13. diseases of the digestive system

Question 1

this is a medical condition characterized by inflammation of the gastrointestinal tract that could involve both the stomach (“gastro”) and/or the small intestine (“entero”) resulting in some combination of diarrhea, vomiting, abdominal pain and cramping

Answer 1

gastro-enteritis

Question 2

globally, most cases of gastroenteritis are caused by ________; a virus transmitted by the fecal-oral route and capable of causing severe diarrhea

Answer 2

rotavirus

Question 3

this is a large family of gram-negative bacteria, many members of this family are causative agents for gastroenteritis

Answer 3

enterobacteriacecae

Question 4

this type of bacteria which is gram-negative and rod shaped is a common member of the normal microbiota of the colon; most strains are harmless, but some serotypes are pathogenic and can cause serious food poisoning in humans and other species

Answer 4

escherichia coli (e. coli)

Question 5

how many groups of pathogenic E.coli are there?

Answer 5

six

Question 6

this is a pathogenic group of e.coli; it is the most common cause of traveller’s diarrhea. it attaches to the intestinal wall and produces a heat stable enterotoxin which induces hyper secretion of electrolytes and water into the intestinal lumen which causes diarrheal illness. can be spread from hand to mouth or through contaminated food/water

Answer 6

enterotoxigenic e.coli (ETEC)

Question 7

what are some symptoms if ETEC/traveller’s diarrhea is present?

Answer 7

water diarrhea, abdominal cramps, low fever

Question 8

T/F: the disease that ETEC causes is usually self limiting

Answer 8

true

Question 9

what may be used to treat ETEC if needed?

Answer 9

antibiotics: fluoroquinolone, doxycycline and rifaximin

Question 10

this is a pathogenic group of e.coli; it is an intracellular invasion into intestinal epithelial tissue, and is similar to shigellosis disease. virulence factors of this e.coli are carried on a large plasmid

Answer 10

enteroinvasic e.coli (EIEC)

Question 11

what are some symptoms if EIEC is present?

Answer 11

diarrhea, chills, cramps and fever -> usually self-limiting

Question 12

this is a pathogenic group of e.coli; strains cause a kind of cell damage called effacing lesions by attaching to the brush border of intestinal epithelial cells using an adhesion factor known as intimin which results in destruction of brush border microvilli (hemorrhagic colitis)

Answer 12

enter-pathogenic E. coli (EPEC)

Question 13

EPEC has __________ encoding for virulence factors such as Tir protein that triggers rearrangement of host cell actin from microvilli

Answer 13

pathogenicity island genes

Question 14

what are some symptoms if EPEC is present?

Answer 14

fever, vomiting, and diarrhea can lead to severe dehydration. can cause fatal diarrhea especially in infants and those in less developed countries. tx is similar to ETEC

Question 15

this is a pathogenic group of e.coli; strains adhere to epithelial cells in localized regions, forming clumps of bacteria with a stacked brick appearance. can also produce several plasmid-encoded toxins that cause diarrhea, especially in children. it is the second most common cause of travellers diarrhea

Answer 15

Enteroaggregative e.col (EAEC)

Question 16

this is a pathogenic group of e.coli; the most dangerous kind of strains, which is capable of causing epidemics. produces a shiga-like toxin (or verotoxin). can cause diseases ranging from relatively mild to life threatening

Answer 16

enterohemorrhagic (EHEC) or shiga toxin-producing e.col (STEC)

Question 17

EHEC/STEC has a strain known as ______ which has been responsible for several recent epidemic outbreaks

Answer 17

O157:H7

Question 18

what are some symptoms if EHEC/STEC is present?

Answer 18

bloody diarrhea with severe cramping, but no fever, it can lead to hemorrhagic colitis and profuse bleeding

Question 19

this is a group of gastrointestinal infections caused by 4 Shigella (rod-shaped, gram-negative) species; these species invade intestinal epithelial cells and then multiply inside the tissue, the epithelium and the M cells of the Peyers patches in the intestine become ulcerated and start loss of fluid

Answer 19

Shigellosis (bacillary Dysentry)

Question 20

what 4 shigella species are responsible for causing shigellosis?

Answer 20

Shigella Sonnei, Shigella flexneri, Shigella boydii and Shigella dysenteriae

Question 21

how is shigellosis spread?

Answer 21

hand to mouth or through contaminated food/water

Question 22

what are some symptoms of Shigellosis?

Answer 22

• fever
• watery diarrhea (may also contain pus, mucus, and/or blood)
• in severe cases: ulceration of the mucosa, dehydration and rectal bleeding

Question 23

________ type 1 produce Shiga toxin, which targets the endothelial cells of the small blood vessels in the intestines and later targets the glomerular endothelium in the kidneys leading to hemolytic uremic syndrome (HUS) and kidney failure

Answer 23

S. dysenteriae

Question 24

T/F: antibiotics are never indicated for Shigellosis

Answer 24

false - severe cases may require antibiotics such as ciprofloxacin and azithromycin

Question 25

what are the two types of salmonellosis?

Answer 25

non-typhoidal and typhoidal

Question 26

the non-typhoidal salmonellosis is caused by over 2,000 salmonella serovars (gram-negative rods) -> all of them are classified as a single species known as _______________

Answer 26

salmonella enterica

Question 27

the two most frequently isolated serovars from humans are ________ & ___________

Answer 27

typhimurium and enteritidis

Question 28

where are the salmonellosis bacteria contracted from?

Answer 28

the bacteria are contracted from chicken, pork, and beef when the meat is prepared incorrectly, eggs, egg products and milk when not prepared, handled, or refrigerated properly

Question 29

the infection process of this type of salmonellosis invades the small intestine and multiplies in tissues. the body is poisoned by endotoxins that are released from the dead Salmonella. the local response to the endotoxins is enteritis and gastrointestinal disorder

Answer 29

non-typhoidal

Question 30

what are some symptoms of non-typhoidal salmonella

Answer 30

• diarrhea
• fever
• vomiting
• abdominal cramps
  these occur 12-72 hours after infection. most people recover without Tx after 4-7 days with rehydration

Question 31

what should occur in severe cases of non-typhoidal salmonella where the infection may spread from the intestines to the bloodstream and then to other body sites (liver, spleen, kidneys)

Answer 31

should be treated with antibiotics