Microbiology of the Gastrointestinal Tract Flashcards Preview

ESA 3 - Gastrointestinal System > Microbiology of the Gastrointestinal Tract > Flashcards

Flashcards in Microbiology of the Gastrointestinal Tract Deck (156):
1

Approximately how many bacteria are there in the GI tract? 

1014

2

Where are the majority of the bacteria in the GI tract found? 

In the colon

3

What is the name given to the bacteria in the GI tract? 

Normal flora 

4

What are the beneficial roles of normal flora? 

  • Synthesise and excrete vitamins 
  • Prevent colonisation by pathogens 
  • Kill non-indigenous bacteria 
  • Stimulate the development of GALT
  • Stimulate production of natural antibodies 

5

What vitamins are synthesised and excreted by the normal GI flora? 

  • Vitamin K 
  • Vitamin B12
  • Thiamine

6

How does the normal GI flora prevent colonisation by pathogens? 

  • Space
  • Bacteriosides 

7

What aspect of the normal GI flora kills non-indigenous bacteria? 

Bacteriosides 

8

What are the possible ways of categorising bacteria? 

  • Cocci or Bacilli
  • Gram positive or negative 
  • Aerobic or anaerobic 
    • Obligate or faculative
  • Do they form protective endospores or not? 
  • Can they stick to surfaces using pili and/or slime

9

Give two examples of bacteria that can form protective endospores? 

  • Bacillus Anthrax 
  • Clostridium Tetani 

10

What is true of obligate aerobes? 

They must have oxygen

11

Give two examples of obligate aerobes? 

  • Pseudomonas
  • Mycobacterium TB

12

What is true of obligate anaerobes? 

They die in the presence of oxygen 

13

Give two examples of obligate anaerobes

  • Bacteroides fragilis
  • Clostridial organisms 

14

Why may clostrial organisms be able to survive in oxygen? 

They form protective spores 

15

What is true of facultative anaerobes?

They prefer oxygen, but can live without it 

16

Give two examples of facultative anaerobes?

  • Gram -ve enteric bacteria, such as E. coli 
  • Gram +ve skin-dwellers such as Staphylococcus

17

Where are the anaerobic zones in the GI tract?

  • Parts of mouth 
  • Small bowel 
  • Colon

18

What parts of the mouth are anaerobic? 

  • Tounge
  • Deep in taste buds
  • Biofilm between teeth 
  • Gingival crevice areas

19

What can bacillus cause? 

Anthrax

20

What are the characteristics of bacillus?

  • Bacilli
  • Gram +ve
  • Aerobic

21

What are the characteristics of bacteroides fragilis?

  • Bacilli
  • Gram -ve
  • Anaerobic

22

What are the characteristics of bordetella pertussis?

  • Bacilli
  • Gram -ve
  • Aerobic
  • Non enteric

23

What are the characteristics of brucella?

  • Bacilli
  • Gram -ve
  • Aerobic
  • Non enteric

24

What are the characteristics of campylobacter?

  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric

25

What are the characteristics of clostridia

  • Bacilli
  • Gram +ve
  • Aerobic

26

Give 3 subspecies of clostridia

  • Tetani
  • Perfringens
  • Difficile

27

What does corynebacterium cause? 

Diphtheria 

28

What are the characteristics of corynebacterium?

  • Bacilli
  • Gram +ve
  • Aerobic

29

What are the characteristics of E. coli?

  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric

30

What are the characteristics of enterococci? 

  • Cocci
  • Gram +ve
  • Aerobic

31

What are the characteristics of haemophilis influenzae?

  • Bacilli
  • Gram -ve 
  • Aerobic
  • Non enteric

32

What are the characteristics of Helicobacter pylori

  • Bacilli
  • Gram -ve 
  • Aerobic
  • Enteric

33

What are the characteristics of klebsiella?

  • Bacilli
  • Gram -ve 
  • Aerobic
  • Enteric

34

What are the characteristics of lactobacillus

  • Bacilli
  • Gram +ve 
  • Aerobic

35

What are the characteristics of mycobacterium TB?

  • Bacilli
  • Gram +ve
  • Aerobic
  • Acid fast

36

What are the characteristics of neisseria meningitides

  • Cocci
  • Gram -ve 
  • Aerobic

37

What are the characteristics of neisseria gonorrhoeae

  • Cocci
  • Gram -ve 
  • Aerobic

 

38

What are the characteristics of proteus

  • Bacilli
  • Gram -ve 
  • Aerobic
  • Enteric

39

What are the characteristics of pseudomonas?

  • Bacilli
  • Gram -ve 
  • Aerobic
  • Enteric

 

40

What are the characteristics of salmonella?

  • Bacilli
  • Gram -ve 
  • Aerobic
  • Enteric

41

What are the characteristics of shigella?

  • Bacilli 
  • Gram -ve 
  • Aerobic
  • Enteric

42

What are the characteristics of staphylococci

  • Cocci
  • Gram +ve
  • Aerobic

43

What are the characteristics of streptococci

  • Cocci
  • Gram +ve
  • Aerobic

44

What are the characteristics of vibrio cholerae?

  • Bacilli
  • Gram -ve 
  • Aerobic
  • Enteric

45

What is the consequence of the mouth having many anaerobic bacteria? 

They can cause very nasty or fatal infections

46

What anaerobic bacteria found in the mouth can cause infections? 

  • Streptococci mutans
  • Staphylococci aureus
  • Candida Albicans
  • Lactobacillus
  • Enterococcus

47

What infection can streptococcus mutans cause in the mouth? 

Dental caries / gingivitis (dental plaque)

48

What infection can staphylococcus aureus cause in the mouth?

Parotitis

49

What infection can Candida Albicans cause in the mouth? 

Oral thrush 

50

What is Noma / Cancrum Oris? 

Tissue destruction in the mouth caused by bacteria 

51

In whom may bacteria cause Noma / Cancrum Oris? 

  • Malnourished
  • Dehydrated
  • Immunocompromised
  • Systemically unwell patients 

52

What bacteria is found in the nose? 

  • Staphylococcus
  • Streptococcus
  • Many others 

53

What are the sites for MRSA screening? 

  • Nose
  • Throat
  • Perineum

54

Why are the nose, throat and perineum used for MRSA swabbing? 

These are the three sites where Staphylococci are found

55

What bacteria and fungi are found in the throat? 

  • Strep. Viridans
  • Strep. Pyogenes
  • Strep. Pneumoniae 
  • Staphylococci
  • Neisseria Meningitidis 
  • Haemophilus Influenza
  • Lactobacilli 
  • Corynebacterium Diptheriae
  • Candda Albicans 

 

56

What kind of bacteria is Strep. Viridans

Non-pathogenic throat commensal 

57

What % of people have Strep. Viridans present in their throat? 

100%

58

How may Strep. Viridans get into the bloodstream? 

During teeth brushing, dental procedures and general anaesthesia 

59

What is it called when there is bacteria in the bloodstream? 

Bacteraemia 

60

What does Strep. Pyogenes cause? 

Tonsillitis 

61

What % of tonsillitis cases are accounted for by Strep. Pyogenes?

30%

62

What accounts for the 70% of tonsillitis cases not caused by Strep. Pyogenes

Viral

63

What does Strep. Pneumoniae cause? 

Community acquired pneumonia

64

What % of community acquired pneumonia cases are caused by Strep. Pneumoniae

30%

65

What % of people is Staphylococci present in? 

100%

66

What % of people is Neisseria Meningitidis present in? 

100%

67

What does Haemophilus Influenzea cause? 

Community acquired pneumonia

68

What % of community acquired pneumonia cases are caused by Haemophilus Influenza?

13%

69

What does Candida Albicans cause? 

Oral and vaginal thrush

70

What does Lactobacili prevent? 

Thrush

71

Why does Lactobacilli prevent thrush? 

It makes the vagina acidic, so Candida Albicans can't grow

72

What viruses can cause tonsillitis? 

  • Adenovirus
  • Rhinovirus
  • Epstein-Barr Virus 

73

What bacteria causes tonsillitis? 

Strep. Pyogenes 

74

What bacteria is found in the stomach? 

Helicobacter Pylori

75

What % of the worlds population is infected with H. Pylori

At least 50%

76

What % of those infected with H. Pylori develop gastric or duodenal ulcers? 

10-20%

77

What % of duodenal ulcers are associated with H. Pylori?

90%

78

What % of gastric ulcers are associated with H. Pylori?

70%

79

How many species of bacteria regularly exist in the human colon? 

More than 100 

80

What % of the bacteria in the human colon are anaerobes? 

95-99% 

81

Which species of bacteria are most of those in the human colon? 

Bacteroides and Clostridial 

82

What bacteria are always present in the colon? 

  • Bacteroides fragilis 
  • Bacteroides oralis 
  • Bacteroides melaninogenicus
  • E. Coli
  • Enterococcus faecalis 

83

What is the most common cause of UTIs? 

E. Coli 

84

What is the second most common cause of UTIs? 

Enterococcus faecialis 

85

What gram negative enteric bacilli are sometimes found in the colon? 

  • Pseudomonas
  • Proteus
  • Klebsiella
  • Salmonella
  • Shigella
  • Vibrio cholera
  • Campylobacter

86

What is all gut surgery regarded as?

'Dirty surgery'

87

What is the consequence of gut surgery being 'dirty surgery'? 

There is a high risk of wound infection

88

Why does gut surgery carry a high risk of wound infection? 

Although the colon normally contains large number of bacteria, if we are operating on the smal bowel it will be abnormal

89

How is surgical wound infection reduced in gut surgery? 

Antibiotics are given prophylactically 

90

What do the prophylactic antibiotics given in gut surgery need to cover? 

  • Anaerobes
  • Gram -ve bacilli 
  • Gram +ve bacilli

 

91

What antibiotics are given prophylactically in gut surgery? 

  • Metronidazole
  • Broad-spectrum antibiotics, such as Gentamicin or Cephalosporin 

 

 

92

Why is metronidazole given after gut surgery? 

It kills anaerobes

93

What clinical conditions can be caused by abnormal bacteria in the colon? 

  • Faecal Peritonitis 
  • Perianal Abscess 

 

94

What causes faecal peritonitis?

Huge numbers of bacteria floating free in the peritoneum 

95

What is the prognosis of faecal peritonitis? 

High mortality rate, even in young fit people 

96

What causes perianal abscesses? 

Glands in the anal canal produce mucus for lubrication to aid with passing faeces. Infection of them leads to abscess around the anus 

97

What bacteria is a normal vaginal flora organism? 

Lactobacillus

98

What kind of bacterium is lactobacillus

Gram +ve bacilli

99

What does lactobacillus do? 

Converts glycogen into lactic acid

100

What is the purpose of the conversion of glycogen to lactic acid in the vagina? 

It provides an acidic environment to prevent other bacteria and candida albicans from growing

101

What bacteria can survive on the perineal skin? 

  • E. Coli 
  • Enterococcus faecalis
  • Lactobacillus

102

What bacteria cannot survive on the perineal skin? 

Bacteroides 

103

Why can bacteroides not survive on perineal skin? 

Because they cannot survive in oxygen 

104

What % of UTIs occur in women? 

90%

105

Why do 90% of UTIs occur in women? 

There is a much shorter distance from anus to urethra 

106

In order, what are the most common organisms causing UTIs? 

  1. E. coli 
  2. Enterococcus faecalis 
  3. Various gram -ve enteric bacilli
    • ​​Klebsiella
    • Proteus 
    • Pseudomonas 

107

What are the types of Clostridia?

  • Tetani 
  • Difficile
  • Perfringens 

108

What does Clostridia Tetani cause? 

Tetanus

109

How many does neonatal tetanus kill a year? 

60,000 

110

What does Clostridia Difficile cause? 

Pseudomembranous colitis 

111

What is pseudomembranous colitis? 

Severe inflammation of the colon

112

When does psuedomembranous colitis often occur? 

After antibiotic treatment 

113

What does Clostridia Difficile produce? 

Spores 

114

What is the problem with the spores produced by Clostridia Difficile?

They are present in hospitals 

115

What does Clostridia Perfringens cause? 

Gas/wet gangrene 

116

How does Clostridia Perfringens cause gangrene? 

Anaerobic digestion of glucose leads to ethanol and CO2 (fluid and gas), thus wet or gas gangrene 

117

Is it easy to disrupt the ecology of the normal gut flora? 

No 

118

What does the disruption of the gut flora lead to? 

Gastrointestinal disturbances such as diarrhoea

119

When does the disruption of the ecoloy of the normal gut flora often happen? 

After treatment with antibiotics 

120

What clinical conditions can arise as a result of gastrointestinal infections? 

  • Noro-virus 
  • Gastroenteritis
  • Cholera
  • Intestinal Parasites 
  • Bacteramia 
  • Septicaemia 

121

What is gastroenteritis? 

Food poisoning 

122

What do noro-viruses produce? 

A short period of vomiting and diarrhoea

123

What may gastroenteritis follow?

Consumption of food or drink contaminated with organisms or toxins, often of bacterial origin but already present in food

124

What are the symptoms of gastroenteritis? 

Vomiting and diarrhoea 

125

When is the onset of gastroenteritis? 

  • Very rapid if toxins are ingested, within a very small number of hours
  • May take up to 48 hours if caused by organisms 

 

126

What are the most common organisms causing gastroenteritis?

  • Salmonella 
  • Campylobacter
  • Listeria

 

127

What toxins can cause gastroenteritis?

  • Staphylococcus
  • Clostridium 

128

What is cholera? 

A severe acute infection

129

Why is cholera clinically relevant? 

It is endemic in many parts of the world, and periodically occurs in epidemics that are a real risk after natural disasters

130

What organism is responsible for cholera? 

Vibrio cholerae 

131

Where does Vibrio Cholerae survive?

In water supplies

132

Where does Vibrio Cholerae have its effect? 

The ileum 

133

What effect does Vibrio Cholerae have on the ileum? 

Causes massive movement of water and salt into the lumen by active secretion 

134

What are the symptoms of cholera? 

  • Very serious diarrhoea
  • Rapid, severe dehydration

135

What characteristic does the diarrhoea in cholera have? 

After initial evacuation, a 'rice-water' appearance 

136

Why does the diarrhoea in cholera have a 'rice-water' appearance? 

It it made up of intestinal secretions and mucus 

137

What is the importance of the dehydration in cholera? 

It is severely life threatening

138

What must the management of cholera do?

Replace lost water and electrolytes with appropriate replacement fluids

139

What is the prevalance of intestinal parasites? 

Common around the world

140

What can intestinal parasites cause? 

  • Gastroenteritis
  • Malabsorption 
  • Other effects

141

What kind of intestinal parasites leads to gastroenteritis? 

Some protozoans, such as Giardia and Cryptospordium

142

What intestinal parasites lead to malabsorption? 

Helminth infestations 

143

What happens in bacteraemia?

The bacteria are rapidly cleared from the bloodstream

144

What clears the bacteria from the bloodstream in bacteraemia?

Liver and spleen macrophages

145

What are the symptoms of bacteriaemia?

No symptoms are produced

146

What happens in septicaemia?

Bacteria are not cleared, and multipy in the blood stream 

147

What develops in septicaemia?

Sepsis symptoms

148

What bacterium is a major cause of Travellers' diarrhoea?

Enterotoxinogenic E. Coli (ETEC)

149

How does ETEC cause Travellers' diarrhoea?

Heat stable or labile toxins produce from the serotype 

150

What are the symptoms of Travellers' diarrhoea?

Severe, cholera-like watery diarrhoea 

151

Does Traveller's diarrhoea cause inflammation?

No

152

What prevents Traveller's diarrhoea from being fatal?

The condition is usually self limiting

153

What causes intestinal inflammation and infection? 

  • Inflammatory Bowel Disease 
  • Infection

154

What causes inflammatory bowel disease? 

  • Ulcerative Colitis 
  • Crohn's Disease 
  • Diversion Colitis 
  • Diverticular colitis 
  • Radiation 
  • Drugs
  • Infections
  • Ischaemic colitis 

155

What can infect the intestine causing inflammation? 

Pathogens or toxins

156

Give two examples of when pathogens or toxins may be able to infect the intestines? 

  • Normal gut flora disturbed
  • Immunosuppressed