Oral Path 1

Front 1

1.       What three bacteria are most often associated with subgingival plaque in healthy individuals and people with periodontal disease?

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A. actinomycetemcomitans

Front 2

2.       What are aerobes?

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B. forsythus

Front 3

3.       Where do anaerobes grow best?

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P. gingivalis

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4.       What are facultative aerobes or facultative anaerobes?

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Organisms that require molecular oxygen to grow.

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5.       Where do microaerophiles grow best?

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In the absence of molecular oxygen.

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6.       Where is the best place to store a microaerophile for it to grow?

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Organisms that can grow in either the presence of oxygen or the absence of oxygen.

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7.       What are aerotolerant organisms?

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They grow best in areas with reduced concentrations of molecular oxygen.

Front 8

8.       Do obligate anaerobes undergo oxidative phosphorylation?

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In a jar with a candle in it. This will allow for growth with increased CO2 levels (reduced O2).

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Bacteria that tolerate oxygen for only short periods of time.

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9.       What methods of metabolism do obligate anaerobes posses if they don’t undergo oxidative phosphorylation?

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No, they do not undergo oxidative phosphorylation.

Front 11

10.   Obligate anaerobe can be killed by what?

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Obligate anaerobes undergo fermentation.

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11.   What distinguishes obligate anaerobes from strict anaerobes?

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Oxygen, they do not live in oxygenated environments.

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12.   What are the three certain enzymes that obligate anaerobes are lacking?

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Obligate anaerobes lack three certain enzymes.

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13.   Why is oxygen directly toxic to obligate anaerobes?

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Superoxide dismutase

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14.   Why is oxygen indirectly toxic to obligate anaerobes?

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O2-+2H+ àH2O2

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15.   What do anaerobes require with respect to oxygen levels?

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Catalase

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16.   Where do you find areas with low redox potentials suited for anaerobic growth?

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H2O2 à H2O + O2

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17.   What is a redox potential (Eh)?

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Peroxidase

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18.   What does a positive reduction potential mean?

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H2O2 à H2O/NAD to NADH

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19.   What does a negative reduction potential mean?

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O2 has a direct toxic effect by oxidation of proteins.

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20.   In anaerobic conditions, how are electrons and protons transferred?

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O2 is indirectly toxic by specific mediators such as H2O2 or by free radicals.

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21.   Does oxygen have a high affinity for electrons or a low affinity for electrons?

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Anaerobes require a low redox potential (Eh =-150 to -250mV), a potential that is not possible in the presence of normal O2 levels.

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22.   When you increase the oxygen concentration in a growth media how is the redox potential affected?

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These conditions are present in septic tanks, the human colon, the gingivo-dental sulcus, and garbage dumps.

Front 24

23.   What is the redox potential in normal healthy tissues?

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Eh – the tendency of a system to accept (+ Eh) or donate electrons (- Eh).

Front 25

24.   How do redox potentials vary with plaque development over 7 days?

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It means that the oxidized form of a substance has a higher affinity for electrons than H2 does; eg oxygen.

Front 26

25.   What are three conditions that may lead to low redox potentials?

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It means that the oxidized form of a substance has a lower affinity for electrons than H2 does; eg NADH.

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26.   What conditions do anaerobic bacteria thrive in?

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They are transferred in reducing reaction that have negative redox potentials:

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27.   Are anaerobic bacteria fastidious?

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Pyruvate + 2e- + 2H+ ↔ lactate (-185mV)

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28.   How do anaerobic bacteria get their energy?

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Oxygen is a powerful electron acceptor (+816mV) and will disrupt hydrogen and electron flow in anaerobic systems.

Front 30

29.   What is characteristic of energy metabolism of anaerobic bacteria?

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Increasing the oxygen concentration increases the redox potential and prevents the growth of anaerobes.

Front 31

30.   How many organisms are found in the human GI tract? How many different species?

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Eh = ~ +150mV. When the Eh falls below this value or becomes more negative certain anaerobes can grow.

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31.   What percentages of the cells in our body are non-human?

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Redox potential falls during plaque development from an initial Eh of >200mV (highly oxidized) to -141mV (highly reduced) after 7 days.

Front 33

32.   What is the main type of bacteria living in the GI tract?

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1. Loss of vascular supply to tissue by trauma, foreign bodies or pressure from casts.

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33.   Where are the majority of these anaerobic bacteria found in the GI tract?

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2. Acid production by aerobes or facultative anaerobes.

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34.   What is the importance of anaerobes living in the human ecosystem?

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3. Tissue necrosis from trauma, infection, or surgical manipulation.

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35.   What are the three virulence factors of non-spore-forming anaerobic bacteria?

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Anaerobic bacteria require an atmosphere enriched in CO2 (~5-10%).

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36.   Deficiencies in individual strains can be supplemented for by other bacteria. What mechanism will allow for this?

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Yes, they are generally very fastidious and require growth factors.

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37.   What are the eight non-spore-forming anaerobic bacteria that are Gram Negative Rods?

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They produce their energy by fermentation, 2-4 molecules of ATP/glucose.

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The end products of energy metabolism are often unique to the genus or even species.

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“Cap’n Fuso previously aggregated @ camp Porphyromonas to tan his bacter.”

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Human GI tract contains>1014 individual microorganisms or ~36,000 species.

Front 41

38.   What are the six non-spore-forming anaerobic bacteria that are Gram Positive Rods?

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>90% are non-human

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39.   What is the one non-spore-forming anaerobic bacterium that is a Gram Negative Cocci?

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Anaerobic bacteria

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40.   What are the two non-spore-forming anaerobic bacteria that are Gram Positive Cocci?

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In the large intestine.

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41.   What are the five non-spore-forming anaerobes other than periodontal pathogens?

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- They are in competition with pathogens.

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42.   Are Bacteriodes fragilis and thetaiomicron Gram positive or Gram negative? Are they rods or cocci, anaerobic or aerobic?

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- Energy salvage by fermenting plant polysaccharides, resistant starches etc. Establish 5-30% of host’s daily energy requirement provided.

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43.   Where can you most frequently isolate these organisms? B. fragilis and thetaiomicron

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- Bacterial metabolism provides essential vitamins and cofactors, eg biotin, folate, vitamin K

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44.   Where do these organisms normally colonize?

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1. Provide for invasion of host tissue

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45.   What is an important characteristic of B. thetaiomicron?

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2. Resistance to host defense mechanisms

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46.   Where else can you find Bacteroides?

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3. Growth and injury of host tissue

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47.   What are the five virulence factors for Bacteroides fragilis?

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- Mixed infections of anaerobes +/- facultative anaerobes is common.

Front 51

48.   What is the most important strict anaerobic non-spore-forming bacterium causing clinical disease?

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- This is synergy or a synergistic infection.

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49.   Bacteroides fragilis is the major cause of infections where?

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- Capnocytophaga sp.

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50.   What other infections does B. fragilis cause?

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- Fusobacterium nucleatum, sulci, necrophorum, mortiferum

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51.   How does Propionibacterium acnes Gram stain? What is its morphology?

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- Prevotella melaninogenica, intermedia, oralis

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52.   Where does P. acnes normally infect?

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- Aggregatibacter (prev. Actinobacillus) actinomycetemcomitans

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53.   Where else might you find P. acnes?

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- Campylobacter (prev. Wolinella) rectus, curvus

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54.   What does Propionibacterium acnes is able to generate what?

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- Porphyromonas gingivalis, asaccharolytica

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55.   How does Mobiluncus Gram stain/morphology?

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- Tannerella forsythia (prev. Bacteroides forsythus)

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56.   Is Mobiluncus motile?

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- Bacteroides fragilis, thetaiomicron, vulgatus, ovatus

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57.   What is Mobiluncus strongly associated with?

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- Actinomyces israelii, naeslundii, viscosus

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58.   Where is Bifidobacterium normal flora?

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- Eubacterium lentum, nodatum

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59.   Bifidobacterium has been linked with evidence to what?

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- Propionibacterium acnes

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60.   Bifidobacterium may constitute >90% of the total intestinal flora in who?

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- Mobiluncus mulieris, curtisii

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61.   Lactobacillus is what kind of organism?

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- Lactobacillus sp.

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62.   Where is Lactobacillus normal flora of?

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- Bifidobacterium

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63.   Give an example of the several vaginal species that produce hydrogen peroxide.

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- Veillonella parvula

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64.   What are the four plaque-induced gingival diseases?

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- Peptostrepococcus

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65.   What are the seven non-plaque induced gingival lesions?

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- Streptococcus morbillorum

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- Bacteroides fragilis

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- Propionibacterium acnes

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- Mobiluncus

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- Bifidobacterium

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- Lactobacillus

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Gram negative, pleiomorphic anaerobic rods.

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Isolated in infections below the diaphragm.

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The colon and the vagina.

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It is the most abundant organism in the ADULT gut.

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In the oral cavity.

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- capsule: anti-phagocytic, involved in abscess formation

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- collagenase, IgA protease

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- endotoxin: differs in composition from typical endotoxin and is of low toxicity: lacks Lipid A

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- organisms are bile resistant and are stimulated by bile

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- 85% produce a potent β-lactamase

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Bacteroides fragilis

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Major cause of infections in the abdominal cavity, such as peritonitis, and liver abscesses.

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- Brain abscess

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- Gynecologic

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- Skin, soft tissue infections

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- Bacteremia

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Gram positive, rods

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Normal inhabitants of the skin, and GI tract.

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Root surface caries, and dental plaque.

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Propionic acid

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Gram positive, curved rod

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Yes

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Bacterial vaginosis

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Mouth, GU and GI tract

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Evidence for involvement in progression of deep childhood caries.

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In breast-fed infants.

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Caries organism

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Mouth, GI tract and often predominant flora of the vagina.

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Lactobacillus acidophilus

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- Plaque-induced gingivitis

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- Gingival diseases modified by systemic factors (eg. Pregnancy, diabetes, leukemia)

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- Gingival diseases modified by medications

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- Gingival diseases modified by nutrition (eg. scurvy)

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- Specific bacterial infection (eg. N. gonorrhea)

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- Specific viral infections (eg. HSV)

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- Specific fungal infections (eg. LGE)

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- Genetic origin (eg. pemphigoid)

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- Manifestations of systemic conditions (eg. allergy, mucocutaneous diseases)

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- Traumatic lesions

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- Foreign body reactions, other…