Enteric Infections and Food Poisoning Overview
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Enteric Infections and Food Poisoning Overview

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Questions and Answers

What is the primary cause of gastroenteritis?

  • Contaminated food
  • Irritating food or drink
  • Psychological factors such as stress
  • All of the above (correct)

    • Which of the following is NOT a common symptom of food poisoning?

  • Liver failure (correct)
  • Gastroenteritis
  • Systemic illness
  • Neurological syndromes

    • Which of the following food items is specifically mentioned as a potential source of food poisoning?

  • Shellfish (correct)
  • Vegetables
  • Grains
  • Fruits

    • What is the minimum number of loose stool episodes in a 24-hour period to define diarrhea?

    <p>3 episodes</p> Signup and view all the answers

    Which virulence factor contributes to the pathogenesis of foodborne pathogens?

    <p>Capsule production</p> Signup and view all the answers

    What method is often used for the laboratory diagnosis of food poisoning?

    <p>Stool culture</p> Signup and view all the answers

    Which of the following is NOT a recommended measure to prevent foodborne illnesses?

    <p>Consuming raw shellfish</p> Signup and view all the answers

    What is the main route of transmission for foodborne pathogens?

    <p>Faecal-oral route</p> Signup and view all the answers

    Which diagnostic method is used to confirm a diagnosis of COLI?

    <p>Stool PCR</p> Signup and view all the answers

    What is the main characteristic of the diarrhoea caused by enterotoxigenic E. coli?

    <p>Watery diarrhoea without blood</p> Signup and view all the answers

    What are the possible outcomes for infants affected by enteropathogenic E. coli?

    <p>Severe dehydration and higher mortality</p> Signup and view all the answers

    Which of the following statements about listeria monocytogenes is correct?

    <p>It can grow at temperatures as low as 2°C.</p> Signup and view all the answers

    What management strategy is recommended for treating COLI?

    <p>Rehydration is the primary treatment.</p> Signup and view all the answers

    What is the primary source of Campylobacter spp. infections in humans?

    <p>Contaminated animal products</p> Signup and view all the answers

    What is the main clinical feature of a Campylobacter infection?

    <p>Severe abdominal pain</p> Signup and view all the answers

    Which condition is a rare complication of Campylobacter infections?

    <p>Guillain-Barre syndrome</p> Signup and view all the answers

    What is the incubation period for Campylobacter infections?

    <p>2-4 days</p> Signup and view all the answers

    Which laboratory finding is characteristic of Campylobacter spp.?

    <p>Curved-shaped, Gram-negative bacilli</p> Signup and view all the answers

    How does Campylobacter typically spread in humans?

    <p>Foodborne transmission</p> Signup and view all the answers

    Which symptom can indicate a severe case of Campylobacter infection?

    <p>Bloody diarrhea</p> Signup and view all the answers

    What pathophysiological mechanism does Campylobacter employ to damage the intestine?

    <p>Adheres and invades mucosal surfaces</p> Signup and view all the answers

    What is the primary characteristic of the toxin produced by Staphylococcus aureus?

    <p>It is a heat-stable enterotoxin that can cause rapid onset symptoms.</p> Signup and view all the answers

    What conditions are most conducive to the growth of Staphylococcus aureus in food?

    <p>Food left at room temperature after being handled.</p> Signup and view all the answers

    Which type of food is primarily associated with Bacillus cereus Type 1 Emetic Syndrome?

    <p>Cooked rice that has cooled slowly.</p> Signup and view all the answers

    What symptom is most commonly associated with Clostridium perfringens infections?

    <p>Profuse diarrhoea.</p> Signup and view all the answers

    What is the recommended incubation period for Clostridium perfringens to cause symptoms?

    <p>8-24 hours.</p> Signup and view all the answers

    Which of the following incorrectly describes the Clostridium botulinum toxin?

    <p>It is a heat-stable toxin that cannot be inactivated by cooking.</p> Signup and view all the answers

    What is the primary treatment approach for foodborne illnesses caused by these toxins?

    <p>Providing supportive care.</p> Signup and view all the answers

    Which of the following practices can help prevent foodborne illnesses from bacterial toxins?

    <p>Keeping cooked and raw food separate.</p> Signup and view all the answers

    What is a significant characteristic of Listeria monocytogenes regarding its survival in the body?

    <p>It survives within macrophages.</p> Signup and view all the answers

    Which group is most at risk for severe illness from Listeria monocytogenes?

    <p>Immunosuppressed patients and pregnant women.</p> Signup and view all the answers

    What is a common clinical feature of neonatal listeriosis?

    <p>CNS involvement and abscesses.</p> Signup and view all the answers

    What complication may occur in pregnant women due to Listeria monocytogenes?

    <p>Miscarriage and intrauterine death.</p> Signup and view all the answers

    How is Listeria monocytogenes typically diagnosed in a patient?

    <p>Blood cultures or CSF analysis.</p> Signup and view all the answers

    What treatment is commonly used for Listeria monocytogenes infections?

    <p>High dose ampicillin with aminoglycoside.</p> Signup and view all the answers

    What preventive measure is recommended for people at high risk of Listeria monocytogenes infection?

    <p>Steer clear of raw or partially cooked animal products.</p> Signup and view all the answers

    Which of the following is a recognized characteristic of late onset neonatal listeriosis compared to early onset?

    <p>More common than early onset.</p> Signup and view all the answers

    What is the primary characteristic of enterotoxigenic E. coli in terms of its biological behavior?

    <p>It adheres to the intestinal lining without invasiveness.</p> Signup and view all the answers

    During which environmental condition is Listeria monocytogenes most likely to peak in infection rates?

    <p>Warmer months when foodborne pathogens thrive.</p> Signup and view all the answers

    What symptom differentiates enteropathogenic E. coli from enterotoxigenic E. coli?

    <p>Major loss of villi leading to malabsorption.</p> Signup and view all the answers

    What is the recommended isolation protocol for managing COLI?

    <p>Isolation in hospital requiring contact precautions.</p> Signup and view all the answers

    Which type of toxin produced by enterotoxigenic E. coli is associated with increased electrolyte secretion leading to diarrhea?

    <p>LT (heat-labile) toxin causing short-term fluid loss.</p> Signup and view all the answers

    Which of the following types of illnesses can result from food poisoning?

    <p>Systemic illnesses like listeriosis and enteric fever</p> Signup and view all the answers

    What is the primary cause of food poisoning caused by bacteria?

    <p>Ingestion of food containing bacteria or their toxins</p> Signup and view all the answers

    Which of the following factors can contribute to the occurrence of foodborne infections?

    <p>Lack of hygiene in food handling</p> Signup and view all the answers

    Which of the following correctly describes the phenomenon of gastroenteritis?

    <p>Acute inflammation of the stomach and intestines from various causes</p> Signup and view all the answers

    What is the primary mechanism by which the toxin from Campylobacter spp. affects the human body?

    <p>Binds to presynaptic nerve endings</p> Signup and view all the answers

    Which pathogen is NOT typically associated with food poisoning?

    <p>Mycobacterium tuberculosis</p> Signup and view all the answers

    Which of the following is a significant complication associated with Campylobacter infection?

    <p>Toxic megacolon</p> Signup and view all the answers

    In the context of food poisoning, what does the term 'faecal-oral route' refer to?

    <p>Ingestion of water contaminated by human waste</p> Signup and view all the answers

    What prevention method is crucial for reducing the spread of foodborne illnesses?

    <p>Ensuring proper hand hygiene among food workers</p> Signup and view all the answers

    Which of the following species is most commonly associated with human disease caused by Campylobacter?

    <p>C. jejuni</p> Signup and view all the answers

    What is the typical laboratory diagnosis feature of Campylobacter spp. on selective charcoal media?

    <p>Curved-shaped greyish colonies</p> Signup and view all the answers

    Which of the following is a common consequence of food poisoning that can occur after initial symptoms?

    <p>Progression to systemic illnesses such as listeriosis</p> Signup and view all the answers

    During what seasonal period do cases of Campylobacter infection tend to peak, and why?

    <p>Summer, due to barbecue season</p> Signup and view all the answers

    What typically follows the incubation period of 2-4 days in a Campylobacter infection?

    <p>Manifestation of prodromal symptoms</p> Signup and view all the answers

    Which of the following transmission routes for Campylobacter is least common?

    <p>Spread through aerosols from infected animals</p> Signup and view all the answers

    In severe cases of Campylobacter infection, what pathological finding may occur in the bowel?

    <p>Crypt abscess formation</p> Signup and view all the answers

    What is the primary rapid effect of the Staphylococcus aureus enterotoxin after ingestion?

    <p>Predominantly vomiting</p> Signup and view all the answers

    What type of food is primarily associated with Bacillus cereus Type 2 Diarrhoeal Syndrome?

    <p>Meats and salads</p> Signup and view all the answers

    Which of the following correctly describes the incubation period for Clostridium perfringens infections?

    <p>8-24 hours</p> Signup and view all the answers

    What symptoms primarily characterize an outbreak of Clostridium perfringens food poisoning?

    <p>Profuse diarrhea and occasional vomiting</p> Signup and view all the answers

    What is the most critical factor contributing to the growth of Staphylococcus aureus in food?

    <p>Poor refrigeration and room temperature storage</p> Signup and view all the answers

    What aspect of Clostridium botulinum toxin is particularly concerning in food safety?

    <p>It is a neurotoxin that can lead to severe neurological symptoms</p> Signup and view all the answers

    Which food safety practice is crucial for preventing the growth of Bacillus cereus?

    <p>Cooling food immediately after cooking</p> Signup and view all the answers

    What factor does NOT contribute to the severity of foodborne illnesses caused by bacterial toxins?

    <p>The color of the contaminated food</p> Signup and view all the answers

    What is the primary reservoir of enterohaemorrhagic E. coli?

    <p>Cattle</p> Signup and view all the answers

    Which serotype is most commonly associated with enterohaemorrhagic E. coli infections?

    <p>E.coli O157:H7</p> Signup and view all the answers

    Which clinical feature indicates a severe case of enterohaemorrhagic E. coli infection, especially in infants?

    <p>Bloody diarrhoea</p> Signup and view all the answers

    Which of the following antibiotics is recommended for use in cases of enterohaemorrhagic E. coli infection?

    <p>Ciprofloxacin</p> Signup and view all the answers

    What complication occurs in approximately 10% of children under 10 years of age infected with enterohaemorrhagic E. coli?

    <p>Hemolytic uremic syndrome</p> Signup and view all the answers

    Which of the following practices can help prevent infections caused by enterohaemorrhagic E. coli?

    <p>Washing hands after contact with animals</p> Signup and view all the answers

    What pathophysiological mechanism does enterohaemorrhagic E. coli primarily use to harm the intestinal lining?

    <p>Disrupting protein synthesis</p> Signup and view all the answers

    What is the typical incubation period for infections caused by enterohaemorrhagic E. coli?

    <p>1-10 days</p> Signup and view all the answers

    Study Notes

    Enteric (GI) Infections

    • Gastroenteritis: inflammation of the stomach and intestines, can be caused by food poisoning, irritants, or stress.
    • Food poisoning: illness caused by consuming contaminated food containing microorganisms, toxins, or poisons.
    • Diarrhoea: 3 or more episodes of loose or liquid stool in a 24-hour period.

    Food Poisoning Epidemiology

    • Common and multi-factorial: with many infectious causes.
    • Sporadic and outbreak potential: often affecting individuals but can cause large outbreaks.
    • Notifiable to Public Health: reported to authorities (full list on HPSC website).
    • Transmission: mainly contaminated food or water, via faecal-oral route.

    Infectious Causes of Food Poisoning

    • Bacterial: Staphylococcus aureus, Clostridium spp, Campylobacter spp.
    • Viral: Refer to viral gastroenteritis lectures.

    Staphylococcus aureus (S. aureus)

    • Heat-stable enterotoxin: ingested through contaminated food.
    • Food sources: dairy, produce, meats, eggs, salads.
    • Contamination process: food handler contaminates food, left at room temperature, organisms multiply producing toxin.
    • Symptoms: vomiting (predominant), occasionally diarrhoea.
    • Duration: 1-8 hours of incubation, lasting 8-24 hours.
    • Outbreak prevalence: common during summer months.
    • Diagnosis: based on history.
    • Treatment: supportive care.

    Bacillus Cereus (B. cereus)

    • Two forms of poisoning: emetic syndrome and diarrhoeal syndrome.
    • Emetic Syndrome: Ingestion of preformed toxin, usually through cooked rice allowed to cool slowly at room temperature.
    • Diarrhoeal Syndrome: Ingestion of spores in foods like meats, salads, chicken soup.
    • Emetic Syndrome symptoms: vomiting, abdominal cramps, may have diarrhoea, lasts 2-10 hours.
    • Diarrhoeal Syndrome symptoms: diarrhoea (main symptom), lasts 8-24 hours.
    • Duration: 1-6 hours (emetic) and 6-14 hours (diarrhoeal).
    • Diagnosis: based on history.
    • Treatment: supportive care.

    Clostridium perfringens (C. perfringens)

    • Spore contamination: food contaminated with heat- resistant spores are ingested.
    • Food sources: Incorrectly stored cooked meat dishes, gravy, dairy products.
    • Toxin production: Multiplication in the small intestine, sporulation and enterotoxin production.
    • Incubation period: 8-24 hours.
    • Symptoms: profuse diarrhoea, occasionally vomiting.
    • Duration: 1-3 days.

    Clostridium botulinum (C. botulinum)

    • Toxin (neurotoxin) ingestion: food contaminated with toxin is ingested.
    • Food sources: improperly canned products, home bottled items (e.g. pickles, honey).
    • Incubation period: 12-36 hours.
    • Toxin action: absorbed from GIT into bloodstream, binds to nerve endings, inhibits acetylcholine release.
    • Symptoms: acute descending symmetrical weakness, bilateral cranial nerve palsies, paralysis, requiring mechanical ventilation.
    • Mortality rate: 20%.
    • Treatment: anti-toxin.

    Campylobacter spp

    • Most common cause of bacterial food poisoning: in developed countries.
    • Species causing disease: C. jejuni (most common), C. coli, C. fetus, C. lari.
    • Source: Normal flora in animals, particularly cattle, swine, and birds.
    • Zoonosis: transmission from animals to humans through contaminated animal products.
    • Contamination: Carcasses/meat contaminated by faeces during slaughter.
    • Routes of transmission: mainly foodborne (undercooked meat, raw or contaminated milk), less common person-person via faecal-oral route.
    • Peak season: summer months.

    Campylobacter spp. Pathogenesis

    • Ingestion: enters the body.
    • Adherence: adheres to jejunum and ileum.
    • Cytotoxin action: causes local damage (mucosal invasion), occasionally causing severe haemorrhagic necrosis of the small intestine.
    • Large bowel involvement: may involve large bowel with crypt abscess formation (severe cases), resembling ulcerative colitis.
    • Bloodstream spread: occurs in some individuals.

    Campylobacter spp. Clinical Features

    • Incubation period: 2-4 days (up to 8-9 days).
    • Symptoms: prodromal illness (fever, headache), diarrhoea (may be bloody), abdominal pain (can be severe).
    • Duration: resolves in 5-7 days.
    • Complications: Toxic megacolon, bacteraemia (extremes of age/immunosuppressed), Guillain-Barre syndrome (rare).

    Campylobacter spp. Laboratory Diagnosis

    • Microscopy: Gram-negative bacilli with typical curved shape.
    • Culture: greyish colonies on selective charcoal-containing media incubated in CO2 at 42°C.
    • Tests: positive oxidase test, hydrolyzes hippurate (blue colour).

    Campylobacter spp. Management

    • Rehydration: essential for managing dehydration.
    • Antibiotics not indicated: may increase toxin release, worsening symptoms.
    • Isolation: require isolation in hospital, contact precautions.

    Enterotoxigenic Escherichia coli (ETEC)

    • Travellers' diarrhoea: common in underdeveloped countries with poor sanitation.
    • Incubation period: 1-3 days.
    • Symptoms: watery (non-bloody) diarrhoea, fever, nausea, ranging from mild discomfort to severe cholera-like syndrome.
    • Duration: self-limiting, 1-5 days.
    • Infected site: small intestine.
    • Pathogenesis: adheres to intestinal mucosa without invasion, enterotoxins (LT and ST) cause fluid and electrolyte secretion, leading to diarrhoea.

    Enteropathogenic Escherichia coli (EPEC)

    • Major cause of infantile gastroenteritis: in infants younger than 6 months old, particularly in developing countries.
    • Mortality rate: high due to severe dehydration.
    • Transmission: person-to-person spread, potentially causing outbreaks.
    • Infected site: small intestine.
    • Pathogenesis: attaches to intestinal mucosa, causing loss of villi, invades host cells and disrupts cellular signal transduction, leading to symptoms.
    • Symptoms: watery diarrhoea, vomiting, fever.

    Listeria monocytogenes (L. monocytogenes)

    • Wide temperature tolerance: grows between 2-37°C.
    • Peak infection: warmer months.
    • Transmission: contaminated milk, certain soft cheeses, pate, animal contact, vertical transmission (mother to foetus).
    • Pathogenesis: crosses mucosal barrier and spreads, survives within macrophages, requiring a T-cell response for killing infected cells.

    Listeria monocytogenes Clinical Features

    • Healthy adults: mostly asymptomatic or mild influenza-like illness/diarrhoea.
    • Occupational risk: farmers, vets, butchers.
    • At-risk groups: pregnant women, neonates, immunosuppressed patients.
    • Complications: pneumonia, meningoencephalitis in immunosuppressed patients.

    Listeria monocytogenes & Pregnancy

    • Perinatal listeriosis: influenza-like illness in mother, usually in the third trimester.
    • Complications: miscarriage, intrauterine death, premature labour, neonatal listeriosis.
    • Neonatal listeriosis: early onset (first 2 days of life) acquired in utero, or late onset (after 5 days) acquired from maternal genital tract.
    • Early Onset symptoms: BSI, pneumonia, cardiopulmonary distress, hepatosplenomegaly, abscesses, CNS involvement.
    • Late Onset symptoms: meningitis, meningoencephalitis, BSI.

    Listeria monocytogenes Diagnosis and Treatment

    • Diagnosis: blood cultures, CSF, vaginal swab, placenta, microscopy (gram-positive bacillus with tumbling motility).
    • Treatment: high dose ampicillin/amoxicillin with an aminoglycoside (e.g. Gentamicin).
    • Resistant to cephalosporins.
    • Prevention: Avoid raw or partially cooked foods of animal origin for high-risk groups.

    Cryptosporidium

    • Species: C. parvum and C. hominis.
    • Clinical presentation: to be discussed further.

    Enteric (GI) Infections

    • Gastroenteritis - acute inflammation of stomach and intestines lining, caused by food poisoning, irritating food/drink, or psychological factors
    • Food Poisoning - illness from contaminated food or food that contains microorganisms/toxins/poisons
    • Diarrhea - 3+ episodes of loose/liquid stools within 24 hours

    Food Poisoning: Epidemiology

    • Common and caused by many infectious agents
    • Usually sporadic but can cause outbreaks
    • Notifiable to Public Health
    • Transmission: Contaminated food/water & Faecal-oral route

    Infectious Causes

    • Bacterial:
      • Staphylococcus aureus, Clostridium spp., Campylobacter spp.
    • Viral:
      • See lecture on viral gastroenteritis

    Toxins: S.aureus

    • Heat-stable enterotoxin ingested in food (dairy, produce, meats, eggs, salads)
    • Food handler contaminates food -> left at room temp -> organisms multiply -> produce toxin
    • Person ingests enteroxin
    • Works fast (1-8 hrs) -> vomiting predominates, occasional diarrhea
    • Lasts 8-24 hrs; outbreaks especially in summer
    • Diagnosis = History; Treatment = Supportive

    Toxins: Bacillus cereus

    • Type 1: Emetic syndrome:
      • Ingested in preformed toxin (cooked rice)
      • Allowed to cool slowly at room temp or held for long period
      • Germination from spores with release of toxin
      • Rapid heating doesn't destroy toxin
    • Type 2: Diarrhoeal syndrome:
      • Spores ingested in food (meats, salads, chicken soup)
      • Toxin production after spores germinate
      • Works fast (1-6 hours) -> Predominantly vomiting, abdominal cramps, may have diarrhea
      • Lasts 2-10 hours
      • Diagnosis = History; Treatment = Supportive

    Toxins: Clostridium perfringens

    • Food contaminated with heat-resistant spores ingested
      • Incorrectly stored cooked meat dishes, gravy, dairy products
    • Toxin production in vivo:
      • Multiplication in small intestine
      • Sporulation + enterotoxin production
    • Incubation 8-24 hours
    • Profuse diarrhea, occasionally vomiting
    • Lasts 1-3 days

    Toxins: Clostridium botulinum

    • Food contaminated with toxin (neurotoxin) ingested
      • Improperly canned products, home bottled products e.g. pickles, honey
    • Incubation 12-36 hours
    • Toxin absorbed from GIT into bloodstream
      • Binds irreversibly to presynaptic nerve endings (peripheral and cranial nerves)
      • Inhibits acetylcholine release
    • Acute descending symmetrical weakness / bilateral cranial nerve palsies
      • Paralysis, mechanical ventilation required
      • High mortality - 20%
    • Treat with anti-toxin

    Campylobacter spp.

    • Most common cause of bacterial food poisoning in developed countries
    • 4 species associated with human disease:
      • C. jejuni (most common), C. coli, C. fetus, C. lari
    • Source: Normal flora: cattle, swine, birds
    • Zoonosis: To humans from animals/animal products
      • Carcasses/meat contaminated from faeces during slaughtering
    • Transmission: Mostly foodborne (undercooked meat, raw/contaminated milk, contaminated water/ice), person-person via faecal oral route (less common)
    • Cases peak in summer

    Campylobacter spp: Pathogenesis

    • Adheres to jejunum and ileum
      • Cytotoxin causes local damage (mucosal invasion)
      • Occasionally severe haemorrhagic necrosis of the small intestine
      • Large bowel involvement with crypt abscess formation
      • Differential Diagnosis = Ulcerative colitis
    • Bloodstream spread in some people

    Campylobacter spp: Clinical Features

    • Incubation period: 2-4 days (can be up to 8-9 days)
    • Clinical features: Prodromal illness (fever, headache), diarrhoea (may be bloody), abdominal pain (can be severe)
    • Resolves 5-7 days
    • Complications: Toxic megacolon, Bacteraemia, Guillain-Barre syndrome

    Campylobacter spp: Laboratory Diagnosis

    • Typical curved-shaped, Gram negative bacilli on Gram stain
    • Greyish colonies on selective charcoal-containing media incubated in CO2 at 42°C
    • Positive oxidase test
    • Hydrolyses hippurate
    • PCR (faeces)
    • Culture (faeces/blood)

    Campylobacter spp: Treatment

    • Rehydration
    • Antibiotics not routine for gastroenteritis
      • Only if bacteraemic or immunosuppressed
      • Azithromycin or Ciprofloxacin if susceptible
    • Prevention: Good food hygiene (cooking/storing of meat/poultry), hand hygiene after contact with animals, meat etc.

    E.coli Associated with Gastroenteritis

    • Not the same E.coli that cause UTI
    • Types: Enterohaemorrhagic E.coli (EHEC), Enterotoxigenic E.coli (ETEC), Enteropathogenic E.coli (EPEC), Enteroinvasive E.coli (EIEC), Enteroaggregative E.coli (EAggEC)

    1. Enterohaemorrhagic E.coli (EHEC)

    • Major reservoir: Cattle and other ruminants
      • Survive for long periods in environment
    • Transmission: Food (minced beef products), contaminated environment (direct/indirect contact with animals or their faeces), Person to person
    • Outbreaks: Often linked to undercooked minced beef, petting animals, water, unpasteurised milk
    • Serotype O + H antigens
      • E.coli O157:H7 most common
      • Particularly serious in infants (bloody diarrhoea and renal failure)

    1. Enterohaemorrhagic E.coli: Pathogenesis

    • Site of infection = colon
    • Adherence + invasion of intestinal epithelial cells
    • Shigella-like Vero toxin (cytotoxin)
      • Cell death by disrupting protein synthesis
      • Acute inflammatory response and tissue destruction
      • Bloody diarrhoea

    1. Enterohaemorrhagic E.coli: Clinical Presentation

    • Incubation period: ~3 days (range 1-10 days)
    • Bloody diarrhoea +/- vomiting
    • More severe in extremes of age
    • Lasts 3 days

    1. Enterohaemorrhagic E.coli: Complications

    • Haemolytic uremic syndrome:
      • 10% children < 10 yrs
      • Acute renal failure
      • Thrombocytopaenia
      • Microangiopathic haemolytic anaemia

    1. Enterohaemorrhagic E.coli: Diagnosis & Management

    • Diagnosis: PCR (faeces), Culture in reference lab to confirm
    • Management: Rehydration, Antibiotics not indicated
      • Increased toxin release -> further cell death and worsening of symptoms
      • Require isolation in hospital (Contact precautions)

    2. Enterotoxigenic E.coli (ETEC)

    • Underdeveloped countries/regions of poor sanitation
    • Short incubation period 1-3 days
    • Symptoms: Watery (non-bloody) diarrhea, fever and nausea (minor discomfort to severe cholera-like syndrome)
    • Self-limiting 1-5 days

    2. Enterotoxigenic E.coli: Pathogenesis

    • Site of infection: small intestine
    • Adherence, does not invade
    • Enterotoxins = secretion of fluid and electrolytes resulting in diarrhea:
      • LT (heat-labile): Similar to cholera toxin
      • ST (heat-stable)

    3. Enteropathogenic E.coli (EPEC)

    • Major cause of Infantile gastroenteritis: < 6 moa in developing countries
    • High mortality rate (severe dehydration)
    • Person-person spread
    • May cause outbreaks

    3. Enteropathogenic E.coli: Pathogenesis

    • Site of infection: small intestine
      • Attach to intestinal mucosa
      • Loss of villi
      • Invasion of host cells and interference with normal cellular signal transduction = symptoms
    • Watery diarrhea, vomiting, fever

    Listeria monocytogenes

    • Grows in a wide range of temperatures (2-37°C)
    • Infection peaks in warmer months
    • Transmission: Contaminated milk, certain soft cheeses, pate, etc.

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