Enterobacter

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Enterobacter
Enterobacter cloacae 01.png
Enterobacter cloacae on trypticase soy agar
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Bacteria
Phylum: Pseudomonadota
Class: Gammaproteobacteria
Order: Enterobacterales
Family: Enterobacteriaceae
Genus: Enterobacter
Hormaeche & Edwards 1960
Species

E. aerogenes
E. amnigenus
E. arachidis
E. asburiae
E. bugandensis
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. soli

Contents

Synonyms

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. Cultures are found in soil, water, sewage, feces and gut environments. It is the type genus of the order Enterobacterales. [1] 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 ] Some of them show quorum sensing properties. [2] [3]

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. [4] [5]

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. [3] [6]

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. [7]

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. [8] Enterobacter bacteremia presents as fever but can progress to SIRS and shock. [8] For Enterobacter pneumonia, symptoms include coughing and shortness of breath. [8]

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. [9]

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. [6] Quinolones can be an effective alternative. [6]

Linked to obesity

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. [10] 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. [10]

Related Research Articles

<span class="mw-page-title-main">Enterobacteriaceae</span> Family of bacteria

Enterobacteriaceae is a large family of Gram-negative bacteria. It includes over 30 genera and more than 100 species. Its classification above the level of family is still a subject of debate, but one classification places it in the order Enterobacterales of the class Gammaproteobacteria in the phylum Pseudomonadota. In 2016, the description and members of this family were emended based on comparative genomic analyses by Adeolu et al.

<span class="mw-page-title-main">Gram-positive bacteria</span> Bacteria that give a positive result in the Gram stain test

In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall.

<span class="mw-page-title-main">Gram-negative bacteria</span> Group of bacteria that do not retain the Gram stain used in bacterial differentiation

Gram-negative bacteria are bacteria that unlike gram-positive bacteria do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is their cell envelope, which consists of a thin peptidoglycan cell wall sandwiched between an inner (cytoplasmic) membrane and an outer membrane. These bacteria are found in all environments that support life on Earth.

<i>Enterococcus</i> Genus of bacteria

Enterococcus is a large genus of lactic acid bacteria of the phylum Bacillota. Enterococci are gram-positive cocci that often occur in pairs (diplococci) or short chains, and are difficult to distinguish from streptococci on physical characteristics alone. Two species are common commensal organisms in the intestines of humans: E. faecalis (90–95%) and E. faecium (5–10%). Rare clusters of infections occur with other species, including E. casseliflavus, E. gallinarum, and E. raffinosus.

<span class="mw-page-title-main">Lipopolysaccharide</span> Class of molecules found in the outer membrane of Gram-negative bacteria

Lipopolysaccharide, now more commonly known as Endotoxin, is a collective term for components of the outermost membrane of cell envelope of Gram-negative bacteria, such as E. coli and Salmonella. with a common structural architecture. Lipopolysaccharides (LPS) are large molecules consisting of 3 parts: an outer core polysaccharide termed the O-antigen, an inner core oligosaccharide and Lipid A, all covalently linked. In current terminology, the term endotoxin is often used synonymously with LPS, although there are a few endotoxins that are not related to LPS, such as the so-called delta endotoxin proteins produced by Bacillus thuringiensis.

<i>Serratia</i> Genus of bacteria

Serratia is a genus of Gram-negative, facultatively anaerobic, rod-shaped bacteria of the family Enterobacteriaceae. They are typically 1–5 μm in length, do not produce spores, and can be found in water, soil, plants, and animals. Some members of this genus produce a characteristic red pigment, prodigiosin, and can be distinguished from other members of the order Enterobacterales by their unique production of three enzymes: DNase (nucA), lipase, and gelatinase (serralysin). Serratia was thought to be a harmless environmental bacteria until it was discovered that the most common species in the genus, S. marcescens, is an opportunistic pathogen of many animals, including humans. In humans, S. marcescens is mostly associated with nosocomial, or hospital-acquired, infections, but can also cause urinary tract infections, pneumonia, and endocarditis. S. marcescens is frequently found in showers, toilet bowls, and around wet tiles as a pinkish to red biofilm but only causes disease in immunocompromised individuals. Aside from S. marcescens, some rare strains of the Serratia species – S. plymuthica, S. liquefaciens, S. rubidaea, and S. odoriferae – have been shown to cause infection such as osteomyelitis and endocarditis.

<i>Proteus</i> (bacterium) Genus of bacteria

Proteus is a genus of Gram-negative bacteria. It is a rod shaped, aerobic and motile bacteria, which is able to migrate across surfaces due its “swarming” characteristic in temperatures between 20 and 37 °C. Their size generally ranges from 0.4 to 0.8 μm in diameter and 1.0–3.0 μm in length. They tend to have an ammonia smell. Proteus bacilli are widely distributed in nature as saprophytes, being found in decomposing animal matter, sewage, manure soil, the mammalian intestine, and human and animal feces. They are opportunistic pathogens, commonly responsible for urinary and septic infections, often nosocomial.

<span class="mw-page-title-main">Enterobacterales</span> Order of gram-negative bacteria

Enterobacterales is an order of Gram-negative, non-spore forming, facultatively anaerobic, rod-shaped bacteria with the class Gammaproteobacteria. The type genus of this order is Enterobacter.

<span class="mw-page-title-main">Coliform bacteria</span> Group of bacterial species

Coliform bacteria are defined as either motile or non-motile Gram-negative non-spore forming bacilli that possess β-galactosidase to produce acids and gases under their optimal growth temperature of 35–37 °C. They can be aerobes or facultative aerobes, and are a commonly used indicator of low sanitary quality of foods, milk, and water. Coliforms can be found in the aquatic environment, in soil and on vegetation; they are universally present in large numbers in the feces of warm-blooded animals as they are known to inhabit the gastrointestinal system. While coliform bacteria are not normally causes of serious illness, they are easy to culture, and their presence is used to infer that other pathogenic organisms of fecal origin may be present in a sample, or that said sample is not safe to consume. Such pathogens include disease-causing bacteria, viruses, or protozoa and many multicellular parasites. Every drinking water source must be tested for the presence of these total coliform bacteria.

<i>Escherichia</i> Genus of bacteria

Escherichia is a genus of Gram-negative, non-spore-forming, facultatively anaerobic, rod-shaped bacteria from the family Enterobacteriaceae. In those species which are inhabitants of the gastrointestinal tracts of warm-blooded animals, Escherichia species provide a portion of the microbially derived vitamin K for their host. A number of the species of Escherichia are pathogenic. The genus is named after Theodor Escherich, the discoverer of Escherichia coli. Escherichia are facultative aerobes, with both aerobic and anaerobic growth, and an optimum temperature of 37 °C. Escherichia are usually motile by flagella, produce gas from fermentable carbohydrates, and do not decarboxylate lysine or hydrolyze arginine. Species include E. albertii, E. fergusonii, E. hermannii, E. ruysiae, E. marmotae and most notably, the model organism and clinically relevant E. coli. Formerly, Shimwellia blattae and Pseudescherichia vulneris were also classified in this genus.

Dysbiosis is characterized by a disruption to the microbiome resulting in an imbalance in the microbiota, changes in their functional composition and metabolic activities, or a shift in their local distribution. For example, a part of the human microbiota such as the skin flora, gut flora, or vaginal flora, can become deranged, with normally dominating species underrepresented and normally outcompeted or contained species increasing to fill the void. Similar to the human gut microbiome, diverse microbes colonize the plant rhizosphere, and dysbiosis in the rhizosphere, can negatively impact plant health. Dysbiosis is most commonly reported as a condition in the gastrointestinal tract or plant rhizosphere.

<i>Enterobacter cloacae</i> Species of bacterium

Enterobacter cloacae is a clinically significant Gram-negative, facultatively-anaerobic, rod-shaped bacterium.

Klebsiella aerogenes, previously known as Enterobacter aerogenes, is a Gram-negative, oxidase-negative, catalase-positive, citrate-positive, indole-negative, rod-shaped bacterium. Capable of motility via peritrichous flagella, the bacterium is approximately 1–3 microns in length.

<span class="mw-page-title-main">Pathogenic bacteria</span> Disease-causing bacteria

Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and are often beneficial but others can cause infectious diseases. The number of these pathogenic species in humans is estimated to be fewer than a hundred. By contrast, several thousand species are part of the gut flora present in the digestive tract.

<i>Hafnia</i> (bacterium) Genus of bacteria

Hafnia is a genus of Gram-negative, facultatively anaerobic, rod-shaped bacteria in the family Hafniaceae.

Moraxella osloensis is a Gram-negative oxidase-positive, aerobic bacterium within the family Moraxellaceae in the gamma subdivision of the purple bacteria.

Clostridium cadaveris is an enteric, gas-forming, motile, strictly anaerobic gram-positive bacterium of the genus Clostridium. First described by Klein in 1899, it was noted to be the most prominent bacteria during human decomposition; historically it was described as "putrefying flora".

Pathogenic <i>Escherichia coli</i> Strains of E. coli that can cause disease

Escherichia coli is a gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most E. coli strains are harmless, but pathogenic varieties cause serious food poisoning, septic shock, meningitis, or urinary tract infections in humans. Unlike normal flora E. coli, the pathogenic varieties produce toxins and other virulence factors that enable them to reside in parts of the body normally not inhabited by E. coli, and to damage host cells. These pathogenic traits are encoded by virulence genes carried only by the pathogens.

<span class="mw-page-title-main">Cefiderocol</span> Antibiotic

Cefiderocol, sold under the brand name Fetroja among others, is an antibiotic used to treat complicated urinary tract infections when no other options are available. It is indicated for the treatment of multi-drug-resistant Gram-negative bacteria including Pseudomonas aeruginosa. It is given by injection into a vein.

Christensenella hongkongensis is a species of clinically relevant gram-positive coccobacilli, first isolated from patients in Hong Kong and Canada in 2006. Although the species remains relatively rare, it has a high mortality rate of up to 50%. Christensenella is thought to be broadly distributed globally, as it has been isolated from patient blood cultures around the world including Hong Kong, South Korea, New Zealand, Canada, Sweden, France and Italy. Fewer than 15 cases of C. hongkongensis have been observed worldwide.

References

  1. Adeolu, M.; et al. (2016). "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". Int. J. Syst. Evol. Microbiol. 66 (12): 5575–5599. doi: 10.1099/ijsem.0.001485 . PMID   27620848.
  2. 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. Bibcode:2014Senso..1410527T. doi: 10.3390/s140610527 . PMC   4118381 . PMID   24932870.
  3. 1 2 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.
  4. BioMed Central (22 November 2018). "ISS microbes should be monitored to avoid threat to astronaut health". EurekAlert! . Retrieved 25 November 2018.
  5. 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 (1): 175. doi: 10.1186/s12866-018-1325-2 . PMC   6251167 . PMID   30466389.
  6. 1 2 3 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.%5B%5D
  7. Davin-Regli, Anne; Lavigne, Jean-Philippe; Pagès, Jean-Marie (17 July 2019). "Enterobacter spp.: Update on Taxonomy, Clinical Aspects, and Emerging Antimicrobial Resistance". Clinical Microbiology Reviews. 32 (4): e00002-19. doi: 10.1128/cmr.00002-19 . PMC   6750132 . PMID   31315895.
  8. 1 2 3 Ramirez, Giron M. (2022). Enterobacter Infections. In: StatPearls Publishing, Treasure Island (FL). PMID   32644722.
  9. Wu, Wenjing (19 October 2018). "Enterobacter huaxiensis sp. nov. and Enterobacter chuandaensis sp. nov., recovered from human blood". International Journal of Systematic and Evolutionary Microbiology. 69 (3): 708–714. doi: 10.1099/ijsem.0.003207 . PMID   30614784.
  10. 1 2 Fei, Na; Zhao, Liping (13 December 2012). "An opportunistic pathogen isolated from the gut of an obese human causes obesity in germfree mice". The ISME Journal. 7 (4): 880–4. doi:10.1038/ismej.2012.153. ISSN   1751-7362. PMC   3603399 . PMID   23235292.

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