Klebsiella planticola

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Klebsiella planticola Image credit: Britannica.

Classification

Bacteria; Pseudomonadota; Gammaproteobacteria; Enterobacterales; Enterobacteriaceae; Klebsiella/Raoultella group; Klebsiella [1]

Species

Klebsiella planticola

Description and Significance

Klebsiella planticola is a primarily environmental species, from plant and aquatic origins, that can also be isolated from clinical specimens and can be associated with various infections-- including urinary tract infections and wound infections. [2] Klebsiella planticola is a bacterium that can be found in multiple environmental sources, such as water, soil, and plants, where they act as nitrogen-fixers. [3]

Significance of this species, along with the rest of its genus, arise from the fact that carrier rates of this bacterium on a person increase drastically in a hospital environment; where colonization rates proportionally increase with length of stay, which is one of the main reasons antibiotic resistance in Klebsiella species is on the rise. [4]

Genome Structure

Most strains of Klebsiella planticola have one circular chromosome and four plasmids. A large number of K. planticola isolates found can have up to four antimicrobial resistant genes, which causes concern for antibiotic treatment for those infected with the bacterium. Strains have a median mega base pair count of 5.85103, 5,371 proteins, and a 55.5% GC content. [5]

Cell Structure, Metabolism and Life Cycle

K. planticola are non-motile, gram-negative, rod-shaped proteobacteria that produces a polysaccharide capsule, allowing it to for large mucoid colonies as well as biofilms. [6] It is a facultative anaerobe, allowing it to respire aerobically as well as ferment. [7]

They are catalase producing, breaking down hydrogen peroxide to water, and ferment glucose, lactose, sorbose and the reduction of nitrates. [8]

Ecology and Pathogenesis

When first discovered, it was thought that K. planticola was a non-pathogenic organism that inhabited soil and various root systems. Although rare, K. planticola has been identified as being able to cause neonatal sepsis-- When infecting humans, this bacterium colonized in the rectum and large intestine. [9] K. planticola, as well as some other members of its genus, is an opportunistic pathogen and do not usually affect healthy individuals. [10] The principle mode of transmission in a hospital setting, where these diseases are the most prevalent, are from the gastrointestinal tract to the hands of a hospital worker or someone similar. [11] This organism is able to spread rapidly in nosocomial outbreaks, especially in neonatal units. K. planticola has been isolated from human infections with a surprisingly high frequency of 3.5 to 18.5% among clinical isolates of Klebsiella species. [12] Klebsiella planticola is susceptible to many different antibiotics, such as piperacillin, amoxicillin-clavulanic acid, cefuroxime, and more. But most, if not all, substrains are resistant to ampicillin and penicillin. [13]

The virulence and pathogenesis of K. planticola are dependant on its acidic polysaccharide capsule. The material of the capsule forms thick bundles of fibrillar structures in large layers on the surface of the capsule, which protects it from phagocytosis and other ways it may be attacked. [14] They also have many other traits that contribute to their virulence factor. Such as capsular polysaccharides, lipopolysaccharides, siderophores, fimbriae, a type VI secretion system, outer-membrane proteins, porins, efflux pumps, an iron transport system, biofilms, and allantoin metabolism-- these factors aid the bacteria in avoiding initial immune response of the host and to survive in different sites within the host. [15]