What is Escherichia Coli (E. Coli)?

Escherichia coli (E. coli) is a species of Gram-negative, rod-shaped, facultatively anaerobic bacteria. Many strains are a part of the normal flora of the gut microbiome. It can also be found in the normal flora of the skin and genital tract (1).

Strains that are part of the microbiome can be pathogenic under certain conditions – often when introduced to a new part of the body. Additionally, strains of E. coli that are not normally found in the microbiome can also cause significant disease (i.e., enterovirulent E. coli).

E. coli is the most common cause of urinary tract infection and biliary sepsis, and a common agent in travelers’ diarrhea, foodborne gastroenteritis, hemorrhagic colitis, and a wide variety of systemic infections (2).

Enterotoxigenic E. Coli (ETEC) Infection

Enterotoxigenic E. coli (ETEC) is the most common cause of diarrhea in children (4) and the leading cause of travelers’ diarrhea (5). It is transmitted via contaminated food and water. Symptoms commonly include watery stool and abdominal cramping. Most cases are self-limited, but it may be life-threatening in infants. 

Enteropathogenic Escherichia Coli (EPEC) Infection

Enteropathogenic E. coli (EPEC) infection is a common cause of infantile diarrhea, although it can affect people of all ages. Like ETEC, diarrhea caused by EPEC is usually watery. The bacteria is also spread via the fecal-oral route, commonly via contaminated food and water. It is usually self-limited.

Uropathogenic E. Coli (UPEC): The Urinary Tract Infections Bacteria

Uropathogenic Escherichia coli (UPEC) cells adhered to bladder epithelial cells (BEC). Cells stained with methylene blue and fuchsine. Author: Stefan Walkowski

The strains that cause urinary tract infections are referred to as uropathogenic E. coli (UPEC). Individuals at increased risk of UPEC infections include neonates, sexually active women, geriatric individuals, and patients with indwelling urinary catheters.

Approximately 40% of adult women will experience cystitis at some point, with UPEC identified as the causative agent in 75-80% of instances of illness (3). Untreated cystitis caused by it can progress to pyelonephritis. Symptoms of cystitis/pyelonephritis may include dysuria, hematuria, increased urinary frequency, cloudy or foul-smelling urine, flank pain, vomiting, and fever.

Many different antibiotics are commonly used to treat UPEC, including penicillins, cephalosporins, fluoroquinolones, and trimethoprim-sulfamethoxazole. Treatment may be complicated by the increasing prevalence of antibiotic-resistant strains.

Shiga Toxin-Producing E. Coli (STEC) Infection

Shiga toxin-producing E. coli (STEC) is also referred to as Verocytotoxin-producing E. coli (VTEC) or Enterohemorrhagic E. coli (EHEC). This variety is most commonly associated with foodborne outbreaks in the developed world. It can be acquired from contaminated bovine meat, milk and dairy products, vegetables, fruit, and water (6).

Unlike ETEC and EPEC, infections with STEC usually cause bloody, loose stool. Treatment of diarrhea from STEC is supportive and includes fluid replacement. Infection with STEC can also cause hemolytic uremic syndrome (HUS), most notably associated with the E. coli O157:H7 strain. Nearly 40% of patients with STEC- hemolytic uremic syndrome require temporary renal replacement therapy, and up to 20% will have permanent residual kidney dysfunction (2).

Worldwide, it is estimated that STEC infection causes approximately 2.8 million acute illnesses annually, 3900 instances of HUS, 270 instances of end-stage renal disease, and 230 deaths (7).

In 1993, E. coli O157:H7 made headlines when an outbreak occurred at the Jack-in-the-Box restaurant chain in the United States, affecting a total of 73 restaurant locations across 4 states. The source of this outbreak was determined to be contaminated hamburger patties. More than 700 people became ill, including 171 hospitalizations and four deaths (8). More recently, in 2019, the CDC issued a warning to avoid Romaine lettuce from the Salinas Valley region in California (9). They reported that E. coli O157:H7 infection from this vegetable affected 167 people across 27 states, with 85 hospitalizations, and 15 instances of a hemolytic uremic syndrome (10).

The United States. E. coli – VTEC infection rates per 100,000

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Enteroaggregative E. Coli (EAEC) Infection

Enteroaggregative E. coli (EAEC) is recognized as the second most common cause of traveler’s diarrhea (10). It can also cause both acute and chronic childhood diarrhea. EAEC has been associated with reduced growth acceleration and failure to thrive among children in developing countries (11). EAEC are also the strains most commonly associated with loose stool among individuals with HIV/AIDS (12). Loose stool caused by EAEC is usually watery in nature. In some cases, infection is self-limiting, while in other cases, antibiotics are warranted. Fluoroquinolones, especially ciprofloxacin, are widely considered the treatments of choice (13).

Enteroinvasive E. Coli (EIEC) Infection

Enteroinvasive E. coli (EIEC) are strains that possess some of the biochemical characteristics of E. coli and have the ability to cause dysentery through an invasion mechanism similar to that of Shigella (14).  As in shigellosis, diarrhea caused by EIEC may be watery or bloody, and mucus is sometimes present. Infection is usually self-limiting. 

Diffusely Adherent E. Coli (DAEC) Infection

Diffusely-adherent E. coli (DAEC) is the most recent diarrheagenic E. coli pathogroup to be identified. DAEC infection is associated with diarrhea in children, where the risk of infection increases with age. These organisms have also been identified as agents of diarrhea in travelers and in patients with HIV/AIDS.  Strains have also been isolated from patients with inflammatory bowel disease and colorectal cancer (15).

Meningitis/Sepsis-Associated E. Coli (MNEC) Infection

Meningitis/Sepsis-Associated E. coli (MNEC) infection is a common cause of severe disease in neonates. MNEC infection has a fatality rate of 15–40% and may result in severe neurological defects in survivors (16). Third-generation cephalosporins are the recommended treatments for neonatal MNEC infection (17). Rarely, MNEC infection occurs in adults, particularly in those who are immunocompromised. 

The GIDEON Difference

GIDEON is one of the most well-known and comprehensive global databases for infectious diseases. Data is refreshed daily, and the GIDEON API allows medical professionals and researchers access to a continuous stream of data. Whether your research involves case count maps, learning about specific microbes, or testing out differential diagnosis tools– GIDEON has you covered with a program that has met standards for accessibility excellence.

References

(1) S. Baron, Medical microbiology. Galveston, Tex.: University of Texas Medical Branch at Galveston, 1996. [Online]

(2) “Escherichia coli”, GIDEON Informatics, Inc, 2021. [Online]

(3) H. Mobley, E. Hagan and M. Donnenberg, “Uropathogenic Escherichia coli”, EcoSal Plus, vol. 3, no. 2, 2009. Available: 10.1128/ecosalplus.8.6.1.3

(4) A. Mirhoseini, J. Amani and S. Nazarian, “Review on pathogenicity mechanism of enterotoxigenic Escherichia coli and vaccines against it”, Microbial Pathogenesis, vol. 117, pp. 162-169, 2018. Available: 10.1016/j.micpath.2018.02.032

(5) “Enterotoxigenic E. coli (ETEC)”, Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Foodborne, Waterborne, and Environmental Diseases (DFWED), 2014. [Online]

(6) “Pathogenicity assessment of Shiga toxin‐producing Escherichia coli (STEC) and the public health risk posed by the contamination of food with STEC”, European Food Safety Authority, 2020. [Online]

(7) Majowicz et al., “Global Incidence of Human Shiga Toxin-Producing Escherichia Coli infections and Deaths: A Systematic Review and Knowledge Synthesis”, Foodborne Pathogens and Disease, vol. 11, no. 6, pp. 447-455, 2014. Available: 10.1089/fpd.2013.1704

(8) “Jack in the Box E. Coli Outbreak – 25 Years Later”, Canadian Institute of Food Safety, 2021. [Online] 

(9) “The Final Update on the Multistate Outbreak of E. coli 0157:H7 Infections”, Centers for Disease Control and Prevention, 2020. [Online]

(10) H. Brüssow, “ESCHERICHIA COLI | Enteroaggregative E. coli”, Encyclopedia of Food Microbiology, pp. 706-712, 2014. Available: 10.1016/b978-0-12-384730-0.00387-6

(11) B. Hebbelstrup Jensen et al., “Enteroaggregative Escherichia coli in Daycare—A 1-Year Dynamic Cohort Study”, Frontiers in Cellular and Infection Microbiology, vol. 6, 2016. Available: 10.3389/fcimb.2016.00075

(12) A. Medina et al., “Diarrheagenic Escherichia coli in Human Immunodeficiency Virus (HIV) Pediatric Patients in Lima, Perú”, The American Journal of Tropical Medicine and Hygiene, vol. 83, no. 1, pp. 158-163, 2010. Available: 10.4269/ajtmh.2010.09-0596

(13) B. Hebbelstrup Jensen et al., “Characterization of Diarrheagenic Enteroaggregative Escherichia coli in Danish Adults—Antibiotic Treatment Does Not Reduce Duration of Diarrhea”, Frontiers in Cellular and Infection Microbiology, vol. 8, 2018. Available: 10.3389/fcimb.2018.00306

(14) M. Beld and F. Reubsaet, “Differentiation between Shigella, enteroinvasive Escherichia coli (EIEC) and noninvasive Escherichia coli”, European Journal of Clinical Microbiology & Infectious Diseases, vol. 31, no. 6, pp. 899-904, 2011. Available: 10.1007/s10096-011-1395-7

(15) M. Meza-Segura and T. Estrada-Garcia, “Diffusely Adherent Escherichia coli”, Escherichia coli in the Americas, pp. 125-147, 2016. Available: 10.1007/978-3-319-45092-6_6

(16) D. Wijetunge et al., “Characterizing the pathotype of neonatal meningitis causing Escherichia coli (NMEC)”, BMC Microbiology, vol. 15, no. 1, 2015. Available: 10.1186/s12866-015-0547-9

(17) Z. Zhao, X. Hua, J. Yu, H. Zhang, J. Li and Z. Li, “Duration of empirical therapy in neonatal bacterial meningitis with third-generation cephalosporin: a multicenter retrospective study”, Archives of Medical Science, vol. 15, no. 6, pp. 1482-1489, 2019. Available: 10.5114/aoms.2018.76938