Klebsiella variicola : an emerging pathogen in humans

Abstract

The Klebsiella pneumoniae complex comprises seven K. pneumoniae- related species, including K. variicola . K. variicola is a versatile bacterium capable of colonizing different hosts such as plants, humans, insects and animals. Currently, K. variicola is gaining recognition as a cause of several human infections; nevertheless, its virulence profile is not fully characterized. The clinical significance of K. variicola infection is hidden by imprecise detection methods that underestimate its real prevalence; however, several methods have been developed to correctly identify this species. Recent studies of carbapenemase-producing and colistin-resistant strains demonstrate a potential reservoir of multidrug-resistant genes. This finding presents an imminent scenario for spreading antimicrobial resistant genes among close relatives and, more concerningly, in clinical and environmental settings. Since K. variicola was identified as a novel bacterial species, different research groups have contributed findings elucidating this pathogen; however, important details about its epidemiology, pathogenesis and ecology are still missing. This review highlights the most significant aspects of K. variicola , discussing its different phenotypes, mechanisms of resistance, and virulence traits, as well as the types of infections associated with this pathogen.

Exploring the Potential of CRISPR-Cas9 Under Challenging Conditions: Facing High-Copy Plasmids and Counteracting Beta-Lactam Resistance in Clinical Strains of Enterobacteriaceae

“…E. hormaechei belongs to the Enterobacter cloacae complex and K. variicola is a member of the Klebsiella pneumoniae complex, as they share some biochemical and phenotypical features with E. cloacae and K. pneumoniae, respectively (Hoffmann et al, 2005;Barrios-Camacho et al, 2019). Because of this similarity, the species are frequently misclassified and the worldwide presence of these bacteria in human infections may be underestimated, although their relevance as clinical pathogens has been demonstrated (Long et al, 2017;Beyrouthy et al, 2018;Barrios-Camacho et al, 2019;Rodríguez-Medina et al, 2019). The selection criteria of the isolates were the absence of a natural chloramphenicol-resistant phenotype, since the antibiotic was used as a selective marker of the pSB1C3 plasmid; the presence of the bla TEM−1 gene and the absence of carbapenemase genes.…”

Severe sepsis caused by a gas-formingClostridium perfringensandKlebsiella variicolaliver abscess following total pancreatectomy

“…2 Due to its new discovery and close resemblance to Klebsiella pneumonia, it is often misclassified as K. pneumonia. 3 Being non-motile the bacteria is extremely rare in liver abscesses. To our knowledge, this is the first described case.…”

Occurrence and determinants of Klebsiella species bloodstream infection in the western interior of British Columbia, Canada

“…Klebsiella pneumoniae has become increasingly important in recent years, as invasive hypermucoid strains have been linked to pyogenic liver abscesses most notably in Taiwan and Korea [4, 5], and there has been an upswing in extended spectrum-β-lactamase (ESBL) producing strains worldwide [6–8]. Species other than K. pneumoniae are overall less frequent and have been associated with conditions including BSIs, urinary tract infections, soft tissue infections, and respiratory tract infections [9–11].…”