BDS 3 Sem 1 > Zilm > Flashcards

Zilm Flashcards

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1
Q

What is the most common bacteria in the healthy periodontium?

A

Low numbers of gram positive bacteria predominate in healthy gingival and periodontal tissue. E.g. Streptococcus bacterial family whichoccur in 100% of isolation speciments.

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2
Q

What is co-aggregation?

A

It is a process by which bacteria bind together. Some bacteria may have adhesins on their cell wall that are able to bind to the receptors on the cell wall of other bacteria.

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3
Q

What are the pioneers of the dental plaque?

A

Streptococcus family

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4
Q

What happens to the number of bacteria in gingivitis?

A

The number of bacteria and diversity of bacteria increases in plaque induced gingivitis. This is associated with hightened immune response.

GCF has nutrients that increase the number of bacteria.

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5
Q

What bacterial shift is associated with periodontitis?

A

The bacterial shift that associated with periodontitis is a shift from facultative gram positive bacteria to anaerobic gram negative bacteria. It is important to state that this shift is seen in cultivable gingival micro-flora meaning this statistic is only understood in lab grown bacteria.

The level of cultivated bacteria also explain why gingivitis is considered a transitional stages, because in gingivits it can be seen that the bacterial makeup is relatively equal.

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6
Q

Why finding the aetiology of periodontal disease and contribution of bacteria so hard to establsh?

A
  1. Lack of understanding of progression
  2. Difficulaties in sampling
  3. Many of the pathogens are also belived to be par of normal microbiota
  4. Complex interactions of pathogen and host are involved
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7
Q

What are the common bacteria that are associated with chronic periodontists?

A
  1. P. Gingivalis
  2. T. denticola
  3. T. Farsythia
  4. A. Actinomycetemcomitans

And more but 75% of them are gram negative and nearly all are strict anaerobes

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8
Q

What can you say about the metabolism of bacteria associated with chronic periodontitis?

A

They are predominantly asaccharolytic and anerobic thus meaning they use amino-acids for metabolism thus propagate during the breakdown of proteins.

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9
Q

Why is the orange group bacteria so essential for the dominance of the red group bacteria?

A

Because orange group bacteria consume oxygen thus are able to reduce the amount of available oxygen thus increasing the number of anaerobic organisms.

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10
Q

Why does the pH of the sulcus increases with the introduction of more anerobic species?

A

This occurs due to decrease in oxygen and redox potential thus increasing the number of available hydrogen ions thus decreasing the pH of the environment.

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11
Q

What are the virulence factors that are asosciated with aeitology of perdiodontitis?

A
  1. Attachemnt - cell surface through adhesins
  2. Multiplication - enzymes to obtain nutrients through tissue damage of the host tissue
  3. Evasion of defense - capsule production, leukotoxin production and other
  4. Tissue damage - direct - through collagenese, hyaluronidase, bone resorbing factors, cytotoxins and more
  5. Tissue damage - indirect - through hightening of the inflammatory response
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12
Q

Where would you find adhesins?

A
  1. Root surface
  2. Gingival epithelial cells
  3. Co-aggregation with other microbes
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13
Q

What are multiplication mechanism used by periodontal bacteria?

A
  1. Range of proteases for break down of protein matrix for nutrients
  2. Glycosidases - break down of glycoproteins for carbohydrates

These enzyme activities are considered to be complimentary because many bacteria collaborate to provide their own enzymes to benefit different bacteria that may benefit from tissue breakdown.

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14
Q

What are some of the evasion mechanisms used by periodontal bacteria?

A
  1. Production of serotype B - cause lyse of neutrophols, monocytes and lymphocytes
  2. Production of molecules that interfere with polymorph function like chemotaxis and phagocytosis
  3. Proteases degrade components of immune system
  4. Capsule production for immune system evsion
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15
Q

What are the mechanism of direct tissue damage used by periodontal bacteria?

A

Use of multiple proteases that are able to degrade fibrinogen, collagen, transferrin, IgG, IgA as well as host protease inhibitors.

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16
Q

What are some of the treatments of periodontal disease?

A
  1. Plaque control
  2. Professional debridement
  3. Potentially antibiotic therapy
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17
Q

What is apical periodotitis & endodontitis?

A

It is an inflammatory process in the peri-radicular tissues, primarily caused by a polymicrobial infection within the root canal system.

It could be symptomatic or asymptomatic.

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18
Q

What is endodontic therapy?

A

It a process of elimination of the causative agents, thereby providing an environment (sterile) conducive to healing.

Basically - remove as much bacteria from he root canal system as possible.

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19
Q

What bacteria is associated with endodontic bacteria?

A

Mainly anaerobic bacteria - becauses of low oxygen availability within the pulpal tissue (autogenic succession - driven by bacterial consumption of oxygen) - anaerobic bacteria are very destructive due to their fastidious nutritional requirements

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20
Q

What are some of the routes of entry of bacteria into the pulp?

A
  1. Caries
  2. Mechanical exposure
  3. Trauma
  4. Anachoresis - bacteremia
  5. Periodontal pockets - when pockets reach root apex
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21
Q

What factors influence bacterial composition in the pulpal infection?

A
  1. Redox potential decreases over time
  2. Nutrient supply and composition
  3. Host immuno-competence
  4. Bacterial inter-relationship - polymicrobial infections require many bacteria
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22
Q

What is antagonistic microbial interaction?

A

It is a net negative interaction - competition for nutrients, production of toxic metabolites and other

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23
Q

What is synergistic microbial interaction?

A

It is a net positive interaction - consumption of O2, production of nutrients for other bacteria

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24
Q

What are some of the locations found in tooth non hard tissue?

A
  1. Root canals
  2. Lateral/ accessory canals
  3. Dentine tubules
  4. Extra-radicular tissues
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25
What are the three steps to endodontic treatment?
1. Instrumentation - physical bacterial reduction of the infected root canal system with irrigation and medication - major challenge: anatomical complexities of the root canal system 2. Irrigation - using a root canal irrigant that has an anti-microbial properties - sodium hypochlorite (hypochlore) could be used - make sure not toxic to the host - major challenge: infiltration into dentinal tubules problematic 3. Medicaments - high pH medicine with strong antimicrobial action - like calcium hydroxide (pH12.5)
26
WHat are some of the causes of endodontic failure?
1. Inadequate treatment or re-infection of the root canal 2. Possible resistance species - enterococcus faecalis - highly resistance to environmental stresses especially pH - may be food-borne 3. Extra-reticular tissues
27
What is the target of chemotherapy?
Nucleotide synthesis - which occurs during nucleic acid synthesis - when it is effected, no DNA can be produce thus a cell can not replicate, thus cancer is stopped in its rapid division
28
What is the structure of nucleotides?
They have a nitrogenous base (AGCT and U in RNA), pentose sugar and a phosphate
29
What does cancer therapy tries to target?
It is made to target the DNA synthesis of a cell and not the RNA through targeting thymine (dTTP nucleotide - highly involved in DNA synthesis) thus you are able to target rapidly dividing cells that require TTP for quick replication. When dTTP is targeted with inhibitors - cancer cells may be combated
30
What are the two pathways of nucleotide collection?
1. De novo pathways - contsruction of new nucleotides 2. Salvage pathway - recycling pathway from dead cells
31
Which enzyme does chemotherapy target?
Thymidylate synthase
32
What are some of the side effects of chemotherapy on other cells of the body?
Due to targeting of dTTP - it is possible that chemotherapy causes damage to some normal but fast replicating cells in the body like immune cells
33
What are the two classes of chemotherapy drugs?
1. Pyrimidine analogs - destroy thymidylate synthase - adrucil is an example - reduction in conversion of dUMP into dTMP 2. Folate analogs - interfere with formation of the methyl group - methotrexate is an example - conversion of serine to glycine
34
How do chemotherapy drugs work?
They are irreversible enzyme inhibitors and cause enzyme inactivation or destruction
35
What is the morphology of streptococci?
Gram-positive, non-motile, non-spore forming. They devide in one plane - in pairs or in chains. They are facultative anerobe, they rely on glycolisis - produce lactic acid - associated with caries
36
What is the classification of streptococci?
1. Alpha - patial lysis of red blood cells 2. Beta - complete lysis or red blood cells 3. Gamma - no haemolysis
37
What is consider the most common group of streptococci that cause human disease?
A groups streptococci (GAS) like S.Pyogenes - causes theumatic fever, pharyngitis, peritonsilar abscess, scarlet fever and more.
38
What is the purpose of the capsule on GAS?
The hyaluronic acid capsule is associated with pathogenecity - reduces the rate of phagocytotis due to molecular mimicry
39
What is an M-protein?
It is common mammalian proteins, act an an antigen, that is usually targeted by anti-bodies due to molecular mimicry to M-protein produces by bacteria - thus unlocking more nutrients
40
What is the alternative to M-protein in high oxygen environment for bacteria?
F -protein - found a lot in the respiratory epithelial cells of the lungs
41
What are superantigens? What superantigen does GAS produce?
Superantigens have the ability to polyclonally activate large fraction of T-cells. They induce a huge immune response. For GAS it is Streptococcal pyrogenic exotoxins and streptococcal M proteins
42
What is necrotizing fasciitis?
It is an aggresive infection by GAS that can cause multi-oran failure. It is associated with the super antigens SPE A. The GAS isolated had a huge hyluronic capsule.
43
What is the treatment of streptococcal infections?
Beta-lactam susceptible - thus use penicillin or other forms - clindamycin is also pretty effective
44
What is Staphylococci?
They are gram positive bacteria which appears as bunches of grapes because of the 2D plain divisions. Common staphylococci are S. aureus (golden staph) and S.epidermidis. Not considered to be commensal bacteria.
45
What type of infections can be cause by S. aureus?
1. Skin infections 2. Food poisoning 3. Toxic shock syndrome - associated with biofilm formation Mostly infections are associated with hospitlaisation
46
What is the danger of Staphylococci and diabetics?
Staphylococci have a unique ability to invade bone tissue thus are able to destroy said tissue - diabetics are more susceptible due to lover immune function and tissue regeneration - oral implications: perimplantitis
47
How do we differentiate between S.Aureus and S.Epidermidis (associated with hospitals)?
Coagulase test - extra-cellular protein that binds to prothrombin - coagulation only occurs with S.aureus
48
What is the most common site of Steph infection and what is the normal presentation?
Skin is generally the most common site of infection. It result in a localised abcess - fibrin clot is formed that isolates the bacteria. If the fibrin clot breaks down - organism may spread to other parts of the body
49
What are the most sever cases of Staphylococcal infection?
1. Staphylococcal Food poisoning - ingestion of enterotoxins already formed by food contaminated by S.Aureus due to inadequate food storage 2. Toxic shock syndrome - associated with use of highly absorbent menstrual tampons that promote growth of bacterial biofilm - TSST-1 antigen Both of these are superantigents
50
What are the common infections caused by S.aureus?
1. Osteomyelitis - bone infections! 2. Sialadentitis - inflammation of the salivary gland 3. Root-canal infection 4. Angular stomatitis - may extend to the oral mucosa
51
What are the mechanisms of the virulence factors of S.Aureus?
1. Capsule made of polysaccharides 2. Coagulase - local coagulation 3. Adhesins
52
What type of toxins are produces by S.Aureus?
1. Aplha toxin 2.Beta toxin 3. Leukocidin - kills leukocytes - asosciated with skin infections
53
How do we treat an S.Aureus infections?
Antiobitcs but S.Aureus is very very drug resistant - thus it is important to reduce it's buildup on surfaces
54
What is another way to classify straptococci?
Lacncefield groups: based on the antigenic composition of the cell wall of CHO
55
What is the function of streptokinase?
Able to break down blood clots in order topenetrate the host physical barrier - also used in medical purposes to break down systemic blood clots
56
What is the significance of hydrogen peroxide in dental setting and how it related to Staphylococci?
In some instances, hydrogen peroxide may be mixed in with the dental hand piece lines in order to reduce the amount of bacteria that might reside in those lines. Sthaphylococci may produce an enzyme calatase which neutralise hydrogen peroxide
57
Where is TB through to be originated?
Associated with M. Bovis infection from cow milk
58
What are some of the outcomes of a TB organisms infection?
1. Primary infection - similar to other infection 2. Controlled infection - only will be activated when defences are weakened - could go for decade
59
What is mycobacterium tuberculosis?
It is a large, non-motile rod-shaped bacterium that is hydrophobic due to it's high lipid content in the cell wall. It is an obligate aerobe - this explain the preference for the lungs. It is faculative intracellular parasite that usually grows in mononuclear phagocytes (e.g macrophages). You can confirm a colony visually in 4-6 weeks in testing plate - so it is a problems for infectious disease labs
60
What stain can we use to stain M.Tuberculosis?
Acid-fast stain can be used - the TB will be seen in red
61
What are some of the predisposing factors for M.Tuberculosis?
1. Close contact with large populations of people - due to lipid nature, can stay without drying for a long time 2. Poor nutrition 3. IV drug use 4. Alcoholism 5. HIV infection is the #1 predisposing factor for M.Tuberculosis infection
62
What is a unique virulence factor for M.Tuberculosis? And what are some other virulence factors possesed by M.Tuberculosis?
It is the complex lipid cell wall structure made of mostly of mycolic acid which make it very protective from immune factors. Other factors include slow generation time and the ability to grow intracellularly.
63
What is the understanding of primary and secondary TB?
1. Primary - acute infection occurs in 5% 2. Secondary - latent infection
64
What is the difference between TB infection and TB disease in lungs?
TB disease: 1. X-ray usually reveals a cavity 2. Suptum smear and cultures positive 3. Symptoms such as cough, fever,w eight loss 4. Often infectious before treatment TB infection will not have any of those but the TB skin test is positive just like in disease
65
What are the stages of TB disease progression
1. Droplet nuclei are inhaled - could we from talking, sneezing and coughing. Organism reach the alveoli. Alveolar macrophages are infected by the bacteria 2. 7-21 day after infection, M.Tuberculosis multiplies in the macrophages 3. Lymphocytes begin infiltrate - surround the infected macrophages - create granulomas - centre of the granulation cbreaks down through caseation necrosis 4, Individuals become tuberculin positive 5. M.Tuberculosis may spread in other system due to reduced immune function 6. Disease development - Simon foci of other organs (more granulomas) - usually caused by the tubercle liquifying
66
What are some of the symptoms of TB? HWat are some of the test can help detect TB?
Symptoms: Fever, night-time sweating, weight loss, persistent cough, constant tiredness and loss of apetite Testing BATEc System - lipid test - 6-9 days turn around AMPLIFIED MTW TEst - turn around 2.5 hours Montoux test - purified protein derivative of TB - uses immune response to antigen - shows infection with TB takes 48-72 hours
67
What is the treatment for TB?
1. Multiple drugs regiment - 4-9 months with 4 different antimicrobial agents - usually very effective above 90% chance of surviving 2. Directly observed therapy
68
What are some of the prevention for TB?
BCG vaccinations against TB - but studies show 60-80% effective in children and may complicate the result of the tuberculin test.
69
Which medical conditions increase the risk of progression of TB to active disease?
All diseases that reduce immune function
70
What is directly observed therapy?
It is when a health personnel observe the taking of multi-drug therapy at a specialist clinic
71
What is a treatment for Multi Drug Resistant Tuberculosis?
Requires chemotherapy and longer treatment duration - DOTS-Plus protocol - drugs are more toxic and expensive - susceptibility testing may be administered
72
What are some of the infection control measures for TB prevention?
First level - education, training and screening of healthcare workers Second level - reduction of droplet nuclei concentration through use of air exhaust ventilation, air cleaning via air filtration Third level - use of personal respiratory protective equipment
73
What are the Koch's Postulates?
1) The microorganism must be found in diseased but not healthy individuals; 2) The microorganism must be cultured from the diseased individual; 3) Inoculation of a healthy individual with the cultured microorganism must recapitulated the disease; 4) The microorganism must be re-isolated from the inoculated, diseased individual and matched to the original microorganism.
74
Why do microorganism preffer to reside in the biofilm?
1. 3D structure of the extra-cellular matrix provide a site for adhesion 2. Provides water and nutrient channels 3. Provides protection from desication 4. Provides protection from host defences - think B-Lactam aggregation
75
What is the most common bacteria associated with fissure caries?
S. Mutants
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