Assigned ESKAPE Pathogen
#6 Enterobacter Species
Why is this ESKAPE Pathogen of interest (in brief)
The Enterobacter species is of interest due to the high rates of hospital-acquired infection that it causes. A study from the National Nosocomial Infections Surveillance System showed that the Enterobacter species is the third most common cause of pneumonia in ICUs. It is of increasing interest because the species has extremely high rates of antibiotic resistance. This is of concern due to the prevalence of infection and the mortality rates associated with the infections it causes. Crude mortality rates range from 15-87%. This is an extremely wide range, making the infections caused by the Enterobacter species highly unpredictable.
https://www.britannica.com/science/Enterobacter
https://emedicine.medscape.com/article/216845-overview
https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540201/all/Enterobacter_species
General Cellular and Morphological Characteristics of the Organism (taxonomic classification, nutrition, cell shape, habitat)
The Enterobacter species is a rod-shaped bacteria that is gram negative. The size of each colony is 0.6-1.0 micrometers by 1.2-3.0 micrometers. The species is not capable of forming spores. It is motile due to flagella. The taxonomic classification is Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacteriales; Enterobacteriaceae. The species are facultative anaerobes; meaning the presence of oxygen is not required. They are capable of fermenting glucose and lactose. Through this fermentation, gases are produced. They are commonly found in intestinal tracts and in soil, water, and sewage. They are not harmful when found in the gut. Less commonly, they are found in urine, pus, and bodily fluids.
https://microbewiki.kenyon.edu/index.php/Enterobacter
https://www.britannica.com/science/Enterobacter
Clinical Importance and Prevalence
This Eskape pathogen is known to cause nosocomial infections. A nosocomial infection is caused due to a bacterium’s prevalence in certain locations. A nosocomial infection can also be called a hospital-acquired infection. The Enterobacter species is prevalent in ICUs and also commonly survives in equipment with water. This is because the species is able to live for a long time on surfaces. In wet environments, it is able to replicate rapidly. The most common source of spreading the bacteria is a lack of cleanliness, i.e. a lack of handwashing. This is a major source of infection in hospitals, with about 50% of infection in the ICU caused by the Enterobacter species. The species causes infections in the respiratory tract, urinary tract, intra abdominal cavity, intravascular devices, and can lead to sepsis.
https://www.healthline.com/health/hospital-acquired-nosocomial-infections
Infection (How does the infection occur and where is it localized?)
The Enterobacter species cause nosocomial infections in immunocompromised patients. The most common types of Enterobacter that cause human infection are E. cloacae, E. aerogenes, E. gergoviae, and E. agglomerans. Infections occur endogenously or exogenously. Endogenous sources of infection are the most common type of nosocomial infections caused by the Enterobacter species. The endogenous sources include the skin, respiratory tract, urinary tract, and gastrointestinal tract. The endogenous source tend to be the site of localization for the species.
https://emedicine.medscape.com/article/216845-overview
Pathology (What disease is caused? What are the symptoms?)
An infection caused by the Enterobacter species include a heart rate exceeding 90 bpm, a respiration rate greater than 20, and a fever above 100.4 °F or below 96.8°F. Other symptoms include hypotension, septic shock, cyanosis, and hypoxemia. Diseases and conditions that can be caused by this species are eye and skin infections, meningitis, bacterial blood infections, pneumonia, and urinary tract infections.
https://emedicine.medscape.com/article/216845-overview
http://www.antimicrobe.org/b97.asp
https://www.britannica.com/science/Enterobacter
Ineffective Antibiotics (Antibiotics to which the organism has acquired resistance)
Effective Antibiotics (Antibiotics known to inhibit the organism)
This species has developed resistance to a number of different antibiotics, especially in hospital settings. Infections and diseases caused by the Enterobacter species have been treated with an aminoglycoside, a fluoroquinolone, a cephalosporin, or imipenem. Over time, however, Enterobacter species has developed resistance to most beta lactam drugs and many other different drug types. Another source suggests that “third generation” cephalosporins, penicillins, and quinolones have become ineffective antibiotics as a result of increasing resistance. However, there are some antibiotics that are still effective. “Fourth generation” cephalosporins and carbapenems remain a viable option for treatment. Aminoglycosides are noted to be viable as well, but need to be combined with another type of antibiotic to allow for successful treatment. Lastly, quinolones are able to be used against many strains of the Enterobacter species, but similar to the trend of other drugs, emerging resistance is of concern. More specifically, Polymyxin B, Levofloxacin, Doripenem, Imipenem, Meropenem, Cefepime, Ciprofloxacin, Trimethoprim-sulfamethoxazole, Ertapenem, and Tigecycline are all examples of antibiotics that seem to remain effective and are largely avoiding resistance for now.
http://www.antimicrobe.org/b97.asp
https://www.britannica.com/science/Enterobacter
https://catalog.hardydiagnostics.com/cp_prod/Content/hugo/Enterobacter.htm
Corresponding Safe Relative
The corresponding safe relatives are the Enterobacter aerogenes and the Erwinia carotovora.
(Source: Lab handout)
Images:
Enterobacter cloacae
https://jamanetwork.com/journals/jamaderm
atology/fullarticle/413232
Sources:
https://microbewiki.kenyon.edu/index.php/Enterobacter
http://www.antimicrobe.org/b97.asp
https://www.britannica.com/science/Enterobacter
https://emedicine.medscape.com/article/216845-overview
https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540201/all/Enterobacter_species
https://catalog.hardydiagnostics.com/cp_prod/Content/hugo/Enterobacter.htm
Davin-Regli, Anne, and Jean-Marie Pagès. “Enterobacter Aerogenes and Enterobacter Cloacae; Versatile Bacterial Pathogens Confronting Antibiotic Treatment.” Frontiers in Microbiology 6 (2015): 392. PMC
Davis, Elizabeth et al. “Antibiotic Discovery throughout the Small World Initiative: A Molecular Strategy to Identify Biosynthetic Gene Clusters Involved in Antagonistic Activity.” MicrobiologyOpen 6.3 (2017): e00435. PMC
Santajit, Sirijan, and Nitaya Indrawattana. “Mechanisms of Antimicrobial Resistance in ESKAPE Pathogens.” BioMed Research International 2016 (2016): 2475067. PMC
