Lecture 18: Bacteria, Parasites and Toxin Mediated Gastroenteritis Flashcards
(37 cards)
1
Q
Rules for Avoiding Enteric Pathogens
A
“Cook it, boil it, peel it, or forget it”
2
Q
Acute Gastroenteritis
A
Diarrheal disease of rapid onset, with or without accompanying symptoms that include nausea, vomiting, fever, or abdominal pain
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
4
Q
Dysentery
A
Blood or mucous in the stool
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
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)
7
Q
Viral Gastroenteritis
A
- small intestine
- watery diarrhea
- vomiting: +++ or +
- abdominal pain: + or -
- tenesmus: -
- anorexia: + or -
- systemic illness symptom: + or -
8
Q
Bacterial Gastroenteritis
A
- colon
- blood, mucoid diarrhea
- vomiting: + or -
- abdominal pain: +++ or ++
- tenesmus: ++ or +
- anorexia: +++ or ++
- systemic illness symptom: +++ or ++
9
Q
Bacterial Gastroenteritis Types
A
Salmonella
Campylobacter
Vibrio
Shigella
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
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
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
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
14
Q
Pathogenesis of intestinal salmonella infection
A
- rapid invasion of GI mucosa following infection
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
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
Risk factors for developing E. coli diarrhea
- 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
STEC
Hemolytic Uremic Syndrome (HUS) most often associated with E. coli (O157 has very BAD outcomes) O157:H7 but others also present
27
Complications with STEC infections
- 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
Campylobacter spp.
- 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
Risk factors for Campylobacteriosis
- 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
Pathogenesis of Campylobacter Infections
- 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
Yersinia enterocolitica
- 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
Pathogenesis of Yersinia enterocolitica
- 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
Toxin Mediated Gastroenteritis
- 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
Pathogenesis of Giardia
- 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
Detection/transmission and treatment of Giardia
- 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
Entamoeba histolytica Gastroenteritis
- 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
Transmission/Epidemiology of Entamoeba histolytica
- 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
