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Enterobacter cloacae 01.png
Enterobacter cloacae on Tryptic Soy Broth agar.
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Enterobacteriales
Family: Enterobacteriaceae
Genus: Enterobacter
Hormaeche & Edwards 1960

E. aerogenes
E. amnigenus
E. agglomerans
E. arachidis
E. asburiae
E. cancerogenous
E. cloacae
E. cowanii
E. dissolvens
E. gergoviae
E. helveticus
E. hormaechei
E. intermedius
E. kobei
E. ludwigii
E. mori
E. nimipressuralis
E. oryzae
E. pulveris
E. pyrinus
E. radicincitans
E. taylorae
E. turicensis
E. sakazakii Enterobacter soli


Cloaca Castellani & Chalmers, 1919
Aerobacter Hormaeche & Edwards, 1958

Enterobacter is a genus of common Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. Several strains of these bacteria are pathogenic and cause opportunistic infections in immunocompromised (usually hospitalized) hosts and in those who are on mechanical ventilation. The urinary and respiratory tracts are the most common sites of infection. The genus Enterobacter is a member of the coliform group of bacteria. It does not belong to the fecal coliforms (or thermotolerant coliforms) group of bacteria, unlike Escherichia coli, because it is incapable of growth at 44.5 °C in the presence of bile salts. Some of them showed quorum sensing properties as reported before [1][2]

Two clinically important species from this genus are E. aerogenes and E. cloacae.

Biochemical characteristics[edit]

The genus Enterobacter ferments lactose with gas production during a 48-hour incubation at 35-37 °C in the presence of bile salts and detergents. It is oxidase-negative, indole-negative, and urease-variable.[2][3]


  1. Cefepime, a fourth-generation cephalosporin from the β-Lactam antibiotic class.
  2. Imipenem (carbapenems) is often the antibiotic of choice.
  3. Aminoglycosides such as amikacin have been found to be very effective, as well.[3]
  4. Quinolones can be an effective alternative.[3]

Linked to obesity[edit]

A recent study has shown that the presence of Enterobacter cloacae B29 in the gut of a morbidly obese individual may have contributed to the patient’s obesity. Reduction of the bacterial load within the patient’s gut, from 35% E. cloacae B29 to non-detectable levels, was associated with a parallel reduction in endotoxin load in the patient and a concomitant, significant reduction in weight.[4] Furthermore, the same bacterial strain, isolated from the patient, induced obesity and insulin resistance in germfree C57BL/6J mice that were being fed a high-fat diet. The study concludes that E. cloacae B29 may contribute to obesity in its human hosts through an endotoxin-induced, inflammation-mediated mechanism.[4]


  1. ^ Tan, Wen-Si; Muhamad Yunos, Nina Yusrina; Tan, Pui-Wan; Mohamad, Nur Izzati; Adrian, Tan-Guan-Sheng; Yin, Wai-Fong; Chan, Kok-Gan (13 June 2014). "Freshwater-Borne Bacteria Isolated from a Malaysian Rainforest Waterfall Exhibiting Quorum Sensing Properties". Sensors. 14 (6): 10527–10537. doi:10.3390/s140610527. 
  2. ^ a b Cabral, JPS (2010). "Water Microbiology. Bacterial Pathogens and Water". Int. J. Environ. Res. Public Health. 7 (10): 3657–3703. doi:10.3390/ijerph7103657. PMC 2996186Freely accessible. PMID 21139855. 
  3. ^ a b c Russo Thomas A, Johnson James R, "Chapter 143. Diseases Caused by Gram-Negative Enteric Bacilli" (Chapter). Fauci AS, Braunwald E, Kasper DL, Hauser SL, Longo DL, Jameson JL, Loscalzo J: Harrison's Principles of Internal Medicine, 17e: http://www.accessmedicine.com/content.aspx?aID=2894446.
  4. ^ a b "An opportunistic pathogen isolated from the gut of an obese human causes obesity in germfree mice". The ISME Journal. 7 (4): 880–4. December 13, 2012. doi:10.1038/ismej.2012.153. ISSN 1751-7362. PMC 3603399Freely accessible. PMID 23235292. Retrieved December 18, 2012. 

External links[edit]