| Species/Subspecies: | Citrobacter freundii | ||||||||
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| Categories: | Motile; in the normal flora | ||||||||
| Etymology: | Genus name: citrate-utilizing rod (bacterium). Species epithet: named after the bacteriologist A. Freund, who first observed that trimethylene glycol was a product of fermentation. | ||||||||
| Significance: | [Of minor importance] | ||||||||
| Taxonomy: | Class Gammaproteobacteria Order Enterobacterales Family Enterobacteriaceae Genus Citrobacter |
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| Type Strain: | ATCC 8090 = CCUG 418 = NCTC 9750. | ||||||||
| Macromorphology (smell):
| Medium-sized translucent to opaque colonies (2-4 mm in diameter) with glossy surface. | ||||||||
| Micromorphology: | Straight rods (1.0 x 2.0-6.0 µm), which usually are motile by means of peritrichous flagella. | ||||||||
| Gram +/Gram -: | G- | ||||||||
| Metabolism: | Facultatively anaerobic. Can utilize citrate as the sole carbon source. | ||||||||
| Catalase/Oxidase: | +/- | ||||||||
| Other Enzymes: | DNase -, esculinase -, ornithine decarboxylase -, tryptophanase v, urease v. | ||||||||
| Biochemical Tests: | Citrate (+), methyl red +, Voges-Proskauer -. | ||||||||
| Fermentation of carbohydrates: | D-glucose + lactose (+) maltose + L-rhamnose + sucrose (+) L-arabinose + cellobiose v D-mannitol + salicin - trehalose + glycerol + inulin ? raffinose v D-sorbitol + starch ? |
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| Spec. Char.: | |||||||||
| Disease: | Is an opportunistic or secondary pathogen, which may cause wound infections. In humans, C. freundii in rare cases, cause food poisoning. |
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| Hosts: | Is an environmental bacterium, which also can be isolated from many different species. | ||||||||
| Clinical Picture: | |||||||||
| 16S rRNA Seq.: |
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| Taxonomy/phylogeny:
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Thirteen species have been described within genus Citrobacter. Citrobacter freundii belongs to the family Enterobacteriaceae and is closely related to members of the genus Klebsiella. In fact, Citrobacter freundii and members of the genus Klebsiella form a monophyletic cluster (see Fig. 142:4 to the left). | ||||||||
| Comment: | Some strains can easily be confused with Salmonella spp. in routine diagnostics. Grows in the same way on BG XLD and purple agar. | ||||||||
| Updated: | 2023-03-29 |