GI Infections

Question 1

GI Pathogen communicability

Highest rate of transmissibility*:

Answer 1

Shigella, Noroviruses: 10 to 100 organisms

Giardia, Cryptosporidium, Salmonella (infants only): 80-500 organisms

Question 2

Non-Typhoid Salmonellosis Tx

Answer 2

• Antibiotics not helpful in non-bacteremic forms

• high-risk people (elderly, infants 1-3 months age,
SS disease, IBD, steroids, Immune suppressed)

Question 3

•Paralytic Shellfish:

Answer 3

• toxin in mollusks
• numbness and tingling after 30- 60 minutes;
• serious cases may need respiratory support

Question 4

•Ciguatera:

“Ciguatoxin”

Answer 4

• toxin from DF around coral reefs ingested by large reef fish, with in turn ingested by humans
• GI symptoms, cold hot reversal and numbness & paresthesias

Question 5

•Neurotoxin Inhalation or Shellfish poisoning:

Answer 5

•inhaled during algal blooms,

Question 6

•Pufferfish:

Answer 6

• toxin from DF in pufferfish (Japanese delicacy)

Question 7

•Scrombroid (histamine-like histidine)

Answer 7

• improperly refrigerated or
preserved fish

• histamine reaction: flushing, headache, palpitations, itching, diarrhea.

• within 10-60 minutes
with resolution in 12 hours

• Peppery, sharp and salty taste
• Heat stable histamine

Question 8

GI Organism-Specific Therapy

Answer 8

• Shigellosis – FQs or
azithromycin

• Non-typhoid salmonellosis – only with sepsis - FQs or
3rd generation cephalosporin

• Campylobacteriosis –
Azithromycin or erythromycin

• Non-cholera Vibrio diarrhea – as shigellosis
• Cholera – doxycyline

• Giardiasis – Tinidazole or
nitazoxanide

• Cryptosporidiosis - nitazoxanide

• Cyclosporiasis or
Cystoisosporiasis – TMP/SMX

• Enterocytozoon diarrhea –
Albendazole

• Intestinal amoebiasis –
metronidazole plus diloxanide
furoate or paromomycin

Question 9

Vomiting as a Primary Symptom

Answer 9

• Viral gastroenteritis with
incubation period: 24 – 48
hours

• Food poisoning/ Performed 
toxin* of Staphylcoccus
aureus or Bacillus cereus 
with incubation period: 
2‐7 hours

Question 10

For bacterial diarrhea transmitted person to person, think . . .

Answer 10

Salmonella typhi carriers and Shigellosis

Question 11

Kaplan criteria for a norovirus:

Answer 11

> vomiting seen in >50%,

> incubation period
between 24-48 hours

> illness lasted between 12-60 hours.

Confirmed by stool PCR.