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

Microbiology of the Gastrointestinal Tract Flashcards

1
Q

Approximately how many bacteria are there in the GI tract?

A

1014

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2
Q

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

A

In the colon

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3
Q

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

A

Normal flora

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4
Q

What are the beneficial roles of normal flora?

A
  • Synthesise and excrete vitamins
  • Prevent colonisation by pathogens
  • Kill non-indigenous bacteria
  • Stimulate the development of GALT
  • Stimulate production of natural antibodies
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5
Q

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

A
  • Vitamin K
  • Vitamin B12
  • Thiamine
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6
Q

How does the normal GI flora prevent colonisation by pathogens?

A
  • Space
  • Bacteriosides
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7
Q

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

A

Bacteriosides

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8
Q

What are the possible ways of categorising bacteria?

A
  • 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
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9
Q

Give two examples of bacteria that can form protective endospores?

A
  • Bacillus Anthrax
  • Clostridium Tetani
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10
Q

What is true of obligate aerobes?

A

They must have oxygen

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11
Q

Give two examples of obligate aerobes?

A
  • Pseudomonas
  • Mycobacterium TB
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12
Q

What is true of obligate anaerobes?

A

They die in the presence of oxygen

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13
Q

Give two examples of obligate anaerobes

A
  • Bacteroides fragilis
  • Clostridial organisms
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14
Q

Why may clostrial organisms be able to survive in oxygen?

A

They form protective spores

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15
Q

What is true of facultative anaerobes?

A

They prefer oxygen, but can live without it

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16
Q

Give two examples of facultative anaerobes?

A
  • Gram -ve enteric bacteria, such as E. coli
  • Gram +ve skin-dwellers such as Staphylococcus
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17
Q

Where are the anaerobic zones in the GI tract?

A
  • Parts of mouth
  • Small bowel
  • Colon
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18
Q

What parts of the mouth are anaerobic?

A
  • Tounge
  • Deep in taste buds
  • Biofilm between teeth
  • Gingival crevice areas
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19
Q

What can bacillus cause?

A

Anthrax

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20
Q

What are the characteristics of bacillus?

A
  • Bacilli
  • Gram +ve
  • Aerobic
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21
Q

What are the characteristics of bacteroides fragilis?

A
  • Bacilli
  • Gram -ve
  • Anaerobic
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22
Q

What are the characteristics of bordetella pertussis?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Non enteric
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23
Q

What are the characteristics of brucella?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Non enteric
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24
Q

What are the characteristics of campylobacter?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric
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25
Q

What are the characteristics of clostridia?

A
  • Bacilli
  • Gram +ve
  • Aerobic
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26
Q

Give 3 subspecies of clostridia?

A
  • Tetani
  • Perfringens
  • Difficile
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27
Q

What does corynebacterium cause?

A

Diphtheria

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28
Q

What are the characteristics of corynebacterium?

A
  • Bacilli
  • Gram +ve
  • Aerobic
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29
Q

What are the characteristics of E. coli?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric
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30
Q

What are the characteristics of enterococci?

A
  • Cocci
  • Gram +ve
  • Aerobic
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31
Q

What are the characteristics of haemophilis influenzae?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Non enteric
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32
Q

What are the characteristics of H**elicobacter pylori?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric
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33
Q

What are the characteristics of klebsiella?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric
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34
Q

What are the characteristics of lactobacillus?

A
  • Bacilli
  • Gram +ve
  • Aerobic
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35
Q

What are the characteristics of mycobacterium TB?

A
  • Bacilli
  • Gram +ve
  • Aerobic
  • Acid fast
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36
Q

What are the characteristics of neisseria meningitides?

A
  • Cocci
  • Gram -ve
  • Aerobic
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37
Q

What are the characteristics of neisseria gonorrhoeae?

A
  • Cocci
  • Gram -ve
  • Aerobic
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38
Q

What are the characteristics of proteus?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric
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39
Q

What are the characteristics of pseudomonas?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric
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40
Q

What are the characteristics of salmonella?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric
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41
Q

What are the characteristics of shigella?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric
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42
Q

What are the characteristics of staphylococci?

A
  • Cocci
  • Gram +ve
  • Aerobic
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43
Q

What are the characteristics of streptococci?

A
  • Cocci
  • Gram +ve
  • Aerobic
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44
Q

What are the characteristics of vibrio cholerae?

A
  • Bacilli
  • Gram -ve
  • Aerobic
  • Enteric
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45
Q

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

A

They can cause very nasty or fatal infections

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46
Q

What anaerobic bacteria found in the mouth can cause infections?

A
  • Streptococci mutans
  • Staphylococci aureus
  • Candida Albicans
  • Lactobacillus
  • Enterococcus
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47
Q

What infection can streptococcus mutans cause in the mouth?

A

Dental caries / gingivitis (dental plaque)

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48
Q

What infection can staphylococcus aureus cause in the mouth?

A

Parotitis

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49
Q

What infection can Candida Albicans cause in the mouth?

A

Oral thrush

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50
Q

What is Noma / Cancrum Oris?

A

Tissue destruction in the mouth caused by bacteria

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51
Q

In whom may bacteria cause Noma / Cancrum Oris?

A
  • Malnourished
  • Dehydrated
  • Immunocompromised
  • Systemically unwell patients
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52
Q

What bacteria is found in the nose?

A
  • Staphylococcus
  • Streptococcus
  • Many others
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53
Q

What are the sites for MRSA screening?

A
  • Nose
  • Throat
  • Perineum
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54
Q

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

A

These are the three sites where Staphylococci are found

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55
Q

What bacteria and fungi are found in the throat?

A
  • Strep. Viridans
  • Strep. Pyogenes
  • Strep. Pneumoniae
  • Staphylococci
  • Neisseria Meningitidis
  • Haemophilus Influenza
  • Lactobacilli
  • Corynebacterium Diptheriae
  • Candda Albicans
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56
Q

What kind of bacteria is Strep. Viridans?

A

Non-pathogenic throat commensal

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57
Q

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

A

100%

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58
Q

How may Strep. Viridans get into the bloodstream?

A

During teeth brushing, dental procedures and general anaesthesia

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59
Q

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

A

Bacteraemia

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60
Q

What does Strep. Pyogenes cause?

A

Tonsillitis

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61
Q

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

A

30%

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62
Q

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

A

Viral

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63
Q

What does Strep. Pneumoniae cause?

A

Community acquired pneumonia

64
Q

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

A

30%

65
Q

What % of people is Staphylococci present in?

A

100%

66
Q

What % of people is Neisseria Meningitidis present in?

A

100%

67
Q

What does Haemophilus Influenzea cause?

A

Community acquired pneumonia

68
Q

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

A

13%

69
Q

What does Candida Albicans cause?

A

Oral and vaginal thrush

70
Q

What does Lactobacili prevent?

A

Thrush

71
Q

Why does Lactobacilli prevent thrush?

A

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

72
Q

What viruses can cause tonsillitis?

A
  • Adenovirus
  • Rhinovirus
  • Epstein-Barr Virus
73
Q

What bacteria causes tonsillitis?

A

Strep. Pyogenes

74
Q

What bacteria is found in the stomach?

A

Helicobacter Pylori

75
Q

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

A

At least 50%

76
Q

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

A

10-20%

77
Q

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

A

90%

78
Q

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

A

70%

79
Q

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

A

More than 100

80
Q

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

A

95-99%

81
Q

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

A

Bacteroides and Clostridial

82
Q

What bacteria are always present in the colon?

A
  • Bacteroides fragilis
  • Bacteroides oralis
  • Bacteroides melaninogenicus
  • E. Coli
  • Enterococcus faecalis
83
Q

What is the most common cause of UTIs?

A

E. Coli

84
Q

What is the second most common cause of UTIs?

A

Enterococcus faecialis

85
Q

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

A
  • Pseudomonas
  • Proteus
  • Klebsiella
  • Salmonella
  • Shigella
  • Vibrio cholera
  • Campylobacter
86
Q

What is all gut surgery regarded as?

A

‘Dirty surgery’

87
Q

What is the consequence of gut surgery being ‘dirty surgery’?

A

There is a high risk of wound infection

88
Q

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

A

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

89
Q

How is surgical wound infection reduced in gut surgery?

A

Antibiotics are given prophylactically

90
Q

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

A
  • Anaerobes
  • Gram -ve bacilli
  • Gram +ve bacilli
91
Q

What antibiotics are given prophylactically in gut surgery?

A
  • Metronidazole
  • Broad-spectrum antibiotics, such as Gentamicin or Cephalosporin
92
Q

Why is metronidazole given after gut surgery?

A

It kills anaerobes

93
Q

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

A
  • Faecal Peritonitis
  • Perianal Abscess
94
Q

What causes faecal peritonitis?

A

Huge numbers of bacteria floating free in the peritoneum

95
Q

What is the prognosis of faecal peritonitis?

A

High mortality rate, even in young fit people

96
Q

What causes perianal abscesses?

A

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

97
Q

What bacteria is a normal vaginal flora organism?

A

Lactobacillus

98
Q

What kind of bacterium is lactobacillus?

A

Gram +ve bacilli

99
Q

What does lactobacillus do?

A

Converts glycogen into lactic acid

100
Q

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

A

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

101
Q

What bacteria can survive on the perineal skin?

A
  • E. Coli
  • Enterococcus faecalis
  • Lactobacillus
102
Q

What bacteria cannot survive on the perineal skin?

A

Bacteroides

103
Q

Why can bacteroides not survive on perineal skin?

A

Because they cannot survive in oxygen

104
Q

What % of UTIs occur in women?

A

90%

105
Q

Why do 90% of UTIs occur in women?

A

There is a much shorter distance from anus to urethra

106
Q

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

A
  1. E. coli
  2. Enterococcus faecalis
  3. Various gram -ve enteric bacilli
    • ​​Klebsiella
    • Proteus
    • Pseudomonas
107
Q

What are the types of Clostridia?

A
  • Tetani
  • Difficile
  • Perfringens
108
Q

What does Clostridia Tetani cause?

A

Tetanus

109
Q

How many does neonatal tetanus kill a year?

A

60,000

110
Q

What does Clostridia Difficile cause?

A

Pseudomembranous colitis

111
Q

What is pseudomembranous colitis?

A

Severe inflammation of the colon

112
Q

When does psuedomembranous colitis often occur?

A

After antibiotic treatment

113
Q

What does Clostridia Difficile produce?

A

Spores

114
Q

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

A

They are present in hospitals

115
Q

What does Clostridia Perfringens cause?

A

Gas/wet gangrene

116
Q

How does Clostridia Perfringens cause gangrene?

A

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

117
Q

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

A

No

118
Q

What does the disruption of the gut flora lead to?

A

Gastrointestinal disturbances such as diarrhoea

119
Q

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

A

After treatment with antibiotics

120
Q

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

A
  • Noro-virus
  • Gastroenteritis
  • Cholera
  • Intestinal Parasites
  • Bacteramia
  • Septicaemia
121
Q

What is gastroenteritis?

A

Food poisoning

122
Q

What do noro-viruses produce?

A

A short period of vomiting and diarrhoea

123
Q

What may gastroenteritis follow?

A

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

124
Q

What are the symptoms of gastroenteritis?

A

Vomiting and diarrhoea

125
Q

When is the onset of gastroenteritis?

A
  • Very rapid if toxins are ingested, within a very small number of hours
  • May take up to 48 hours if caused by organisms
126
Q

What are the most common organisms causing gastroenteritis?

A
  • Salmonella
  • Campylobacter
  • Listeria
127
Q

What toxins can cause gastroenteritis?

A
  • Staphylococcus
  • Clostridium
128
Q

What is cholera?

A

A severe acute infection

129
Q

Why is cholera clinically relevant?

A

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

130
Q

What organism is responsible for cholera?

A

Vibrio cholerae

131
Q

Where does Vibrio Cholerae survive?

A

In water supplies

132
Q

Where does Vibrio Cholerae have its effect?

A

The ileum

133
Q

What effect does Vibrio Cholerae have on the ileum?

A

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

134
Q

What are the symptoms of cholera?

A
  • Very serious diarrhoea
  • Rapid, severe dehydration
135
Q

What characteristic does the diarrhoea in cholera have?

A

After initial evacuation, a ‘rice-water’ appearance

136
Q

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

A

It it made up of intestinal secretions and mucus

137
Q

What is the importance of the dehydration in cholera?

A

It is severely life threatening

138
Q

What must the management of cholera do?

A

Replace lost water and electrolytes with appropriate replacement fluids

139
Q

What is the prevalance of intestinal parasites?

A

Common around the world

140
Q

What can intestinal parasites cause?

A
  • Gastroenteritis
  • Malabsorption
  • Other effects
141
Q

What kind of intestinal parasites leads to gastroenteritis?

A

Some protozoans, such as Giardia and Cryptospordium

142
Q

What intestinal parasites lead to malabsorption?

A

Helminth infestations

143
Q

What happens in bacteraemia?

A

The bacteria are rapidly cleared from the bloodstream

144
Q

What clears the bacteria from the bloodstream in bacteraemia?

A

Liver and spleen macrophages

145
Q

What are the symptoms of bacteriaemia?

A

No symptoms are produced

146
Q

What happens in septicaemia?

A

Bacteria are not cleared, and multipy in the blood stream

147
Q

What develops in septicaemia?

A

Sepsis symptoms

148
Q

What bacterium is a major cause of Travellers’ diarrhoea?

A

Enterotoxinogenic E. Coli (ETEC)

149
Q

How does ETEC cause Travellers’ diarrhoea?

A

Heat stable or labile toxins produce from the serotype

150
Q

What are the symptoms of Travellers’ diarrhoea?

A

Severe, cholera-like watery diarrhoea

151
Q

Does Traveller’s diarrhoea cause inflammation?

A

No

152
Q

What prevents Traveller’s diarrhoea from being fatal?

A

The condition is usually self limiting

153
Q

What causes intestinal inflammation and infection?

A
  • Inflammatory Bowel Disease
  • Infection
154
Q

What causes inflammatory bowel disease?

A
  • Ulcerative Colitis
  • Crohn’s Disease
  • Diversion Colitis
  • Diverticular colitis
  • Radiation
  • Drugs
  • Infections
  • Ischaemic colitis
155
Q

What can infect the intestine causing inflammation?

A

Pathogens or toxins

156
Q

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

A
  • Normal gut flora disturbed
  • Immunosuppressed

ESA 3 - Gastrointestinal System (12 decks)

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