97 - Gastrointestinal Infections

Question 1

Reasons why diarrhoea kills
1
2

Answer 1

1) Immediate: fluid and electrolyte imbalance

2) Delayed: malnutrition

Question 2

Reasons why diarrhoea kills

Answer 2

1) Immediate: fluid and electrolyte imbalance

2) Delayed: malnutrition

Question 3

Fluid moving through GIT in 24 hours

Answer 3

~10L

Question 4

Amount of fluid absorbed per day through GIT

Answer 4

~9.9L of 10L taken in (excrete ~100mL)

Question 5

Two ways in which diarrhoea can come about
1
2

Answer 5

1) Small intestine origin - Too much fluid for intestine to absorb.
2) Diarrhoea of large intestinal origin - Large intestine becomes inflamed, stops retaining gut contents (can’t operate properly)

Question 6

What characterises diarrhoea of small intestine origin

Answer 6

More volume, watery, frequent

Question 7

What characterises diarrhoea of large intestine origin

Answer 7

Less volume, can be bloody or purulent

Question 8

Dysentery

Answer 8

Presence of blood, pus, mucus in the faeces

Question 9

Predominant aetiological agents of infective diarrhoea in developed vs developing countries

Answer 9

More bacteria in developing countries, more viral in developed countries

Question 10

Aetiological agents of non-specific gastro

Answer 10

Bacteria, viruses, protozoa

Question 11

Aetiological agents of dysentaery

Answer 11

Shigella/EIEC, protozoa

Question 12

Typical protozoal cause of dysentary

Answer 12

Entamoeba histolytica

Question 13

Aetiological agents of foodborne infections/intoxications

Answer 13

Salmonella, Virbio, Listeria, Yersinia, Campylobacter, EHEC, Staph, Clostridium, Bacillus, ciguatoxin, viruses.

Question 14

Aetiological agents of foodborne infections/intoxications

Answer 14

Salmonella, Virbio, Listeria, Yersinia, Campylobacter, EHEC, Staph, Clostridium, Bacillus cereus, ciguatoxin, viruses.

Question 15

Where is ciguatoxin found?

Answer 15

Some species of fish

Question 16

Aetiological agents of travellers’ diarrhoea

Answer 16

ETEC, viruses, protozoa

Question 17

Most common cause of travellers’ diarrhoea

Answer 17

ETEC (~50% of cases)

Question 18

Aetiological agent of pseudomembranous colitis

Answer 18

Clostridium difficile

Question 19

Most serious cause of antibiotic diarrhoea

Answer 19

Clostridium difficile

Question 20

Aetiological agent of haemorrhagic colitis

Answer 20

EHEC

Question 21

Most severe Shigella species

Answer 21

Shigella dysenteriae

Question 22

Only infectious cause of haemolytic uremic syndrome

Answer 22

Shigatoxin (EHEC or S. dysentariae)

Question 23

Only infectious cause of haemolytic uremic syndrome

Answer 23

Shigatoxin (EHEC or S. dysentariae)

Question 24

Only Shigella species that releases shigatoxin

Answer 24

S. dysenteriae

Question 25

Difference between dysentery and haemorrhagic colitis

Answer 25

Dysentery has blood, pus, mucus in faeces. | Haemorrhagic colitis only has blood

Question 26

Aetiological agents of cholera-like diarrhoea

Answer 26

Vibrio cholerae, ETEC

Question 27

Only serotypes of V cholerae that cause epidemic cholera

Answer 27

O1 and O139

Question 28

Aetiological causes of enteric fever

Answer 28

Salmonella typhi, Salmonella paratyphi

Question 29

Aetiological causes of enteric fever

Answer 29

Salmonella enterica serotype Typhi, Salmonella enterica serotype Paratyphi

Question 30

Aetiological causes of enteric fever

Answer 30

Salmonella enterica serotype Typhi, Salmonella enterica serotype Paratyphi

Question 31

ETEC virulence factors

Answer 31

CFA adhesin, enterotoxin

Question 32

EPEC virulence factors

Answer 32

Intimin and bfp adhesins, type III secretion system effectors

Question 33

EHEC virulence factors

Answer 33

Intimin and Efa adhesins, shigatoxins

Question 34

EIEC virulence factors

Answer 34

IpaC adhesin, ShET toxin | Same as Shigella (as they are pretty much Shigella)

Question 35

Symptoms of ETEC

Answer 35

Watery diarrhoea

Question 36

Epidemiology of ETEC

Answer 36

Infants in LDCs, travellers

Question 37

Symptoms of EPEC

Answer 37

Non-specific gastro

Question 38

Epidemiology of EPEC

Answer 38

Children in LDCs

Question 39

Symptoms of EIEC

Answer 39

Dysentery

Question 40

Epidemiology of EIEC

Answer 40

Any age, mainly in LDCs

Question 41

EHEC symptoms

Answer 41

Bloody diarrhoea

Question 42

EHEC epidemiology

Answer 42

Any age, developed countries

Question 43

EAEC symptoms

Answer 43

Watery diarrhoea

Question 44

Adhesive enterotoxigenic bacteria

Answer 44

ETEC

Question 45

Bacteria that are adhesive with brush border damage

Answer 45

Cholera, EPEC

Question 46

Enterobacteria that invade, restricted to mucosa

Answer 46

Shigella

Question 47

Enterobacteria that invade submucosa

Answer 47

Salmonella, Campylobacter

Question 48

Enterobacteria that invade systemically

Answer 48

Salmonella

Question 49

Enterobacteria that invade systemically

Answer 49

Salmonella

Question 50

What do ETEC adhere to?

Answer 50

Microvili

Question 51

Lesions caused by EPEC

Answer 51

Attaching-effacing lesions

Question 52

How do EPEC adhere to gut wall? 1 2

Answer 52

``` Stage 1 (plasmid mediated) - Bundle-forming pili attach to intact microvili Step 2 (chromosomal) - Late adherence, forming attaching, effacing lesions ```

Question 53

Only Shigella species that releases shigatoxin

Answer 53

S. dysenteriae type 1

Question 54

Pathogenicity island

Answer 54

Collection of genes that are found in a pathogen, that are involved in pathogenesis. Are chromosomally-encoded

Question 55

ETEC toxins

Answer 55

LT and ST

Question 56

Enteric Yersinia species

Answer 56

Yersinia enterocolitica, Yersinia pseudotuberculosis. | Use Invasin to invade cells.

Question 57

Can LPS be neutralised by antibodies?

Answer 57

No, because LPS acts as an enterotoxin by being recognised by the innate immune system, which still happens if LPS is bound by antibodies.