Oral Microbiology Flashcards
3 features/capacities of Pathogens:
Host colonization
Overcome host immunity
Replicate within the host
Name 5 virulence factors
Adherence Toxins Inflammatory mediators Anti-host enzymes Bacterial capsules
What are the two types of cells
Prokaryotic
(includes archea)
Eukaryotic
What is a major virulence factor in Gram negative bacteria?
LPS
*lipopolysaccharide
T/F
Bacteria contain no membrane-bound organelles
True
How is bacterial genetic material packaged?
circular dsDNA
*one molecule
Bacterial Ribosomes ______
Eukaryotic Ribosomes ______
70s
80s
What do bacteria use for attachment and conjugation?
Fimbrae
What is made of carbohydrate polymers and a major virulence factor for bacteria?
Capsule
Why must bacteria secrete many digestive enzymes?
Only small molecular weight molecules can pass through cell wall and membrane
The ecological biosystem of bacteria are referred to as…
Biofilms
T/F
There is often a battle over Fe resources between host and bacteria
True
Describe the outer layers of a Gram Positive bacteria?
Thick wall
Single inner plasma membrane
*often 50% wall by weight
Describe the outer layers of a Gram Negative bacteria.
Outer membrane (LPS)
Thin cell wall
Cell (inner) membrane
Gram+ bacteria have ___ layers
Gram- bacteria have ____ layers
2
3
What often slimy secretion do some bacteria surround themselves with that has strong anti-phagocytic properties?
Capsule
What is the essential, all enclosing, rigid, porous, protective girdle that surrounds the bacterial cell?
What is its primary function?
Cell Wall
Protect from surrounding Osmotic Pressure
What 2 acetylated amine groups make up the glucose dimers that make the polysaccharide of cell wall?
NAG - N-acetylglucosamine
NAM - N-acetylmuramic acid
After the export of 20-ish NAG-NAM from the bacterial cell to the cell wall, what cross links the peptides and affixes the new unit to the cell wall?
Transpeptidases
What constantly synthesizes and degrades the peptidoglycan making up cell wall?
Autolysins
The toxic LPS found on the outer leaflet of the outer membrane of Gram- bacteria is…
Endotoxin
A Gram- can’t hold its alcohol:
Crystal violet washes off by alcohol/acetone and accounts for lighter stain
The pattern recognition receptor that binds to LPS is…
TLR-4
TNF-alpha is a…
Cytokine
Large amounts of LPS that activate the clotting system is know as what?
Disseminated intravascular coagulation
What are 2 important pro-inflammatory mediators produced by Macrophage in response to LPS?
PGE-2
(osteoclast activator)
TNF-alpha
(signals NO production, causing pre-capillary sphincters to relax)
If TNF-alpha causes too much of an NO reaction, what could happen?
Blood pressure falls leading to
Hypovolemic Shock (aka septic shock)
What enzyme breaks down starch and glycogen?
Amylase
What enzyme breaks down peptidoglycan NAG-NAM molecules?
Lysozyme
T/F
ECF matrix often has glucose polymers that make them up
True
Bacteria capable or respiration have what?
Heme proteins
*no heme proteins = no respiration
Bacteria that must have oxygen:
Bacteria that can respire if Oxygen present, use fermentation if Oxygen absent:
Not killed by Oxygen but only ferment:
Like small amounts of oxygen
Always killed by Oxygen
Obligate aerobes
Facultative
Aerotolerant
Microaerophilic
Anaerobes
What process gains energy by partially breaking down substrate to other organic molecules like lactic acid or alcohol?
Fermentation
What 2 enzymes are of utmost importance when dealing with toxic oxygen radicals?
Superoxide dismutase
Catalase
Superoxide dismutase:
Catalase:
radical to hydrogen peroxide
hydrogen peroxide to water and oxygen
Both Superoxide dismutase and Catalase are found in what type of bacteria?
Aerobes and Facultative aerobes
T/F
Strict aerobes have neither Superoxide Dismutase or Catalase.
True
T/F
Supragingival plaque is mostly made up of microaerophilic and facultative bacteria, while sub-gingival plaque is primarily facultative and anaerobic
True
What inserts into bacterial DNA, can exit, and often carries resistance or toxic coding sequences?
Plasmids
What system acts in a fast, non-specific way that does not require specific recognition of a pathogen?
Innate
T/F
Innate immunity includes inflammation
True
*however, inflammation interacts with mechanisms of adaptive
What system of immunity is slow and specific and remembers?
What does it use?
Adaptive
Specific B and T lymphocytes
What kind of cells live below all our epithelial barriers and recognize insults?
What do they release?
Sentinal
*Mast cells or Basophils
Releases Histamine
The “stop signs” that tell neutrophils to exit circulation in an acute condition are known as…
Tells what to exit during chronic condition?
Cell adhesion molecules
(CAMS)
Lymphocytes and Macrophage
S. pneumoniae is Gram…
S. pneumonia can cross BBB and initiate an inflammatory response called…
Positive
Meningitis
What blocks phagocytosis by PMN’s and Macrophage and is a major virulence factor in S. pneumonia?
Capsule
*CHO
The capsule in S. pneumoniae induces what response from the immune systym?
Specifically?
Immunogenic
Opsonization with antibodies
What receptors on S. pneumoniae allow for opsonization?
Fc receptors
T/F
Cell surface receptors are utilized by cytokines (which are activated by T-cells)
Cytokines are required for a full and effective adaptive immune response
True
What causes the T and B cells to divide into clones?
Cytokines
*stimulated by T cells that received part of bacteria targeted from presenting cells
What causes a Cytokine Storm?
Super-antigen
What is the most biologically toxic bacterial product?
A-B toxin
What is the most common cold sore treatment?
Acyclovir
What increases the potency of vaccines?
Adjuvants
Hypersensitivity reactions 1-3 are…
Hypersensitivity 4 is…
Immunoglobulin mediated
T-cell mediated
T/F
Gingival, sulcular, and junctional epithelium are all rapidly dividing, shedding, physical barriers.
True
What defines gingival junctional epithelium?
4 things
Poor differentiation
not much keratin
not many hydrophobic, granular materials
loosely linked
How do Junctional epithelial cells activate T-helper cells?
with HLA class II
*present extracellular antigenic peptides
Junctional epithelial cells have numerous cytokines and chemokines. What one is found in large amounts?
Chemokine IL-8
Cytokines and chemokines are _____ for PMN’s
chemotactic
How is junctional epithelium different from sulcular/gingival?
Junctional epithelium allows for easy _____.
Non-shedding
Egress of PMN’s
What is the exception to epithelia of the mouth being tough, highly keratinized, and mostly impermeable?
What does this allow?
Junctional Epithelium
*epithelium that attaches to the tooth
PMN’s easy access to the mouth
Outside of the cervicular space, what is a major protective barrier?
Saliva
*sIgA
2/3 of the WBC’s are..
PMN
*neutrophils
Name two cell surface receptors PMN’s use to attach foreign microorganisms.
Fc
C3b
PMN’s either kill pathogens by ingesting them, or ____
drooling
*this leads to many side-effects of inflammation
Salivary glands are Ig__ dominant and inflamed gingiva (Crevicular fluid) is Ig__ dominant
IgA
IgG
What two sources of fluid bathe the oral cavity?
Crevicular fluid
Saliva
What are the 2 major defense features of Crevicular fluid?
IgG
PMN’s
What is a big anti-carie effect of saliva?
Buffers
Dimeric IgA cells from B cells are cleaved at what site?
When released to mucosa the complex at site is called?
Fc
Secretory component
What are 4 unique attributes of sIgA?
Sticks to mucins
Protease resistant
Neutralizes viruses/toxins
Blocks microbe colonization
Name 3 supragingival plaque film Gram+ bacteria associated with Caries.
Streptococcus
Lactobacillus
Actinomyces
Name 5 Gram- facultative and anaerobic rods bacteria associated with Periodontal Disease
Treponema Aggregatibacter Bacteroides Tannerella Porphyromonas/Prevotella
How many different species of bacteria call the mouth home?
800
What has been shown to inhabit some perio pockets?
Archea
Where do most bacteria live in the mouth
(what 2 places)?
Plaque
Tongue crypts
Supragingival plaque biofilm is primarily made of _______ and _______ bacteria.
Facultative
Microaerophilic
______ and ______ make up most of the subgingival plaque biofilm
Facultative
Anaerobic
T/F
Gingivitis usually has both G+ and G- associated with it.
True
Describe Streptococcus Viridans
7 features
Alpha Hemolytic Green on blood agar Facultative ECM producer saccharolytic Acidogenic
What are the 4 subgroups of Streptococcus Viridans?
Which are good/bad?
S. anginosus
S. mutans - the bad guys
S. mitis
S. salivarius
Name 2 species in the Streptococcus mutans subgroup
Mutans
Sobrinus
*these 2 species most often associated with dental plaque
What Strep. species is a major cause of caries?
Name 3 features of this species
Mutans
insoluble polysaccharides
prefers low pH
Lactic Acid producer
What S. Viridans subgroup is found in plaque, mucosa, and respiratory tract and is pus forming?
S. anginosus
What S. Viridans subgroup is the pioneer species, making insoluble and soluble polysaccharides, and associated with bacterial endocarditis?
S. mitis
Name 4 species in the S. mitis group
S. sanguinis
S. gornonii
S. oralis
S. mitis
What S. Viridans subgroup colonizes mucosa and not plaque?
is a good guy
S. salivarius
Name 2 species in the S. salivarius subgroup of S. Viridans.
S. salivarius
S. vestibularis
T/F
Peptostreptococcus is Anaerobic
True
What bacterial species is an opportunist that causes nosocomial problems and can survive harsh environments?
Enterococcus
What species of Enterococcus is commonly implicated in endodontic root canal failures and persistent infections
E. faecalis
Streptococcus are all Gram___ cocci arranged in ____
Positive
Chains
Subacute Bacterial Endocarditis is often caused by what?
also pneumonia and caries
Viridans Strep
What type of bacteria is associated with Root caries, ECM production, eats sugars, and tolerates a low pH?
Name a specific species
Actinomyces
A. israelii
What species of bacteria is correlated with a high-sugar cariogenic diet, dentin caries, and is the Advancing Front of caries lesions?
(also produces ECM, eats sugar, tolerates low pH)
Lactobacillus acidophilus
What 2 bacteria can metabolize lactate (and theoretically reduce caries)?
Neisseria
Veillonella
Name 4 Oral G+ rods.
Actinomyces
Lactobacillus
Neisseria
Veillonella
What G- rod is associated with aggressive Periodontitis in young adults?
What kind of toxin does it produce?
Aggregatibacter actinomycetemcomitans
Leukotoxin
What G- rod associated with Periodontitis has very long thin rod that other bacteria attach to?
Fusobacterium nucleatum
Name 4 black pigmenting species of G- rods that (might be) causative agents in Periodontal Disease
Bacteroides
Tanerella
Porphyromonas
Prevotella
What 3 species form the Red Complex associated with aggressive Perio infections?
T. forsythensis (Tannerella)
P. gingivalis (Porphyromonas)
T. denticola (Treponema)
Name an Asachrolytic G- rod.
Porphyromonas gingivalis
What species of Prevotella is associated with periodontitis?
What type (G)
*all Prevotella sacharolytic
P. intermedia
G-
What very anaerobic species is found in gingivitis and periodontitis?
Treponema denticola
2 shapes of viral capsid
Icosahedral
helical
What are the 2 ways a newly replicated virus leaves the cell
Budding (envelope with spikes)
Lysis
*enveloped vs. naked
5 cellular outcomes of viral infection
Abortive (no progeny) Lysis Chronic non-lytic Latent (integration) Transformation (cell proliferates uncontrollably)
4 binary viral classifications:
helical or icosahedral
enveloped or naked
DNA or RNA
ds or ss
The protein shell of a virus is called a…
Capsid
What 2 things must a virus do to replicate within the cell?
Replicate their genetic material
Produce +mRNA for protein components
What plant infecting nucleic acids lack capsids?
Viroids
Horizontal infection:
Vertical infection:
person to person
mother to fetus/neonate
No symptoms can lead to a large ______
Iceberg effect
Herpes viruses are enveloped/naked?
ds/ss?
DNA/RNA?
Enveloped
dsDNA (large - many targets)
Where do herpes viruses replicate and assemble?
nucleus
Herpes virus acquires their membrane before/after they reach the cytoplasmic membrane.
Before
***this is unique
Herpes initially infects the _______ and lasts _____
mucosal epithelium
lifetime
Example of an antiviral therapy for Herpes:
Acyclovir
T/F
Herpes is serious if fetus infected, mild if child, and moderate to serious in adults
True
HHV 1-4:
1: cold sores
2: genital
3: Varicella Zoster (chickenpox, shingles)
4: EBV
What HHV strains are latent in the neuron?
1-3
What HHV is an important congenital infection?
Cytomegalovirus
What Herpes virus is Kaposi’s sarcoma?
HHV-8
DNA viruses can cause…
Tumors
What HHV isn’t spread through mucosal contact?
Varicella zoster (3)
Viremic (first) infections can be dangerous to…
Fetus
What is the name for the manifestation of HSV-1?
Herpetic Stomatitis
What is the most common cause of viral encephalitis in the USA?
HSV-1
Describe Herpetic Stomatitis
small vesicles
clear liquid
rupture and leave small painful ulcer
What is the leading infectious cause of blindness in the USA?
HSV-1 keratitis
HIV transmission is increased 2-4 fold with the presence of what?
HSV-2
In the 1st 5 years of life HSV-1 primarily presents with a lip lesion, but is ____ asymptomatic
85%
Lesions of HSV-1 present in what 2 places?
area called what
gingivostomatitis
herpes labialis
What ganglia are typically infected in HSV-1?
HSV-2?
Trigeminal
Sacral
T/F
Primary HSV-1 and HSV-2 infections can pass to fetus
Secondary recurrences of HSV-2 can pass to fetus during delivery
True
The only HHV spread by respiratory droplets is
infects lung mucosal lining initially
Varicella Zoster
*zoster is the shingles bit
What are the 2 major diseases caused by EBV?
Infections mononucleosis
Burkitt’s B Cell Lymphoma
Burkitt’s lymphoma, aside from having an association with EBV, is associated with…
Malaria
Hairy Leukoplakia is caused by what virus?
*benign, which lesion, hyperkeratosis
EBV
2 cancers associated with EBV
Burkitt’s lymphoma
Nasopharyngeal Carcinoma
T-cell leukemia is associated with what virus?
HTLV-1
What percentage of young adults infected with EBV develop Mono?
20-50%
What is the number 1 cause of retardation?
Cytomegalovirus primary infection when pregnant
T/F
Acyclovir works on Cytomegalovirus
False
T/F
There is no vaccine for the multiple strains of Cytomegalovirus
True
Worldwide ____% seropositive for cytomegalovirus
US ____ %
100% ww
50% US
Of the 1% pregnant that develop primary Cyto infections, ___% develop neural sequelae in fetus
20%
CMV is the most common cause of intrauterine infections and congenital abnormalities in the US
True
Primary or reactivation of latent CMV is very serious in what population?
Immunosuppressed
Describe the Coxsackie virus
ssRNA
non-enveloped
picornaviridae
common and mild diseases in young
What is the non-specific flu-like illness caused by the Coxsackie virus?
Herpangina
What 2 diseases does the Coxsackie virus cause?
Herpangina
Hand, foot and mouth disease
*both mostly young children
What is the most communicable disease worldwide (no iceberg effect)?
Measles
Describe the measles virus (capsid, genome)
Enveloped
ssRNA
Describe the Mumps virus (capsid, genome)
Enveloped
ssRNA
The characteristic symptom for mumps is…
Inflammation associated with this does what?
Parotitis
blocks salivary fluids
HPV - describe (capsid, genome)
non-enveloped
dsDNA
*warts - hyperplastic epithelial lesions
HPV is associated with what type of cancer?
Cervical
What is the most common fungal infection relevant to dentistry?
Candida albicans
Candidiasis is an _________.
Opportunistic bloom
What is an organism that lives on dead/decaying matter?
Saprobe
What is different about a fungal cell membrane?
compared with human cell mem
Ergostal instead of cholesterol
What inhibits ergostol synthesis?
Azoles
What drug binds to and forms holes in ergostol-containing membranes?
polyenes
What makes up the cell wall of fungi?
cross-linked glucans
*Chitin
T/F
Compared to antibiotics, there are relatively few anti-fungals.
True
*Because non-toxic anti-eukaryotic drugs hard to find
2 basic morphologies of fungus:
Yeast
Hyphae/filamentous
The collective term for a mass of hyphae is…
mycelium
Some yeast are ______ , and can exist in both yeast and filamentous forms
Dimorphic
What fungus of oral concern can assume a pseudohyphae form and is dimorphic/polymorphic
C. albicans
T/F
Fungi has a huge cell wall, up to 90% of dry weight
True
Why is humoral immunity no good in combating fungi?
Proteases/enzymes of fungi
T/F
Fatty acids, pH, epithelial cell turnover, and normal bactera all help resist against fungal invasions
True
Mycotoxicoses are _____
rare
Hay fever and asthma is a Type ____ hypersensitivity
Contact Dermatitis to a fungal product is a Type ____ hypersensitivity
Type I
Type IV
T/F
Superficial mycoses typically don’t cause pathology
True
______, think cutaneous mycoses
Tinea
What 3 Dermatophytes cause Tinea (cutaneous mycoses)?
Trichophyton
Micosporum
Epidermophyton
T/F
Subcutaneous mycoses are common
False
Systemic fungal infections tend to enter via what?
Lungs
inhaled spores
List 4 opportunistic mycoses from common to rare:
Candidiasis
Cryptococcus
Aspergillosis
Pneumocystis
T/F
Candida albicans, along with being an opportunist, is part of the normal flora
True
80%
What should a clinician think in an otherwise healthy adult in case of oral thrush?
Immuno-compromising conditions
HIV
The yeast or hyphae form of Candida depends on what?
Acidity
- acidic favors yeast, alkaline favors hyphae
- *remember it’s pseudohyphae for Candida
- **Polymorphic
A pH switch to alkaline promotes what kind of Candida?
Filamentous
Why doesn’t humoral immunity do much against fungi?
Antibodies are degraded quickly by enzymes / proteases
What type of cells typically respond to fungal antigens?
How?
Th1
stimulate cytokines
which initiates inflammation, cell turnover, etc
T/F
An immune dysfunction will almost always have thrush
True
PMN’s attacking Candida can sometimes form what?
Loosely adherent pseudomembranes
- easily wiped off
- *diptheria firmly adhere
Primary Candidiasis is found where?
Secondary Candidiasis is found where?
Which is seen in immunosuppression and HIV?
Orally (and surrounding)
Other mucosal/cutaneous sites
Secondary
4 types of Primary Oral Candidiasis:
Acute Pseudomembranous
Erythematous (acute/chronic atrophic)
Chronic hyperplastic (leukoplakia EBV associated)
Chronic mucocutaneous (immune defect)
