|Enterobacter cloacae on Tryptic Soy Broth agar.|
Hormaeche & Edwards 1960
Cloaca Castellani & Chalmers, 1919
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 
Researchers in 2018 reported, after detecting the presence on the International Space Station (ISS) of five Enterobacter bugandensis bacterial strains, none pathogenic to humans, that microorganisms on ISS should be carefully monitored to continue assuring a medically healthy environment for the astronauts.
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.
- Note: Treatment is dependent on local trends of antibiotic resistance.
- Cefepime, a fourth-generation cephalosporin from the β-Lactam antibiotic class.
- Imipenem (carbapenems) is often the antibiotic of choice.
- Aminoglycosides such as amikacin have been found to be very effective, as well.
- Quinolones can be an effective alternative.
Linked to obesity
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. 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.
- 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.
- Cabral, JPS (2010). "Water Microbiology. Bacterial Pathogens and Water". Int. J. Environ. Res. Public Health. 7 (10): 3657–3703. doi:10.3390/ijerph7103657. PMC 2996186. PMID 21139855.
- BioMed Central (22 November 2018). "ISS microbes should be monitored to avoid threat to astronaut health". EurekAlert!. Retrieved 25 November 2018.
- Singh, Nitin K.; et al. (23 November 2018). "Multi-drug resistant Enterobacter bugandensis species isolated from the International Space Station and comparative genomic analyses with human pathogenic strains". BMC Microbiology. 18: 175. doi:10.1186/s12866-018-1325-2. Retrieved 25 November 2018.CS1 maint: Explicit use of et al. (link)
- 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.
- "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 3603399. PMID 23235292. Retrieved December 18, 2012.
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