital, between October 2019 and December 2021. The colistin susceptibilities of the isolates obtained from pure cultures using the BMD, Sensititre™, colistin broth disk elution (CBDE), ETEST®, and VITEK®2 methods were determined. The concordance of alternative methods with BMD was evaluated. Additionally, the presence of mcr genes in the study group strains was assessed using polymerase chain reaction.</p><p><strong>Results: </strong>The colistin resistance rate in the study group was found to be 16.6%. Sensititre™, colistin broth disk elution (CBDE), and ETEST® methods showed 100% concordance with BMD in determining susceptibility results, while VITEK®2 exhibited categorical agreement (CA), major error (ME), and very major error (VME) rates of 98%, 0.79%, and 8%, respectively. Essential agreement (EA) assessment was performed for Sensititre™, ETEST®, and VITEK®2 methods, resulting in 92.7%, 52.3%, and 78.1% agreement rates, respectively. No transferable <em>mcr</em> gene which responsible for colistin resistance was detected in any of the strains.</p><p><strong>Conclusion: </strong>The development of resistance against colistin, which is used as the last resort in the treatment of multidrug-resistant bacterial infections, is concerning. Due to the challenging implementation of the broth microdilution method (BMD), surveillance data on colistin resistance remains insufficient in our country and worldwide, compared to monitoring conducted for other antibiotics. It is necessary to establish continuous epidemiological studies that monitor resistance rates. Alternative methods to BMD can be incorporated into laboratory routines through controlled studies. In the future, there is a need for a greater number of samples and comparative studies involving diverse bacterial groups.</p>