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. 2022 Jan 19;35(1):e0000621.
doi: 10.1128/CMR.00006-21. Epub 2021 Dec 1.

Klebsiella oxytoca Complex: Update on Taxonomy, Antimicrobial Resistance, and Virulence

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Klebsiella oxytoca Complex: Update on Taxonomy, Antimicrobial Resistance, and Virulence

Jing Yang et al. Clin Microbiol Rev. .

Abstract

Klebsiella oxytoca is actually a complex of nine species-Klebsiella grimontii, Klebsiella huaxiensis, Klebsiella michiganensis, K. oxytoca, Klebsiella pasteurii, Klebsiella spallanzanii, and three unnamed novel species. Phenotypic tests can assign isolates to the complex, but precise species identification requires genome-based analysis. The K. oxytoca complex is a human commensal but also an opportunistic pathogen causing various infections, such as antibiotic-associated hemorrhagic colitis (AAHC), urinary tract infection, and bacteremia, and has caused outbreaks. Production of the cytotoxins tilivalline and tilimycin lead to AAHC, while many virulence factors seen in Klebsiella pneumoniae, such as capsular polysaccharides and fimbriae, have been found in the complex; however, their association with pathogenicity remains unclear. Among the 5,724 K. oxytoca clinical isolates in the SENTRY surveillance system, the rates of nonsusceptibility to carbapenems, ceftriaxone, ciprofloxacin, colistin, and tigecycline were 1.8%, 12.5%, 7.1%, 0.8%, and 0.1%, respectively. Resistance to carbapenems is increasing alarmingly. In addition to the intrinsic blaOXY, many genes encoding β-lactamases with varying spectra of hydrolysis, including extended-spectrum β-lactamases, such as a few CTX-M variants and several TEM and SHV variants, have been found. blaKPC-2 is the most common carbapenemase gene found in the complex and is mainly seen on IncN or IncF plasmids. Due to the ability to acquire antimicrobial resistance and the carriage of multiple virulence genes, the K. oxytoca complex has the potential to become a major threat to human health.

Keywords: Klebsiella; Klebsiella oxytoca; antimicrobial resistance; carbapenemases; resistance; taxonomy; virulence; β-lactamases.

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Conflict of interest statement

We declare no conflict of interest.

Figures

FIG 1
FIG 1
Phylogenomic tree based on the concatenated nucleotide sequence of core genes of Klebsiella species. Strains and their nucleotide accession numbers are listed alongside the species names. Species belonging to the K. oxytoca complex are in red, while other Klebsiella species are in blue. Raoultella species that were separated from Klebsiella 20 years ago (399) are included, while the genus Kluyvera, which is closely related to Klebsiella and Raoultella (400), is used as an outgroup. The tree was inferred by the core genome identification using PIRATE v1.0.4 (401) and subsequent phylogenetic inference using IQ-TREE v2.1.4 (402) using the GTR+G+ASC model with 10,000 rapid bootstraps. Branches with support over 70% are indicated by gradients. The bar shows nucleotide substitutions per site.
FIG 2
FIG 2
Worldwide distribution of CRKO strains and their carbapenemase types. nd, not determined. The number of carbapenemase variants that have been reported in a given country is indicated by color gradients.

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References

    1. Evans HJ, Campbell NE, Hill S. 1972. Asymbiotic nitrogen-fixing bacteria from the surfaces of nodules and roots of legumes. Can J Microbiol 18:13–21. 10.1139/m72-003. - DOI - PubMed
    1. Podschun R, Pietsch S, Holler C, Ullmann U. 2001. Incidence of Klebsiella species in surface waters and their expression of virulence factors. Appl Environ Microbiol 67:3325–3327. 10.1128/AEM.67.7.3325-3327.2001. - DOI - PMC - PubMed
    1. Bagley ST. 1985. Habitat association of Klebsiella species. Infect Control 6:52–58. 10.1017/s0195941700062603. - DOI - PubMed
    1. Savino F, Cordisco L, Tarasco V, Calabrese R, Palumeri E, Matteuzzi D. 2009. Molecular identification of coliform bacteria from colicky breastfed infants. Acta Paediatr 98:1582–1588. 10.1111/j.1651-2227.2009.01419.x. - DOI - PubMed
    1. Podschun R, Ullmann U. 1998. Klebsiella spp. as nosocomial pathogens: epidemiology, taxonomy, typing methods, and pathogenicity factors. Clin Microbiol Rev 11:589–603. 10.1128/CMR.11.4.589. - DOI - PMC - PubMed

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