E. coli - Pathogenic

Table of Contents

Escherichia coli includes over a hundred different serotypes belonging to the group of gram-negative bacteria.  Most serotypes are harmless and live in the intestines of healthy humans and animals. 

Disease Information

Overview

Potential Bioterrorism Agent: Category B

Responsibilities

  • Hospital: Report by IDSS, facsimile, mail or phone
  • Lab: Report by IDSS, facsimile, mail or phone, send isolate to SHL - (319) 335-4500
  • Physician: Report by facsimile, mail or phone

Local Public Health Agency (LPHA): Follow-up required

Iowa HHS
Disease Reporting Hotline: (800) 362-2736
Secure Fax: (515) 281-5698

Six major categories of Escherichia coli strains cause diarrhea:

  1. Shiga-toxin producing E. coli,  (STEC) including Enterohemorrhagic E. coli (EHEC)
  2. Enterotoxigenic (individual cases are not reportable)
  3. Enteroinvasive (individual cases are not reportable)
  4. Enteropathogenic (individual cases are not reportable)
  5. Intestinal E. coli infection-Other enteroaggregative 
  6. E. coli and diffuse-adherent E. coli (individual cases are not reportable)

A. Agent

Escherichia coli includes over a hundred different serotypes belonging to the group of gram-negative bacteria.  Most serotypes are harmless and live in the intestines of healthy humans and animals. 

  • Shiga toxin-producing E. coli (STEC) include O157:H7, O26, O111, O103, O45, and O121. EHEC produce potent cytotoxins called Shiga toxin 1 and 2.
  • Enterotoxigenic (ETEC) category includes E. coli O6,08,O15, O020, O25, O27, O49, O63, O78, O128ac, O148, O153, O159, 167, and O169. This category of E. coli is a major cause of travelers’ diarrhea in people from industrialized countries who visit developing countries.
  • Enteroinvasive (EIEC) category includes O28ac, O29, O112, O124, O0136, O143, O144, O152, O164, and O167. The inflammatory disease of the gut mucosa and submucosa caused by EIEC strains of E. coli closely resembles that produced by Shigella.
  • Enteropathogenic (EPEC) category includes O55:NM, O55:H6, O55:H7, O86:NM, O86:H34, O111:NM, O111:H2, O111:H12, O111:H21, O114:NM, O127:H6, O127:H9, O127:H21, O128:H2, O128:H7, O128:H12, O142:H6, and O157:H45. Diarrheal disease in this category almost always occurs in children aged less than one year.

  • Intestinal E. coli infection – Other Enteroaggregative (EAEC) category includes O3:H2 and O44:H18. This category of diarrhea-producing E. coli is increasingly recognized as a cause of both acute and persistent diarrhea among children and adults. However, there is some debate about whether all strains of EAEC cause diarrhea.

    Diffuse-adherence (DAEC) category. DAEC is the least well-defined category of diarrhea-causing E. coli. Little is known at present about the reservoir, modes of transmission, host risk factors, or period of communicability of DAEC.

    Only cases of Shiga toxin-producing E. coli are reportable in Iowa. Individual cases of other types of E. coli do not require public health investigation. However, all outbreaks of any type of E. coli are reportable to IDPH.

B. Clinical Description

Infection with pathogenic E. coli may present with a wide spectrum of clinical manifestations. An individual may be asymptomatic, have mild non-bloody diarrhea, or have grossly bloody diarrhea. Most diagnosed cases develop bloody diarrhea 6 to 48 hours after the onset of non-bloody diarrhea. Abdominal cramps, nausea and vomiting may also be present. Fever is usually absent. In severe cases, the patient may progress to develop other clinical syndromes such as hemolytic uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP).  Hemolytic uremic syndrome (HUS) is characterized by the acute onset of microangiopathic hemolytic anemia, renal injury, and low platelet count. Thrombotic thrombocytopenic purpura (TTP) is characterized by anemia and low platelet counts but can include central nervous system (CNS) involvement and fever.

C. Reservoirs

  • EHEC: Cattle appear to be a reservoir of significant public health importance; however, other animals, such as deer, are also known to carry EHEC. In addition, humans serve as a reservoir.
  • ETEC: Humans; although also occurs in animals people are the reservoir for strains causing diarrhea in humans.
  • EIEC and EPEC: humans

D. Modes of Transmission

  • STEC and ETEC transmission occurs fecal-orally via contaminated food, drinking water or recreational water. Transmission may also occur directly from person-to-person; and can include certain types of sexual contact. The infectious dose for E. coli O157:H7 is very low (about 100 organisms). E. coli O157:H7 has been associated with the consumption of undercooked contaminated ground beef, unpasteurized apple juice and cider, unpasteurized milk and other dairy products, raw fruits and vegetables, and salami.
  • EIEC: Scant available evidence suggests that it is transmitted by contaminated food.
  • EPEC transmission has occurred through contaminated infant formula and weaning foods. In infant nurseries, transmission by fomites and contaminated hands can occur. Outbreaks due to contaminated rice and water have been reported.

E. Incubation Period

  • STEC: The incubation ranges from 2 - 10 days with a median of 3 - 4 days.
  • ETEC: The incubation ranges from 10 to 72 hours.
  • EIEC: The incubation period of 10 to 18 hours have been observed
  • EPEC: Incubations periods as short as 9 to 12 hours have been observed in adults studies

F. Period of Communicability or Infectious Period

  • STEC: One week or less in adults but up to 3 weeks in about one-third of infected children. Prolonged carriage is uncommon.
  • ETEC and EPEC: for duration of excretion of the pathogen, which may be prolonged.
  • EIEC: for the duration of the pathogen excretion.

G. Epidemiology

  • STEC was first identified in 1982 in an outbreak in the United States. Since then, infections have been recognized as an important cause of bloody diarrhea in North America, Europe, Japan, Australia and southern South America. As with other enteric illnesses, the young and old are usually more severely ill when infected. Infection in young children may lead to complications such as HUS in about 5 to 10% of cases. Sporadic cases of E. coli O157:H7 infections occur throughout the year with a peak in the incidence of disease during the summer months. Outbreaks in the United States have been associated with undercooked ground beef, unpasteurized milk and apple cider, and other food products. Most cases are due to inadequately cooked ground beef.
  • ETEC: This category of E. coli is a major cause of travelers’ diarrhea in people from industrialized countries who visit developing countries. ETEC is also a major cause of dehydrating diarrhea in infants and children in developing countries, especially among children less than 2 years of age. It has been estimated that globally ETEC causes as many as 380,000 deaths annually in children under five.
  • EIEC infections are endemic in developing countries and cause about 1%-5% of diarrheal episodes among people visiting treatment centers. Rarely, infection and outbreaks of EIEC diarrhea have been reported in industrialized countries.
  • EPEC: The oldest recognized category of diarrhea-producing E. coli, implicated in outbreaks in the 1940’s and 1950’s. Diarrheal disease in this category is virtually confined to children aged less than one year. It is rarely seen in North America and Europe but remains a major agent of infant diarrhea in many developing area, including South America sub-Saharan Africa, and Asia.
  • EAEC: This category of diarrhea-producing E. coli is increasingly recognized as a cause of both acute and persistent diarrhea among children and adults. EAEC associated with infant diarrhea have been reported from Latin America, Asia, and sub-Saharan Africa and may be responsible for a proportion of diarrheal disease in developed countries. EAEC associated diarrhea has also been associated with HIV-infected adults and international travelers to developing countries.

H. Bioterrorism Potential

Category B Agent: E. coli has been identified as a potential category B bioterrorism agent as a food safety threat.

I. Additional Information

The Council of State and Territorial Epidemiologists (CSTE) surveillance case definitions for pathogenic E. coli can be found at:  https://ndc.services.cdc.gov/conditions/escherichia-coli-o157h7/

CSTE case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain uniform standards for national reporting.)

Fact Sheets and Forms

References

American Academy of Pediatrics. 2006 Red Book: Report of the Committee on Infectious Diseases, 27th Edition. Illinois, Academy of Pediatrics, 2003.

CDC Website. Escherichia coli O157:H7. www.cdc.gov/ecoli/index.html

Heymann, D.L., ed. Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015.

Iowa Administrative Code (641) Chapter 1   Notification & Surveillance of Reportable Communicable & Infectious Diseases, Poisonings & Conditions.

Resources