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E. coli:A Cause of Renal Failure and Disseminated Intravascular Coagulation

Rick Russotti, CI/C, EMTP September 2007

Another outbreak of pathologic Escherichia coli (E. coli) O157:H7 has emerged in the United States as a result of contaminated hamburger meat. Contaminated meat and meat products are the major cause of food-borne E. coli infection. Other routes of infection include contaminated water, non-pasteurized milk and juice, and some raw lettuce/vegetables. Although food- and water-borne vectors may account for many E. coli infections, transmission of the bacteria can occur by person-to-person contact.

E. coli O157:H7 was discovered in the human colon in 1885 by German bacteriologist Dr. Theodor Escherich and identified as a disease causing agent, or pathogen, as a result of an outbreak of gastrointestinal illness in 1982. E. coli is a bacterium that lives in the intestine of healthy cattle and has been found in the intestines of healthy chickens, deer, sheep, and pigs. Because these animals lack the specific protein receptors for the disease, they do not get sick but are reservoirs for the bacteria. The O157:H7 indicates the subspecies of the E. coli bacteria; the O157 designates the specific carbohydrate and the H7 identifies the flagella protein. Although hundreds of variations of E. coli exist, the O157:H7 strain is different and belongs to a class of pathologic E. coli known as enterohemorrhagic Escherichia coli or EHEC. This strain of E. coli has the ability to produce a toxin; Verocytoxin E. coli (VTEC) or Shiga-like toxin (STEC). These toxins are known to cause severe complications from E. coli infection.

As previously noted, infection with E. coli can occur from eating undercooked contaminated meat, ingesting contaminated water or un-pasteurized beverages, contact with contaminated surfaces, or person to person contact. Contaminated meat looks and smells perfectly normal and the number of microbes needed to cause infection is very small. Transmission of the disease can occur from eating produce exposed to contaminated run-off or irrigation. Contamination of irrigation and soil can occur from infected manure being spread as fertilizer. As the bacteria can penetrate plant material; crops, even those not normally considered as a reservoir for E. coli, can harbor the bacteria and cause infection. Person-to-person contact among family members, close contact work environment, and child care centers can be difficult to manage. Bacteria found in the loose stool of a person infected with E. coli can be passed via the fecal/oral route if hygiene is lacking. Hand washing is of particular importance in the prevention of contamination and infection from the fecal/oral route.

Signs and symptoms of E. coli range from mild to severe and most often include brutal bloody diarrhea and abdominal cramps, with or without fever. Symptoms often resolve within ten-days and require little medical treatment. Oral and intravenous fluid replacement can be helpful, but antidiarrheal agents and antibiotics should be avoided. According to the Centers for Disease Control, antibiotics may actually precipitate renal complications. Deaths from E. coli occur annually in the United States and are caused by complications of the toxins (VTEC/STEC). These toxins are responsible for a condition known as Hemolytic Uremic Syndrome or HUS with approximately 2% to 7% of E. coli infections progressing with this complication. Hemolytic Uremic Syndrome (HUS) causes several life-threatening conditions including Acute Renal Failure (ARF) and Disseminated Intravascular Coagulation (DIC). Acute Renal Failure and Disseminated Intravascular Coagulation impact long-term health and recovery of E. coli patients. HUS causes 61 deaths annually (about 2-7% of E. coli patients) and another 8% go on to suffer complications of ARF such as high blood pressure, seizure, blindness and paralysis. ARF is diagnosed on the basis of increased blood urea nitrogen (BUN) and can be further classified as oliguric (urine output<400ml/24h)>
The development of DIC is more ominous. DIC is a condition of blood coagulation throughout the entire body. E. coli, sepsis, and viral hemorrhagic fevers are infectious causes of DIC. Other medical causes include amniotic emboli, eclampsia and Abrutio Plancentae; with burn trauma and profound decompensated shock states as traumatic causes. DIC can also be caused by some species of venomous snakes. Complications of renal failure and DIC are most often associated with patients in extremes of age; particularly children under five-years of age and the elderly. Increased potential of renal failure and DIC in the patient with a compromised immune system is not clear. Treatment for these conditions in the pre-hospital setting is to support the ABC’s and initiate intravenous fluid replacement per local protocol and medical direction.
There are a number of steps that can be taken to prevent E. coli infection. Since cattle intestine is the major source of the bacteria, strict adherence to regulations for the slaughter and processing of meat may decrease the contamination of meat products. Manure is another source of E. coli O157:H7 and can contaminate the environment, including ground and irrigation water. Containment and prevention of infection at the source, during processing and packaging, is key to abatement of outbreaks. There are numerous actions that can be taken to prevent infection and spread of E. coli; cooking all meat products thoroughly, proper storage of meat products, washing fruits and vegetables, consuming pasteurized milk, ciders, and juices, and by avoiding swallowing of pool water or lake water while swimming. For those engaged in patient care in the pre-hospital setting the most important preventative strategy is the easiest to employ: simple hand washing with soap and water and good hygiene practice coupled with body substance isolation and infection control practices. Each agency is required to have and implement an infection control plan. These plans are required to address agency-specific policy regarding body substance isolation and exposure incidents, reporting requirements, post exposure prophylaxis and treatment. The foundation of any infection control program and plan is based on training, management/employee buy-in, and prevention.
Situational awareness and education are the best defense against the spread of diseases like E. coli. Pre hospital care providers at all levels must arm themselves with the information needed to make good clinical decisions for their patients and good protective choices for themselves.

Recommended Reading:
Escherichia coli O157:H7; Wikipedia accessed 27 September 2007

E. coli O157:H7 - Escherichia coli O157:H7; accessed 16 September 2007

Escherichia coli O157:H7, General Information; CDC Bacterial, Mycotic Diseases accessed 16 September 2007

E. coli Questions and Answers; CDC

E. coli Outbreak from Fresh Spinach, October 12, 2006; CDC accessed 21 September 2007

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Influenza: The H’s and N’s

A tremendous amount of media attention has been placed on avian flu and pandemic situations. Hyped media attention and public confusion on the topic underscores the need for emergency responders to have the basic information and understanding of key concepts regarding types of influenza, terminology, and other details. Responders not armed with a basic understanding may lack the ability to gain situational awareness placing themselves, the public, and potentially their families at risk.

The term influenza is not synonymous with Avian Flu or pandemic. Influenza can be categorized in a variety of ways, but in general, influenza or flu is caused by a family of viruses known as Orthomyxoviridae and can be broken out into three types; type A, B, and C. There are numerous illnesses that can be responsible for the classic flu symptoms like body aches, chills and fever. Symptoms can range from mild to severe and include serious complications such as bacterial infections and pneumonia. Type A influenza crosses species and is the most hearty, or virulent, of the three strains. Highly Pathogenic Avian Influenza, or HPAI, is a type A flu virus. Type B flu virus targets only humans, is common and less severe than type A while type C, which impacts humans and swine, is rare and my have only mild symptoms or none at all.

Type A flu viruses receive much of our attention and is home to H5N1 or avian flu. The H’s and N’s represent designation of proteins of the virus and are important to the classification of Type A flu. Understanding the role of the H’s and N’s will also aid in understanding why vaccine development can be difficult. Designations such as H5N1 are used to further classify one type A virus from another. The “H” stands for hemagglutinin antigen (sometimes HA is used rather than just H). There are fifteen different hemagglutinin antigen (H/HA) proteins. The H proteins give the virus the ability to attach to the host cell. The “N” represents neuraminidase antigen (again, sometimes documented as NA rather than N). The neuraminidase protein allows the virus to be released from the cell and spread infection. There are nine neuraminidase antigen (N/NA) proteins. The numerous combinations of H’s and N’s allow the type A virus to infect such a large number of species. Remember, there are 15 different H proteins and 9 N proteins...that means there are 135 combinations of protein variations for type A influenza virus. Here’s the catch; a vaccine designed to work for one combination of proteins will not work for another and since type A (and B) influenza changes slightly from one flu season to another, creation of a vaccine for that particular season is tricky business. Keep in mind that the virus wants to survive and to do so will have to change; either slightly or drastically. A slight change in the virus is known as antigenic drift while drastic changes are called antigenic shifts. It is the antigenic shift that can cause a virus to change enough to cause severe disease or pandemic.

References: Pandemic Planning and Preparedness