Gastroenteritis

Question 1

What is the commonest cause of GASTROENTERITIS?

Answer 1

Campylobacter

Question 2

What bacteria cause OUTBREAKS of GASTROENTERITIS?

Answer 2

Salmonella and E coli 0157

E coli is rare but has high morbidity

Question 3

Which bacteria can be invasive (cause bacteremia and sepsis) in immunosupressed patients?

Answer 3

Campylobacter and Salmonella

Question 4

What is incubation?

Answer 4

Period between first exposure to pathogen and appearance of symptoms

Question 5

Which bacteria have SHORT intubation periods? (1-6hrs)

Answer 5

Staph aureous: preoformed EMETOGENIC toxin in food
Bacillus cereus: Heat resistant spores, bacterial growth results in production of EMETOGENIC toxins

EMETOGENIC TOXINS STIMULAT VOMITING CENTRE AND FAST!

Question 6

Which bacteria causes “fried rice syndrome”?

Answer 6

bacillus cereus

Question 7

T/f
Bacillus cereus will present with lower GI tract symptoms (cramps, diarrhea) then upper GI tract symptoms (nausea vomiting)

Answer 7

F
other way round
EMETOGENIC TOXIN PRODUCER!

Question 8

T/F

Toxins simulate outpouring of fluid into bowel lumen due to inflammatory processes

Answer 8

T

Question 9

Bacteria with medium incubation periods? (12-48hrs)

Answer 9

Salmonella

These invade the gut and cause mucosal daamage via ulceration and inflammation.

bloody diarrhea

Question 10

Bacteria with long incubation periods? (2-14 days)

Answer 10

Campylobacter
E coli 1057

These INVADE the gut and cause mucosal daamage via ulceration and inflammation.

bloody diarrhea

Question 11

Where is campylobcter found/how does it spread?

Answer 11

food hygiene (raw poultry especially)

less likely to spread person to person

Question 12

How does campylobacter present?

Answer 12

cramps, bloody diarrhea/dysentry (30%), fever, pain

Question 13

What type of bacteria is campylobacter?

Answer 13

spirillum with bi polar flagella

Question 14

What is the structure of salmonellla

Answer 14

Lipopolysachharide (endotoxins)
Antigens on cell wall (O antigens)
Antigens on flagellum (H antigens)

Question 15

How to treat campylobacter?

Answer 15

Macrolide (clarithromycin, erythromycin)

Question 16

Transmission salmonella?

Answer 16

poultry, meat, raw egg

animal gut, multiplies in food

Question 17

Why does gastroenteritis cause vomiting?

Answer 17

• EMETOGENIC toxins such as from staph aureous and bacillus cerus, absorbed systemically and stimulate vomiting centre. (emesis=vomiting)
• Toxins cause inflammation which leads to
  1. Distension and mucosal damage which stimulates efferent nerves to vomit

Question 18

Why does gastroenteritis cause diarrhea?

Answer 18

• ENTEROTOXINS (enterotoxigenic e coli 1507) drive excessive intestinal secretion
• Inflammation reduces digestive ability which increases osmotic load (watery diarrhea)
• inflammation leads to build up of exudate fluid & cells (inc. vasopermeability)

Question 19

Why is serotyping significant in salmonella?

Answer 19

Serotyping is looking at stuff on pathogen surface (serology antibodies)
Help to pinpoint infection (whether local or abroad)
Typhoidal or non typhoidal?

Question 20

What are the toxins produced by E coli 01507 called?

Answer 20

Shiga-like toxins, functionally simmular to shigella toxins

Question 21

Lab tests for typing e coli?

Answer 21

Maconkey Agar
Antisera: Serum with antibodies - detect which ones bind to which antigen (01507 antigen)
ELISA Enzyme autoimmunessay
DNA of toxin genes

Question 22

How does Maconkey agar show presence of E coli?

Answer 22

Lactose fermentation - enteric bacteria can do this

Question 23

Transmission e coli?

Answer 23

LOW infectious does
Food
Person to person
drinking water contaminated with faeces

Question 24

Complications/presentation of SHIGA LIKE TOXIN PRODUCING E coli?

Answer 24

Bloody diarrhea
Haemorrhagic colitis - invades submucosa LOTS inflammation, SEVERE CRAMPING and super bloody diarrhea
Haemolytic Uraemic Syndrome - anaemia and kidney failure

Question 25

What does shiga-like toxin do?

Answer 25

Binds to receptors on renal cells, RBCs and others
Inhibit protein synthesis - cell death
CAUSES HAEMOLYTIC URAEMIC SYNDROME!!!!!

Question 26

T/F

Rotavirus outbreaks more common in the summertime

Answer 26

F

MORE COMMON IN WINTER

Question 27

Rotavirus spread?

Answer 27

Contaminated water and food
faecal oral
Fomites - objects that can carry the virus i.e. telephone, water play tables in day-care nurseries

Question 28

T/F

all kids get rotavirus before age 5

Answer 28

T

Question 29

Presentation rotavirus

Answer 29

Acute onset vomiting& FEVER

followed by frequent NON BLOODY DIARRHOEA

Question 30

Diagnosis rotavirus?

Answer 30

PCR faeces

billions shed in faeces

Question 31

Norovirus spread?

Answer 31

Contaminated water and food
faecal oral
Fomites - objects that can carry the virus i.e. telephone, water play tables in day-care nurseries

Question 32

Which virus causes outbreaks nursing homes, hospitals, cruise ships, leisure centres etc?

Answer 32

NOROVIRUS

Rotavirus also has low infectious dose and transmission pathways but more associated with infants!

Question 33

Which virus is characterized by sudden explosive diarrhea and vomiting?

Answer 33

NOROVIRUS!

Question 34

T/F

Norovirus has asymptomatic shedding 48hrs post symptoms

Answer 34

T

Question 35

Rotavirus has post infective what?

Answer 35

Malabsorption

Question 36

Diagnose norovirus?

Answer 36

PCR stool 6hrs

PCR vomit using red copan viral swabs

Question 37

Presentation norovirus?

Answer 37

Nausea, vomiting, cramping, diarrhea non bloody, fever, myalgia, headache

Question 38

Non typhi salmonella presentation?

Answer 38

Diarrhea, fever, abdominal cramps, vomiting

Question 39

Presentation of entertoxigenic E coli?

Answer 39

NOT SHIGA LIKE TOXIN PROD

watery diarrhea, cramps, some vomiting