Multidrug-Resistant (MDR) Klebsiella variicola Strains Isolated in a Brazilian Hospital Belong to New Clones

Abstract

<i>Klebsiella variicola</i> is mainly associated with opportunistic infections and frequently identified as <i>Klebsiella pneumoniae.</i> This misidentification implies a wrong epidemiology result as well as incorrect attribution to <i>K. pneumoniae</i> as the etiology of some severe infections. Recently, huge efforts have been made to study <i>K. variicola</i>, however, the biological aspects of this species are still unclear. Here we characterized five <i>K. variicola</i> strains initially identified as <i>K. pneumoniae</i>, with a Vitek-2 System and 16S rRNA sequencing. One-step multiplex polymerase chain reaction and Whole Genome Sequencing (WGS) identified them as <i>K. variicola.</i> Additionally, WGS analysis showed that all the strains are closely related with <i>K. variicola</i> genomes, forming a clustered group, apart from <i>K. pneumoniae</i> and <i>K. quasipneumoniae.</i> Multilocus sequence typing analysis showed four different sequence types (STs) among the strains and for two of them (Kv97 and Kv104) the same ST was assigned. All strains were multidrug-resistant (MDR) and three showed virulence phenotypes including invasion capacity to epithelial cells, and survival in human blood and serum. These results showed the emergence of new <i>K. variicola</i> clones with pathogenic potential to colonize and cause infection in different tissues. These characteristics associated with MDR strains raise great concern for human health.