Microbiology of the Gastrointestinal Tract Flashcards
1
Q
Approximately how many bacteria are there in the GI tract?
A
1014
2
Q
Where are the majority of the bacteria in the GI tract found?
A
In the colon
3
Q
What is the name given to the bacteria in the GI tract?
A
Normal flora
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
5
Q
What vitamins are synthesised and excreted by the normal GI flora?
A
- Vitamin K
- Vitamin B12
- Thiamine
6
Q
How does the normal GI flora prevent colonisation by pathogens?
A
- Space
- Bacteriosides
7
Q
What aspect of the normal GI flora kills non-indigenous bacteria?
A
Bacteriosides
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
9
Q
Give two examples of bacteria that can form protective endospores?
A
- Bacillus Anthrax
- Clostridium Tetani
10
Q
What is true of obligate aerobes?
A
They must have oxygen
11
Q
Give two examples of obligate aerobes?
A
- Pseudomonas
- Mycobacterium TB
12
Q
What is true of obligate anaerobes?
A
They die in the presence of oxygen
13
Q
Give two examples of obligate anaerobes
A
- Bacteroides fragilis
- Clostridial organisms
14
Q
Why may clostrial organisms be able to survive in oxygen?
A
They form protective spores
15
Q
What is true of facultative anaerobes?
A
They prefer oxygen, but can live without it
16
Q
Give two examples of facultative anaerobes?
A
- Gram -ve enteric bacteria, such as E. coli
- Gram +ve skin-dwellers such as Staphylococcus
17
Q
Where are the anaerobic zones in the GI tract?
A
- Parts of mouth
- Small bowel
- Colon
18
Q
What parts of the mouth are anaerobic?
A
- Tounge
- Deep in taste buds
- Biofilm between teeth
- Gingival crevice areas
19
Q
What can bacillus cause?
A
Anthrax
20
Q
What are the characteristics of bacillus?
A
- Bacilli
- Gram +ve
- Aerobic
21
Q
What are the characteristics of bacteroides fragilis?
A
- Bacilli
- Gram -ve
- Anaerobic
22
Q
What are the characteristics of bordetella pertussis?
A
- Bacilli
- Gram -ve
- Aerobic
- Non enteric
23
Q
What are the characteristics of brucella?
A
- Bacilli
- Gram -ve
- Aerobic
- Non enteric
24
Q
What are the characteristics of campylobacter?
A
- 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 *H**elicobacter 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
