periodontal diseases microbiology - kajimoto

_____ describes the various microbial types frequently found by culture or microscopy on the skin and mucous membranes and certain body cavities in normal healthy individuals

normal flora

what bacteria are present 4-12 hours after birth

lactobacilli and streptococci from environment

what bacteria are present are tooth eruption

- nondesquamating surface = streptococcus mutans and streptococcus parasanguis

- gingival crevice area = anaerobic species and yeast

what bacteria are present at puberty

anaerobes: Bacteroides and spirochetes

- increase number of teeth and changes in diet create a complex oral flora

what bacteria are present at adult age

dental plaque and presence of periodontal disease influence the number and types of bacteria present

what bacteria are present at old age

- with loss of teeth, microorganisms decrease

- lactobacilli, strep mutans, and yeast

- unless they have complete dentures

adult oral flora:

aerobic

- strep mutans

- salivarius

- sanguis

- mitior

- staph epidermidis

- neisseria spp

- diphtheroids

adult oral flora:

anaerobic

- lactobacilli

- bacteroides

- actinomyces

- veillonella

- spirochetes

adult oral flora:

candida

present in 20-80% of adults

adult oral flora:

protozoa

- entamoeba gingivalis

- trichomonas temax

the microorganisms found in the oral cavity are ____

commensals

the flourishing in a given area depends upon physiological factors including:

- temperature

- moisture

- presence of nutrients

the oral flora contribute to _____ through the synthesis of vitamins, and they contribute to ____ by inducing low levels of circulating and secretory antibodies that may cross react with pathogens

- host nutrition

- immunity

the oral bacteria exert _____ against nonindigenous species by production of inhibitory substances such as _____, _____, and ____

- microbial antagonism

- fatty acids

- peroxides

- bacteriocins

if oral bacteria can gain entrance into deeper tissues, they may cause abscesses of ____, ____, ____, or the ____

- alveolar bone

- lung

- brain

- extremities

what is the sequence of causing disease

1. acquisition

2. adhesion or retention

3. initial survival

4. prosperity and long-term survival

5. avoidance of elimination

6. multiplication

7. elaboration of virulence factors

early colonizers are _____ which produce ____ that will glue the cells to the surface and eventually form the ____

- gram positive cocci bacteria

- EPS (extracellular polymeric substances)

- biofilm matrix

initial adhesion is dictated by _____

physicochemical variables

initial adhesion between bacteria and non-living surfaces is usually mediated by ______ whereas adhesion to living surfaces is usually accomplished through specific _____

- non-specific interactions

- molecular docking mechanisms

during biofilm growth, cell-to-cell adhesion can be mediated by specific adhesins or cell surface modifications such as ____ or ____

- pili

- fimbriae

______ of genetically distinct bacteria via specific molecules has been show common in the development of oral mixed-species biofilms

coaggregation

____ is a rich source of nutrients but it also contains host-derived elements which can decrease bacterial survival such as ____ and ____

- gingival crevicular fluid

- antibodies

- complement

gingival crevicular fluid contains _____ and ____

- glucose

- iron

cells in different regions of a biofilm can exhibit different patterns of ______ called ____

- gene expression

- quorum sensing

how do bacteria avoid elimination

- adhesion

- IgA protease

- prevent migration of phagocytes

- intra-cellular residence: vacuole or free in cytoplasm

- capsule - prevent phagocytosis

- evade antibody response - antigenic variation

- iron acquisition mechanisms

some organisms are able to sequester themselves within the host tissues, such as _____, _____, or the ____ thus providing a pool for recolonization on ____ once biomechanical therapy has been provided to the patient

- epithelial cells

- WBCs

- dentinal tubules

- periodontal pockets

the use of _____ is counter-productive in chronic periodontitis because by the time the active agent has penetrated the ______, its concentration is too low to be effective and _______ of bacteria can emerge

- antibiotics

- biofilm

- resistant strains

potential periodontal pathogens needs to reach a certain critical ____ within the subgingival biofilm to survive

mass

_____ are typically proteins or other molecules of bacterial origin, produced to cause disease in the host and allow the pathogen to thrive

virulence factors

virulence factors can be ___, _____, or ____

- enzymes

- metabolic waste products

- toxins

how do virulence factors cause disease

- production of toxic cell constituents

- disruption of host cell membranes or stimulate endocytosis into host cells

- inhibition of the host's immune system defenses

virulence factors:

adhesion and colonization

- fimbriae

- capsule

- microbial antagonisms/synergy

virulence factors:

evasion of host response

- leukoaggressins

- chemotaxis inhibitors

- phagocytosis inhibitors

- proteases

virulence factors:

tissue destruction

- collagenase

- hyaluronidase

- LPS

- endotoxins

the ability of bacteria to cause disease is based on:

- the number and type of infecting bacteria

- the route of entry into the body

- the effects of host defense mechanisms

- extrinsic characteristics of bacteria

- intrinsic characteristics of the bacteria or virulence factors

progression of untreated gingivitis to periodontitis pathway

1. dental biofilm

2. subgingival extension

3. toxin secretion

4. gingival irritation

5. inflammation

6. attachment breakdown

7. attachment loss

8. deep pocket colonized by bacteria

the tooth associate bacteria is always the _____

primary colonizer

the bacteria associated with the tissues are the _____

secondary or third colonizers

what are the healthy bacteria

- gram positive

- aerobic

- non-motile

what are the disease presenting bacteria

- gram negative

- anaerobic

- motile

bacteria that are associated with periodontal health include ____

primary or early colonizers

what are the top three bacteria causing periodontal disease

- porphyromonas gingivalis

- tannerella forsynthia

- aggregatibacter actinomycetemcomitans

porphyromonas gingivalis

- gram negative

- black pigmented

- anaerobic

- cell surface adhesion

- host response evasion

- low MW cytotoxic metabolic end products allow for damaging host tissues and spreading

major site of colonization for porphyromonas gingivalis is ____

gingival sulcus

porphyromonas gingivalis has evidence for its role in the pathogenesis of ____

chronic periodontitis

porphyromonas gingivalis are elevated in _____

periodontal lesions

tannerella forsynthia

- formerly bacteroides forsythus

- gram negative

- non-motile

- filament shaped

- non-pigmented

- difficult to culture (pathogenicity is virtually unknown)

- cell surface proteolytic enzymes

- leucin-rich surface protein (BspA)

tannerella forsynthia is associated with ____

refractory periodontitis

aggregatibacter actinomycetemcomitans

- formerly actinobacillus actinomycetemcomitans

- star shaped internal structure

- short, straight, or curved

- ferments most sugars

- gram negative rod

- facultative anaerobe

- growth enhanced by the presence of carbon dioxide

- related to systemic infections

aggregatibacter actinomycetemcomitans has evidence of antibody titers in _____

localized aggressive periodontitis patients

what are the suspected virulence factors of aggregatibacter actinomycetemcomitans

- leukotoxin (RTK)

- LPS

- B barrel outer membrane proteins (OMP), vesicles

- fimbriae

- collagenase

- immunosuppressive factor

leukotoxin

induces apoptosis of WBC

LPS

apoptosis and bone resorption

fimbriae

adherence

collagenase

secreted by bacteria for reduction in collagen density

serotypes of aggregatibacter actinomycetemcomitans:

a strain

- oral cavity

- variable leukotoxin expression

serotypes of aggregatibacter actinomycetemcomitans:

b strain

- localized aggressive periodontitis

- strong leukotoxin expression

serotypes of aggregatibacter actinomycetemcomitans:

c strain

low leukotoxin expression

spirochetes

- gram negative

- anaerobic

- spiral

- highly motile

- increased numbers in deep periodontal pockets

- difficult to distinguish individual species

- necrotizing periodontal disease

prevotella intermedia and prevotella nigrescens

- strains of P intermedia

- hemagglutination activity

- adherence

- gram negative

- induces alveolar bone loss

fusobacterium nucleatum

- gram negative

- anaerobic

- spindle shaped rod

- subgingival microbiota

- invasion of epithelium cells

- apoptosis activity

- most common isolate found in subgingival plaque samples

- prevalent in periodontitis and periodontal abscesses