Diarrheagenic E. coli (Clinical)

Overview

Microbiology^[4,6]

• Escherichia coli Escherichia coli The gram-negative bacterium Escherichia coli is a key component of the human gut microbiota. Most strains of E. coli are avirulent, but occasionally they escape the GI tract, infecting the urinary tract and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain and diarrhea. Escherichia coli is a gram-negative bacillus Bacillus Bacillus are aerobic, spore-forming, gram-positive bacilli. Two pathogenic species are Bacillus anthracis (B. anthracis) and B. cereus. Bacillus bacterium.
• Family: Enterobacteriaceae Enterobacteriaceae A family of gram-negative, facultatively anaerobic, rod-shaped bacteria that do not form endospores. Its organisms are distributed worldwide with some being saprophytes and others being plant and animal parasites. Many species are of considerable economic importance due to their pathogenic effects on agriculture and livestock. Cephalosporins
• Characteristics:
  • Ferments lactose
  • Facultatively anaerobic 
  • Oxidase-negative
  • Catalase-positive
• Most strains are harmless:
  • Aid in the synthesis Synthesis Polymerase Chain Reaction (PCR) of vitamins K and B₁₂
  • Protect against colonization Colonization Bacteriology by pathogenic organisms
  • Many are normal inhabitants of the GI tract.
• Pathogenic strains are:
  • Highly virulent enteric pathogens
  • Indistinguishable from other strains on culture plates and require additional identification Identification Defense Mechanisms techniques

Classification of diarrheagenic of E. coli^[1,3,4,6]

Diarrheagenic strains of E. coli can be classified into 5 key “pathotypes,” each of which has unique virulence factors Virulence factors Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: toxins, biological and surface adhesion molecules that affect the ability of the microorganism to invade and colonize a host. Haemophilus and pathologic mechanisms.

• Enterotoxigenic E. coli (ETEC)
• Enteropathogenic E. coli (EPEC)
• Enteroaggregative E. coli ( EAEC EAEC Escherichia coli)
• Enteroinvasive E. coli ( EIEC EIEC Escherichia coli)
• Enterohemorrhagic E. coli (EHEC)/ Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli–producing E. coli (STEC)

Virulence factors Virulence factors Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: toxins, biological and surface adhesion molecules that affect the ability of the microorganism to invade and colonize a host. Haemophilus^[4,6]

Virulence Virulence The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its virulence factors. Proteus traits are distinct for each category of pathogenic E. coli:

• Adherence factors: allow attachment to the intestinal mucosa Intestinal Mucosa Lining of the intestines, consisting of an inner epithelium, a middle lamina propria, and an outer muscularis mucosae. In the small intestine, the mucosa is characterized by a series of folds and abundance of absorptive cells (enterocytes) with microvilli. Small Intestine: Anatomy
• Toxins: interrupt normal intestinal cell secretion Secretion Coagulation Studies and absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption
• Adherence factors and toxins are encoded on accessory genetic elements:
  • Plasmids Plasmids Extrachromosomal, usually circular DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in genetic engineering as cloning vectors. DNA Types and Structure
  • Transposons
  • Bacteriophages Bacteriophages Viruses whose hosts are bacterial cells. Virology

Transmission^[3,4,6]

• Fecal–oral route
• Contaminated meat or produce (E. coli serotype O157:H7 and other STEC have a bovine reservoir Reservoir Animate or inanimate sources which normally harbor disease-causing organisms and thus serve as potential sources of disease outbreaks. Reservoirs are distinguished from vectors (disease vectors) and carriers, which are agents of disease transmission rather than continuing sources of potential disease outbreaks. Humans may serve both as disease reservoirs and carriers. Escherichia coli)
• Contaminated water (ingestion by drinking or while swimming)

Pathophysiology 

Each of the 5 main pathotypes has unique pathologic mechanisms.

Enterotoxigenic E. coli (ETEC)^[1,4,5]

Enterotoxigenic E. coli is a noninvasive pathogen. It uses fimbrial adhesins Adhesins Cell-surface components or appendages of bacteria that facilitate adhesion (bacterial adhesion) to other cells or to inanimate surfaces. Most fimbriae of gram-negative bacteria function as adhesins, but in many cases it is a minor subunit protein at the tip of the fimbriae that is the actual adhesin. In gram-positive bacteria, a protein or polysaccharide surface layer serves as the specific adhesin. What is sometimes called polymeric adhesin (biofilms) is distinct from protein adhesin. Diarrheagenic E. coli to bind BIND Hyperbilirubinemia of the Newborn enterocytes in the small intestine Small intestine The small intestine is the longest part of the GI tract, extending from the pyloric orifice of the stomach to the ileocecal junction. The small intestine is the major organ responsible for chemical digestion and absorption of nutrients. It is divided into 3 segments: the duodenum, the jejunum, and the ileum. Small Intestine: Anatomy and produces the following enterotoxins:

• Heat-stable enterotoxin Heat-stable enterotoxin Escherichia coli (ST):
  • Activates guanylate cyclase Guanylate cyclase An enzyme that catalyzes the conversion of GTP to 3. Diarrheagenic E. coli → ↑ intracellular cyclic guanosine monophosphate Cyclic guanosine monophosphate Guanosine cyclic 3. Second Messengers ( cGMP cGMP Guanosine cyclic 3. Phosphodiesterase Inhibitors) 
  • ↑ Chloride Chloride Inorganic compounds derived from hydrochloric acid that contain the Cl- ion. Electrolytes secretion Secretion Coagulation Studies and ↓ NaCl absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption → water efflux into the intestinal lumen → watery diarrhea Watery diarrhea Rotavirus
• Heat-labile enterotoxin Heat-labile enterotoxin Escherichia coli (LT):
  • Activates adenylate cyclase → ↑ intracellular cAMP cAMP An adenine nucleotide containing one phosphate group which is esterified to both the 3′- and 5′-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and acth. Phosphodiesterase Inhibitors 
  • ↑ Chloride Chloride Inorganic compounds derived from hydrochloric acid that contain the Cl- ion. Electrolytes secretion Secretion Coagulation Studies and ↓ NaCl absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption → water efflux into the intestinal lumen → watery diarrhea Watery diarrhea Rotavirus
  • Similar to cholera Cholera An acute diarrheal disease endemic in india and southeast Asia whose causative agent is Vibrio cholerae. This condition can lead to severe dehydration in a matter of hours unless quickly treated. Vibrio toxin (less severe)

Enteropathogenic E. coli (EPEC)^[1,4,5]

• Adherence factors:
  • Bundle-forming pilus (BFP)
  • Intimin Intimin Escherichia coli adhesin (an outer membrane protein)
• Attachment → cell deformation 
• > 20 protein toxins are injected into the cells. 
• Results in:
  • Effacement of microvilli
  • ↑ Tight junction permeability
  • Altered water and electrolyte secretion Secretion Coagulation Studies and absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption

Enteroaggregative E. coli ( EAEC EAEC Escherichia coli)^[1,4,5]

• Aggregative adherence fimbriae Aggregative adherence fimbriae Escherichia coli ( AAF AAF Escherichia coli) help bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology adhere to intestinal mucosa Intestinal Mucosa Lining of the intestines, consisting of an inner epithelium, a middle lamina propria, and an outer muscularis mucosae. In the small intestine, the mucosa is characterized by a series of folds and abundance of absorptive cells (enterocytes) with microvilli. Small Intestine: Anatomy.
  • The transcription Transcription Transcription of genetic information is the first step in gene expression. Transcription is the process by which DNA is used as a template to make mRNA. This process is divided into 3 stages: initiation, elongation, and termination. Stages of Transcription activator AggR controls AAF AAF Escherichia coli and numerous other pathogenic genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure.
  • AAF-encoding genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure are carried on a plasmid.
• Aggregation Aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Coagulation Studies of bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology forms a biofilm Biofilm Encrustations formed from microbes (bacteria, algae, fungi, plankton, or protozoa) embedded in an extracellular polymeric substance matrix that is secreted by the microbes. They occur on body surfaces such as teeth (dental deposits); inanimate objects, and bodies of water. Biofilms are prevented from forming by treating surfaces with dentifrices; disinfectants; anti-infective agents; and anti-fouling agents. Staphylococcus.
• Toxins produced:
  • Enterotoxins
  • Cytotoxins Cytotoxins Substances that are toxic to cells; they may be involved in immunity or may be contained in venoms. These are distinguished from cytostatic agents in degree of effect. Some of them are used as cytotoxic antibiotics. The mechanism of action of many of these are as alkylating agents or mitosis modulators. Helicobacter
  • Some produce Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli.

Enteroinvasive E. coli ( EIEC EIEC Escherichia coli)^[1,4,5]

• Related to Shigella Shigella Shigella is a genus of gram-negative, non-lactose-fermenting facultative intracellular bacilli. Infection spreads most commonly via person-to-person contact or through contaminated food and water. Humans are the only known reservoir. Shigella. The same genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure facilitate the pathogenesis of both organisms. 
• EIEC EIEC Escherichia coli invades an intestinal cell, multiplies intracellularly, and extends into the adjacent intestinal cells.
• Inflammatory response → necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage (can produce ulceration Ulceration Corneal Abrasions, Erosion, and Ulcers) → dysentery Dysentery Acute inflammation of the intestine associated with infectious diarrhea of various etiologies, generally acquired by eating contaminated food containing toxins, biological derived from bacteria or other microorganisms. Dysentery is characterized initially by watery feces then by bloody mucoid stools. It is often associated with abdominal pain; fever; and dehydration. Gastroenteritis

Enterohemorrhagic E. coli (EHEC)/ Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli–producing E. coli (STEC)^[1,4–6]

• The most common EHEC/STEC strain is O157:H7
• Enterohemorrhagic E. coli results in symptoms via Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli production:
  • Localized effect: inhibits enterocyte protein synthesis Synthesis Polymerase Chain Reaction (PCR) → enterocyte death → inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation
  • Systemic effect: vascular endothelial injury in glomeruli → microthrombi and renal dysfunction ( hemolytic uremic syndrome Hemolytic uremic syndrome A syndrome that is associated with microvascular diseases of the kidney, such as renal cortical necrosis. It is characterized by hemolytic anemia; thrombocytopenia; and acute renal failure. Hypocoagulable Conditions [ HUS HUS Hemolytic uremic syndrome (HUS) is a clinical phenomenon most commonly seen in children that consists of a classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome is a major cause of acute kidney injury in children and is most commonly associated with a prodrome of diarrheal illness caused by shiga-like toxin-producing bacteria. Hemolytic Uremic Syndrome])
• STEC falls into 2 clinically relevant categories:
  • High-risk STEC:
    • Either produce Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli 2 (with or without genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure for Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli 1) AND/OR are O157:H7 strains
    • Are associated with bloody diarrhea Bloody diarrhea Diarrhea and risk of HUS HUS Hemolytic uremic syndrome (HUS) is a clinical phenomenon most commonly seen in children that consists of a classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome is a major cause of acute kidney injury in children and is most commonly associated with a prodrome of diarrheal illness caused by shiga-like toxin-producing bacteria. Hemolytic Uremic Syndrome
  • Those without a gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics encoding Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli 2 (e.g., only encode Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli 1)
• Almost all E. coli O157:H7 contain a gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics encoding Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli 2.
• A few non-O157:H7 contain a gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics encoding Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli 2.
• Other virulence factors Virulence factors Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: toxins, biological and surface adhesion molecules that affect the ability of the microorganism to invade and colonize a host. Haemophilus:
  • Intimin Intimin Escherichia coli
  • Adherence factors
  • EHEC-hemolysin

Clinical Presentation

The epidemiologic and clinical features of the different types of diarrheagenic E. coli are described in the table.^[3–5]

Diagnosis

Diagnosing diarrheagenic E. coli requires a careful history; the diagnosis is confirmed through stool testing.^[1,2,6]

History

• Clinical presentation:
  • Watery and/or bloody diarrhea Bloody diarrhea Diarrhea
  • Associated symptoms: abdominal tenderness, nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics/ vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
• Detailed exposure history:
  • International travel
  • Recent consumption of:
    • Unpasteurized milk or dairy products
    • Raw or undercooked meat
    • Fruits or unpasteurized fruit juices, vegetables, leafy greens, or sprouts
  • Attend or work in:
    • Childcare center, long-term care facility, or prison
    • Hospital
    • Foodservice
    • Recreational water venue (pool or lake)
    • Farm or petting zoo
  • Exposure to a person with STEC infection or HUS HUS Hemolytic uremic syndrome (HUS) is a clinical phenomenon most commonly seen in children that consists of a classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome is a major cause of acute kidney injury in children and is most commonly associated with a prodrome of diarrheal illness caused by shiga-like toxin-producing bacteria. Hemolytic Uremic Syndrome, even without diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
  • Immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis host 
• A high degree of clinical correlation Correlation Determination of whether or not two variables are correlated. This means to study whether an increase or decrease in one variable corresponds to an increase or decrease in the other variable. Causality, Validity, and Reliability is needed, as:
  • Clinically insignificant pathogens may be identified.
  • Heat-labile or heat-stable enterotoxins must be correlated with a history of travel to endemic ETEC areas.

Stool testing^[2,3,13]

Distinguishes diarrheagenic E. coli strains from other types of infectious diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea.

Indications:^[2,13] 

• People presenting with diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea PLUS 1 of the following:
  • Bloody or mucoid stools
  • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
  • Severe abdominal cramping Abdominal cramping Norovirus/tenderness
  • Signs of sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock
• Occurs during suspected outbreaks Outbreaks Sudden increase in the incidence of a disease. The concept includes epidemics and pandemics. Influenza Viruses/Influenza
• Symptoms lasting > 7 days
• Note: Stool testing is not indicated in most cases of routine, nonbloody diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea.

Stool tests:

• Molecular stool testing ( nucleic acid amplification Nucleic acid amplification Laboratory techniques that involve the in-vitro synthesis of many copies of DNA or RNA from one original template. Septic Arthritis/PCR-based tests): Identifies relevant gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics targets in ETEC, EPEC, EAEC EAEC Escherichia coli, and EIEC EIEC Escherichia coli and for Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli.
  • Testing to distinguish between Shiga toxins 1 and 2 must be specifically requested.
  • Detection of a single gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics target is not equivalent to pathogen detection (except for Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli, a presumed STEC infection).
• Culture for E. coli O157:H7 on sorbitol-MacConkey agar
• Enzyme immunoassay Enzyme immunoassay HIV Infection and AIDS ( EIA EIA HIV Infection and AIDS) for Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli: can be used in addition to (but not instead of) selective culture

Specimens:

• Optimal specimen to diagnose EHEC: diarrheal stool sample
• Rectal swab if there is suspicion for STEC and the patient is unable to produce a stool specimen immediately 

Additional testing^[2]

• Blood cultures indicated for:^[2]
  • Infants < 3 months
  • Any individuals with signs of sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock
  • Immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship
  • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with recent travel or contact with travelers from endemic areas
• Laboratory tests:
  • CBC and peripheral smear for RBC fragments (when HUS HUS Hemolytic uremic syndrome (HUS) is a clinical phenomenon most commonly seen in children that consists of a classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome is a major cause of acute kidney injury in children and is most commonly associated with a prodrome of diarrheal illness caused by shiga-like toxin-producing bacteria. Hemolytic Uremic Syndrome is suspected)
  • Electrolytes Electrolytes Electrolytes are mineral salts that dissolve in water and dissociate into charged particles called ions, which can be either be positively (cations) or negatively (anions) charged. Electrolytes are distributed in the extracellular and intracellular compartments in different concentrations. Electrolytes are essential for various basic life-sustaining functions. Electrolytes, BUN, creatinine
  • Serologic testing to establish the etiology of infectious diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea is generally not recommended.
• Consider endoscopy Endoscopy Procedures of applying endoscopes for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. Transluminal, to examine or perform surgery on the interior parts of the body. Gastroesophageal Reflux Disease (GERD) in:
  • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with HIV HIV Anti-HIV Drugs and unexplained diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
  • Acute diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea with clinical colitis Colitis Inflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever. Pseudomembranous Colitis/ proctitis Proctitis Inflammation of the mucous membrane of the rectum, the distal end of the large intestine. Chronic Granulomatous Disease
  • Persistent diarrhea Persistent Diarrhea Entamoeba spp./Amebiasis in people who engage in receptive anal intercourse Anal intercourse Hemorrhoids

Management

Management is primarily supportive and may include antibiotics.^[2,5,6] Confirmed infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease should be reported to the local health department.

Treatment^[2,9,10]

Evaluate for dehydration Dehydration The condition that results from excessive loss of water from a living organism. Volume Depletion and Dehydration and provide supportive care:

• Indications for hospitalization Hospitalization The confinement of a patient in a hospital. Delirium:
  • EHEC/STEC
  • Evidence of significant dehydration Dehydration The condition that results from excessive loss of water from a living organism. Volume Depletion and Dehydration/severe disease
• Daily monitoring:
  • CBC
  • Electrolytes Electrolytes Electrolytes are mineral salts that dissolve in water and dissociate into charged particles called ions, which can be either be positively (cations) or negatively (anions) charged. Electrolytes are distributed in the extracellular and intracellular compartments in different concentrations. Electrolytes are essential for various basic life-sustaining functions. Electrolytes, BUN, creatinine
  • +/– albumin Albumin Serum albumin from humans. It is an essential carrier of both endogenous substances, such as fatty acids and bilirubin, and of xenobiotics in the blood. Liver Function Tests
• Isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids:
  • Lactated Ringer or normal saline Normal saline A crystalloid solution that contains 9. 0g of sodium chloride per liter of water. It has a variety of uses, including: as a contact lens solution, in ophthalmic solutions and nasal lavage, in wound irrigation, and for fluid therapy. Intravenous Fluids:
    • Often with 5% dextrose Dextrose Intravenous Fluids (except for boluses)
    • Consider adding potassium chloride Potassium chloride A white crystal or crystalline powder used in buffers; fertilizers; and explosives. It can be used to replenish electrolytes and restore water-electrolyte balance in treating hypokalemia. Esophagitis (based on lab results)
  • For confirmed STEC infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease in children:
    • Bolus: IV fluid 20 mL/kg 
    • Maintenance fluids: 2 L/m²/day
  • In adults:
    • Aggressive isotonic Isotonic Solutions having the same osmotic pressure as blood serum, or another solution with which they are compared. Renal Sodium and Water Regulation fluid administration, keeping in mind the entire clinical picture (e.g., cardiopulmonary conditions are exacerbated by fluid)
    • Watch for hemodilution to monitor effects of volume expansion.
• Electrolyte repletion:
  • Reduced osmolarity Osmolarity The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent. Hypernatremia oral rehydration Rehydration Dengue Virus solution (ORS): 1st-line for infants, children, and adults with acute diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea 
  • May be given via nasogastric tube Nasogastric tube Malnutrition in children in resource-limited countries in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia or severe weakness
• Antidiarrheals (for milder disease):
  • Bismuth subsalicylate Bismuth Subsalicylate Antidiarrheal Drugs: children ≥ 12 years and adults: 524 mg orally 4 times daily
  • Loperamide Loperamide One of the long-acting synthetic antidiarrheals; it is not significantly absorbed from the gut, and has no effect on the adrenergic system or central nervous system, but may antagonize histamine and interfere with acetylcholine release locally. Antidiarrheal Drugs:
    • Avoid in children < 18 years
    • Avoid in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with toxic megacolon Toxic megacolon An acute form of megacolon, severe pathological dilatation of the colon. It is associated with clinical conditions such as ulcerative colitis; Crohn disease; amebic dysentery; or Clostridium enterocolitis. Megacolon.
    • Start with 4 mg for the 1st dose, then 2 mg after each loose stool; maximum, 16 mg/day
• Antiemetics Antiemetics Antiemetics are medications used to treat and/or prevent nausea and vomiting. These drugs act on different target receptors. The main classes include benzodiazepines, corticosteroids, atypical antipsychotics, cannabinoids, and antagonists of the following receptors: serotonin, dopamine, and muscarinic and neurokinin receptors. Antiemetics: ondansetron Ondansetron A competitive serotonin type 3 receptor antagonist. It is effective in the treatment of nausea and vomiting caused by cytotoxic chemotherapy drugs, including cisplatin, and has reported anxiolytic and neuroleptic properties. Antiemetics 8 mg IV or orally every 8 hours as needed

Antibiotics:

• Typically, noempiric antibiotic therapy is needed.
  • Most cases resolve spontaneously.
  • Avoid antibiotics in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with confirmed high-risk STEC infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease (use is associated with HUS HUS Hemolytic uremic syndrome (HUS) is a clinical phenomenon most commonly seen in children that consists of a classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome is a major cause of acute kidney injury in children and is most commonly associated with a prodrome of diarrheal illness caused by shiga-like toxin-producing bacteria. Hemolytic Uremic Syndrome).
• Antibiotics may be needed for severe pathogenic E. coli infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease in:
  • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever and bloody diarrhea Bloody diarrhea Diarrhea
  • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with > 6 stools/day
  • Infants < 3 months with suspected bacterial etiology
  • Cases of volume depletion Volume depletion Volume status is a balance between water and solutes, the majority of which is Na. Volume depletion refers to a loss of both water and Na, whereas dehydration refers only to a loss of water. Volume depletion can be caused by GI losses, renal losses, bleeding, poor oral Na intake, or third spacing of fluids. Volume Depletion and Dehydration requiring hospitalization Hospitalization The confinement of a patient in a hospital. Delirium
  • Immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with severe illness and bloody diarrhea Bloody diarrhea Diarrhea
  • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with recent international travel and fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever ≥ 38.5°C or signs of sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock
• Antibiotics for confirmed positive patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship (ETEC or EHEC):^[9,10]
  • Ciprofloxacin Ciprofloxacin A broad-spectrum antimicrobial carboxyfluoroquinoline. Fluoroquinolones:
    • Children: 20–30 mg/kg/day orally in 1–2 divided doses for 1–3 days
    • Adults: 750 mg orally as a single dose; continue 500 mg twice daily for up to 3 days if symptoms do not resolve within 24 hours
  • Azithromycin Azithromycin A semi-synthetic macrolide antibiotic structurally related to erythromycin. It has been used in the treatment of Mycobacterium avium intracellulare infections, toxoplasmosis, and cryptosporidiosis. Macrolides and Ketolides:
    • Children: 10 mg/kg orally once daily for 1–3 days; maximum, 500 mg/day
    • Adults: 1000 mg orally for 1 dose; continue 500 mg once daily up to 3 days if symptoms do not resolve within 24 hours
  • Ofloxacin Ofloxacin A synthetic fluoroquinolone antibacterial agent that inhibits the supercoiling activity of bacterial DNA gyrase, halting DNA replication. Fluoroquinolones in adults: 400 mg orally twice daily for 1–3 days
  • Rifamycin in adults: 388 mg orally twice daily for 3 days
  • Rifaximin Rifaximin A synthetic rifamycin derivative and anti-bacterial agent that is used for the treatment of gastroenteritis caused by Escherichia coli infections. It may also be used in the treatment of hepatic encephalopathy. Hepatic Encephalopathy: 200 mg 3 times daily for 3 days
• Antibiotics in infants < 3 months and in others with neurologic involvement:
  • 3rd-generation cephalosporin Cephalosporin Multidrug-resistant Organisms and Nosocomial Infections, or
  • Azithromycin Azithromycin A semi-synthetic macrolide antibiotic structurally related to erythromycin. It has been used in the treatment of Mycobacterium avium intracellulare infections, toxoplasmosis, and cryptosporidiosis. Macrolides and Ketolides

Prevention^[9,10]

• Infection control:
  • Contact precautions (gloves, gowns)
  • Hand hygiene Hand hygiene Practices involved in preventing the transmission of diseases by hand. Surgical Infections with soap and water or alcohol-based sanitizers
• Food safety practices to avoid cross-contamination of other foods
• Individuals with diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea should avoid:
  • Swimming and water-related activities
  • Sexual contact while symptomatic
• A negative stool culture is often requested before returning to daycare, school, or food-preparation occupations.

Prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas^[8,9]

• Most cases of diarrheagenic E. coli infection resolve spontaneously in a few days.
• Most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with EHEC have spontaneous resolution (85%), but approximately 15% of children < 10 years of age develop HUS HUS Hemolytic uremic syndrome (HUS) is a clinical phenomenon most commonly seen in children that consists of a classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome is a major cause of acute kidney injury in children and is most commonly associated with a prodrome of diarrheal illness caused by shiga-like toxin-producing bacteria. Hemolytic Uremic Syndrome.

Differential Diagnosis

• Viral gastroenteritis Gastroenteritis Gastroenteritis is inflammation of the stomach and intestines, commonly caused by infections from bacteria, viruses, or parasites. Transmission may be foodborne, fecal-oral, or through animal contact. Common clinical features include abdominal pain, diarrhea, vomiting, fever, and dehydration. Gastroenteritis: inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the stomach Stomach The stomach is a muscular sac in the upper left portion of the abdomen that plays a critical role in digestion. The stomach develops from the foregut and connects the esophagus with the duodenum. Structurally, the stomach is C-shaped and forms a greater and lesser curvature and is divided grossly into regions: the cardia, fundus, body, and pylorus. Stomach: Anatomy and intestines caused by a variety of viruses Viruses Minute infectious agents whose genomes are composed of DNA or RNA, but not both. They are characterized by a lack of independent metabolism and the inability to replicate outside living host cells. Virology. Common clinical features include abdominal pain Abdominal Pain Acute Abdomen, diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea, vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, and dehydration Dehydration The condition that results from excessive loss of water from a living organism. Volume Depletion and Dehydration. The majority of cases of gastroenteritis Gastroenteritis Gastroenteritis is inflammation of the stomach and intestines, commonly caused by infections from bacteria, viruses, or parasites. Transmission may be foodborne, fecal-oral, or through animal contact. Common clinical features include abdominal pain, diarrhea, vomiting, fever, and dehydration. Gastroenteritis are self-limited; therefore, the diagnosis is generally clinical, and the only necessary treatment is supportive therapy.
• Shigellosis Shigellosis Shigella: caused by Shigella Shigella Shigella is a genus of gram-negative, non-lactose-fermenting facultative intracellular bacilli. Infection spreads most commonly via person-to-person contact or through contaminated food and water. Humans are the only known reservoir. Shigella species. S. dysenteriae S. dysenteriae A species of gram-negative, facultatively anaerobic, rod-shaped bacteria that is extremely pathogenic and causes severe dysentery. Infection with this organism often leads to ulceration of the intestinal epithelium. Shigella produces Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli. Individuals may experience fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, abdominal cramping Abdominal cramping Norovirus, and inflammatory diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea (with mucus, pus, and blood). Hemolytic uremic syndrome Hemolytic uremic syndrome A syndrome that is associated with microvascular diseases of the kidney, such as renal cortical necrosis. It is characterized by hemolytic anemia; thrombocytopenia; and acute renal failure. Hypocoagulable Conditions is a potential complication. The diagnosis is confirmed with a stool culture. Management includes supportive therapy and antibiotics (for moderate to severe disease).
• Giardiasis Giardiasis An infection of the small intestine caused by the flagellated protozoan giardia. It is spread via contaminated food and water and by direct person-to-person contact. Giardia/Giardiasis: caused by Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles lamblia, a flagellated protozoan that can infect the intestinal tract. The hallmark symptom of giardiasis Giardiasis An infection of the small intestine caused by the flagellated protozoan giardia. It is spread via contaminated food and water and by direct person-to-person contact. Giardia/Giardiasis is foul-smelling diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea and steatorrhea Steatorrhea A condition that is characterized by chronic fatty diarrhea, a result of abnormal digestion and/or intestinal absorption of fats. Diarrhea. Individuals who develop chronic infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease may suffer from weight loss Weight loss Decrease in existing body weight. Bariatric Surgery, failure to thrive Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive, and vitamin deficiencies as a result of malabsorption Malabsorption General term for a group of malnutrition syndromes caused by failure of normal intestinal absorption of nutrients. Malabsorption and Maldigestion. The diagnosis is made through detection of Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles organisms, antigens, or DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure in the stool. Management includes supportive treatment and antimicrobial therapy.
• Pseudomembranous colitis Colitis Inflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever. Pseudomembranous Colitis: infection caused by Clostridioides difficile. This species is commonly found in the normal gut microbiome Microbiome Commensal organisms living in and on the body Innate Immunity: Barriers, Complement, and Cytokines, but pathogenesis occurs when there is an overabundance of C. difficile. Common symptoms include foul-smelling, nonbloody diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea, abdominal pain Abdominal Pain Acute Abdomen, and nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics with vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia. Diagnosis is made with stool PCR Stool PCR Norovirus or enzyme assays. Treatment generally consists of discontinuing the offending antibiotic and administering oral fidaxomicin or vancomycin Vancomycin Antibacterial obtained from streptomyces orientalis. It is a glycopeptide related to ristocetin that inhibits bacterial cell wall assembly and is toxic to kidneys and the inner ear. Glycopeptides.
• Colonic ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage: hypoperfusion to areas of the colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix: Anatomy (often in regions without redundant sources of arterial blood). This hypoperfusion can be due to thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus, embolism, or hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension. The acute phase Acute phase Short Bowel Syndrome of colonic ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage is characterized by a classic triad of severe abdominal pain Abdominal Pain Acute Abdomen, vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia, and diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea that may be bloody. Individuals may have a history of cardiovascular disease. Diagnosis is generally made with laboratory studies and CTA CTA A non-invasive method that uses a ct scanner for capturing images of blood vessels and tissues. A contrast material is injected, which helps produce detailed images that aid in diagnosing vascular diseases. Pulmonary Function Tests. Treatment includes fluid replacement, antibiotics, systemic anticoagulation Anticoagulation Pulmonary Hypertension Drugs, and often surgery.
• Diverticulitis Diverticulitis Inflammation of a diverticulum or diverticula. Diverticular Disease: inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of diverticula (small outpouching regions of the colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix: Anatomy) often due to obstruction with fecal matter. Diverticulitis Diverticulitis Inflammation of a diverticulum or diverticula. Diverticular Disease presents with abdominal pain Abdominal Pain Acute Abdomen (most frequently in the LLQ), nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics, and diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea that may be bloody. The definitive diagnosis is usually made with a CT scan. Treatment involves bowel rest, IV fluids IV fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids, and antibiotics.