Whole Genome Sequencing of Klebsiella variicola Strains Isolated from Patients with Cancer

Background:Klebsiella variicola is a Gram-negative, capsulated, nonmotile, facultative anaerobic rod. It is one of the species belonging to the K. pneumoniae complex. The objective of this study was to gain insights into the antimicrobial resistance and virulence of K. variicola strains isolated from clinical samples from oncologic patients. Methods: Strain identification was performed using a mass spectrometry method. Whole genome sequencing was conducted for all analyzed strains. Antimicrobial susceptibility was determined using an automated method. The presence of antimicrobial resistance mechanisms and genes encoding extended-spectrum beta-lactamases (ESBL) was assessed using the double-disc synergy test and genotypic methods. Results: All isolates were identified as K. variicola using mass spectrometry and whole genome sequencing (WGS). All isolates were ESBL-positive, and two of them harbored the bla_CTX-M-15 gene. In our study, the bla_LEN-17 gene was detected in all strains. Genome sequence analysis of the K. variicola isolates revealed the presence of virulence factor genes, including entAB, fepC, ompA, ykgK, and yagWXYZ. Two different plasmids, IncFIB(K) and IncFII, were identified in all of the analyzed K. variicola strains. The detected virulence factors suggest the ability of the bacteria to survive in the environment and infect host cells. All isolates demonstrated in vitro susceptibility to carbapenems. Conclusions: Further studies are needed to confirm whether multidrug-resistant K. variicola strains represent an important pathogen in infections among oncologic patients.