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MICRO 121 > Lecture 18: Bacteria, Parasites and Toxin Mediated Gastroenteritis > Flashcards

Lecture 18: Bacteria, Parasites and Toxin Mediated Gastroenteritis Flashcards

1
Q

Rules for Avoiding Enteric Pathogens

A

“Cook it, boil it, peel it, or forget it”

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2
Q

Acute Gastroenteritis

A

Diarrheal disease of rapid onset, with or without accompanying symptoms that include nausea, vomiting, fever, or abdominal pain

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3
Q

Diarrhea

A
  • Frequent passage of uninformed liquid stool (>3 or more loose watery stool per day)
    Acute diarrhea: <14 days
    Chronic diarrhea: >14 days
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4
Q

Dysentery

A

Blood or mucous in the stool

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5
Q

Bacterial Gastroenteritis

A
  • Inflammation of GI tract due to bacteria
  • Abdominal pain, bloody stool, loss of appetite, nausea and vomiting
    Blood stool: associated with mucosal invasion of bacteria
    Watery stool: no mucosal invasion
  • Typically bacterial gastroenteritis is associated with BBQ season
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6
Q

Acute Diarrhea (2 types)

A

Acute watery diarrhoea: most common, presents within 48hrs, usually self limiting, main complication is dehydration (rota, e. coli, vibrio cholera)
Acute bloody diarrhoea: passage of bloody stools, result of damage to intestinal mucosa by an invasive organism, complications like sepsis, malnutrition, and dehydration (shigella spp, entamoeba histolytica)

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7
Q

Viral Gastroenteritis

A
  • small intestine
  • watery diarrhea
  • vomiting: +++ or +
  • abdominal pain: + or -
  • tenesmus: -
  • anorexia: + or -
  • systemic illness symptom: + or -
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8
Q

Bacterial Gastroenteritis

A
  • colon
  • blood, mucoid diarrhea
  • vomiting: + or -
  • abdominal pain: +++ or ++
  • tenesmus: ++ or +
  • anorexia: +++ or ++
  • systemic illness symptom: +++ or ++
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9
Q

Bacterial Gastroenteritis Types

A

Salmonella
Campylobacter
Vibrio
Shigella

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10
Q

Bacterial Gastroenteritis Epidemiology

A
  • one of most common causes of illness in children and adults
  • acquired thru fecal-oral route, but contaminated water and food play a role
  • age 3 children become infected by most common agents
  • deaths usually a result of dehydration with episodes usually lasting 5-10 days
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11
Q

Pathophysiology of Enteric Pathogens

A
  • alterations to natural defences of the body
  • risk and disease associated with organism dose
  • exposure to disease causing organism
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12
Q

Salmonella Risk Factors

A
  • Gram -‘ve
  • Majority of infections from beef, poultry, unpasteurized milk, unpasteurized eggs but any veg
  • Inadequate thawing from freezing is a common source
  • International travel
  • reptiles carry salmonella in their gut
  • stomach acid provides some protection
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13
Q

Clinically salmonella

A
  • incubation period of 6-72 hrs
  • usually tends to be relatively mild and self limiting
  • under age of 2 + over age of 65 TREAT b/c increased risk
  • diarrhea starts w fever, ab cramps, chills, myalgia, can be bloody, may be nausea or vomiting
  • illness typically lasts 4-7 days and is usually self limiting
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14
Q

Pathogenesis of intestinal salmonella infection

A
  • rapid invasion of GI mucosa following infection
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15
Q

xtra-intestinal salmonella

A
  • called typhoid fever
  • typically result of infection with salmonella typhi or salmonella paratyphi
  • salmonella bacteria causes gastroenteritis can enter blood stream or body cavity by breaks in the intestinal wall
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16
Q

Treatment for Salmonella infections

A
  • Intestinal salmonella spp.
  • Often self limiting and does NOT need to be treated
  • Treat with antibiotics for anyone <2 yrs or >65 yrs or immunocompromised
  • ALWAYS treat xtra-intestinal Salmonella
  • Starting to see increasing resistance
17
Q

Shigella spp.

A
  • Gram -‘ve bacilli
  • Acquired via poultry, causes bloody stool
  • Incubation of 1-7 days, with acute diarrhea in 1-2 days
  • Organisms can be shed for up to 4 weeks after incubation
  • Non motile bacteria
  • Ingested pathogens can survive the gastric acidity and can cause illness by infection the colonic mucosa
18
Q

Clinical presentation of Shigella spp.

A
  • Sudden onset
  • Initial symptoms include abdominal colic and cramps
  • Progresses from watery diarrhea to bloody mucus filled stool
  • Fever, headache, malaise and anorexia
19
Q

Risk factors for Shigellosis

A
  • Children in daycare centers
  • International travelers
  • Immunocompromised individuals
  • Ppl living with inadequately tested water supply
20
Q

Pathogenesis of Shigella spp.

A
  • Significant proportion of damage is a result of host immune responses
  • Bacteria also produce specific toxin that can lead to cell death
  • Shiga toxin has 2 parts. Part B binds to cells and injects Part A which prevents protein synthesis and causes cell death
21
Q

Pathogenesis of Shigella spp.

A
  • Significant proportion of damage is a result of host immune responses
  • Bacteria also produce specific toxin that can lead to cell death
  • Shiga toxin has 2 parts. Part B binds to cells and injects Part A which prevents protein synthesis and causes cell death
22
Q

Infection of Shigella spp.

A
  • Hard to control outbreaks
  • Ill patients and workers should not be allowed to return for at least 24 hrs
  • Ppl should refrain from rec water venues for 1 week after symptoms resolve
23
Q

Treatment/Prevention for Shigella spp.

A
  • Most intestinal cases are self-limiting, mild cases doesn’t require antibiotics
  • Severe cases should be treated with antimicrobials or in anyone that has underlying immunodeficiency
  • Antibiotics can shorten duration of illness and to prevent the spread of infection
  • Wash hands, ensure food is handled appropriately
24
Q

E. coli diarrhea

A
  • Gram -‘ve bacilli commonly in GI tract
  • Specific pathotypes are associated with diarrhea NOT all E. coli produce infection
25
Q

Risk factors for developing E. coli diarrhea

A
  • E. coli with specific virulence factor
  • Consumption of undercooked beef and unpasteurized foods
  • Consumption of raw vegetables
  • Visiting farms and/or working in farms
  • Travel - common cause of “travellers diarrhea”
26
Q

STEC

A

Hemolytic Uremic Syndrome (HUS) most often associated with E. coli (O157 has very BAD outcomes) O157:H7 but others also present

27
Q

Complications with STEC infections

A
  • Serious and typically develops 7 days after the onset the diarrhea
  • More than 50% of children require dialysis and 3-5% of children will die
  • HUS can develop neurologic complications
  • HUS is associated with antibiotic therapy
28
Q

Campylobacter spp.

A
  • Gram -‘ve curved bacteria
  • Diarrhea, abdominal pain, malaise and fever
  • Incubation time usually 2-5 days can present with mild symptoms that last 1-2 days resembles viral gastroenteritis
29
Q

Risk factors for Campylobacteriosis

A
  • campylobacter spp is normal flora in chickens and wild birds
  • improper cooking of poultry and unpasteurized eggs, milk and other animal products are all potential sources
  • outbreaks are rare but happen
  • transmission documents from mammalian pets
30
Q

Pathogenesis of Campylobacter Infections

A
  • Fever, abdominal pain, and cramps
  • Bloody mucoid stool with minimal vomiting
  • Self resolving w rehydration therapy
  • Antimicrobial therapy is indicated for more serious presentations
31
Q

Yersinia enterocolitica

A
  • Gram -‘ve bacteria - only 3 are pathogens
  • Yersinia enterocolitica causes age-specific syndromes presenting with fever, watery stool, abdominal pain, and acute lymphadenitis
  • Major of all cases occur in children under age of 24 months
32
Q

Pathogenesis of Yersinia enterocolitica

A
  • Fecal-oral transmission from animals to humans
  • Found in contaminated foods including pork, tofu, unpasteurized animal products
  • Incubation is 4-6 days
  • Tissue invasion associated w bloody diarrhea
  • Mostly self-limiting
33
Q

Toxin Mediated Gastroenteritis

A
  • Rapid onset - diarrhea, vomiting, and abdominal cramps most common presentations
  • Toxin pre-formed in food is heat stable and not sensitive to degradation
  • Organisms produce toxins after ingestion
    - Clostridium spp. produce spores which are resistant to stomach acids and cooking
34
Q

Pathogenesis of Giardia

A
  • Has a trough and cyst
  • Very enviro stable
  • Gets destroyed by stomach acid
  • Infection is slight
  • Lead to development of diarrhea, excess gas, stomach or abdominal cramps, nausea
  • Transmission via the cyst
  • Incubation period is 1-3 weeks
35
Q

Detection/transmission and treatment of Giardia

A
  • Contaminated water, hands, food, and other fomites
  • Transmission by asympt carriers
  • Some self-limiting and may require treatment but more serious infections should be treated with anti-parasitic drugs
  • Ensure patients are not dehydrated
  • Detection by EIA or PCR or ova/parasite detection
36
Q

Entamoeba histolytica Gastroenteritis

A
  • Syndromes include non-invasive intestinal amebiasis infection
  • Can lead to liver abscess
  • Gradual onset of symptoms over 1-3 weeks
  • Offensive odour of stool simulating bacillary dysentery or ulcerative colitis
  • Detection via ova/parasites, PCR, and antigen detection
37
Q

Transmission/Epidemiology of Entamoeba histolytica

A
  • Global, but common in lower socioeconomic status
  • Transmitted via asympt. ppl and contaminated water
  • Cysts once ingested are unaffected by gastric acid and lead to disease
  • Can go for yrs without diagnoses

MICRO 121 (19 decks)

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