|Enterobacter cloacae haemolytic (right) and
non-haemolytic (left) colonies on sheep blood agar
Legend: + positive 90-100%, - negative 90-100%, [+] positive 75-89%, [-] negative 75-89%, d positive 25-74% of strains
Differential characters between species:
Phylum Proteobacteria, Class Gammaproteobacteria, Order Enterobacteriales, Family Enterobacteriaceae, Genus Enterobacter,
- Enterobacter cloacae Hormaeche and Edwards 1960, Jordan 1890 - type species of the genus.
- Enterobacter aerogenes Hormaeche and Edwards 1960. Synonum: Klebsiella mobilis Bascomb et al. 1971.
- Enterobacter agglomerans Ewing and Fife 1972. Changed to Pantoea agglomerans (Ewing and Fife 1972) Gavini et al. 1989.
- Enterobacter amnigenus Izard et al. 1981.
- Enterobacter asburiae (previously CDC Enteric Group 17), Brenner et al. 1988.
- Enterobacter cancerogenus (previously CDC Enteric Group 19, Erwinia
cancerogena), Farmer et al. 1985. Synonym: Enterobacter taylorae.
- Enterobacter cowanii Inoue et al. 2001.
- Enterobacter dissolvens Rosen 1922. Basonym: Erwinia dissolvens (Rosen 1922)
Burkholder 1948. Old synonyms: Pseudomonas dissolvens, Bacterium dissolvens,
Phytomonas dissolvens, Aplanobacter dissolvens, Aerobacter dissolvens,
- Enterobacter gergoviae Brenner et al. 1980.
- Enterobacter hormaechei (previously CDC Enteric Group 75), O’Hara et al. 1990.
- Enterobacter intermedius Izard et al. 1980, (formerly group H1). Transfered to
genus Kluyvera as Kluyvera intermedia.
- Enterobacter nimipressuralis (Erwinia nimipressuralis), Carter 1945.
- Enterobacter kobei Kosako et al. 1997 (previously NIH group 21).
- Enterobacter ludwigii Hoffmann et al. 2005.
- Enterobacter pyrinus Chung et al. 1993.
- Enterobacter radicincitans Kämpfer et al. 2005.
- Enterobacter sakazakii, Farmer et al. 1980. Moved to genus Cronobacter as
Cronobacter sakazakii (Farmer et al. 1980) Iversen et al. 2008.
Gram-negative, straight, bacilli, usually motile by 4-6 peritrichous flagella, some
encapsulated. Measures 0.6-1.0 x 1.2-3.0 µm.
Colonies on nutritive agar are round, 2-3 mm in diameter, and slightly iridescent or
flat with irregular edges, nonpigmented. Exception: E. sakazakii which forms bright
yellow colonies at 25 ºC or pale yellow colonies at 37 ºC, 1-3 mm in diameter.
Facultatively anaerobic. Incubation temperature 30-37 ºC. E. sakazakii is able to grow
at 44 ºC. Grow on simple media and on selective media for Enterobacteriaceae.
Can be found on human skin and plants as well as in soil, water, sewage, intestinal
tracts of humans and animals, clinical specimens (feces, urine, blood, wound
exudates, sputum) and some dairy products.
Enterobacter spp. rarely cause disease in a healthy individual. This opportunistic
pathogen, similar to other members of the Enterobacteriaceae family, possesses an
endotoxin known to play a major role in the pathophysiology of sepsis and its
complications. Adhesins are often also hemagglutinins (HA) and may or may not be
located on fimbriae.
E. asburiae is a cotton endophyte that is able to colonize internal tissues of different
E. cloacae and E. aerogenes, are important nosocomial pathogens responsible for
various infections, including bacteremia, lower respiratory infections, skin and soft
tissue infections, urinary tract infections, endocarditis, osteomyelitis, ophthalmic
infections and arthritis.
Enterobacter cloacae is also the causal agent of internal yellowing of papaya fruit.
Enterobacter dissolvens (Erwinia dissolvens) is the causal agent of corn stalk rot.
Pantoea (Enterobacter) agglomerans can cause opportunistic infections in immune
compromised patients. Some reports of arthritis caused by P. agglomerans wound
infection (plant thorn injury).
Enterobacter sakazakii may cause invasive infections with high death rates in
neonates (meningitis, necrotizing enterocolitis and sepsis).
E. nimipressuralis is the causal agent of wetwood in elm trees.
Enterobacter pyrinus is associated with brown leaf spot disease of pear trees.
E. cancerogenus has been described as the causal agent of a canker disease of
poplar (Populus spp.). Has been rarely found associated with human infections
(septicemia and urinary tract infections reported) , is generally recovered from
environmental or vegetal sources and is considered mostly phytopathogenic.
One report of lower respiratory tract infection due to Enterobacter gergoviae.
- J. G. Holt et al., 1994. Facultatively Anaerobic Gram-Negative Rods. Subgroup 1. Family Enterobacteriaceae. In: Begey’s Manual of
Determinative Bacteriology, 9th-edition, Williams & Wilkins, pp 175-189.
- Don J. Brenner and J.J. Farmer III, 2001. Family I. Enterobacteriaceae. In: Bergey’s Manual of Systematic Bacteriology, Second
edition, Vol two, part B, George M. Garrity (Editor-in-Chief), pp 587-897.
- Ewing (W.H.) and Fife (M.A.): Enterobacter agglomerans (Beijernick) comb. nov. (the Herbicola-Lathyri Bacteria). International
Journal of Systematic Bacteriology, 1972, 22, 4-11.
- Schonheyder (H.C.) et al.: Taxonomic notes: synonymy of Enterobacter cancerogenus (Urosevic 1966) Dickey and Zumoff 1988
and Enterobacter taylorae Farmer et al. 1985 and resolution of an ambiguity in the biochemical profile. Int. J. Syst. Bacteriol., 1994,
- Farmer III (J.J.) et al.: Enterobacter sakazakii: a new species of "Enterobacteriaceae" isolated from clinical specimens. Int. J. Syst.
Bacteriol., 1980, 30, 569-584.
- Chung (Y.R.) et al.: Enterobacter pyrinus sp. nov., an organism associated with brown leaf spot disease of pear trees. Int. J. Syst.
Bacteriol., 1993, 43, 157-161.
- Farmer III (J.J.) et al: Escherichia fergusonii and Enterobacter taylorae, two new species of Enterobacteriaceae isolated from
clinical specimens. J. Clin. Microbiol., 1985, 21, 77-81.
- Hoffmann (H.) et al.: Description of Enterobacter ludwigii sp. nov., a novel Enterobacter species of clinical relevance. Syst. Appl.
Microbiol., 2005, 28, 206-212.
- Kosako (Y.) et al.: Enterobacter kobei sp. nov., a new species of the familiy Enterobacteriaceae resembling Enterobacter cloacae.
Curr. Microbiol., 1996, 33, 261-265.
- O’Hara(C.M.) et al.: Enterobacter hormaechei, a new species of the family Enterobacteriaceae formerly known as Enteric Group
75. J. Clin. Microbiol., 1989, 27, 2046-2049.
- Brenner (D.J.) et al.: Enterobacter gergoviae sp. nov.: a new species of Enterobacteriaceae found in clinical specimens and the
environment. Int. J. Syst. Bacteriol., 1980, 30, 1-6.
- Abbott, S. L., and J. M. Janda. 1997. Enterobacter cancerogenus (“Enterobacter taylorae”) infections associated with severe
trauma or crush injuries. Am. J. Clin. Pathol. 107:359-361.
Some environmental strains may give erratic biochemical reactions at 37 °C.
Positive results for catalase, ONPG, ornithine decarboxylase, nitrate reduction, acid production from L-arabinose, cellobiose, glucose
(with gas), mannitol, maltose, mannose, salicin (most of strains), trehalose and xylose (with the exception of E. pyrinus).
Negative results for oxidase, indole production, H2S production, phenylalanine, gelatin hydrolysis, DN-ase and lipase.
(c) Costin Stoica
|Enterobacter cloacae Gram-negative cells