Klebsiella

Kleb.si.el' la . M.L. dim. ending ‐ ella; M.L. fem. n. Klebsiella named after Edwin Klebs (1834–1913), a German bacteriologist. Proteobacteria / Gammaproteobacteria / Enterobacteriales / Enterobacteriaceae / Klebsiella Straight rods, 0.3–1.0 × 0.6–6.0 μm , arranged singly, in pairs or short chains; often surrounded by a capsule . Conform to the general definition of the family Enterobacteriaceae . Gram negative. Nonmotile (except K . mobilis ). Facultatively anaerobic, having both a respiratory and a fermentative type of metabolism. Grow on meat extract media (except K . granulomatis , which has not been cultured), producing more or less dome‐shaped, glistening colonies of varying degrees of stickiness depending on the strain and the composition of the medium. Oxidase negative . Glucose is fermented with the production of acid and gas (more CO 2 is produced than H 2 ), but anaerogenic strains occur. Most strains produce 2,3‐butanediol as a major end product of glucose fermentation. The Voges–Proskauer test is usually positive . Lactic, acetic, and formic acids are formed in smaller amounts and ethanol in larger amounts than in a mixed acid fermentation. All strains utilize L ‐arabinose, D ‐arabitol, D ‐cellobiose, citrate, D ‐fructose, D ‐galactose, D ‐glucose, 2‐ketogluconate, maltose, D ‐mannitol, D ‐melibiose, D ‐raffinose, D ‐trehalose, and D ‐xylose as sole carbon sources. With the exception of some K . pneumoniae subsp. ozaenae strains, all Klebsiella strains utilize myo ‐inositol , l ‐ rhamnose, and sucrose as sole carbon sources . With the exception of some K . pneumoniae subsp. ozaenae and K . pneumoniae subsp. rhinoscleromatis strains, all strains utilize lactose and D ‐sorbitol as sole carbon sources. No strain utilizes betaine, caprate, caprylate, glutarate, itaconate, 3‐phenylpropionate, and propionate. H 2 S is not produced, β‐glucuronides are not hydrolyzed, and L ‐tryptophan and L ‐histidine are not deaminated. Ornithine is not decarboxylated by klebsiellae strains except K . mobilis, K . ornithinolytica , and rare strains of K . pneumoniae . Most strains hydrolyze urea and β‐galactosides. Some strains fix nitrogen. Occur in intestinal contents, clinical specimens from humans and animals (e.g., horses, swine, monkeys), soil, water, or on plants. The mol % G + C of the DNA is : 53–58. Type species : Klebsiella pneumoniae (Schroeter 1886) Trevisan 1887, 94 ( Hyalococcus pneumoniae Schroeter 1886, 1952.)