Microbiology Flashcards
1
Q
What is gastroenteritis
A
Diarrhea + vomiting due to enteric infections
2
Q
What is dysentery
A
Diarrhea with blood / mucus
3
Q
Infection at which part of GI tract causes large volume of diarrhea
A
Large intestine
4
Q
What is considered as acute diarrhea
A
< 14 days
5
Q
What is considered as chronic diarrhea
A
> 4 weeks
6
Q
What is considered as traveller’s diarrhea
A
Diarrhea that develops during or within 10 days of returning from a resource limited country
7
Q
Common pathogens causing traveller’s diarrhea
A
E. coli
Campylobacter
Shigella
Salmonella
8
Q
List the bacteria causing gastroenteritis
A
Campylobacter Bacillus cereus Shigella Salmonella Staph. aureus E. coli
9
Q
Which bacteria is the most common cause of gastroenteritis
A
Campylobacter
10
Q
Which virus is the most common cause of gastroenteritis
A
Norovirus
11
Q
List the viruses causing gastroenteritis
A
Rotavirus
Norovirus
Adenovirus
12
Q
Gram stain of campylobacter
A
Gram negative bacillus
13
Q
Which strain of campylobacter is the most common
A
C. jejuni
14
Q
Symptoms caused by campylobacter
A
Watery /blood (30%) diarrhea + pain + fever
15
Q
Which age group does campylobacter usually affect
A
young adults
16
Q
How does campylobacter spread
A
from ingestion of
- uncooked poultry
- unpasteurized milk
- contaminated water
17
Q
Incubation period of campylobacter
A
16 - 48 hours
18
Q
What are the possible post Campylobacter infection conditions
A
Reactive arthiritis
Guillain Barre syndrome
19
Q
What protein is reactive arthiritis associated to
A
HLA B27
20
Q
When does Guillain Barre syndrome usually occur
A
1-2 weeks after infection
21
Q
Gram stain of bacillus cereus
A
Gram positive bacillus
22
Q
What toxins do bacillus cereus produce
A
Heat stable vomiting enterotoxin
Heat labile diarrheal toxin
23
Q
What type of food does Bacillus cereus like
A
Starchy food left in room temperature overnight then reheated
24
Q
Symptoms caused by bacillus cereus
A
Profuse vomiting +/- diarrhea
25
Why may diarrhea not occur in bacillus cereus infection
Because the enterotoxin that causes diarrhea is heat labile so does not tolerate heat when the starchy food is reheated
26
Incubation period of Bacillus cereus
0.5-6 hours for vomiting
| 8-12 hours for diarrhea
27
Gram stain of staphylococcus aureus
Gram positive
28
How does staphylococcus cause symptoms
Preformed toxin in poultry / milk / fish
| toxin act on vomiting centre
29
Symptoms caused by staphylococcus aureus
Vomiting + diarrhea + nausea
| maybe fever and pain
30
Incubation period of Staph. aureus
1-6 hours
31
Gram stain of Salmonella
gram negative
32
Bacteria in enterobacteriaceae family
```
E.coli
Klebsiella
Salmonella
Shigella
Citrobacter
```
33
Which type of salmonella causes gastroenteritis
Non-typhoidal salmonella
34
Examples of non-typhoidal salmonella
Salmonella enterica
| Salmonella typhimurium
35
Transmission of salmonella
Ingestion of
- raw poultry
- raw egg
- unpasteurized milk
- contaminated fruits and veg
- contaminated water
- anal sex
36
Who are more at risk of salmonella infections
Haemochromatosis people
immunocompromised
infant sand adults
37
Why are haemochromatosis patients more at risk of salmonella infection
They have high iron levels. Salmonella needs iron to determine their virulence and pathogenicity
38
Symptoms caused by salmonella
Watery / bloody diarrhea + vomiting + fever + pain
39
Incubation period of salmonella
8 - 72 hours
40
Gram stain of shigella
Gram negative bacilli
41
Are enterobacteriaceae aerobic / obligate anaerobes / facultative anaerobic
Facultative anaerobic
42
Serotypes of shigella
Serogroup A
Serogroup B
Serogroup C
Serogroup D
43
Which serogroup of shigella is most pathogenic
A
44
Name of serogroup B of Shigella
S. flexneri
45
Name of serogroup A
S. dysenteriae
46
Which serogroup of shigella causes the mildest infection
D
47
What toxins do shigella produce
Shigella toxins (stx) - type 1 and 2
48
How does shigella toxin damage cells
Inhibit protein synthesis of the cell
49
Which STx is more potent
Type 2
50
Which age group is most commonly affected by shigella
young children
51
Transmission of shigella
From contaminated water / human to human
52
Symptoms caused by shigella
watery / bloody diarrhea + fever + pain
53
Which serogroup of shigella can cause HUS
S. dysenteriae (Serogroup A)
54
What is HUS (haematuria and renal failure)
Microangiopathic haemolytic anaemia + thrombocytopenia + kidney injury
55
Which STx is the most common cause of HUS
type 2
56
Which STx is more potent
Type 2
57
How does STx cause HUS
1) STx inhibits protein synthesis of the enterocyte
2) enterocyte dies, STx enters bloodstream
3) STx damage endothelial cells
4) causes platelet activation and aggregation
5) clot forms
6) STx carried to kidneys to cause haematuria, kidney injury
58
Which E.coli produces shiga toxin
E. coli 0157
59
Strains of E. coli
EHEC
EIEC
ETEC
EAIC
60
Which strain does E.coli 0157 belong to
EHEC enterohaemorrhagic
61
Transmission of E.coli 0157
from
- contaminated water
- unpasteurised milk
- contaminated meat and veg
- human to human
62
Which age groups do E.coli 0157 most commonly affect
young children below 5 years old
| elderly
63
Incubation period of shigella
1 - 2 days
64
Incubation period of E. coli
3- 4 days
65
What should you must do after discovering e.coli 0157
Notify health protection unit
66
Which E. coli strains are related to traveller's diarrhea
ETEC
| EAIC
67
Which E. coli strain produces shiga like toxin
EIEC
68
Management of gastroenteritis
Rehydration is key
| Antibiotics are reserved for immunosuppressed / elderly / systemically unwell patients
69
Antibiotics against campylobacter
Macrolide - erythromycin
70
What type of antibiotic is macrolide
Broad spectrum antibiotic
71
Antibiotics against salmonella and shigella
Ciprofloxacin (levofloxacin)
72
Which virus causing gastroenteritis is associated with daycare exposure
Rotavirus
73
Transmission of rotavirus
person - person
| faecal - oral
74
Which age group is most commonly affected by rotavirus
Young children
75
What may develop post rotavirus infection
Malabsorption, causing more diarrhea
76
How to diagnose rotavirus
PCR in faeces
77
Symptoms caused by rotavirus
watery diarrhea + vomiting + fever
78
What pathogens do not cause bloody diarrhea
Bacillus cereus
Rotavirus
Staph. aureus
EIEC
79
Type of vaccine for rotavirus
Live attenuated
80
Transmission of norovirus
faecal - oral
| droplet
81
Effect of norovirus on healthy vs frail
Self limiting in healthy people but can cause kidney injury in frail
82
Symptoms caused by norovirus
explosive diarrhea + vomiting + fever + myalgia
83
What is special about norovirus
Symptoms come abruptly and unpredictably
84
Incubation period of norovirus
< 24 hours
85
How is norovirus diagnosed
PCR on vomit
86
What immune cells are for protection against worms
Eosinophils
| Mast cells
87
What immune cells are for protection against bacteria
T lymphocytes
B lymphocytes
Complement system
88
What immune cells are for protection against viruses
T lymphocytes
| B lymphocytes
89
What immune cells are for protection against fungi
T lymphocytes
| eosinophils
90
What immune cells are for protection against protozoa
t lymphocytes
| eosinophils
91
Which pathogens causes dysenteric gastroenteritis
E.coli 0157
Campylobacter
Salmonella
Shigella
92
What are the characteristics of enterobacteriaceae
```
Gram negative bacilli
Oxidase negative
Glucose fermenting
Facultative anaerobic
Non spore forming
```
93
What agar is used to test for lactose
Macconkey agar
94
Which enterobacteriaceae are lactose negative
Shigella
| Salmonella
95
Which enterobacteriaceae are lactose positive
Klebsiella
Citrobacter
E.coli
96
What molecular tests are used to classify bacteria
MALDI-TOF
| 16sRNA
97
What does MALDI-TOF look at
mass spectrometry, analyses protein components in cell wall
98
Gram positives in GI tract
Candida
Strep. viridans
Staphylococci
99
Where are gram positives mostly located
In mouth, only few in stomach
100
Timeline of septic shock
Infection -> SIRS -> Sepsis -> Septic shock
101
What is SIRS and what causes it
Systemic inflammatory response syndrome; caused by infection / burns / trauma / injury / pancreatitis
102
What are the signs that show SIRS
```
HR = <90
Temp = >38 or <36
RR = >20
WCC = >12000
```
103
What is sepsis
Organ dysfunction caused by a dysregulated host response to infection
104
What causes of SIRS do not cause sepsis
Burns / trauma / injury / pancreatitis; sepsis must be due to infection
105
What pathogens are commonly found in hospitals
Staphylococcus aureus (often MRSA)
E. coli
Klebsiella
Pseudomonas
106
What should be monitored when giving gentamicin
Renal function
107
Complications of gastroenteritis
```
Post infectious IBS
Sepsis / septic shock
Acute kidney injury
HUS
Dehydration
Guillain Barre / reactive arthritis - campylobacter
```
108
Gram stain for C. difficile
Gram positive
109
When does C.difficile become infectious
When the normal gut flora becomes suppressed by broad spectrum antibiotics
110
What drug increases risk of C.difficile infection
Any broad spectrum antibiotics
| PPI
111
Complication of C.difficile
toxic megacolon
112
Symptoms and signs of C.difficile infection
abdominal pain
Diarrhea
Raised WCC
Neutrophilia
113
Treatment of C.difficile
oral vancomycin
114
Second line treatment of C.difficile
oral fidaxomicin
115
Third line treatment of C.difficile
Oral vancomycin + IV metronidazole
116
What is the treatment for recurrent C.difficile infection
Faecal microbiota transplant
117
Antibiotic for travellers diarrhea due to E. coli
Rifaximin
118
Which antibiotics are highly associated with C.difficile infection
Cephalosporins - ceftriaxone
Clindamycin
Co-amoxiclav
