Bacterial Gastroenteritis Flashcards

1
Q

How is bacterial gastroenteritis diagnosed? (4)

A
  1. bacteria culture on selective media
  2. confirm ID of colonies
  3. antimicrobial susceptibility testing
  4. multiplex PCR
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2
Q

What species of campylobacter cause gastroenteritis?

A
  1. c. jejuni
  2. c. coli
  3. c. foetus
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3
Q

When do campylobacter cases peak?

A

summer

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4
Q

How do people contract campylobacter? (2)

A
  1. raw or undercooked foods

2. cross contamination from raw to cooked/ready to eat foods

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5
Q

What is the pathogenesis of campylobacter in the GIT?

A

attach to and invade the GI epithelium of the jejunum, ileum, colon, rectum

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6
Q

What is the incubation period of campylobacter infection?

A

1-7 days

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7
Q

What are the clinical features of campylobacter infection? (5)

A
  1. abdominal pain
  2. diarrhoea (may be bloody)
  3. nausea
  4. vomiting
  5. fever
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8
Q

what are the complications of campylobacter infection? (2)

A
  1. guillain-barre syndrome

2. reactive arthritis

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9
Q

How is campylobacter managed? (3)

A
  1. rehydration
  2. electrolyte replacement
  3. antimicrobials usually not indicated
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10
Q

When should antibiotics be considered? (5)

A
  1. worsening symptoms
  2. symptoms lasting >1 week
  3. severe disease
  4. immunocompromised
  5. pregnant
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11
Q

What antibiotics can be used to treat campylobacter infections if neccessary? (2)

A
  1. macrolides

2. fluoroquinolones

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12
Q

What is the morphology of campylobacter?

A

gram negative curved bacilli

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13
Q

What selective media is used to culture campylobacter?

A

charcoal based selective media - flat colonies

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14
Q

How is campylobacter diagnosed in a lab?

A
  1. culture on charcoal based selective media
  2. susceptibility testing
  3. PCR
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15
Q

What salmonellae cause enteric fever? (2)

A
  1. salmonella enterica serotype typhi

2. salmonella enterica serotype paratyphi

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16
Q

What are non-typhoidal salmonellae? (2)

A
  1. salmonella enteritidis

2. salmonella typhimurium

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17
Q

Where is enteric fever found?

A

developing countries

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18
Q

What are the routes of transmission of enteric fever? (3)

A
  1. contaminated food and water
  2. poor sanitation and hygiene
  3. person to person occasionally
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19
Q

What is the pathogenesis of salmonella enterica?

A
  1. penetration of small intestinal epithelium

2. proliferation in submucosa - hypertrophy of peyers patches

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20
Q

What is the incubation period for enteric fever?

A

usually 2 weeks

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21
Q

What are the clinical features of enteric fever? (10)

A
  1. fever
  2. chills
  3. relative bradycardia
  4. abdominal pain
  5. rose spots
  6. hepatosplenomegaly
  7. GI bleeding
  8. perforation
  9. diarrhoea
  10. constipation
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22
Q

What are the complications of enteric fever?

A
  1. GI perforation
  2. seeding
  3. carriage
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23
Q

How is enteric fever diagnosed? (3)

A
  1. blood culture
  2. faeces culture
  3. bone marrow culture
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24
Q

How is enteric fever treated? (3)

A
  1. rehydration
  2. fluoroquinolones
  3. 3rd generation cephalosporins
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25
Q

How can enteric fever be prevented? (3)

A
  1. sanitation
  2. hygiene
  3. vaccination
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26
Q

How is non-typhoidal salmonellosis transmitted?

A
  1. contaminated food and water
  2. exotic pets
  3. person to person
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27
Q

What is the incubation period for non-typhoidal salmellosis?

A

6-48 hours

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28
Q

How long does diarrhoea last in NTS?

A

3-7 days

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29
Q

How is NTS treated?

A
  1. rehydration

2. antimicrobial usually not required

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30
Q

When is antimicrobial use indicated in treating NTS?

A
  1. severe illness
  2. less than 1 or over 50
  3. HIV
  4. immunocompromised
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31
Q

How is Salmonella diagnosed? (3)

A
  1. selective media - salmonella shigella agar
  2. serotyping - antigen determination
  3. PCR
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32
Q

What is antigens does salmonella have? (3)

A
  1. O cell wall
  2. H flagella
  3. Vi Surface
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33
Q

What is EHEC and VTEC?

A

enterohaemorrhagic e coli

verocytotoxin producing e coli

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34
Q

What is ETEC?

A

enterotoxigenic e coli

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35
Q

What is EIEC?

A

enteroinvasive e coli

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36
Q

What is EPEC?

A

enteropathogenic e coli

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37
Q

What is EAEC?

A

enteroaggregative e coli

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38
Q

What is the important serotype of VTEC?

A

O157

39
Q

When is the peak of VTEC?

A

seasonal pattern - summer peak

40
Q

What is the main reservoir of VTEC?

A

cattle

41
Q

What is the pathogenesis of VTEC?

A

release of verotoxin - shiga like toxins causing haemorrhagic colitis and haemolytic uraemic syndrome

42
Q

What is the incubation period of VTEC?

A

3-4 days

43
Q

What are the symptoms of VTEC?

A

diarrhoea may be bloody

44
Q

What is a complication of VTEC that 5-10% develop?

A

haemolytic uraemic syndrome

45
Q

What happens in haemolytic uraemic syndrome? (2)

A
  1. renal failure

2. haemolytic anaemia and/or low platelets

46
Q

What is the treatment for VTEC? (2)

A
  1. rehydration

2. antibiotics not of proven value

47
Q

How is VTEC cultured? (2)

A
  1. sorbitol MacConkey agar

2. test non-fermenters with antiserum

48
Q

How is VTEC diagnosed? (2)

A
  1. culture

2. PCR

49
Q

What is shigellosis?

A

bacterial dysentery

50
Q

What are the species of shigella that cause human illness? (4)

A
  1. s sonnei
  2. s flexnari
  3. s boydii
  4. s dysenteriae
51
Q

Who is at risk for shigellosis? (2)

A
  1. children

2. MSM

52
Q

How is shigella transmitted?

A
  1. faecal-oral route

2. person to person

53
Q

What cells does shigella adhere to and invade?

A

M cells of peyers patches

54
Q

What is a complication of s dysentariae infection?

A

shiga toxin mediated haemolytic uraemic syndrome

55
Q

What is the incubation period of shigellosis?

A

1-3 days

56
Q

What are the clinical features of shigellosis? (3)

A
  1. abdominal cramps
  2. fever
  3. bloody diarrhoea
57
Q

What is s flexneri associated with?

A

reactive arthritis

58
Q

How is shigellosis managed? (2)

A
  1. rehydrate

2. antibiotics usually not indicated

59
Q

When is antibiotic use indicated in shigellosis?

A
  1. immunocompromised
  2. severe disease
  3. food handler
  4. childcare provider
  5. institutional resident
60
Q

How is shigellosis diagnosed?

A
  1. selective media - XLD

2. PCR

61
Q

What causes s aureus gastroenteritis?

A

ingestion of pre-formed heat stable enterotoxin

62
Q

What are the characteristics of s aureus gastroenteritis?

A
  1. rapid onset 2-6 hours

2. short lived 6-12 hours

63
Q

What are the symptoms of s aureus gastroenteritis? (6)

A
  1. malaise
  2. nausea,
  3. vomiting
  4. abdominal pain
  5. diarrhoea
  6. NO fever
64
Q

What are the enterotoxins produced by bacillus cereus? (2)

A
  1. diarrhoeal toxin

2. emetic toxin

65
Q

What are the characteristics of bacillus cereus emetic syndrome? (3)

A
  1. ingestion of toxin in food
  2. illness within 1-5 hours
  3. lasts 6-24 hours
66
Q

What are the characteristics of bacillus cereus diarrhoeal syndrome?

A
  1. toxin produced in small bowel
  2. illness within 8-16 hours
  3. lasts 24 hours
67
Q

What are the bacterial characteristics of clostridioides? (4)

A
  1. anaerobic
  2. spore forming
  3. gram positive
  4. bacilli
68
Q

What species of clostridiodes causes food poisoning?

A

c. perfringens

69
Q

What species of clostridiodes causes antibiotic related diarrhoea?

A

c difficile

70
Q

What is the commonest food source of c perfringens?

A

pre-cooked meat

71
Q

how does c perfringens cause food poisoning? (2)

A
  1. heat resistant spores

2. enterotoxin production

72
Q

What is the incubation period of c perfringens food poisoning?

A

8-12 hours

73
Q

What are the symptoms of c perfringens food poisoning? (2)

A
  1. abdominal cramps

2. diarrhoea

74
Q

What toxins does c difficile produces?

A

toxins A and B

75
Q

What c difficile strains are hypervirulent?

A
  1. 027

2. 078

76
Q

What is the pathogenesis of c difficile? (4)

A
  1. toxin mediated
  2. colonic inflammation
  3. mucosal damage
  4. intestinal fluid secretion
77
Q

What are the risk factors for c difficile infection? (6)

A
  1. antimicrobials
  2. advanced age
  3. hospitalisation
  4. GI surgery
  5. immunosuppression
  6. proton pump inhibitor use (?)
78
Q

What antimicrobials put you at risk for c difficile infection?

A
  1. broad spectrum penicillins
  2. clindamycin
  3. cephalosporins
  4. fluoroquinolones
79
Q

What are the clinical features of c difficile infection? (5)

A
  1. watery diarrhoea
  2. abdominal cramping/pain
  3. colitis
  4. fever
  5. elevated WCC
80
Q

What are the complications of c difficile infection? (3)

A
  1. pseudomembranous colitis
  2. toxic megacolon
  3. colonic perforation
81
Q

What is the two step process for diagnosing c difficile infection?

A
  1. ELISA for glutamate dehydrogenase OR PCR

2. ELISA for toxin detection

82
Q

How is non-severe c difficile managed? (3)

A
  1. vancomycin po
  2. fidaxomicin po
  3. metronidazole po
83
Q

How is severe c difficile managed? (4)

A
  1. vancomycin po
  2. metronidazole iv
  3. surgical review
  4. intravenous immunoglobulin
84
Q

What are the risk factors for recurrence of c difficile infection?

A
  1. concomitant antimicrobial use during CDI treatment
  2. 027 infection
  3. elderly
85
Q

What is the treatment for the 1st recurrence of c difficile infection?

A

fidaxomycin po

86
Q

What is the treatment for the 2nd recurrence of c difficile infection? (3)

A
  1. tapering vancomycin po
  2. fidaxomicin po
  3. faecal microbiota transplant
87
Q

How can c difficile spread be prevented?

A
  1. single room isolation
  2. contact precautions
  3. hand hygiene
  4. environmental cleaning
88
Q

How does vibrio cholerae spread?

A

contaminated food and water

89
Q

What are the virulence factors of v cholerae

A
  1. pili

2. cholera toxin

90
Q

What is the incubation period of v cholerae?

A

2-3 days

91
Q

What are the symptoms of v cholerae infection? (2)

A
  1. rice water stools

2. effortless vomiting

92
Q

What are the clinical features of v cholerae infection? (4)

A
  1. dehydration
  2. hypovolaemia
  3. cardiac arrhythmia
  4. renal failure
93
Q

What is v cholerae cultured on?

A

Thiosuphate Citrate Bile salt Sucrose TCBS

94
Q

How is v cholerae managed?

A
  1. rehydration with fluids and electrolytes
  2. tetracyclines
  3. co-trimoxaxole