Enterobacter
{{Short description|Genus of bacteria}}
{{Use dmy dates|date=January 2021}}
{{Automatic taxobox
| image = Enterobacter_cloacae_01.png
| image_caption = Enterobacter cloacae on trypticase soy agar
| taxon = Enterobacter
| authority = Hormaeche & Edwards 1960
| subdivision_ranks = Species
| subdivision =
{{Incomplete list|date=October 2021}}
| synonyms = Cloaca Castellani & Chalmers, 1919
{{Break}}Aerobacter Hormaeche & Edwards, 1958
}}
Enterobacter is a genus of common Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. Cultures are found in soil, water, sewage, feces and gut environments. It is the type genus of the order Enterobacterales.{{cite journal|last1=Adeolu|first1=M.|display-authors=etal|title=Genome based phylogeny and taxonomy of the 'Enterobacteriales': proposal for Enterobacterales ord. nov. divided into the families Enterobacteriaceae, Erwiniaceae fam. nov., Pectobacteriaceae fam. nov., Yersiniaceae fam. nov., Hafniaceae fam. nov., Morganellaceae fam. nov., and Budviciaceae fam. nov.|journal=Int. J. Syst. Evol. Microbiol.|date=2016|volume=66 |issue=12 |pages=5575–5599 |doi=10.1099/ijsem.0.001485 |pmid=27620848 |doi-access=free}} 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.{{Citation needed|date=November 2020}} Some of them show quorum sensing properties.{{cite journal|last1=Tan|first1=Wen-Si|last2=Muhamad Yunos|first2=Nina Yusrina|last3=Tan|first3=Pui-Wan|last4=Mohamad|first4=Nur Izzati|last5=Adrian|first5=Tan-Guan-Sheng|last6=Yin|first6=Wai-Fong|last7=Chan|first7=Kok-Gan|title=Freshwater-Borne Bacteria Isolated from a Malaysian Rainforest Waterfall Exhibiting Quorum Sensing Properties|journal=Sensors|date=13 June 2014|volume=14|issue=6|pages=10527–10537|doi=10.3390/s140610527|pmid=24932870|pmc=4118381|bibcode=2014Senso..1410527T |doi-access=free }}{{cite journal|last=Cabral|first=JPS|title=Water Microbiology. Bacterial Pathogens and Water.|journal=Int. J. Environ. Res. Public Health|year=2010|volume=7|pages=3657–3703|doi=10.3390/ijerph7103657|pmc=2996186|pmid=21139855|issue=10|doi-access=free }}
One clinically important species from this genus is E. cloacae.
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.{{cite web |author=BioMed Central |title=ISS microbes should be monitored to avoid threat to astronaut health |url=https://www.eurekalert.org/pub_releases/2018-11/bc-ims112018.php |date=22 November 2018 |work=EurekAlert! |access-date=25 November 2018 }}{{cite journal |author=Singh, Nitin K.|display-authors=etal|title=Multi-drug resistant Enterobacter bugandensis species isolated from the International Space Station and comparative genomic analyses with human pathogenic strains |date=23 November 2018 |journal=BMC Microbiology |volume=18 |issue=1|page=175 |doi=10.1186/s12866-018-1325-2 |pmid=30466389|pmc=6251167 |doi-access=free }}
Biochemical characteristics
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.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: [https://web.archive.org/web/20080322062654/http://www.accessmedicine.com/content.aspx?aid=2894446]
Virulent characteristics
For Enterobacter species, the flagella is used for adhesion, biofilm formation, and protein export as well as motility. Between the strains, the microbial genus produces endotoxins unique to the species.{{Cite journal |last1=Davin-Regli |first1=Anne |last2=Lavigne |first2=Jean-Philippe |last3=Pagès |first3=Jean-Marie |date=17 July 2019 |title=Enterobacter spp.: Update on Taxonomy, Clinical Aspects, and Emerging Antimicrobial Resistance |journal=Clinical Microbiology Reviews |volume=32 |issue=4|pages=e00002-19 |doi=10.1128/cmr.00002-19 |doi-access=free |pmid=31315895 |pmc=6750132 }}
As a gram negative bacterium, the lipopolysaccharide capsule helps to avoid phagocytosis and can initiate inflammatory response.
Symptoms
In patients, pathogenic strains were found in the sputum, blood, wounds, and stool. Enterobacter is associated with common nosocomial infections including respiratory, endocarditis, bacteremia, urinary tract infections, osteomyelitis, among others. Enterobacter bacteremia presents as fever but can progress to SIRS and shock. For Enterobacter pneumonia, symptoms include coughing and shortness of breath.{{Cite book |last=Ramirez |first=Giron M. |date=2022 |title=Enterobacter Infections. In: StatPearls Publishing, Treasure Island (FL) |url=https://europepmc.org/article/nbk/nbk559296 |pmid=32644722}}
Treatment
Treatment is dependent on local trends of antibiotic resistance. Enterobacter huaxiensis and Enterobacter chuandaensis are two recently discovered species that exhibit especially antibiotic resistant characteristics.{{cite journal |last1=Wu |first1=Wenjing |title=Enterobacter huaxiensis sp. nov. and Enterobacter chuandaensis sp. nov., recovered from human blood |journal=International Journal of Systematic and Evolutionary Microbiology |date=19 October 2018 |volume=69 |issue=3 |pages=708–714 |doi=10.1099/ijsem.0.003207|pmid=30614784 |doi-access=free}}
Cefepime, a fourth-generation cephalosporin from the β-Lactam antibiotic class.{{More detail needed}} Imipenem (a carbapenem) 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
{{Main|Endotoxin}}
A 2012 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.{{cite journal|title=An opportunistic pathogen isolated from the gut of an obese human causes obesity in germfree mice|journal=The ISME Journal|issn=1751-7362|date=13 December 2012|doi=10.1038/ismej.2012.153|pmc=3603399|pmid=23235292|volume=7|issue=4|pages=880–4|last1=Fei|first1=Na|last2=Zhao|first2=Liping}} 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.
References
{{reflist}}
Davin-Regli, A., Lavigne, J. P., & Pagès, J. M. (2019). Enterobacter spp.: Update on Taxonomy, Clinical Aspects, and Emerging Antimicrobial Resistance. Clinical microbiology reviews, 32(4), e00002-19. https://doi.org/10.1128/CMR.00002-19
External links
- {{Wikispecies-inline}}
- [http://bacdive.dsmz.de/index.php?search=Enterobacter&submit=Search Enterobacter at BacDive - the Bacterial Diversity Metadatabase]
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