General
Bacteria: 0.1-10µm
Viruses: 0.03-0.3µm
Protozoa Fungi: 4-40µm

Bacteria

Viruses

Structure

Structure

Gram Staining Streptococcus-gallolyticus

Process

  1. Stain with crystal violet
  2. Wash alcohol
  3. Stain Saffrin
    Peptidoglycan maintains crystal violet better so positive (blue), negative (red)

Implications

Negative more resistant:
LPS outer membrane blocks diffusion of low molecular weight compounds. (eg. antibiotics/lysozymes)

Differences

Negative: Endotoxin
Positive: No Endotoxin

Negative: LPS (Spans between Cell wall layer & Outer membrane)
Positive: No LPS

Negative: More lipid
Positive: Less lipid

Cell Membrane

Negative: Thinner less crosslinking
Positive: Thicker more crosslinking

Positive (2layers):

  • Cell wall (60-100% Peptidoglycan)
  • Cytoplasmic membrane

Negative (3layers):

  • Outer membrane
  • Cell wall (5-10% Peptidoglycan)
  • Cytoplasmic membrane

Negative: Periplasmic Space, Porin channel
Positive: No space, No Porin channel

Mycobacteria:

  • Weakly gram positive
  • Stains: Acid fast aka. Ziehl Neelsen
  • Hot carbol fuchsin, Acid-alcohol wash
  • Mycobacteria retain thick waxy cell walls

Mycoplasma

  • No cell wall
  • Are not stainned

Prokaryotic

Smaller Ribosome

DNA/RNA/Plasmid

No mitochondria

Endospores only by 2 genus (Gram positive)

  • Resistant to heat
  • Resistant to cold
  • Dormant
  • Resistant to drying and chemicals
  • Multi-layered protective coat

Capsular:

  • Usually more pathogenic
  • Harder to detect by WBC

Prions

Examples

Fatal Familial insomnia (FFI)

Kuru (Shivering)

Creutzfeldt-Jakob (CJD)

Gerstmann-Straussler-Scheinker (GSS)

Properties

Long incubation
No immune response
Non-inflammatory process
Macro: Normal
Micro: Spongiform changes

What are they

Inanimate, mishapen proteins that multiply in the brain

Implications

Hard to detect

Very resistent to heat, disinfectants (Iatrogenic transmission)

Oral Flora benarkah-seks-oral-sebabkan-kanker-tenggorokan

  1. Pneumonia
  2. Bacterial Endocarditis
  3. Atheromatous
  4. Diabetes

Variation

Age

1y/o (Mucosal)

Hours from birth (Mucosal):

Teeth errupt (Mucosal, Tooth, Crevice)

Adolescence

Increases

Old age

Locality

Edentulous (Same as pre-erruption)

Acrylic (Candida)

Staphylococcus Aureus

Lactobacilli

Yeast

  • Anaerobes
    Porphyromonas
    Prevotellas
  • S. mutans
  • S. sanguis
  • Actinomyces
    Sub-Gingival
  • Fusobacteria
    Sub-Gingival
  • Streptococci
    Supra-gingival
  • Staphylococci
  • Neisseriae
  • Lactobacilli
  • Veillonella spp
    Sub-Gingival

Supra-Gingival

Sub-Gingival

Anaerobes

  • Actinomyces
  • Gram negative

Streptococci

L2: Spread

L3: Lab Diagnosis

Classification

Active:

  • Pathogen
  • Symptoms
  • eg. Influenza, Common cold

Carrier

  • May go on to develop
  • Source of infection
  • Chronic Carriage: Unable to eradicate infection
  • eg. HIV, Hep B & C, herpes

Prodromal

  • Early signs
  • Not full blown
  • eg. (Measles, Mumps, Chickenpox)

Routes

Faceal-oral

  • Fingers
  • Flies
  • Fomites
  • Food
  • Fluids

Airborne

  • Droplets
  • Droplet nuclei
  • Spores
  • Skin scales

Contact

  • Horizontal: Between generation
  • Vertical: Mother to child

Percutaneous & Mucous membrane

  • Needles
  • Vectors eg. Mosquitos
  • Splash of blood into eye / mucous membrane
  1. Encourage bleeding
  2. Wash/rinse
  3. Post-exposure prophylaxis

Investigations

Serology (serum)

Culture

Microscopy

Antigen detection

Molecular Biology

Ziehl Neelsen / Acid Fast

Bacteria Florescence

Gram Stain

Disadvantages

  • Limited information

Advantages

  • Same-day tests
  • Faster than culture

Advantages

  • More info than microscopy
  • Definitive identification (Individual)

Disadvantages

  • Slow (1day-weeks)

Solid / Liquid

  • Cannot see individual cells

Selective: Supress normal flora
Differential: Indicate presence
Enrichment: Liquid to amplify

Advantages

  • Measures Ab in late phase
  • When PCR and culture negative

Advantages

  • Faster than culture
  • Requires little sample

Disadvantages

  • More expensive

Disadvantages

  • Long wait time

Only on surface

Immunofluorescene

  • Streptococcus Salivarius

Ecological plaque hypothesis
(Marsh, 1991, 1994)
Periodontal disease results from
upset in microbial balance

Health/Disease
Blue: Facultative Anaerobes
White: Obligate Anaerobes

Disease

Periodontitis
laba
Obligate Anerobes
Gram -ve

  • Porphyromonas gingivalis
  • Tannerella forsythia
  • Treponema denticola

Health

Experimental Gingivitis in Man
(Loe et al 1965)
Initial: Gram +ve cocci & rods (>80%)
Gingivitis: Gram +ve cocci & rods (45-60%)
Fusobacteria, Gram -ve

Biofilm

Attachment

Transport

Pellicle formation

Co-aggregation

Detachment

Early Colonizers: +ve Facultative Anaerobes
Late Colonizers: -ve Obligate Anaerobes

Obligate Aerobes: Requires O2
Obligate Anaerobes: Cannot have O2
Facultative Anaerobes: With or without O2
Capnophilic: Like CO2

Obligate Anaerobes

  • Tannerella forsythia
  • Porphyromonas gingivalis
    • Proteolytic
    • Raise pH
    • Promote bacterial growth

Health
LA
Facultative Anerobes
Gram +ve

Gingivitis LAB
Obligate Anaerobes
Gram -ve

Aggressive/LJP

  • High numbers of A.actinomycetemcomitans

Pili/Fimbria:

  1. Attachment: To host and cause disease
  2. Conjugative: Transfer genetic material

Toxins

Endotoxin (LPS membrane)

  1. Stable can withstand high temp
  2. Released at cell death, after phagocytosis
    Triggers host immunity
  3. Usually gram negative
  4. Fever
  5. Cannot be converted to toxoid
  6. Non-specific, fever, aches
  7. Acts via multiple mechanisms
    • Blood clotting (anyhow)
    • Anyhow fibrinolysis
    • Cytokines

Porphyromonas Gingivalis

  • Gram -ve
  • Strict anerobe

Exotoxin

Collagenase

Proteases

  • Destroy immunoglobulins
  • Antibody reduction
  • Immune suppression

Gingipains

Hemolysins

  • Break down RBC
  • Requires Heme

Tannerella forsythia

  • Gram -ve
  • Strict anerobe

A.actinomycetemcomitans

  • Gram -ve
  • Capnophilic

Endotoxin

Exotoxin

Cytolethal distending toxin

  • G2/M arrest
  • G1 Cell substance multiply
  • S Chromosome multiply

Leukotoxin

  • Kill WBC
  • Found in aggressive Perio

Slide 19
Perio II

No cytoplasm

Envelope (Optional)

  • Having an envelope makes it easier to kill

Genome

Capsid Protein

  • Helix
  • Icosahedral

RNA

DNA

Sense
Antisense
Double stranded

Linear
Circular

Single stranded
Double stranded

Determinants of Pathogenicity

Treatment of Sepsis - Endotoxin

  1. Deal with underlying infection
  2. Support failing body systems
  3. Block harmful inflammation

Exotoxin

  1. Denaturable
  2. Excreted
  3. Usually gram positive
  4. No fever
  5. Can be converted to toxoid
    eg. cytolethal, collagenase
  6. Specific sites / effects
  7. Acts directly

Pathogenicity

Lytic

  • Viral replication kills target cell
  • Affect structure & function
  • Expression of viral antigens immune cytolysis

Persistent (Non-lytic)
eg: Adeno, Hep B/C, measles, rubella, HSV, HIV

Latent-recurrent

  • Incorporation of DNA
  • mRNA inhibit lytic cycle
  • allow integration
  • Activated upon stress immune suppression
    eg: Chickenpox (Varicella)

Abortive

  • Failed infection
  • No multiplication

Transforming

  • Immortalizing
  • Stimulate uncontrolled cell growth

Recurrent

  • Latency then viral production

Latent

  • No virus synthesis

Chronic

  • Nonlytic
  • Productive