Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Medical Microbiology lectures > L.3 GPB Bacillus cereus > Flashcards

L.3 GPB Bacillus cereus Flashcards

1
Q

What type of bacteria are Bacillus spp.?

A

Aerobic or Facultative aerobic bacteria

They are capable of surviving in both the presence and absence of oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the defining characteristic of Bacillus spp. regarding their structure?

A

Endospore forming

Endospores are resistant structures that allow survival under adverse conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of Gram stain do Bacillus spp. exhibit?

A

Gram Positive Bacilli

This indicates that they retain the crystal violet stain used in the Gram staining procedure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

To which phylum do Bacillus spp. belong?

A

Firmicutes

Firmicutes is a phylum of bacteria that includes many important genera.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How many species of Bacillus have been identified?

A

> 260 species identified

This number indicates the diversity within the Bacillus genus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the two groups of Bacillus spp.?

A
  • B. subtilis group
  • B. cereus group

These groups are distinguished based on genetic and phenotypic characteristics.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which species are included in the B. cereus sensu lato group?

A
  • B. anthracis
  • B. cereus
  • B. thuringiensis

These species are known for their pathogenic potential.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a key feature of the B. cereus group?

A

Closely related genome

They share genetic similarities that classify them together.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How are the species in the B. cereus group differentiated?

A

By phenotypic characteristics and pathological properties

These differences help in identifying specific species and their effects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the pathogenic potential of most Bacillus spp.?

A

Little pathogenic potential

Most species are not harmful, but some can act as opportunistic pathogens.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which two species of Bacillus are clinically important?

A
  • B. cereus
  • B. anthracis

These species are associated with significant clinical infections.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What type of organism is B. cereus?

A

GP spore forming motile bacilli

This describes its Gram-positive nature, ability to form spores, and motility.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where does B. cereus typically dwell?

A

Soil dwelling organism

This habitat allows B. cereus to thrive in various environments.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What types of food poisoning are caused by B. cereus?

A
  • Diarrhoeal disease
  • Vomiting disease

These represent common foodborne illnesses associated with B. cereus consumption.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What infections can B. cereus cause?

A
  • Localised wound infections
  • Eye infections
  • Respiratory infections
  • Systemic infections

B. cereus can lead to a range of infections beyond food poisoning.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What conditions can B. cereus spores survive?

A

Cooking
High temperatures (up to 126C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What conditions allow the survival of B. cereus endospores?

A
  • Cooking/heat treatment
  • Sanitizers
  • Routine cleaning

These factors contribute to the persistence of contamination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the risk associated with biofilm formation by B. cereus?

A

Spores adhere to food-processing surfaces, making it hard to eliminate contamination

Biofilms can lead to persistent food safety issues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the combined risk in the food industry posed by B. cereus?

A

Biofilms + spores = persistent contamination

This combination poses significant challenges for food safety management.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the primary reservoir for B. cereus?

A

Decaying organic matter, fresh and marine waters, vegetables, fomites, soil, sediments, dust, and plants

B. cereus is commonly found in various environments and can germinate, grow, and sporulate in soil.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How can B. cereus spores be transmitted to food?

A

Spores in soil transferred to food, especially rice, pasta, and dairy

Temperature abuse is a key risk factor for transmission.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the key risk factor for B. cereus transmission in food?

A

Temperature abuse

This occurs when cooked food is left too long at unsafe temperatures before reheating.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What types of food are commonly associated with B. cereus?

A
  • Rice
  • Pasta
  • Dairy products
  • Meats
  • Vegetable dishes
  • Desserts

B. cereus can contaminate a variety of foods.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the two distinct types of B. cereus food-borne illness?

A
  • Diarrhoeal Syndrome
  • Emetic Disease

Both types are generally mild but can lead to more serious cases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What causes Diarrhoeal Syndrome in B. cereus infections?
Ingestion of bacteria and/or enterotoxin ## Footnote The toxin can be released in food or in the small intestine.
26
What is the onset time for symptoms of Diarrhoeal Syndrome?
8 to 16 hours after consumption ## Footnote Symptoms include watery diarrhoea and cramps.
27
What is the duration of Diarrhoeal Syndrome symptoms?
12-24 hours ## Footnote Symptoms are generally self-limiting.
28
What is the primary toxin involved in Emetic Disease?
Cereulide toxin ## Footnote This toxin is heat-stable and can withstand high temperatures.
29
What are the symptoms of Emetic Disease?
* Vomiting * Nausea * Abdominal cramps ## Footnote Symptoms typically occur within 1-5 hours of ingestion.
30
What is the association of Emetic Disease with specific foods?
Primarily associated with starchy foods, especially cooked rice ## Footnote Outbreaks have been linked to fried rice left to cool at room temperature.
31
True or False: B. cereus infections can lead to serious and lethal cases.
True ## Footnote While most cases are mild, severe cases can occur.
32
Fill in the blank: B. cereus spores can survive _______ and then germinate.
cooking ## Footnote This allows them to release toxins or grow into vegetative cells.
33
What types of infections can non-gastrointestinal diseases cause?
Systemic and local infections e.g. Blood Stream Infections, endocarditis, Meningitis, Abscesses, Gas gangrene-like cutaneous infections, Osteomyelitis, Keratitis ## Footnote Non-gastrointestinal diseases can infect medical devices and affect both immunologically compromised and immunocompetent individuals.
34
Which populations are particularly at risk for infections from non-gastrointestinal diseases?
Neonates, intravenous drug abusers, patients with traumatic or surgical wounds, those with indwelling catheters ## Footnote These groups have increased vulnerability to infections.
35
What is the first step in the pathogenesis of B. cereus?
Entry – Ingestion of contaminated food with preformed toxin or bacterium ## Footnote This step initiates the infection process.
36
How does B. cereus colonize its host?
Formation of biofilm promotes adherence in food processing lines and gastrointestinal epithelium ## Footnote Biofilm formation is crucial for colonization.
37
What mechanisms does B. cereus use to evade the host immune system?
Biofilm and endospores ## Footnote These structures help B. cereus resist immune responses.
38
What are some virulence factors of B. cereus?
* Hemolysin BL * Non-hemolytic enterotoxin (Nhe) * Cytotoxin K (CytK) * Collagenase * Protease * Cerulide toxin * Phospholipase C ## Footnote These factors contribute to host damage.
39
What is the last step in the pathogenesis of B. cereus?
Spread – spores excreted in faeces contaminate more food ## Footnote This step facilitates the transmission of the bacteria.
40
What is the main toxin responsible for emetic disease caused by B. cereus?
Cereulide toxin ## Footnote This toxin is released in food before ingestion.
41
How resistant is the cereulide toxin?
Extremely resistant – survives autoclaving, pH changes, protease ## Footnote Its resistance makes it a significant food safety concern.
42
What mechanism does cereulide use to induce vomiting?
Binds to gastrointestinal mucosal chemoreceptors and excessively stimulates the vagus nerve ## Footnote This stimulation triggers the vomiting reflex.
43
What is the infectious dose range for B. cereus?
As low as 103 and as high as 1010 B. cereus CFU per gram of implicated food ## Footnote The precise infectious dose has not been determined.
44
What dose of cereulide toxin was suggested to cause a serious outbreak of emetic disease?
<8μg/kg body weight ## Footnote This finding highlights the potency of the toxin.
45
What are the three enterotoxins responsible for diarrhoeal syndrome?
* Haemolysins * Non-haemolytic enterotoxin * Cytotoxin K ## Footnote These toxins are membrane pore-forming toxins that may act in synergy with each other and other virulence factors, increasing severity.
46
What is the infectious dose range for the enterotoxins?
10^5–10^8 cells or spores ## Footnote Doses as low as 10^3 B. cereus CFU g of implicated food can cause infection.
47
What is the lowest infectious dose reported in an outbreak?
10^4 CFU g ## Footnote This refers to the minimum number of bacteria needed to cause an outbreak.
48
Why are spores better equipped than vegetative cells?
Spores are better equipped to survive the passage through gastric acid ## Footnote This allows spores to reach the intestines more effectively.
49
How common is the bacterium responsible for foodborne infectious diseases in the USA?
Fifth most common bacterium causing foodborne infectious diseases and food poisoning ## Footnote This highlights the significance of the bacterium in public health.
50
Is gastrointestinal syndrome reportable in Ireland?
Not reportable ## Footnote In Europe and North America, diarrhoeal disease is reported more frequently than emetic disease.
51
What is the average annual number of invasive disease cases reported in Ireland?
About one case per year ## Footnote This indicates a low incidence rate for invasive disease.
52
Is there a seasonal pattern of incidence for the bacterium's infections?
No seasonal pattern of incidence ## Footnote This suggests that infections can occur year-round.
53
What is the frequency of outbreaks reported in Europe?
One outbreak per week ## Footnote This statistic provides insight into the ongoing risk of outbreaks.
54
What types of specimens are collected in a lab investigation?
Clinical and Environmental specimens ## Footnote Clinical specimens include faeces, non-GI sites, and vomitus. Environmental specimens include soil and food.
55
What is the purpose of General Purpose agar?
Isolation of microorganisms ## Footnote General Purpose agar is represented by blood agar.
56
What are the components of PEMBA agar?
Polymyxin, egg yolk, mannitol, bromothymol blue ## Footnote PEMBA is a selective and differential agar.
57
What type of agar is PEMBA considered?
Selective and Differential agar ## Footnote Selective due to polymyxin and differential due to egg yolk and mannitol.
58
What is the appearance of colonies on blood agar?
Cream/grey with slight green tinge & zone of beta-haemolysis ## Footnote This indicates the presence of certain bacteria.
59
What is the colonial morphology of PEMBA?
Crenated colonies, 5mm diameter, turquoise colour ## Footnote These colonies do not ferment mannitol and show a zone of egg yolk precipitation.
60
What are the basic characteristics of the bacteria being investigated?
Gram Positive Bacilli, KOH Negative, Catalase Positive, Oxidase Negative ## Footnote They have large box car ends and central spores.
61
What indicates that bacteria are motile?
Flagellated bacteria ## Footnote Motility can be tested using a hanging drop test.
62
What molecular confirmation tests are used?
MALDI-top, Vitek, PCR (ces genes) ## Footnote These tests help confirm the presence of specific bacteria.
63
What does the cell culture assay detect in B.cereus?
B.cereus emetic toxin ## Footnote It uses Hep 2 cell lines to observe for vacuoles in cell lines.
64
How is B.cereus enterotoxin detected?
Detection of antibodies targeting Nhe and Hbl ## Footnote Commercial kits are available for this detection.
65
What is the purpose of the Oxoid BCET-RPLA kit?
Detects the L2 component of Hbl by reversed antibody agglutination ## Footnote It requires food samples and cultures of B.cereus.
66
What does the TECRA-BDE kit detect?
NheA component of the Nhe toxin by ELISA test ## Footnote It requires food and environmental samples.
67
What is the sensitivity of the TECRA-BDE kit?
>1ng/mL prepared sample ## Footnote This indicates the minimum concentration that can be detected.
68
What type of treatment is recommended for B.cereus infections?
Supportive treatment ## Footnote This treatment aims to alleviate symptoms.

Medical Microbiology lectures (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions