GI Infections Flashcards
(127 cards)
1
Q
What symptoms characterise gastroenteritis?
A
Nausea
Vomiting
Diarrhoea
Abdominal. discomfort
2
Q
Define diarrhoea
A
Frequent and/or fluid stool, at least 3 episodes a day
3
Q
What is dysentery?
A
The presence of blood and pus in the stools usually accompanied with abdominal pain and fever
4
Q
What is endocolitis?
A
Inflammation involving the mucosa of the small and large intestines
5
Q
Which groups of people are at higher risk of viral gastroenteritis?
A
Children under five
Elderly people (especially those in nursing homes)
Immunocompromised patients
6
Q
Give five examples of important viruses which cause gastroenteritis
A
Norovirus Rotavirus Adenovirus (40 and 41) Astrovirus Sapovirus
7
Q
Which viruses most commonly affects children under two, elderly people and immunocompromised people to cause gastroenteritis?
A
Rotavirus
Adenovrius
Astrovirus
8
Q
Most viruses can’t be cultures. How then, are viruses which cause gastroenteritis detected?
A
PCR
9
Q
Describe the structure of norovirus?
A
Non-enveloped
Single stranded RNA
10
Q
How can norovirus be transmitted?
A
Direct person-person transmisssion via faecal-oral route or aerosolised droplets
Food/water borne transmission
11
Q
Norovirus has a high infectious dose. T/F?
A
False- the infectious dose of norovirus is low (10-100 viridons)
12
Q
What is the incubation period of norovirus?
A
24-48 hours
13
Q
Norovirus can shed for up to how many weeks post-infection?
A
3 weeks
14
Q
What are the clinical features of norovirus?
A
Vomiting Diarrhoea Nausea Abdominal cramps Headache Muscle aches Fever Dehydration
15
Q
How long do the symptoms of norovirus last for?
A
12-60 hours
16
Q
For how long post-infection can norovirus shed for in solid organ/bone marrow transplant patients?
A
2 years
17
Q
How is norovirus infection treated?
A
Oral/IV fluids
Antispasmodics
Analgesics
Antipyretics
18
Q
Antibodies are developed to norovirus but these only remain for a short period, provide no long-lasting immunity. T/F?
A
True
19
Q
What are the infection control policies for norovirus infection?
A
Isolation and cohosting of patients
Symptomatic staff excluded until symptom free for 48 hours
Patients should not be moved
New patients should not be admitted
20
Q
Describe the structure of rotavirus?
A
Non enveloped
Double stranded RNA virus
21
Q
Rotavirus has a low infectious dose and is stable in the environment. T/F?
A
True
22
Q
What is the incubation period of rotavirus?
A
1-3 days
23
Q
How is rotavirus transmitted?
A
Mainly by the faecal-oral route or fomites
Food/water borne spread possible
24
Q
What are the symptoms of rotavirus infection?
A
Watery diarrhoea
Abdominal pain
Vomiting
Loss of electrolytes leading to dehydration
25
For how long do the symptoms of rotavirus infection normally last?
3-7 days
26
What are the possible complications of rotavirus infection?
Severe chronic diarrhoea
Dehydration
Electrolyte imbalance
Metabolic acidosis
27
Antibodies against rotavirus are produced and this leads to immunity against further infection. T/F?
False - the antibodies which are produced don't lead to permanent immunity but do lessen the severity of subsequent infection
28
A rotavirus vaccine is available. T/F?
True
29
Describe the structure of adenovirus?
Double stranded DNA virus
30
Which serotypes of adenovirus cause gastroenteritis?
Adenovirus 40 and 41
31
What are the symptoms fo adenovirus 40/41 infection?
Fever
| Watery diarrhoea
32
Describe the structure fo astrovirus
Single stranded RNA virus
| Non-enveloped
33
Astrovirus causes very severe gastroenteritis compared to other aetiologies. T/F?
False - astrovirus causes less severe gastroenteritis than other enteric pathogens
34
In the developed world, what mode of transmission is mainly associated with GI infection?
Food-borne infection
35
In the developing world, what is the biggest factor contributing to GI infection?
Lack fo clean water and poor sanitation
36
Give examples of the physiological barriers to infection of the GI tract.
Lysoyme in the mouth
Acidic pH of the stomach
Mucous/bile/secretory IgA/ lymphoid tissue/epithelial turnover/normal flora of the small intestine
Epithelial turnover/normal flora of the large intestine
37
The normal flora of the small and large intestines are mostly what type of microorganisms?
Anaerobes
38
Many GI infections are zoonotic. What does this mean?
They are transmitted to humans from animals
39
What key factors are important to establish when taking a history from a patient with GI infection?
```
Nature of diarrhoea
Timing (acute/chronic)
Food history
Recent antibiotic usage
Foreign travel
Occupation
```
40
What investigations should be conducted for a patient with GI infection?
```
FBC
U&Es
Blood film
Stool sample
Sigmoidscopy
Abdominal X-RAY/CT
```
41
What is an enrichment broth?
Contains nutrients that promote the preferential growth of the pathogen
42
What is selective culture media?
Suppresses the growth of background flora while allowing the growth of the pathogen
43
What is differential culture media?
Distinguishes mixed microorganisms on the same plate using biochemical characteristics of microorganisms growing in the presence of specific nutrients combined with an indicator which changes colour
44
What is the most important factor in the treatment of GI infection?
Hydration / giving the patient fluids
45
Why is antibiotic treatment generally not used for GI infection?
May prolong symptom duration
Exacerbate symptoms
Promote emergence of antibiotic resistance
Be harmful such as in STEC infection
46
How can GI infections be prevented?
```
Provision of safe, clean drinking water
Proper sewage d isposal
Education in hygienic food preparation
Pasteurisation of milk and dairy products
Sensible travel food practices
```
47
Describe why there is such as potential for new enteric pathogens to emerge?
Pathogenecity traits are often grouped together in large interns of pathogenicity. These can be transferred to other organisms via bacteriophages, plasmids and transposons.
Pathogenicity traits frequently contain antibiotic resistance genes
48
Why do GI infections caused by intoxication have a short incubation time?
Because the preformed toxin is present in food and usually takes only a few hours for symptoms to appear.
49
What are three of the most common causes of GI infection?
Salmonella
Campylobacter
E.coli
50
What type of bacteria is salmonella?
Gram negative bacilli
51
Salmonella are non-lactose fermenters. T/F?
True
52
How can salmonella infection be acquired?
Contaminated food especially pork, poultry and other meat and dairy products
Waterborne infection is less common
53
There are seasonal peaks of salmonella infection in which months?
Summer and autumn
54
How does salmonella cause diarrhoea?
By invading epithelial cells in the distal small intestine, causing inflammation
55
What are the possible results of metastatic salmonella infection?
Osteomyelitis
Septic arthritis
Meningitis
56
What is the incubation period of salmonella?
12-72 hours
57
What are the symptoms of salmonella infection?
Watery diarrhoea
Fever
Vomiting
58
In severe salmonella infections, what antibiotics may eb used?
Beta lactams
Quinolones
Aminoglycosides
59
What type of bacteria are campylobacter?
Gram negative bacilli
60
What is the most clinically important species of campylobacter?
C.jejuni
61
What animals can acts as a reservoir for campylobacter?
```
Poultry
Cattle
Sheep
Rodents
Wild birds
```
62
In what months is there seasonal peaks of campylobacter infection?
May
| September
63
How is campylobacter transmitted?
Contaminated food, milk and water
64
How does campylobacter infection cause diarrhoea?
Causes inflammation, ulceration and bleeding in the small and large intestines via bacterial invasion
65
In rare cases campylobacter infection can cause post-infectious demyelinated syndrome. T/F?
True
66
What is the incubation period of campylobacter?
2-5 days
67
How long do the symptoms fo campylobacter infection last?
2-10 days
68
What are the symptoms fo campylobacter?
Bloody diarrhoea
Cramping abdominal pain
Fever
(Vomiting not usually a feature)
69
Which antibiotics can be used to treat severe or persistent campylobacter infection?
Clarithromycin
| Erythromycin
70
What type of bacteria is e.coli?
Gram negative bacilli
71
What are the six diarrhoeagenic groups of E.coli?
```
Enteropathogenic E.coli
Enterotoxigenic. e.coli
enterohaemorrhagic e.coli
enteroinvasive e.coli
entero-agrgegative e.coli
diffuse aggregative e.coli
```
72
What syndrome may result form the use fo antibiotics in e.coli infection?
Haemolytic uraemic syndrome
73
What are the symptoms of enteropathogenic e.coli infection?
Watery diarrhoea
Abdominal pain
Vomiting
Fever
74
Describe the pathophysiology fo enteropathogenic e.coli infection?
Adheres via pili, forms attaching and effacing. lesion which is mediated by intimin protein
Disrupts intestinal microvilli
75
What is the major bacterial cause fo diarrhoea in infants and children in the developing world?
Enterotoxigenic e.coli
76
What are the symptoms of enterotoxigenic e.coli infection?
Watery diarrhoea
Abdominal pain
Vomitng
No associated fever
77
What is the incubation period of enterotoxigenic e.coli?
1-7 days
78
How long do the symptoms fo enterotoxigenic e.coli infection last for?
2-6 days
79
How does enterotoxigenic e.coli cause diarrhoea?
Heat labile and heat stabile toxins which are structural and functional analogues of the cholera toxin
80
What is the most common serotype of enterohaemorrhagic e.coli?
E.coli 0157
81
What is the main mode of transmission of enterohaemorrhagic e.coli?
Contaminated food, water and dairy products
| Direct environmental contact with animal faeces
82
What toxins are produced by enterohaemorrhagic e.coli?
Shiga like toxins
83
What is the incubation period of enterohaemorrhagic e.coli?
1-7 days
84
How long do the symptoms fo enterohaemorrhagic e.coli infection last for?
5-10 days
85
What are the symptoms of enterohaemorrhagic e.coli infection?
Bloody diarrhoea
Abdominal pain
Vomiting
No associated fever
86
What is haemolytic uraemiac syndrome?
A triad of microangiopathic haemolytic anaemia, thrombocytopenia and acute renal failure
87
What type of bacteria is shigella?
Gram negative bacilli
88
What are the four species fo shigella?
Shigella sonnei
Shigella boydii
Shigella flexneri
Shigella dysenteriae
89
Which. species of shigella is associated with milder infections?
Shigella sonnei
90
Which species of shigella is associated with the most severe disease?
Shigella dysenteriae
91
Shigella does not persist in the environment. Thus, what is the most important mode of transmission of shigella?
Person to person spread via the faecal-oral route
92
S.dysenteriae produces a potent protein exotoxin (shiga toxin) which damages the intestinal epithelium. What other structures can this target?
Glomerular epithelium causing renal failure
93
Infection with which organism is the most common cause of dysentery?
Shigella
94
What are the symptoms fo shigella infection?
Marked, cramping abdominal pain
Dysentery
Fever
Vomiting is uncommon
95
What type of bacteria is vibrio cholerae?
Gram negative bacilli
96
In what parts of the world is vibrio cholerae endemic?
Southeast Asia
Africa
South America
97
Vibrio cholerae has many. animal reservoirs. T/F?
False - it only infects humans
98
How does vibrio cholerae spread?
Contaminated food and water
99
What are the symptoms fo vibrio cholerae infection?
Sever, profuse water diarrhoea
| Profound fluid loss and dehydration causing hypokaelamia, metabolic acidosis, hypovolaemic shock, cardiac failure
100
What type fo antibiotics may shorten the duration of shedding of vibrio cholerae?
Tetracyclines
101
S.aurerus toxins causing Gi infection are especially present in which foodstuffs?
Meats
Cakes
Pastries
102
What are the symptoms of s.auerus toxin mediated GI infection?
Profuse vomiting
Abdominal cramps
No fever or diarrhoea
103
What is the incubation time for s.auerus toxin mediated GI infection?
30 minutes
104
What type of bacteria are bacillus cereus?
Gram positive bacilli
105
What foodstuffs are typically associated with b.cereus GI infection?
Fried rice
106
What are the symptoms of b.cereus toxin mediated emetic GI infection?
Profuse vomiting
Abdominal cramps
Watery diarrhoea
No fever
107
What is the incubation period of b.cereus toxin mediated emetic GI infection?
30mins-6hours
108
What are the symptoms of b.cereus toxin mediated diarrhoea GI infection?
Watery diarrhoea
Cramping abdominal pain
No vomiting or fever
109
What is the incubation period of b.cereus toxin mediated diarrhoeal GI infection?
8-12 hours
110
What type of bacteria is clostridium perfringens?
Anaerobic gram positive bacilli
111
What are the symptoms of c.perfringens toxin mediated GI infection?
Watery diarrhoea
Abdominal cramps
No fever or vomiting
112
What is the incubation period of c.perfringens toxin mediated GI infection?
6-24hours
113
Which heat-labile protein neurotoxins of clostridium botulinum cause disease in humans?
Types A, B and E
114
What foodstuffs is preformed botulism toxin particularly associated with?
Improperly processed canned foodstuffs
115
What are the symptoms fo clostridium botulinum toxin mediated disease?
Flaccid paralysis
Progressive muscle weakness
Respiratory failure of chest/diaphragm involved
116
What is used to treat clostridium botulinum toxin mediated disease?
Antitoxin
117
Other than antibiotics, which drugs are associated with c.difficile infection?
Proton pump inhibitors
118
What condition may result from severe c.difficile infection?
Pseudomembranous colitis
119
In mild c.difficile infection what antibiotic is given?
Oral metronidazole
120
In severe c.difficile infection what antibiotic is given?
Oral vancomycin
121
What type of bacteria is listeria monocytogenes?
Gram positive coccobacili
122
What groups of people are more likely to become infected with listeria monocytogenes?
Pregnant women
Elderly people
Immunocompromised individuals
123
Which foodstuffs are particularly associated with listeria monocytogenes?
```
Unpasteurised milk
Soft cheese
pate
Cooked meats
Smoked fish
Coleslaw
```
124
What can result from severe, systemic infection with listeria monocytogenes?
Septicaemia
| Meningitis
125
Which antibiotics are used to treat listeria monocytogenes infection?
IV Ampicillin and gentamicin
126
What is the incubation period of listeria monocytogenes?
3 weeks
127
For how long does listeria monocytogenes infection cause symptoms?
1-2 weeks
