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34 Cards in this Set

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What is the differential diagnosis for a patient presenting with esophagitis?
- Candida albicans
- Herpes simplex virus
- CMV
What is the differential diagnosis for a patient who has consumed a toxin?
- S. aureus
- B. cereus
- C. perfringens
- C. botulinum
What is the differential diagnosis for a patient presenting with inflammatory diarrhea (dysentery)?
- Shigella spp.
- E. coli
- Salmonella
- Campylobacteriosis
- Pseudomembranous colitis
- Amoebiasis (E. histolytica)
What is the differential diagnosis for a patient presenting with enteric fever?
- Typhoid fever: Salmonella typhi
- Yersiniosis: Yersinia enterocolitica and Yersinia pseudotubercuolosis
What is the differential diagnosis for a patient presenting with peptic ulcers?
- Heliobacter pylori
What is the differential diagnosis for a patient presenting with hepatitis?
- Yellow fever virus
- Leptospira interrogans
- Hepatitis A, B, C, D, E, G Virus
What is the differential diagnosis for a patient presenting with intestinal blockage from a cestode (tapeworm)?
- Diphyllobothriasis
- Echinococcosis
- Taenisasis
- Cysticercosis
What is the differential diagnosis for a patient presenting with intestinal blockage from a trematode (flukes)?
- Schistosomiasis
What is the differential diagnosis for a patient presenting with intestinal blockage from a nematode (roundworm)?
- Enterobiasis
- Trichuriaisis
- Hoockworm
- Trichinellosis
- Toxocariasis
What are the symptoms of esophagitis?
- Pain and difficulty swallowing
- Heart burn
- Acid regurgitation
Candida albicans esophagitis
- Risk factors: HIV, diabetes, broad spectrum antibiotics
- Clincal presentation: Yellow-white mucosal plaques, ulceration, and luminal narrowing.
- Complications: Performation
- Treatment: Fluconazole
Herpes Simplex Virus esophagitis
- Risk factors: Hematologic malignancies, chemotherapy, or immunosupppressive therapy.
- Clinical presentation: Small ulcers on the distal third of the esophagus. Pseudomembranes or volcano ulcers may occur with progression.
- Treatment: Acyclovir.
CMV esophagitis
- Risk factors: AIDS and immunosupression.
- Clinical presentation: "Punch-out" ulcers (well circumscribed) in mid to distal esophagus.
- Treatment: Ganciclovir.
What are the signs and symptoms of GI infections?
- Fever
- Loss of apetite
- Nausea
- Vomiting
- Weight loss
- Dehydration
- Mucus or blood in stool
Staph aureus intoxication
- Risk factors: Many strains have enterotoxins (exotoxins) that infect custards, creamy dishes, mayonaise, salad dressing, and meat.
- Clinical presentation: Vomiting, diarrhea, and headache.
- Virulence factors: Produces toxins lettered A through E.
- Rapid onset.
- Treatment: Symptoms pass within 24-48 hours so antibiotic therpay is not needed.
Staphlococcal enterotoxins
- A: Most commonly associated with food poisoning.
- B: Associated with enterocolitis
- C: Rare
- D: Second most common alone or assciated with toxin A. Associated with milk products.
- E: Rare
Mechanism of action of Staphlocoocal enterotoxins?
- Stimulate the vagal nerve endings in the stomach that control the vomiting response.
- Act as superantigens in the blood stream to cause T-cell proliferation, which causes malaise.
- Different amounts are produced among strains due to differing promoter strengths.
Bacilus cereus emetic syndrome
- Intoxication: From preformed, heat stable toxin ingestion.
- Duration: After 1-6 hour incubation period, symptoms prosist for 24 hours.
- Virulence factors: Cereulide, a circular peptide
- Clinical presentation: Profuse vomiting, nausea, and abdominal cramps are present, but fever and diarrhea are absent.
- Diagnosis: Retreive 10^5 orgaisms from the infected food.
Bacilus cereus diarrheal syndrome
- Infection: Caused by ingestion of organisms with subsequent production of toxin.
- Duration: Slow onset and symptoms last for 24 hours.
- Virulence factors: Diarrheal enterotoxin and hemolysins
- Risk factors: Meat, stew, gravy, vanilla sauce, vegetable, puddings, and milk.
- Clinical presentation: Watery diarrhea, nausea, and abdominal cramps, but vomiting is absent.
- Diagnosis: Recovery of the organism in stools, oucherterlony assay for toxin.
Bacilus cereus characterisitics
- Gram positive rod
- Grows aerobically or anaerobically
- Beta hemolytic
- Motile
- Heat resistant, radiation, dessication, and disinfectants
- Spores survive cooking and grow in the refrigerator.
Clostridium botulism general characterisitics
- Gram positive bacili
- Virulence factors: produces eight distinc toxins, four of which cause disease in humans.
- Diagnosis: Eggyolk agar or anti-Ig mouse antibodies.
- Treatment: Trivalent botulinum antiboxin (ABE), and BabyBIG for the infantile form (AB).
- Prevention: Adequate cooking and maintaining acid pH.
Botulism toxin
- Botulism toxin is an A-B type toxin (A is the toxin and B attatches).
- The B chain is called the heavy chain and the A chain is called the light chain.
- Targets cholinergic nerves and inhibits the release of acetyl choline causing flacid paralysis.
Botulism toxin serotypes
- A and E: Target SNAP-25 previnting neurtransmitter release.
- B, D, and F: Target synaptobrevin
- C cleaves syntaxin on the membrane.
Clostridium botulism intoxication
- Duration: Incubation period is 12-72 hours with symptoms lasting days to months.
- Risk factors: Home canned food, herb infused oils, cheese sauce, bottled garlic.
- Clinical presentation: Nausea, vomiting, blurred vision, dilated pupils, bilateral descending parlysis, respitory involvement.
Infantile infection of clostridium botulism
- Duration: 3 to 30 days of incubation.
- Infection: Spores infect the gut of infants because they do not have normal flora to fight the infection.
- Clinical presentation: "Floppy baby syndrome"
- Assocaited with bottled honey.
What are the symptoms associated with non-inflammatory diarrhea?
- Mucousal hypersecretion or hypoabsorption without inflammation changes to the wall of the intestine.
- Typically involve the small intestine.
- Less severe than the inflammatory diseases.
General characteristics of Clostridium perfingins
- Risk factors: Meats (pork)
- Infection: Food poisoning because of ingestion of the toxin.
- Duration: 8-16 hours.
- Clinical presentation: Abdominal cramps, watery diarrhea, and nausea.
- Complication: Rarely a cause of necrotic enteritis (most often from the C sub-strain).
- Diagnosis: Toxin is detected in feces.
- Prevention: Reheating to denature the toxin.
General characterisitics of family Enterobacteridae.
- Gram negative bacilli
- Ferment glucose
- Part of the normal intestinal flora.
- Cause a wide range of diseases.
- Biotyping is required for the final diagnosis.
- Virulence factors: Lipid A compoent of LPS, capsule, Type III secretion systems, Iron chelating.
E. coli general characteristics
- Produces adhesins CFA, Bfp, and AAF.
- Causes septicemia, UTIs, and neonatal meningitis.
- Colonizes the small intestine and causes traveler's diarrhea (ETEC).
Travelers diarrhea
- Duration: 1-3 days incubation with a week of symptoms.
- Clinical presentation: Toxins cause the hypersecretion of fluids.
- Virulence factors: CFA, LT, STa, STb, and heat liable toxin.
- HL is a A-B type toxin with an ADP-ribosylating toxin that causes cAMP to accumulate, which alters sodium and choloride transporteres.
- There is also heat stable toxin that causes cGMP to accumulate.
Infantile diarrhea (EAEC)
- Virulence factors: Produces ST-like toxin (EAST 1).
- E. coli colonization causes the bacteria to become lodged in the growing mucous.
- Causes a shortening of the microvilli.
Infantile Diarrhea (EPEC)
- More common is less developed countries.
- Causes the intestine to take on a patchy appearance.
- No toxin is produced, but destruction of the microvilli leads to malabsorption.
E. coli attatchment (EPEC)
- E. coli lodge to the intestinal mucous membrane and secrete TIR into the epithelial cells via a type III secretion system.
- TIR insertes into the membrane and binds to E.coli via EPEC.
- A cascade of signaling events lead to cytoskeleton rearrangement, pedistle formation, and loss of the microvilli.
Diagnosising E. coli infections.
- MacConkey agar: Bile and crystal violet inhibiit gram poisitive growth. Lactose fermenters will appear as pink colonies and others will be clear.
- Eosine methyline blue: Eosin will inhibit gram positive growth and lactose inhibitors turn pink purple. E. coli has a greenish sheen.