GI Disease

Question 1

Moderate inoculum size to cause diarrhea?

Answer 1

Giardia
Cryptosporidium
Shiga toxin
Salmonella

Question 2

Low rate of spread in diarrhea?

Answer 2

Campylobacter
Enteroinvasive E. coli
Enterotoxigenic E. Coli
Vibrio cholerae

Question 3

Norovirus

Answer 3

Endemic in nursing homes and cruise ships
Rapid onset
Nausea, vomiting, fever and 3-5 d of diarrhea

Question 4

Enterotoxigenic e. Coli

Answer 4

Virulence: fimbriae, heat labile and heat stable endotoxins

Tx: bactrim or FQ

Question 5

Enterohemorrhagic E. Coli (EHEC)

Aw Heck….shiga what?

Answer 5

E. coli 0157 (Shiga toxin producing
Sorbitol negative)

Non 0157 ( sorbitol positive)

Can cause HUS (hemolytic anemia, thrombocytopenia, renal failure) in 10% of pts

Tx: none
FQ enhance toxin production
If necessary –> azithro

Question 6

Which Ecoli caused outbreak in 2011 in Germany and France?

Answer 6

Enteroaggregative E. coli with shiga toxin from sprouts

26% developed HUS

Question 7

Organisms that cause diarrhea with smallest inoculum (most contagious)?

Answer 7

Shigella

Norovirus

Question 8

Vibrio cholerae

Answer 8

Curved Gram negative bacillus with a flagellum
Profuse watery diarrhea
Tx: fluids, electrolytes

Abx: cipro, tetracycline, doxycycline, azithro (decrease diarrhea duration and volume)

Question 9

Vibrio vulnificus/parahaemolyticus

Answer 9

Causes enteritis, Ssti w/ sepsis after contact with sea water or ingestion of raw seafood
Fulminant infxn in cirrhotic pts
Tx: doxycycline AND ceftazidime/cipro

Question 10

Toxigenic vs invasive diarrhea

Answer 10

Toxigenic: occurs in hrs
Upper GI sx: watery diarrhea, no fecal WBC,
Vibrio, etec, b. Cereus, staph aureus, clostridium perfringens
———————————————
Invasive: 1-3 d
Abd pain, fever, fecal WBC, inflammatory diarrhea
Shigella, campylobacter, salmonella, EHEC, yersinia, v. Parahaemolyticus

Question 11

Shigella diarrhea

Answer 11

High rate of spread with low inoculum
Dysentery (bloody diarrhea)
Reactive arthritis, iritis, persistent illness
RF: daycare, MSM

Dx: EIA for shiga toxin in stool, stool cx

Tx: yes! With cipro or bactrim To decrease shedding

Question 12

Salmonella (non typhoid)

Non lactose fermenter

Answer 12

95% infxns from food (associated with peanut butter) reptiles, amphibians

8% healthy pts develop bacteremia
50% high risk pts develop bacteremia (sickle cell pts at risk for osteo)

Sx: rose spots, HSM, enteric fever, can colonize GB, can have ileal perforation from necrotic peyers patches

If resistant to nalidixic acid, then resistant to FQ

Tx: none,
If IC, 65 yrs:
cipro/azithro, ceftriaxone x 7-14d

Question 13

Campylobacter jejuni

Answer 13

80% infxns from food
Hx of contact with poultry puppies

Sx: Prodrome of fever and h/a,
Complications: GBS (asc weakness), IBS, reactive arthritis

Tx: erythromycin

Question 14

Salmonella, shigella, and campylobacter in Asia, India

Answer 14

Incr FQ resistance, treat with azithromycin instead

Question 15

Giardia

Answer 15

“Cross eyed” flagellated Protozoa
RF: beavers, stream water, day care

Dx: rapid ag test, stool pcr
Tx: tinidazole, flagyl, Nitazoxanide

Question 16

Cryptosporidium

Answer 16

Animal and human reservoirs
RF: waterparks, pools, daycare, wells

Tx: Nitazoxanide

Question 17

Cyclospora

Answer 17

Nepal, Haiti, Peru, Guatemalan raspberries, snow peas

Often o&p is negative, seen on modified acid fast stain

Tx: bactrim x 7d

Question 18

Paralytic shellfish

Answer 18

Toxin from dinoflagellates in water taken in by mollusks like clams and mussels

Sx: onset in minutes to hours, facial paresthesia and paralysis, mouth numbness, LE weakness

Question 19

Ciguatera

Answer 19

Toxin from dinoflagellates in large fish or eel (grouper, snapper, barracuda, amberjack, parrotfish), tastes peppery or pungent

Sx: mixed Neuro and GI sx (decreased BP x 2-3 wks, decreased heart rate, blurred vision, lip numbness, teeth pain, loose teeth, metallic taste in mouth, tingling extremities, temperature dyesthesia, heart block, vomiting, resp failure)
Sx worse with caffeine and alcohol

** freezing or cooking has no effect on killing toxin

Question 20

Neurotoxin inhalation

Answer 20

Toxin inhaled during algal blooms (red tide)

Mild illness, short lasting

Question 21

Tetrodotoxin

Answer 21

Toxin in pufferfish, can be fatal

Sx: within hours, weakness, dizziness, headache, paresthesia, hypotension, resp failure

Tx: supportive

Question 22

Scombroid

Answer 22

Histamine like reaction
Food tastes peppery, salty, bubbly (spoiled fish at room temp)

To prevent, refrigerate from catch to cooking

Gram negative produce histamine like substance –> hives, wheezing, headache, dizziness, urticaria, diarrhea, vomiting, mouth burning, flushing

*Resolves in 10-12 hours with antihistamines

Question 23

Diarrhea that occurs 2-7 hrs after a meal?

Answer 23

Preformed toxin -

1. ) staph aureus (presents with nausea and vomiting)
2. ) or bacillus cereus

Question 24

Diarrhea with an 8-14 hr incubation?

Answer 24

Clostridium perfringens

Watery diarrhea

Question 25

Diarrhea that has a 24-48 hr incubation?

Answer 25

Norovirus E.coli Listeria

Question 26

21 yo student with vomiting, fever, bloody diarrhea few hrs after eating?

Answer 26

Not food from the restaurant, Fever and bloody BMs take time to develop Preformed toxin usually presents with just vomiting

Question 27

Norovirus

Answer 27

24-48 hr incubation 90% cases with vomiting 50% with diarrhea 30% with fever Usually recover in 12-60 hrs Supportive care, bismuth *clean with a chlorine bleach 1:50-1:10 dilution

Question 28

Nursing home resident with diarrhea?

Answer 28

Treat with abx to decrease risk of complications

Question 29

Which organism can cause abx associated hemorrhagic colitis

Answer 29

Klebsiella oxytoca due to cytotoxic Also hypermucoid colonies, + string test Can cause liver abscess and meningitis

Question 30

Helicobacter pylori

Answer 30

GNR, spiral shaped, flagellated, catalase +, oxidase+, urease + Transmitted person to person or mother to child Associated with gastritis, duodenal ulcer, gastric ulcer, MALT lymphoma, gastric cancer Testing: d/c ppi x2 weeks, d/c abx x 4 wks, (if GI bleed, wait 4-8 wks before testing) and then get stool antigen, or urea breath test, Serology is less sensitive and specific If alarm sx: EGD with biopsies

Question 31

H.pylori tx?

Answer 31

1. ) PPI + clarithromycin 500mg twice daily + amoxicillin 1gm twice daily x 10-14 d 2. ) quad tx: ppi+ bismuth+ metro+ tetracycline 3. ) If ß-lactam allergy: PPI + clarithromycin 500mg twice daily + metronidazole 500mg twice daily. TEST OF CURE 4 wks post tx with stool ag test or urea breath test ** flagyl resistance 37%, clarithro resistance 11%, amox and tetracycline resistance is rare

Question 32

HIV pts with h. Pylori infxn

Answer 32

Quad tx Dose adjust Clarithromycin if pt on ritonavir or cobicistat Can't use atazanavir/r with Omeprazole, typically switch art

Question 33

Clostridium dificile - which abx are high risk?

Answer 33

Diarrhea with either + stool test or cscy with pseudo membranous colitis Most commonly with clindamycin, 3rd generation cephalosporins (e.g., ceftriaxone, cefotaxime), fluoroquinolones (e.g., ciprofloxacin, levofloxacin, moxifloxacin) » Medium: amoxicillin/clavulanate, other ß-lactams or ß-lactam/ß-lactamase inhibitor combinations, carbapenems (e.g., imipenem) » Low or minimal risk: metronidazole, vancomycin (IV), aminoglycosides, nitrifurantoin, methenamine, fosfomycin, sulfonamides, tetracyclines.

Question 34

C dificile infection control

Answer 34

Gloves, gowns, wash hands with soap and water Private rooms Post - clean room with chlorine containing sporicidal agent

Question 35

C dificile

Answer 35

Sx: no fever, leukocytosis, Hyper virulent strain with binary toxin - increased toxin A and B production, mutation in tcdc gene Dx: 1 diarrheal stool (unless ileus is suspected) for pcr/naat for toxin A and B • Complications: ileus and toxic megacolon, hypoalbuminemia, shock, renal failure, leukemoid reaction. Tx: • Mild or moderate: patients with WBC 15, 000 or creatinine >1.5 x baseline. » Vancomycin 125 mg PO four times daily x 10-14 d. • Severe infection and complicated: hypotension, ileus, toxic megacolon; concern regarding whether oral drug reaches large bowel. » Vancomycin 500 mg four times daily PO or by NG tube plus metronidazole 500 mg IV q8h. » If complete ileus, also administer vancomycin 500mg q6h per rectal retention enema if feasible.

Question 36

C dificile recurrence

Answer 36

• Relapse CDI: 20-25% of cases after initial course of therap. » First relapse: treat as above. » Second or more relapses: No more flagyl due to neurotoxicity vancomycin 125 mg PO four times daily x 10-14 days and then "taper and pulse" with 125 mg PO twice daily x 7 days then 125 mg every other day x 6 weeks. * rifaximin after last course of vanco with some success

Question 37

Probiotics to prevent c. Dificile?

Answer 37

No per IDSA