Infectious Diarrhea 1 Flashcards
1
Q
- _____ diseases are the second leading cause of morbidity and mortality worldwide
- Leading cause of childhood death worldwide.
- No good incidence studies b/c most self-limited
A
Infectious diarrheal
2
Q
Acute Diarrhea Clinical Course
A
- Usually self limited – Usually infectious – But even non-infectious causes will typically resolve
- Average 3-7 BM per day
- Volume <1 L / day
- Most occur in winter months (viral).
3
Q
Function of intestine
A
- The length of the adult small intestine: – 3 to 8 meters (Mean 6 M)
- Most macronutrients – Carbohydrates, fat, and protein
– Absorbed in the proximal 100 to 150 cm
4
Q
Infectious diarrhea causes what kind?
A
• Watery diarrhea, large volume
5
Q
- Large Bowel:Functions as storage and fluid absorption
- Lack of function –> Lack of absorption –>_____ stools
- Inflammation –>intracelluar leakage –>____ stools
A
Frequent
Frequent
6
Q
Painful BM, tenesmus, urgency
- Fever, bloody, mucoid stools
- RBCs and WBC on stool smear
A
Large bowel
7
Q
• Most gastroenteritis is_____ – cultures only positive in 1.5-5.6% of cases.
A
viral
8
Q
– defined as ≥4 fluid stools per day
– > three days
– 87% bacterial
A
• Severe community acquired diarrhea
9
Q
Gram negative encapsulated bacilli
- Poultry, eggs and milk association
- Pet turtles association
A
Salmonella typhi
10
Q
Salmonella typhi
• _______ is much more common in US than typhoid type – 40% in patients <15 y/o
A
Non-Typhoid Salmonella
11
Q
Risk factors for salmonella typhi
A
summer and fall, young age, IBD, immune deficiencies.
12
Q
• ________ may be associated with gallstones and a chronic carrier state – Carrier state may cause falsely elevated frequency in Typhoid Fever
A
Gallbladder colonization
13
Q
•Symtoms of Acute infection of Typhoid Fever
A
: anorexia, abdominal pain, bloating, nausea, vomiting, and bloody diarrhea.
Can develop bacteremia with associated fever
14
Q
• Patients with sickle cell disease are particularly susceptible to ______
– S. Aureus is still the most common cause of osteomyelitis, even in this population
A
Salmonella osteomyelitis
15
Q
Salmonella quickly adapts to the _____ but the microbiome protects against pathogenesis which is why what is bad?
A
adapts to low pH
Antibiotics are BAD in salmonella
16
Q
How does salmonella survive in host and cause immune respone?
A
- Uptake into cell, survive in modified phagosome, and replicate
- Induce migration of neutrophils to cause inflammatory response
17
Q
• Non-typhoid Salmonella generally is self-limited, except:
A
– High-fevers, Severe Diarrhea (>10 stools/day), Hospitalized patient
18
Q
Gram-negative bacilli that are unencapsulated, facultative anaerobes.
A
Shigella
19
Q
Shigella
- Responsible for ~ 10% of pediatric diarrheal disease but ___ of diarrheal deaths
- Fecal oral route, highly contagious with As few as____ organisms
– Acid resistant
• Daycare and institutional settings, can be transmitted person to person.
A
75%
10
20
Q
Describe disease processes in Shigella and its symptoms
A
- Self-limited disease
- ~6 days of diarrhea, fever, and abdominal pain.
- Most commonly effect the left colon, but the ileum may also be involved. (can mimic Crohn’s disease)
21
Q
What should we and shouldn’t we use to treat Shigella?
A
- Antibiotic treatment shortens the clinical course
- Antidiarrheal medications are contraindicated – Delay bacterial clearance
22
Q
Rare complication of Shigella
A
• Rarely: Hemolytic Uremic Syndrome, Seizures, or Reactive arthritis – Shiga-like toxin of other organisms can lead to these events
23
Q
- Leading cause of acute bacterial diarrhea worldwide
- 33% of foodborne illnesses
- Undercooked poultry, unpasteurized milk or contaminated water
A
Campylobacter jejuni
24
Q
Campylobacter jejuni:
- Ingestion of as few as____ C. jejuni organisms
- Incubation period of up to __ days.
A
500
8
25
Disease process in Campylobacter jejuni
* Usually an influenza-like prodrome – Fever, malaise, myalgias
* Dysentery develops in 15% to 50% of patients.
* Self limited and therefore antibiotic therapy generally is not required
* Watery or hemorrhagic, both small and large bowel symptoms
26
* Self limited and therefore antibiotic therapy generally is not required
* Watery or hemorrhagic, both small and large bowel symptoms
Campylobacter jejuni
27
Complications of campylobacter jejuni
* Can result in reactive arthritis or erythema nodosum
* Guillain-Barré syndrome.
– Peripheral --\> Central progressive paralysis caused by autoimmune-induced inflammation of peripheral nerves.
28
* Can result in reactive arthritis or erythema nodosum
* Guillain-Barré syndrome.
– Peripheral --\> Central progressive paralysis caused by autoimmune-induced inflammation of peripheral nerves.
Camplobacter jejuni
29
Causes pseudoapendicitis; RLQ pain and yersinia also does this
campylobacter jejuni
30
describe campylobacter jejuni
pseudoappenticitis
erythema nodosum, reactive arthrtis
Guillian barre
water or hemorrhagic diarrhea; sm and large bowel involvemnt
influenza like prodrome
31
* Flagellated protozoan
* Most common pathogenic parasitic infection in humans
* Fecally contaminated water or food.
Giarda lamblia
32
Where do we aquire Giardia lamblia
• Endemic in unfiltered public and rural water supplies – Well water / “drinking from mountain streams”
33
What disease does Giardia cause?
* Acute or chronic diarrhea with upper abdominal bloating
* Small bowel disease
34
Gram-negative bacilli that colonize the healthy GI tract; most are nonpathogenic, but a subset cause human disease
Eschericia coli
35
– Principal cause of traveler's diarrhea
– Fecal-oral route
– Express either LT or ST, or both
• Enterotoxigenic E. coli (ETEC) organisms
36
* Heat labile toxin (LT) that is similar to\_\_\_\_ toxin
* Heat-stable toxin (ST) that increases intracellular\_\_\_\_ with effects similar to the cAMP elevations caused by LT
Both are in ETEC/travelers diarrhea
cholera
cGMP
37
Why does incresae cGMP cause diarrhea
– cAMP ==\>
* (1) Secretion of Cl- thru its channel
* (2) Prevent reabsorption of NaCl at villus tips
THUS: Net Water Secretion or osmotic diarrhea
38
– Resemble Shigella in its pathogenesis
– Invade the **gut epithelial** cells
– Produce a **bloody** diarrhea
• Enteroinvasive E. coli (EIEC) organisms
39
• Enteroaggregative E. coli (EAEC) organisms
– Attach to enterocytes by \_\_\_\_\_
– Flagellan --\> ↑ ____ --\> Intestinal Inflammation
adherence fimbriae
IL-8
40
– Attach to enterocytes by adherence fimbriae
– Flagellan --\> ↑ IL-8 --\> Intestinal Inflammation
– Although they produce a LT and Shiga-like toxins, histologic damage is minimal from these
Enteroaggregative E. coli (EAEC) organisms
41
Undercooked g**round beef** or mishandling of ground beef.
* 4% of foodborne illness.
* 39% of cultured pathogens in visibly bloody specimens
* Association with **Hemolytic Uremic Syndrome (HUS)**
Enterohemorrhagic E.Coli (EHEC)
• E. coli 0157:H7
42
antibiotics can induce:
– Hemolysis, Thrombocytopenia and Renal Failure
HUS in Enterohemorrhagic E.Coli (EHEC)
43
* Gram-negative bacteria
* Contaminated drinking water
* Seafood-associated disease: animal reservoirs are shellfish and plankton
Vibrio cholerae
44
What causes disease in vibrio cholera
• Enterotoxin, cholera toxin, which causes disease
45
Mechanism by which cholera cuaes watery diarrhea
– Causes increased in intracellular cAMP which
– Opens the (CFTR)--\> Releases Cl- ions into the lumen --\>Draws water into the lumen
46
HOw does vibrio cholera present?
most asymptomatic or mild diarrhea
severe: abrupt onset watery diarrhea up to 1 L/hour!!!
47
incubation of vibrio cholera
1 to 5 days
48
Concners with severe vibrio cholera infectionDehydration, hypotension, electrolyte imbalances, anuria, shock, and death.
49
* Approximately half of all gastroenteritis outbreaks worldwide
* Contaminated food or water, but person-toperson transmission as well.
* Schools, hospitals, and nursing homes and, most recently, on cruise ships.
* Nausea, vomiting, watery diarrhea, and abdominal pain.
* Self-limited
Norovirus
50
Pre-vaccine: 10% of diarrhea “requiring treatment” & 50% of “required hospitalization”
– If in hospital for diarrhea & winter: 70-90%
51
Previously: Most common cause of childhood diarrhea and diarrhea-related deaths worldwide.
rotavirus
52
Who is susceptible to rotavirus?
whre are outbreaks?
What are symptoms?
children 6 to 24 months most vulnerable
outbreaks in hospital and daycare
vomit and watery diarrhea for several days
vaccines now available
53
– Nematode
– Infects more than 1 billion people worldwide
– Fecal-oral
– Can cause Ascaris pneumonitis
• Ascaris lumbricoides
54
Lifecycle of Ascarisis lumbricoides
person ingest feces with worms--\> to intestine--\> travesl to liver = abcess--\> to lungs = cough and swallow and autoinnoculte
shit out fertalized eggs
55
Strongyloides lifecyle– Larvae live in fecally contaminated ground soil – Can penetrate unbroken skin, such as feet – Migrate through the lungs to the trachea from where they are swallowed – Mature into adult worms in the intestines. – Eggs can hatch within the intestine and release larvae that penetrate the mucosa • creates a vicious cycle referred to as autoinfection. – Persist for life, and immunosuppressed individuals can develop overwhelming infections.
– Larvae live in fecally contaminated ground soil
– Can penetrate unbroken skin, such as feet
– Migrate through the lungs to the trachea from where they are swallowed
– Mature into adult worms in the intestines.
– Eggs can hatch within the intestine and release larvae that penetrate the mucosa
• creates a vicious cycle referred to as autoinfection. – Persist for life, and immunosuppressed individuals can develop overwhelming infections.
56
– Hookworms
– Infect 1 billion people worldwide
– Infection by larval penetration through the skin.
Necator americanus and Ancylostoma duodenale
57
Lifecycle of necator americanus and ancylostoma duodenale
– Infection by larval penetration through the skin.
– After further development in the lungs, the larvae migrate up the trachea and are swallowed.
– Once in the duodenum, the larvae mature and the adult worms attach to the mucosa, suck blood, and reproduce.
58
Leading cause of iron deficiency anemia in the developing world.
Necator americanus and Ancylostoma duodenale.
59
Immunocompromised host: have Lymphoma, BMT, HIV worry about what other
parasites and Bacteria
Parasites: Cryptosporidium parvum, Isospora belli, Cyclospora, and Microsporia. – Bacteria: MAC
Viral: CMV, HIV, adenovirus
60
New diarrhea at least 72 hours after admission to hospital.
• Increases the length of stay from one week to one month
Nosocomial diarrhea
61
Causes of nosocomial diarrhea
* Clostridium difficile
* Tube feeds (Osmotic)
* Medications
* Fecal impaction (Overflow incontinence)
* Ischemic Colitis
* BMT patients – Besides infection: GVHD
62
History of a fever with diarrhea suggests:
* Invasive bacteria
* Enteric viruses
* Cytotoxic organism – Clostridium difficile or Entamoeba histolytica
* Ischemia
* IBD
63
• Began within 6 hours
– Suggest ingestion of a toxin
– _______ (potato salad) or _____ (Chinese food/rice)
Staphylococcus aureus
Bacillus cereus
64
Diarrhea began 8-14 hours w/in food consumption is suggestive of infection with:
Clostridium perfringens
65
For infectious colitis, Most bacterial infections all induce a similar histopathology Termed \_\_\_\_\_\_\_
You need what do diagnose this?
“acute self-limited colitis”
stool study (endoscopy not helpful in acute diarrhea)
66
Pt has Acute diarrhea, non-toxic appearing, non-bloody diarrhea
to test or not?
– No testing is needed
67
Key points for BACTERIAL stool studies
Bacterial pathogens generally are excreted continuously.
* Negative culture usually not a false negative
* Repeat specimens are rarely required
68
When should we order a stool study?
* Severely Ill
* Outbreaks
* Require hospitalization
* Immunocompromised patients, e.g. HIV
* Patients with comorbidities (e.g. IBD)
* Some employees, such as food handlers or daycare providers, may require negative stool cultures to return to work
69
What is the challenge we face when ordering O and P tests if we suspect parasites?
• Many false negative b/c ova shed intermittently • Repeated X3 – 3 consecutive days – 24 hours apart • Useless in most patients • Not cost effective
70
When should we order O and P test?
• Persistent diarrhea \>14 days • Travel to mountainous regions • Exposure to infants in daycare centers • Immune-compromised. • A community waterborne outbreak
71
ELISAs and DFA microscopy are useful in diagnosising which pathogens?
Giardiasis & Cryptosporidium antigen in stool
– Sensitivities \>90%
– Specificities close to 100%
