Microbiology - Periodontal disease medium

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Questions and Answers

What characterizes a stable state of gingivitis?

An abundance of pathogenic bacteria.

A dynamic equilibrium between dental plaque and host defences. (correct)

Constant tissue destruction.

Decreased host immune response.

What can disturb the balance between dental plaque and host defences?

Reduction of plaque amount.

Increase in pathogenicity of microorganisms. (correct)

Improved host immune response.

Stable levels of beneficial bacteria.

Which factor can lead to tissue damage in periodontal diseases?

Increased host immunity.

Consistent equilibrium of pathogens.

An increase of beneficial bacteria.

An increased amount of plaque. (correct)

Which statement about host response and tissue damage is correct?

A balanced host response prevents tissue damage. Signup and view all the answers

What is a recognized periodontal pathogen?

12-15 types of particularly virulent bacteria. Signup and view all the answers

How does compromised host defence affect periodontal health?

It may tip the balance towards tissue destruction. Signup and view all the answers

What happens when the pathogenicity of bacteria increases?

It can cause greater tissue damage. Signup and view all the answers

What concept helps to explain the health status of gum tissues?

Dynamic equilibrium between plaque and host defences. Signup and view all the answers

What consequence arises from an imbalance in the oral biofilm?

Increased susceptibility to periodontal disease. Signup and view all the answers

What is the primary trigger that leads to changes in microbial types according to the Ecological Plaque Hypothesis?

Shift in local environment Signup and view all the answers

Which of the following factors is NOT mentioned as being altered in the subgingival environment that favors pathogenic bacteria growth?

Increased temperature Signup and view all the answers

How does subgingival debridement impact the ecosystem according to the Ecological Plaque Hypothesis?

Reduces the number of pathogens Signup and view all the answers

What does the Microbial Homeostasis-Host Response Hypothesis propose about the pathogenic biofilm community?

It triggers an uncontrolled host immune response Signup and view all the answers

What role do genetic variations play in the progression of periodontal disease, according to the content provided?

They are one of several factors influencing disease progression. Signup and view all the answers

Which environmental factor is highlighted as contributing to the dysbiosis in gingival sulcus?

Decreased oxygen concentration Signup and view all the answers

What role do fimbrae play in bacterial infection?

They facilitate adhesion to epithelium. Signup and view all the answers

How do gingipains contribute to the survival of Porphyromonas gingivalis?

They allow the bacterium to utilize gingival crevicular fluid as a nutrient source. Signup and view all the answers

What impact do endotoxins have on the host's immune response?

They trigger an inflammatory response. Signup and view all the answers

What is the primary characteristic of Porphyromonas gingivalis in terms of its metabolic processes?

It is non-saccharolytic and cannot break down carbohydrates. Signup and view all the answers

Which factor helps protect Porphyromonas gingivalis from host defenses?

Carbohydrate capsule Signup and view all the answers

What is haemagglutination, and how does it benefit Porphyromonas gingivalis?

It causes clumping of red blood cells, releasing nutrients. Signup and view all the answers

What potential health implication is associated with the haemagglutinins produced by Porphyromonas gingivalis?

Contribution to heart disease Signup and view all the answers

In what way does Porphyromonas gingivalis destroy host tissues?

By breaking down collagen and other tissue components. Signup and view all the answers

Which statement is true about the motility of Porphyromonas gingivalis?

It cannot move by itself. Signup and view all the answers

Which bacteria are identified as major causative agents of periodontal disease?

Tannerella forsythia Signup and view all the answers

What is the primary grouping method Socransky used for periodontal pathogens?

By their color-coded complexes Signup and view all the answers

Which complex is considered compatible with gingival health?

Yellow/green/blue/purple complex Signup and view all the answers

What challenge has been presented to the Specific Plaque Hypothesis?

A greater diversity of oral microbes exists than previously recognized. Signup and view all the answers

What nutrient source do periodontal pathogens utilize from the host?

Gingival crevicular fluid Signup and view all the answers

Which of the following bacteria is part of the red complex associated with periodontal disease?

Treponema denticola Signup and view all the answers

What relationship exists among the bacteria in the red complex?

They depend on each other to survive. Signup and view all the answers

Which bacterial group tends to be found in larger amounts in periodontal pockets according to recent research?

A mix of Gram-positive and Gram-negative bacteria Signup and view all the answers

What key aspect of the red complex microorganisms challenges their role in periodontal disease?

They can exist in healthy periodontal sites. Signup and view all the answers

What is one of the roles of adherence factors in bacteria?

They bind to fibroblasts. Signup and view all the answers

The concept of specific types of bacteria causing periodontal destruction is considered to be what?

Less certain based on newer research. Signup and view all the answers

Which bacterium is associated with aggressive periodontitis?

Aggregatibacter actinomycetemcomitans Signup and view all the answers

What type of bacteria is Aggregatibacter actinomycetemcomitans?

Gram-negative coccoid bacillus Signup and view all the answers

What is one effect of leukotoxin produced by Aggregatibacter actinomycetemcomitans?

It kills white blood cells. Signup and view all the answers

Which hypothesis does not belong to the contemporary theories of bacterial role in periodontal disease?

Specific Plaque Hypothesis Signup and view all the answers

What can delay wound healing according to the content?

Inhibition of PMN migration Signup and view all the answers

How do some bacteria disrupt host defenses?

By degrading cytokines Signup and view all the answers

In what way do T. denticola affect the immune system?

By inducing lysis of antibodies Signup and view all the answers

What is NOT a characteristic of Aggregatibacter actinomycetemcomitans?

It is motile. Signup and view all the answers

What can happen if chemical mediators are absent in the immune system?

The immune response may become compromised. Signup and view all the answers

Study Notes

Bacteria Virulence Factors

Bacteria can digest tissue proteins for nutrient and to destroy host defences.
Endotoxins (LPS) produced by Gram-negative organisms can damage the host.
Haemagglutination: Clumping of red blood cells (RBC) can release haem as nutrients.
Fimbrae: These virulence factors can aid bacterial binding to epithelium and tissue invasion.

Porphyromonas gingivalis

Gram-negative bacillus, anaerobic, non-saccharolytic, non-motile
Carbohydrate capsule helps resist host defences
Produces gingipains: Enable bacteria to use gingival crevicular fluid (GCF) as a nutrient source
Lipopolysaccharide (LPS) helps to break down tissue
Haemagglutins and platelet aggregators may contribute to heart disease
Fimbrae aids with adhesion to epithelium
Gingipains: a protease that enable pathogen to use gingival crevicular fluid as nutrient source and destroy antibodies.
Destroys complement factors
Destroys host cell inhibitors to break down tissues
Inflammation can cause more immune response and inflammatory factors of bone and soft tissue

Host-Bacteria Balance in Periodontal Disease

There is a dynamic equilibrium between dental plaque and host defences in health.
This equilibrium is disrupted in periodontitis.
A balance exists between bacterial virulence and host response and little damage occurs if the balance is maintained.
An increase in pathogenicity or decrease in host response can tip the balance, causing tissue damage.

Reasons for Loss of Balance & Tissue Damage

Increased plaque
Increase in virulence factors of the microorganisms in the biofilm
Compromised host defence (e.g., immunocompromised patients)

Periodontal Pathogens and their Virulence Factors

About 12-15 types of bacteria are particularly likely to cause periodontal breakdown.
These bacteria use GCF components for energy and multiplication.
Adherence factors can bind to fibroblasts.
They are motile and can invade tissue.
They disrupt host defences by inducing and degrading cytokines.
They can delay wound healing by inhibiting migration of polymorphonuclear leukocytes (PMNs)

Treponema denticola Virulence Factors

Produces enzymes that use lysis to destroy antibodies and complement factors.

Aggregatibacter actinomycetemcomitans

Associated with aggressive periodontitis and periodontitis refractory to treatment.
Gram-negative coccoid bacillus (short rod)
Not motile or anaerobic.
Virulence factors include leukotoxin that kills white blood cells (WBCs), disrupting host defences.
Toxins destroy fibroblasts and epithelial cells.
Produces proteases, including collagenase.
Can invade host epithelial cells.

Theories on the Role of Bacteria in Periodontal Disease

The role of bacteria in periodontal disease is complex and has evolved over time.

Theories

Non-specific Plaque Hypothesis: This is a historical hypothesis that suggests all plaque is harmful.
Specific Plaque Hypothesis: This hypothesis suggests specific bacteria are responsible for periodontal disease.
Ecological Plaque Hypothesis: This hypothesis suggests that changes in the subgingival environment favour the growth of pathogenic bacteria.
Microbial Homeostasis- Host Response Hypothesis: This hypothesis suggests that pathogenic biofilm communities trigger an uncontrolled host response, leading to tissue damage.
Keystone Pathogen- Host Response Hypothesis: This hypothesis suggests that certain keystone pathogens can disrupt the microbial community and trigger a host response leading to disease.

Socransky’s Microbial Complexes

Socransky grouped microbes into color-coded complexes based on their pathogenicity.
- Orange/red: Major causative agents of periodontal disease
- Yellow/green/blue/purple: Compatible with gingival health

Issues with the Specific Plaque Hypothesis

Recent research has challenged the specific plaque hypothesis, suggesting that the red complex microorganisms can exist in healthy periodontal sites.
There is a more diverse oral microbiome than originally thought with 700+ bacteria.
Gram-positive bacteria are found in larger amounts in periodontal pockets.

Ecological Plaque Hypothesis (Contemporary Theory)

Changes in the subgingival environment can favor the growth of pathogenic bacteria.
These changes can include:
- Increased GCF flow
- Increased bleeding
- Raised pH
- Decreased oxygen concentration
This shift in local environment drives changes in microbial types, potentially leading to periodontal destruction.

Support for the Ecological Plaque Hypothesis

Deeper pocket sites and bleeding on probing sites have increased GCF.
GCF changes the microbial ecology, enabling growth of pathogenic bacteria.
Changes in environmental factors (GCF, pH, temperature, oxygen) drive dysbiosis in the gingival sulcus.
Subgingival debridement can reduce the number of pathogens, reduce gingival inflammation, and decrease GCF, halting the nutrient source for bacterial growth

Microbial Homeostasis- Host Response Hypothesis (Contemporary Theory)

This hypothesis proposes that a pathogenic biofilm community triggers an uncontrolled host response, resulting in tissue damage.
Genetic variations, inflammatory immune response, and environmental factors influence the start and progression of periodontal disease.

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Description

This quiz covers the key virulence factors of bacteria, focusing on their mechanisms of tissue invasion and host damage. It specifically highlights the role of Porphyromonas gingivalis and its adaptations, such as fimbrae and gingipains. Test your knowledge on how these factors contribute to bacterial pathogenesis and their implications for health.