Spijsvertering

Question 1

Name two bacterial pathogens that grow in foods and produce toxins

Answer 1

Bacillus cereus

Staphylococcus aureus

Question 2

Dysentery

Answer 2

o Inflammatory disorder of the large bowel

o Blood and pus in faeces

o Pain, fever and abdominal cramps

Question 3

Diarrhoea

Answer 3

o Abnormal frequency and/or fluid stool

o Usually indicates small bowel disease

o Causes fluid and electrolyte loss

o Severity varies from mild self-limiting to severe/fatal

Question 4

Gastroenteritis

Answer 4

inflammation of the stomach and intestines, typically resulting from bacterial toxins or viral infection and causing vomiting and diarrhoea.

Symptoms: Nausea, vomiting, diarrhoea and abdominal discomfort

Question 5

Enterocolitis

Answer 5

inflammation of both the small intestine and the colon

Question 6

zoonotic definition

Answer 6

can be transmitted from animals to people

Question 7

What are the 3 Fs of Faecal-oral transmission?

Answer 7

1) Food
o Contamination – Farm to fork
o Cross-contamination – Distribution chain or domestic kitchen

2) Fluids
o contaminated Water

3) Fingers
o Importance of washing hands

Question 8

What is Enrichment broth?

Answer 8

Contains nutrients that promote preferential growth of the pathogen

used for laboratory diagnosis

Question 9

What are Selective media?

Answer 9

o culture mediumthat is enriched with a particular substance to allow the growth of particular
strains of organisms.

o Used to isolate or identify particular organisms.

o i.e. Suppress growth of background flora while allowing growth of the pathogen

Question 10

What are Differential media?

Answer 10

used to differentiate between closely related organisms or groups of organisms.

due to the presence of certain dyes or chemicals in the media, the organisms will produce characteristic changes or growth patterns that are used for identification or differentiation

Question 11

How will MacConkey’s agar look with both lactose and non-lactose fermenting colonies?

Answer 11

Lactose fermenting colonies (E.coli)
are pink

non-lactose fermenting ones (Shigella spp.) are colourless.

Remember: Non-lactose fermenting have No colour

Question 12

Who should get antibiotics for GI infections?

Answer 12

Very ill patients

Sepsis or evident bacteraemia

Significant co-morbidity
o Patients with minimal ability to handle physiological upset of several days of diarrhoea

C. difficile associated diarrhoea (metronidazole)

Question 13

Campylobacter gram stain

Answer 13

Gram-negative

Question 14

Campylobacter carriers and transmission

Answer 14

Large animal reservoir (poultry, cattle, sheep, rodents & wild birds)

Infection transmitted via contaminated food (especially poultry), milk or water

Question 15

Campylobacter Pathogenesis

Answer 15

bacterial invasion of the small and large bowel, causing:
o Inflammation
o ulceration
o bleeding

Bacteraemia can occur

Rarely causes post-infectious Guillain-Barre and reactive arthritis

Question 16

Campylobacter Clinical Presentation

Answer 16

 Bloody diarrhoea
 Cramping abdominal pain
 Fever

Question 17

Campylobacter Treatment

Answer 17

Fluid replacement is sufficient in most cases

Clarithromycin for severe/persistent disease

Quinolone (ciprofloxacin) or aminoglycoside (gentamicin) for invasive disease

Question 18

Salmonella gram stain + causative species

Answer 18

Gram-negative

Majority of human infection caused by single species Salmonella enterica

Question 19

Salmonella carriers and transmission

Answer 19

wide range of warm and cold blooded animals

Acquired via contaminated food, especially pork, poultry & other meat/dairy products

Secondary spread via person-to-person transmission

NB: S. Typhi & S. Paratyphi (enteric fever) do not have an animal reservoir

Question 20

Salmonella Pathogenesis

Answer 20

invasion of epithelial cells in the distal small intestine, and subsequent inflammation

Bacteraemia can occur

metastatic infection:
o e.g. osteomyelitis
o septic arthritis
o meningitis

Question 21

Salmonella Clinical Presentation

Answer 21

 Watery diarrhoea
 Vomiting
 Fever usually associated with invasive disease

Question 22

Salmonella Treatment

Answer 22

Fluid replacement is sufficient in most cases

Antibiotics reserved for severe infections and bacteraemia

Beta-lactams, quinolones or aminoglycosides may be used

Question 23

Salmonella Prevention

Answer 23

immunisation of poultry

Question 24

Shigella gram stain and species

Answer 24

Gram-negative bacilli

4 species
Shigella dysenteriae - most severe disease

Question 25

Shigella Epidemiology

Answer 25

Mainly associated with diarrhoeal disease in children S. dysenteriae in developing world Humans are only reservoir Person-to-person spread via faecal-oral route Low infectious dose Recent outbreaks associated with MSM

Question 26

Shigella Pathogenesis

Answer 26

Organisms attach to and colonise mucosal epithelium of terminal ileum & colon No systemic invasion S. dysenteriae produces potent exotoxin (Shiga toxin) o damages intestinal epithelium o can cause renal failure as part of HUS

Question 27

Shigella Clinical Presentation

Answer 27

 Dysentery  Initially watery diarrhoea followed by bloody diarhoea  cramping abdominal pain  Fever

Question 28

Shigella Treatment

Answer 28

Fluid replacement is usually sufficient Some cases of S.dysenteriae will require treatment of renal failure

Question 29

Shigella Prevention

Answer 29

Only found in humans, so good standards of sanitation and personal hygiene are key measures

Question 30

Vibrio cholerae gram stain

Answer 30

Gram-negative

Question 31

Vibrio cholerae Pathogenesis

Answer 31

Flagellae and mucinase facilitate penetration of intestinal mucous production of a potent protein exotoxin

Question 32

Vibrio cholerae Clinical Presentation

Answer 32

Severe, profuse, watery diarrhoea (rice water stool) ```  Profound fluid loss & dehydration: o Hypokalaemia o metabolic acidosis o hypovolaemic shock o cardiac failure ```  Untreated -> mortality 30-40%

Question 33

Vibrio cholerae Treatment

Answer 33

rehydration is lifesaving (mortality reduced to <1%) Tetracycline antibiotics may shorten duration of shedding

Question 34

Vibrio cholerae Prevention

Answer 34

Clean drinking water supply and proper sanitation

Question 35

Vibrio cholerae Epidemiology

Answer 35

Endemic in parts of SE Asia, Africa, South America Can live in fresh water Only infects humans. Asymptomatic human reservoir Spreads via contaminated food or water person-to-person transmission uncommon

Question 36

Escherichia coli gram stain

Answer 36

Gram-negative Important component of gut flora of man and animals Some strains possess virulence factors which enable them to cause infections

Question 37

Enteropathogenic E. coli (EPEC) summary

Answer 37

Cause of some cases of “traveller’s” diarrhoea adherence and formation of characteristic “attaching & effacing” lesion o Watery diarrhoea with abdominal pain and vomiting o Often accompanied by fever

Question 38

Enterotoxigenic E. coli (ETEC) summary

Answer 38

The major bacterial cause of diarrhoea in infants & children in developing world o major cause of “travellers” diarrhoea caused by toxin production  Heat-labile (LT) analogue of cholera toxin  Heat-stable (ST). o Watery diarrhoea with abdominal pain and vomiting

Question 39

Enterohaemorrhagic E. coli (EHEC) summary

Answer 39

many types, but E. coli 0157 is most well known Consumption of contaminated food, water and dairy products & direct environmental contact with animal faeces e.g. petting zoos Secondary person-to-person spread Attaching and effacing lesion Production of Shiga-like toxins. o Bloody diarrhoea with abdominal pain and vomiting o No associated fever o Haemolytic uraemic syndrome (5-10% )

Question 40

Which bacterial are key causes of diarrhoea in children in the developing world?

Answer 40

EPEC & ETEC Severity may be related to underlying malnutrition ETEC may mimic cholera clinically

Question 41

Staphylococcus aureus gram stain

Answer 41

Gram-positive cocci

Question 42

Staphylococcus aureus carriers/transmission

Answer 42

food is contaminated by human carriers Especially cooked meats, cakes and pastries Bacteria multiply at room temperature and produce toxins

Question 43

Staphylococcus aureus pathogenesis

Answer 43

50% of S.aureus produce enterotoxins (types A-E) Heat stable and acid-resistant protein toxins

Question 44

Staphylococcus aureus Clinical Presentation

Answer 44

 Profuse vomiting and abdominal cramps |  No fever and no diarrhoea

Question 45

Staphylococcus aureus prevention

Answer 45

Hygienic food preparation to minimise contamination Refrigerated storage

Question 46

Bacillus cereus gram stain

Answer 46

Gram-positive

Question 47

Bacillus cereus pathogenesis

Answer 47

2 types of disease: 1) Emetic disease o fried rice o Heat stable toxin survives further frying 2) Diarrhoeal disease o Ingested organisms produce a heat-labile toxin in the gut with similar mode of action to cholera toxin

Question 48

Bacillus cereus Clinical Presentation

Answer 48

Emetic disease o Profuse vomiting with abdominal cramps and watery diarrhoea  Diarrhoeal o Watery diarrhoea with cramping abdominal pain, but no vomiting

Question 49

Clostridium perfringens gram stain

Answer 49

Gram-positive

Question 50

Clostridium perfringens pathogenesis

Answer 50

Organisms ingested & sporulate in large intestine with production of enterotoxin Often involves bulk-cooking of stews, meat pies

Question 51

Clostridium perfringens Clinical Presentation

Answer 51

 Watery diarrhoea and abdominal cramps

Question 52

Clostridium perfringens control

Answer 52

 Rapid chilling/freezing of bulk-cooked foods |  Thorough re-heating before consumption

Question 53

Clostridium botulinum gram stain

Answer 53

Gram-positive

Question 54

Clostridium botulinum Clinical Presentation

Answer 54

Neuromuscular blockade results in flaccid paralysis & progressive muscle weakness Involvement of muscles of chest/diaphragm causes respiratory failure High mortality if untreated

Question 55

Clostridium botulinum pathogenesis

Answer 55

Produces powerful heat-labile neurotoxin  Foodborne botulism- pre-formed toxin in food. associated with improperly processed canned foods  Infant botulism- organisms germinate in gut of babies fed honey containing spores, and toxins are produced in gut  Wound botulism- organisms implanted in wound produce toxin Absorbed toxins spread via bloodstream and enter peripheral nerves where they cause neuromuscular blockade at the synapses

Question 56

Clostridium botulinum treatment

Answer 56

Urgent intensive supportive care due to difficulties breathing and swallowing Antitoxin

Question 57

Clostridium botulinum control

Answer 57

 Proper manufacturing controls in canning industry  Hygienic food preparation  Proper cooking  Refrigerated storage

Question 58

Clostridium difficile Microbiology

Answer 58

Gram-positive Spores resistant to heat, drying, disinfection, alcohol

Question 59

Clostridium difficile pathogenesis

Answer 59

Infection requires disruption of the normal “protective” gut flora Clinical features due to production of potent toxins

Question 60

Clostridium difficile clinical presentation

Answer 60

 Mild to severe with abdominal pain  Severe cases -> pseudomembranous colitis  Fulminant cases -> colonic dilatation and perforation  Severe cases may be fatal  Relapses are common and may be multiple

Question 61

Clostridium difficile treatment

Answer 61

Stop precipitating antibiotics  Oral metronidazole (mild [0 severity markers]).  Oral vancomycin (severe [≥ 1 severity markers or no improvement after 5 days metronidazole])  Refractory recurrent disease may require faecal transplant

Question 62

Clostridium difficile prevention

Answer 62

Antimicrobial stewardship ``` minimise use of “high risk” antibiotics  Cephalosporins  Fluoroquinolones  Clindamycin  Co-amoxyclav ``` Infection Prevention & Control measures o Source isolation o Hand hygiene o Use of Personal Protective Equipment  Cleaning/disinfection with hypochlorite disinfectants

Question 63

Clostridium difficile Severity markers

Answer 63

``` o Colonic dilatation >6cm o WCC >15 x10^9 /L o Creatinine >1.5 x baseline o Temp >38.5 C o Immunosuppression ```

Question 64

Listeria monocytogenes gram stain

Answer 64

Gram-positive

Question 65

Listeria monocytogenes Epidemiology

Answer 65

Widespread among animals and the environment Pregnant women, elderly and immunocompromised Overall number of cases small, but mortality high Infection associated with contaminated foods, especially unpasteurised milk and soft cheeses, pate, cooked meats, smoked fish, and coleslaw

Question 66

Listeria monocytogenes pathogenesis

Answer 66

Invasive infection from GIT results in systemic spread via bloodstream

Question 67

Listeria monocytogenes Clinical presentation

Answer 67

 Initial flu-like illness, with or without diarrhoea Majority of cases present with severe systemic infection o Septicaemia o Meningitis

Question 68

Listeria monocytogenes treatment

Answer 68

Intravenous antibiotics (usually Ampicillin and synergistic gentamicin) is required

Question 69

Listeria monocytogenes Control

Answer 69

Susceptible groups should avoid high risk foods Observe use by dates Wash raw fruit and vegetables and avoid cross contamination

Question 70

Helicobacter pylori gram stain

Answer 70

Gram-negative

Question 71

Helicobacter pylori clinical presentation

Answer 71

 Infection is asymptomatic unless peptic ulceration develops  Now established as cause of >90% of duodenal ulcers, and 70-80% of gastric ulcers  Gastric cancer risk

Question 72

Stool cultures take at least 48 hours. Which antibiotic (group) is usually used for empirical treatment of GI infections?

Answer 72

Ciprofloxacin (Quinolones)

Question 73

Which antibiotic is used to treat C. difficile infection?

Answer 73

metronidazole

Question 74

What are some methods for breaking the chain of infection?

Answer 74

public health measures - sanitation and clean water education - hand hygiene pasteurisation of milk

Question 75

What is the Commonest bacterial foodborne infection in the UK?

Answer 75

campylobacter

Question 76

Which GI infection can cause post-infectious Guillain-Barre Syndrome?

Answer 76

Campylobacter Can also cause reactive arthritis

Question 77

Salmonella types

Answer 77

salmonella typhi/paratyphi - invasive, usually cause bloodstream infections and require antibiotic therapy all other salmonella species - usually self-limiting and don’t behave invasively

Question 78

Which organisms only have a human carrier?

Answer 78

typhoid/paratyphoid (salmonella typhi/paratyphi ) Shigella dysenteriae Vibrio cholerae Helicobacter pylori

Question 79

What are 4 causes of bloody diarrhoea?

Answer 79

shigella E. coli 0157 Campylobacter salmonella

Question 80

What's the major cause of traveller's diarrhoea?

Answer 80

Enterotoxigenic E. coli (ETEC)

Question 81

Which bacterial infections cause a vomiting illness?

Answer 81

``` salmonella EPEC ETEC EHEC Staphylococcus aureus Bacillus cereus ```

Question 82

Name 3 bacteria that can cause bacteraemia from GI infection

Answer 82

campylobacter salmonella listeria

Question 83

Name 2 bacteria that can cause meningitis from GI infection

Answer 83

listeria | salmonella

Question 84

Name 2 bacteria that can cause Microangiopathic haemolytic anaemia from GI infection

Answer 84

E.coli O157:H7 causes haemolytic uraemic syndrome Shigella causes haemolytic uraemic syndrome "Shiga toxin"

Question 85

most common cause of GI infection in the UK

Answer 85

norovirus