GastroIntestinal Pathogens.

Question 1

Pathogen most likely to cause gastric ulcers, gastritis, gastric carcinoma, or gastric MALT Lymphoma.

Answer 1

Helicobacter pylori: produce urease to neutralize the local region stomach acid.

Question 2

What pathogens are major contributors to esophagitis?

Answer 2

• Candida albicans: superficial fungal infection forming pesudomembranes with yeast and pseudohyphae. Opportunistic.
• Herpes simplex virus: consist of punched out ulcers and nuclear viral inclusions.
• Cytomegalovirus: superficial ulcers with nuclear and cytoplasmic viral inclusions. Include enlarged cells.

Question 3

Pathogens to cause viral enteritis/colitis.

Answer 3

• Norovirus
• Rotavirus
• Adenovirus

Question 4

Most common causes of bacterial enteritis/colitis?

Answer 4

• Vibrio cholera: human to human fecal transmission with rice water stool
• Vibrio vulnificus: more common. associated with seafood consumption.
• Campylobacter jejuni: evertoinvasive diarrhea from contaminated water, milk, food.
• Clostridium difficili: overgrowth of pathogen with pseudomembrane post broad spectrum antibiotics.
• Tropheryma whipplei: non-motile facultative intracellular gram positive bacilli. gastroenteritis and malabsorptive syndrome.
• Staphylococcus aureus: heat stable enterotoxin
• Enterobacteria

Question 5

List the type of E.coli associated with the type of diarrhea:

1. Traveler’s diarrhea
2. Infantile
3. Shigella-like
4. Hemorrhagic colitis/ HUS

Answer 5

1. Enterotoxigenic
2. Enteropathogenic/ Enteroaggregative
3. Enteroinvasive
4. Enterohemorrhagic

Question 6

Entamoeba histolytica

Answer 6

• Invasive intestinal amebiasis with extraintestinal amebiasis from ingestion of feces contaminated water.
• Amoeba exist as trophozoite or cyst (infective form)
• Diagnose with flask-shaped ulcer on mucosa and RBC in the ulcer.

Question 7

Giardia lamblia

Answer 7

• Causes fatty diarrhea with fatty stool. Lives on surface mucosa affecting fat absorption.
• Motile trophozoite with cyst form
• note fatty/oily stools that float

Question 8

Cryptosporidium parvum

Answer 8

• Opportunistic, causing gastroenteritis and watery diarrhea.
• Positive AFB stian or presence of immunofluorescent antibodies.

Question 9

Trichuris trichura

Answer 9

• Whipworm infection
• Soil transmitted helminth.
• anemia and growth retardation
• more common in warm climates
• Barrel-shaped eggs with 2 polar caps.

Question 10

Ancylostoma duodenale/ Necatur americanus

Answer 10

• Hookwarm infection
• soil transmitted helminth
• asymptomatic to diarrhea, abd pain, anemia.
• locate ova in stool

Question 11

Strongyloides stercoralis

Answer 11

• Threadworm
• soil transmitted helminth tropics and subtropics
• Sever disseminated strongyloidiasis in HTLV-1
• Can infect at perianal skin causing hyperinfection.

Question 12

Enterobius Vermicularis

Answer 12

• Pinworm
• most common worm infection in US causing enterobiasis.
• Live in liver, and migrate at night causing perianal itch.
• Spread with ingestion of egg from feces.

Question 13

Ascaris lumbricoides

Answer 13

• Giant roundworm
• # 1 soil transmitted helminth causing ascariasis
• human fecal consumption
• Can be found in mouth while coughing, due to dissemination through body. Associated with GI blockage.