Infectious Diarrhea Flashcards
What are big three diarrheal pathogens that are often tested for?
What categories/buzzwords should clue you?
Salmonella, shigella and campylobacter
See with BBQ (beef/pork/poultry), fever, bleeding
Pet lizard: salmonella
Veggies/salad: Shigella
What are major cause of acute viral gastroenteritis?
What are other major viral pathogens?
Norovirus is leading viral pathogen.
Also see rotavirus, adenovirus, astrovirus
What are long term concerns of norovirus? (3)
Postviral gastroparesis
Chronic infections create asymptomatics that are reservoir
IBD
How does salmonella differ in US vs. outside of US?
Typhoid fever outside of US
Nontyphoidal infections in US==>most common cause of bacterial food borne illness
What things are associated with transmission of salmonella?
Food: Eggs, milk, fresh produce, meat
Pets: lizards and turtles
What are clinical features of typhoid fever?
Weeks 1-3
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
What are acute complications of campylobacter? (2)
Pseudoappendicitis in kids (acute ileoececitis w/ RLQ pain)
Cholecystitis
What are long-term complications of campylobacter infection? (3)
Possible association with lymphoma
Reactive arthritis
Giullain-Barre
What is main virulence factor in shigella? What is its significance?
Shiga toxin, which can lead to HUS (hemolytic uremic syndrome)
What are significant strains of E. Coli?
EHEC (O157:H7)=>HUS risk due to shiga toxin
ETEC/EPEC==>watery diarrhea in young children in developing countries
What are the major virulence factors in EHEC? (2)
Attaching and effacing lesions
Shig toxins==> hemorrhagic colitis and HUS
Should you prescribe antibiotics in EHEC?
No! Increases risk of HUS
What is the triad of HUS?
What two other factors are in TTP?
Acute renal failure
Microangiopathic hemolytic anemia
Thrombocytopenia
Add in fever, neurologic symptoms for TTP
In which populations do we see ETEC? (2)
Young children in developing countries
Travelers diarrhea
EPEC: who gets it?
Children
What is the mechanism of the cholera toxin?
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
What are clinical manifestations of cholera? (3)
painless rice-water stool
Vomiting, clammy/wrinkled skin
Lactic acidosis due to loss of Na, K, bicarbonate
How does C-diff arise? Why has current strain (NAP1) emerged?
Arises after widespread use of abx; interruption of normal microbiome
Current strain (most virulent) is due to fluoroquinolone use
What are risk factors for C diff infection?
Abx, chemotherapy, BM transplant, GI surgery, PPIs
What are clinical findings of C Diff? (5)
Watery diarrhea
Abdominal cramping
Fever
High leukocytosis Pseudomembranes
What is major complication of C Diff?
Toxic megacolon– observe distention, constipation and must do colectomy
What are treatment options for C Diff? What is most efficacious option?
Fecal microbial transplant=#1
Also metronidazole–> vancomycin–> vacnomycin taper
What are risk factors for Clostridium perfringens? (3)
Consumption of pig guts Sweet potatoes (inhibit trypsin ) Antipsychotic drugs (decreased GI motility)
What is most common yersinia strain? How is most commonly transmitted?
Y. Enterocolitica
Contaminated pork
Patients with what disease are susceptible to Y. enterocolitica? Why?
Hemophiliacs with iron overload are susceptible because Y Enterocolitica is ferrophilic
What is clinical presentation of Yersinia? (5)
Dysentery Fever Pharygitis Pseudoappendicitis NO ABDOMINAL PAIN
What are serious diseases that can result from Listeria monocytogenes? (2)
Who do you test? (2)
Bacteremia
Meningitis
Test in pregnancy/immunosuppressed patients
How is Bacillus Cereus classically transmitted?
Reheated fried rice==>it can survive in extreme temperatures
What is giardia lamblia? How is it commonly acquired?
Guard is the most common parasitic enteric pathogen
It is highly associated with contaminated water
What are clinical presentations of giardia?
Asymptomatic carrier (2/3) Acute giardiasis: weight loss, steatorrhea, cramps, flatulence Chronic giardiasis: profound weight loss, lactose intolerance, malabsorption, fatigue, depression
Which populations are most commonly infected by cryptosporidium?
How is it acquired?
Children and HIV patients
Normally it is a waterborne outbreak from a contaminated reservoir
What is major complication of cryptosporidium?
cholangitis due to spread to biliary system
