Infectious Diarrhea

Question 1

What are big three diarrheal pathogens that are often tested for?

What categories/buzzwords should clue you?

Answer 1

Salmonella, shigella and campylobacter

See with BBQ (beef/pork/poultry), fever, bleeding
Pet lizard: salmonella
Veggies/salad: Shigella

Question 2

What are major cause of acute viral gastroenteritis?

What are other major viral pathogens?

Answer 2

Norovirus is leading viral pathogen.

Also see rotavirus, adenovirus, astrovirus

Question 3

What are long term concerns of norovirus? (3)

Answer 3

Postviral gastroparesis
Chronic infections create asymptomatics that are reservoir
IBD

Question 4

How does salmonella differ in US vs. outside of US?

Answer 4

Typhoid fever outside of US

Nontyphoidal infections in US==>most common cause of bacterial food borne illness

Question 5

What things are associated with transmission of salmonella?

Answer 5

Food: Eggs, milk, fresh produce, meat

Pets: lizards and turtles

Question 6

What are clinical features of typhoid fever?

Weeks 1-3

Answer 6

Initially presents with diarrhea/constipation
Week 1: stepwise fever with relative bradychardia (pulse-temperature dissociation)
Week 2: Rose spots on trunk/abdomen
Week 3: hepatosplenomegaly, GI bleeding

Question 7

What are acute complications of campylobacter? (2)

Answer 7

Pseudoappendicitis in kids (acute ileoececitis w/ RLQ pain)

Cholecystitis

Question 8

What are long-term complications of campylobacter infection? (3)

Answer 8

Possible association with lymphoma
Reactive arthritis
Giullain-Barre

Question 9

What is main virulence factor in shigella? What is its significance?

Answer 9

Shiga toxin, which can lead to HUS (hemolytic uremic syndrome)

Question 10

What are significant strains of E. Coli?

Answer 10

EHEC (O157:H7)=>HUS risk due to shiga toxin

ETEC/EPEC==>watery diarrhea in young children in developing countries

Question 11

What are the major virulence factors in EHEC? (2)

Answer 11

Attaching and effacing lesions

Shig toxins==> hemorrhagic colitis and HUS

Question 12

Should you prescribe antibiotics in EHEC?

Answer 12

No! Increases risk of HUS

Question 13

What is the triad of HUS?

What two other factors are in TTP?

Answer 13

Acute renal failure
Microangiopathic hemolytic anemia
Thrombocytopenia

Add in fever, neurologic symptoms for TTP

Question 14

In which populations do we see ETEC? (2)

Answer 14

Young children in developing countries

Travelers diarrhea

Question 15

EPEC: who gets it?

Answer 15

Children

Question 16

What is the mechanism of the cholera toxin?

Answer 16

Contains A subunit and 5 B subunits. B subunit binds gnaglioside receptor on apical surface of enterocytes. A enters enterocyte; is cleaved then A1 irreversibly acts on G protein to increase cAMP. cAMP dependent kinases inhibit NaCl transport, inhibit Cl secretion. Water follows ion efflux out of cell

Question 17

What are clinical manifestations of cholera? (3)

Answer 17

painless rice-water stool
Vomiting, clammy/wrinkled skin
Lactic acidosis due to loss of Na, K, bicarbonate

Question 18

How does C-diff arise? Why has current strain (NAP1) emerged?

Answer 18

Arises after widespread use of abx; interruption of normal microbiome

Current strain (most virulent) is due to fluoroquinolone use

Question 19

What are risk factors for C diff infection?

Answer 19

Abx, chemotherapy, BM transplant, GI surgery, PPIs

Question 20

What are clinical findings of C Diff? (5)

Answer 20

Watery diarrhea
Abdominal cramping
Fever
High leukocytosis Pseudomembranes

Question 21

What is major complication of C Diff?

Answer 21

Toxic megacolon– observe distention, constipation and must do colectomy

Question 22

What are treatment options for C Diff? What is most efficacious option?

Answer 22

Fecal microbial transplant=#1

Also metronidazole–> vancomycin–> vacnomycin taper

Question 23

What are risk factors for Clostridium perfringens? (3)

Answer 23

Consumption of pig guts
Sweet potatoes (inhibit trypsin )
Antipsychotic drugs (decreased GI motility)

Question 24

What is most common yersinia strain? How is most commonly transmitted?

Answer 24

Y. Enterocolitica

Contaminated pork

Question 25

Patients with what disease are susceptible to Y. enterocolitica? Why?

Answer 25

Hemophiliacs with iron overload are susceptible because Y Enterocolitica is ferrophilic

Question 26

What is clinical presentation of Yersinia? (5)

Answer 26

Dysentery
Fever
Pharygitis
Pseudoappendicitis
NO ABDOMINAL PAIN

Question 27

What are serious diseases that can result from Listeria monocytogenes? (2)

Who do you test? (2)

Answer 27

Bacteremia
Meningitis

Test in pregnancy/immunosuppressed patients

Question 28

How is Bacillus Cereus classically transmitted?

Answer 28

Reheated fried rice==>it can survive in extreme temperatures

Question 29

What is giardia lamblia? How is it commonly acquired?

Answer 29

Guard is the most common parasitic enteric pathogen

It is highly associated with contaminated water

Question 30

What are clinical presentations of giardia?

Answer 30

Asymptomatic carrier (2/3)
Acute giardiasis: weight loss, steatorrhea, cramps, flatulence
Chronic giardiasis: profound weight loss, lactose intolerance, malabsorption, fatigue, depression

Question 31

Which populations are most commonly infected by cryptosporidium?

How is it acquired?

Answer 31

Children and HIV patients

Normally it is a waterborne outbreak from a contaminated reservoir

Question 32

What is major complication of cryptosporidium?

Answer 32

cholangitis due to spread to biliary system