Phenotypical and genotypical assessment of resistance of carbapenemase producing Klebsiella pneumoniae strains

Abstract

Introduction. The emergence and global spread of antimicrobial resistance genes, such as genes for extended-spectrum beta-lactamases and carbapenemases in Klebsiella pneumoniae strains, poses a significant threat to public health. The reason for this is that carbapenems are the latest therapeutic agent used to treat diseases caused by multi-resistant gram-negative bacteria. The detection of carbapenemases is epidemiologically important because ESBL-genes are plasmid-mediated and can be transmitted horizontally among different bacterial species. The aim of this research was to assess the spectrum of antibiotic resistance of carbapenemase-producing strains of K. pneumoniae circulating in hospitals in St. Petersburg using phenotypic and genotypic methods. Materials and methods. The susceptibility of K. pneumoniae strains (n=182), isolated from samples from patients admitted to hospitals in St. Petersburg in the period from 2016 to 2018, was assessed with 16 antimicrobials. Resistance to antibiotics was assessed by the gradient diffusion method. Carbapenemase genes were detected by molecular (PCR) and phenotypic (CIM) methods. Results. Most of the strains demonstrated a high percentage of resistance to ticarcillin/clavulanate (96.7%), quinolones (nalidixic acid (91.8%), norfloxacin (91.2%), ciprofloxacin (90.1%), ofloxacin (89%)), III and IV generation cephalosporins (cefotaxime (92.9%), ceftazidime (88.5%), cefoperazone (87.9%), ceftriaxone (86.8%), cefepime (91.2%)), netilmicin (83.5%) and gentamicin (80.2%). The investigated strains showed moderate resistance to amikacin (74.2%), meropenem (72.5%) and imepenem (65.9%). The main type of carbapenemases produced by the studied isolates of K. pneumoniae were NDM metallo-beta-lactamases (60.4%) and OXA-48 serine carbapenemases (49.5 %). KPC carbapenemases were found in only 1.1% of the strains. Discussion. The results of the study demonstrate a high resistance level of K. pneumoniae nosocomial isolates to various antibiotics. Therefore, the range of antimicrobials for treatment of Klebsiella infections is significantly reduced, which can lead to a decrease in the effectiveness of clinical therapy. Acknowledgments. The study had no sponsorship. Conflict of interest. The authors declare no apparent or potential conflicts of interest related to the publication of this article.