microbiology of periodontal diseasest

8/2/2019 Microbiology of Periodontal DiseasesT

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Microbiology of

Periodontal DiseasesPart I



Introduction

Bacterial Colonization of oral cavity (OC)starts at birth

> 700 species can colonize OC

Individuals harbor > 150 species

Subgingival site: 103 – 108 cell

Supraginigival: >109

per tooth surface

ONLY Mino r i t y o f s it es i n m ino r i t y o f i nd i v idua lsa re e xh ib i t i n g n e w d e st r u c t i o n at a n y g i ven t im e



Bacterial-Host Interactions

The ecological relationship between theperiodontal bacteria and the host isgenerally benign

Equilibrium is stressed when bacteria is:

• Newly introduced

• Overgrow

• Acquire new properties

Damage to the supportingstructure is infrequent

Spon tan eous cor rec t ion

Therapy

Bacte r ia p resen t in

“ p e ace f u l” e q u i li b r i u m



Similarities of PD to other

Infectious Diseases

Example; Upper Respiratory infection:

• Pathogen introduced from individualharboring the pathogen or from environment

• Caused by a single pathogen or accumulationof several pathogens

• Colonize; within tissues or on mm./skin

Disease ( I n f ect ion ) Car r ier st a t e

Ba t t l e b e t w e en p a ra si t e ( s) a n d h o st



To t u r n o n / sh u t o f f v ir u l e n ce f act o r s

Periodontal Pathogens Aggregatibacter (Actinobacillus)

actinomycetemicomitans Tannerella forsythia Campylobacter rectus Eicenella corrodens Fusobacterium nuecleatum

Peptost reptococcus m icros Porphyrom onas gingivalis Prevotella int ermedia Streptococcus interm edia Treponema denticola

Need t o a t t ach

Need t o sense env i ron m en t

Need t o ove rcom e hos t de fense m echan ism



Similraties; Conclusion

Periodontal diseases are infections thatmay have properties similar to bacterialinfections in other parts of the body and

consequently can be controlled in similarfashion



Unique features of PD One of the most unusual infections in human;

unusual anatomic feature:

• A mineralized structure (tooth) passes through theintegument, so that part of it is exposed to theexternal environment while part is within theconnective tissue

• Colonization is enhanced;

Tooth surface; No cell shedding

Epithelium surface C.T. surface

Other bacteria

• Complexity of host-parasite interaction is

increased

Bact er ia ar e St ab le ;m o r e t h r e at t o so f t

t i ssue



Complexity of host-parasite

interaction is increased

Bacteria on tooth are less affected by immunemechanism

Plaque environment on tooth increased in:• Hydrogen ion conc (pH)

• Oxidation-Reduction potential (Eh)

Tooth is a hide place for pathogens; dentinaltubules:

Favo rs t h e pa th ogens v s h o st i m m u n e sy st e m

Bac te r ia sm a l l ; can en t e r

Hos t ce l l s t oo l a rge t o en t e r

Hos t Enzym es absorbed in den t in

Those ins ide so f t t i ssues m ore a f f ect ed



Un iqu e ana t om ica lf e a tu re s



Unique Anatomic feature

Must be kept in mind when considering:

• Etiology

• Pathogenicity

• Plan treatment or prevention



Evidence for Bacterial Role in

Etiology for PD1. Acute Periodontal infections are alleviated

by antibiotics: Acute necrotizing gingivitis (ANG) Necrotizing periodontitis (NP); as in AIDS

patients

Antibiotics reduce or resolve chronicperiodontal infection




Etiology for PD

2. Level of plaque related to level of disease:

Gingivitis severity increased with

increased plaque levels

Increased bone loss with increasedplaque accumulation

Periodontitis controlled by mechanicalremoval of plaque

Expe r im en ta l g i ng i v i t i s :Absta i n f r om o ra l hyg iene lead t o g i ng i v i t i s

Plaque con t ro l r eso lved g ing iv i t i s




Etiology for PD

3. Host immune response to putativeperiodontal pathogens;

- Antibodies

- Celluar immune response




Etiology for PD

4.Pathogenic potential of plaque bacteria;

• Endotoxin

• Cell wall mucopeptides

• Fatty and organic acids

• H2S & NH3

• Indole, amonia, leukotoxins

• Enzymes

• Ags; host mediated events; tissuedestruction




Etiology for PD

5. Experimental animals:

Plaque accumulation leads to infection

Removal leads to control of disease

Th S h f P i d t l P th



The Search for Periodontal Pathogen;The non-specific approach

Early 1900s; amoebae, spirochetes, fusiforms,streptococci

1950s; Control of the whole plaque essential for ttt of PD

“Non-specific Plaque Hypothesis”: Accumulation of ANY microbial species at the gingival margininduces gingivitis/periodontitis

“Mixed Anaerobic Hypothesis”: Any combination of species that collectively possessed an essential arrayof virulence factors induces gingivitis, and laterperiodontitis



Specific Plaque Hypothesis

1960s;

- Ti ssu e in va sio n i n AN G- Transm iss ion o f PD by speci f i c bact e r i a ina n im a l m o d el s

“ Speci f i c Plaque Hyp o t hes is” : PD a re caused byon ly f ew species am ong b act e r i a l p laque bact e r i a

Var ia t i ons o f bact e r i a l p laque ; be t w eensi t e s/ i n d i v i d u al s w e re a p p reci at e d

Pu t a t i ve Pe r i od o n t a l Pa t h o g e n s; 2 0 – 4 0species



Difficulties in defining PP

> 4 0 0 sp ecies i so lat e d so f ar ; 3 0 – 1 0 0 i n s in g l es i te .

Many species d i f f icu l t t o g r o w / i den t i f y

Po cke t s ; n a r ro w ; d i f f i cu l t t o sa m p le

Tim e o f sam p l ing cr i t i ca l ; d i sease act i v i t y n o tco n t i n u o u s

Var ia t ion s o f species a m o n g si t e s/ i n d iv i d u al s

Oppor t un is t i c species; cause o r e f f ect ?

Mixed in fec t ions ; sever a l species con t r ib u t e

Pa t h o g e n s i n l ow n u m b e rs; Car r ie r s ta t e?

Colona l v a r ia t ions in pa th ogen ic po t en t i al

Species exchange pat hogen ic po t en t i a l t h r o u g hphages and p lasm ids



Criteria for defining PP

“koch’s Postulates” 1882; causalrelation between an infectious agentand a disease;

1. Agent must be isolated from every case of

a disease2. Not recovered from health or other

diseases

3. Pure culture of agent cause disease inexperimental animals

“ ca r r i e r st a t e ”

Ab ro g at e d 1 8 8 4



Criteria for defining PP

Assoc ia t ion : PP r ecover ed f r om d iseasedsi t e s m o re f r e q u e n t l y

El im ina t i on : r em ova l o f t he PP i s pa r a l l el

t o rem ission o f d i sease Host r espon se : a n t i b o d ies/ cel l u l ar

im m u n e re sp o n se d i re ct ed t o t h epa r t i cu la r PP

Vir u lence fact o r s: p a th o g en i c p ro p e r t i esw h i ch l e ad t o d a m a g e o f h o st t i ssu e s

An i m a l m o d el s fo r Per iod on t a l d i sease ;

g ive sug gest i ve ev idence

Modifications of Koch’s Postulates



A. actinomycetemcomitans

Small, nonmotile,

gram-ve, sacchrolytic,capnophilic round-ended rod

Star-shaped center on

blood agar plates



A. actinomycetemcomitans Criteria Findings

Association - Elevated in LAP, pre-pubertal & some CP- Lower in health, gingivitis or edentulous

- Detected in tissues of LAP lesions

Elimination - Elimination/suppression; successful therapy

- Recurrent lesions harbored species

HostResponse

- Elevated serum/saliva Ab in LAP and CP

- Elevated local Ab LAP

VirulenceFactors

- Leukotoxin, collagenase, epitheliotoxin, fibroplastihibitory factor, bone resorption inducing factor,

induction of cytocaine production from microphages,modification of neutrophil function, degrdation of immunoglubulins

Invades epithelial cells in vitro

Animal

Studies

Induced disease in rats; subcutaneous abscesses



Porphyromonas gingivalis

Gram-ve, anaerobic,nonmotile,

asacchrolytic rods Forms brown to black

colonies on blood agarplates

Porphyromonas gingivalis



Porphyromonas gingivalis Criteria Findings

Association - Elevated in leisons of periodontitis

- Lower in health, gingivitis or edentulous

- Detected in tissues or cells from lesions



Host

Response

- Elevated serum/saliva Ab in periodontitis patients

- Elevated local Ab in periodontitis

VirulenceFactors

- Collagenase, endotoxin, trypsin-like activity,fibrinolysin, other proteases, phospholibase A,fibroplast ihibitory factor, H2S, NH3, fatty acids,factors adversly affecting PMNs, bone resorption

inducing factor, induction of cytocaine production fromvarious cells, generate chemotactic activity, degrdationof immunoglubulins

- Invades epithelial cells in vitro

AnimalStudies Induced disease in rats; subcutaneous abscesses

Additi l S i



Additional SpeciesAssociation Elimination Host

responseVirulencefactors

Animalstudies

P. int erm edia +++ +++ ++ +++ ++F. nuecleatum +++ + ++ ++ +B. forsythus +++ ++ + + +

C. Rectus +++ + + +E. corrodens +++ + + + +P. m icros ++ + + +

Selenomonas sp. ++Eubaterium sp ++ ++ +Spirochetes +++ +++ ++ +++ +

S. int ermedius +



P. intermedia F. nucleatum

Tannerlla forsythia (B. forsythus)



Next lecture; Part II

More on the host-bacterial interactions



Periodontal Diseases are Mixed

Infections

Microbial complexes colonizing thesubgingival area

• Spectrum of relations with the host;

Benef ic ia l Species;Preven t D isease

Harm fu l Spec ies ;Cau se Disease



Var ious re lat i onsh ips be tw een b act e r i a i nsub g ing i va l p laqu e :• Ant agon ism ; species aga ins t species• Syn er g is t i c; species add t o species

Ev idence o f t he r o le o f com p lexes; an im a ls tud ies :

• Com bin a t ion o f spec ies causesexpe r im en t a l abscess

• Sing le species f rom t he com b ina t i onsm ay n o t cause abscess

Mix ed I n f ect io n s



Examples of Combinations in

Clinical Samples

F. nuecleatum + T. forsythia + C. rectus

S. interm edius + P. gingivalis + P. m icros

S. interm edius + F. nucleatum + P. gingivalis

P. gingivalis + A. act inomycetemcomitans

P. gingivalis + T. forsyt hia

P. gingivalis + T. dent icola

The presence of these species alone or in combination is used to determ ine the risk for disease to occur



Conditions for Periodontal diseases

Initiation and Progression

Susceptible Host; to the disease

Virulent Pathogen; to cause disease

Suitable Local factors; to help the

pathogen

The simultaneous occurrence of:

This does not happen frequently;Periodontitis affect 8% – 20% of population



The Virulent Periodontal Pathogen

A periodontal pathogen has;• Virulent strains; found in diseased sites

• Avirulent strains; in healthy sites

For a pathogen to cause disease;• Must be of a virulent type

• Must be able to express virulence ability

• In sufficient numbers• In the right location; apical of pocket/

adjacent to epithelium



The Local Environment

A. Microbial Interactions; detemine natureof colonizing species; outcome of healthor disease

B. Factors affecting the “Regulon” (ability

of the pathogen to turn on/off production of virulence abilities):

• Temperature

• Osmotic pressure• Conc. Of iron, calcium, magnisium

• Pocket depth; level of oxygen

• pH

Mi bi l I t ti



Microbial Interactions

Harmful; mixed infection

Beneficial to Host: no disease Host compatible species:

• Prevent colonization of harmful species

• Dilute no. of pathogen

• Compete for/alter binding sites of pathogen

• Destroy virulence factors produced by

pathogen

S. San gu is S. Ube r is A. v iscosus

A. a ct i n o m yce t e m ico m i t a n s H y d r o g en p e r o x i d e

Bacter ioc in

An tagon ism



Host Susceptibility Differences in host susceptibility leads

to differences in disease pattern Host factors;

• Defects in polymorphnuclear leukocytes

Level and function

• Poorly regulated immune response

• Smoking

• Diet• Various systemic debilitating diseases;

HIV

Diabetes



Systemic Debilitating Diseases (SDD)

Individuals with SDD has morePeriodontal destruction compared tothose without SDD

Periodontal pathogens are similar in bothgroups of patients

Those with SDD can also be treated

successfully THE ALTERED HOST SUSCEBTIBILITY

LEADS TO CHANGES IN THE RATE OF

PROGRESSI ON



Periodontal Disease and Diabetes

The diabetic state is associated with:

• Decreased collagen synthesis

• Increased collagenase activity

• Altered neutrophil function

Elevated blood sugar levels suppress thehost’s immune response and results in:

• Poor wound healing

• Susceptibility to recurrent infections Periodontal disease is often considered the

6th complication of diabetes and may placethe individual at risk for future diabetic

complications



Smoking and Periodontal Disease Smoking is a major factor in the initiation and

progression of periodontal disease. Smokers are 4x as likely to develop

periodontitis as non-smokers. Smoking may be responsible for more than

half of the periodontal disease among adultsin the U.S.

Up to 90% of refractory periodontitis patientsare smokers.



Smoking and Periodontal Disease

Smoking may increase levelsof certain periodontalpathogens.

Smoking has a negative

effect on host response,such as neutrophil functionand antibody production.

Smoking has been shown tohave a cytotoxic effect ongingival fibroblasts and couldslow down wound healing.



Smoking and Periodontal Disease

Smoking is one parameter indeciding to treat refractoryperiodontitis in smokers with a

systemic antibiotic therapydirected against smoking-associated periodontal bacteria.

Smoking cessation has abeneficial effect on periodontalhealth.

M h i f P th i it



Mechanism of Pathogenicity

For periodontal pathogen to cause disease, it

must:

• Colonize the subgingival area;

Attach

MultiplyCompete with other species

Defend itself against host factors

• Produce harmful factors; Tissue damage: Tissue invasion

Indirect tissue damage



Periodontal Pathogen Attachment

Adhesins: molecules onthe bacterial cell surfaceattach specifically to

receptors on:• host surfaces; tooth,

sulcular or pocketepithelium

• Other bacteria surfaces;bacterial-bacterialattachment is calledcoaggregation

• Fimbriae

• Cell proteins

Adhesins:

- Galactosyl residues

- Proline rich proteins

- Collagens type I or IV

Receptors



Coaggregation

Bacteria attached to other bacteriaattached to tooth surface:

• Specific receptor-adhesin interactions;

not all bacteria attach together

• Non coaggregating bacteria could attachtogether by a third species



Multiplication

Subgingival area is stringent forbacteria to live in:

• Physical restrictions:

Temp. range between 30 – 38C

pH 7.0 – 8.5

Oxidation reduction potential (Eh)

• Nutritional restrictions: Limited nutritional availability; from Diet,

host or other bacteria

I t b t i l R l ti hi



Interbacterial Relationships Play important roles in

species survival;• Favorable; one species

provides growth factorsfor, or facilitatesattachment of another

• Antagonistic;

competition for nutrientsand binding sites, orproduction of substanceswhich restrict or preventgrowth of a secondspecies

Gr o w t h f a ct o r s ;-Fat t y ac ids , Po lyam ies,

Ana loges o f v i t K , Lact a teFo rm a te , Hyd rogen

A t t a c h m e n t ;-I n t e r species agg lu t i na t i on

-Ext race ll u la r enzym esAerobes & facu l ta t i ves ;-Use oxy gen ; anaerob i c env i r onm en t-Dest r oy oxyg en r ad i ca l s

An t agon is t i c subs tan ces:-Af fect b i nd ing-Ki l l o th er spec ies;

-Bacter ioc in-Hydrogen perox i de

-Org an ic ac ids

Overcoming Host defense




Mechanisms Saliva & GCF;

• Flow has washing effects

• Bacterial binding blockedby; Abs, glycoproteins,mucins, proline rich

proteins Chewing & Speaking;

• mech. displacement

Epithelial desqumation;

• cleansing effects

Specific Abs;• Prevent binding

• Make bacteria susceptibleto phacocytosis

- So m e sp e ci es b i n d t ound e r l y i ng ep i t h . Laye r

- Ot h e r s i n v a d e e p it h . ce ll s

- Ba ct e r i a p r o d u ce p r o t e ase sw h i ch deg rade Abs- Ch a n g e b in d i n g si t e s t o A b s

O i H d f




Mechanisms PMN;

• Phagocytosis

• Lysosomal enzymes

Connective tissues; moredefense systems:

• Macrophages, lymphocytes

• PMN, Abs

Artificial agents;• Antibiotics

• Antiseptics

Bact er ia res ist ;Leuko t ox i n ( A .a .)Capsu le ( P.g. )

More soph is t i ca tedBact er ia l r es is tan ce;•t o evade,•h ide f r om•dest r oy oppos i t i on

•Evo lved m echan ism s o f r esi st ance•Can be p assed t o o t her species

F t th t R lt i Ti



Factors that Result in Tissue

Damage

Two mechanisims of pathogenesis;• Invasion:

Spirochetes, A. a., P. g., F. n.

• “long-range” attack (Virulence factors); Direct tissue damage; Substances that:

• Cause cell damage; H2S

• Cause cell to release biologically active

agents; lipopolysacharrides (LPS)• Affect intercellular matrix; collagenase

Immune pathology;

• Indirect tissue damage

Actinobacillus actinomycetemcomitans



Actinobacillus actinomycetemcomitans

Criteria Findings

Association - Elevated in LJP, pre-pubertal & some AP

- Lower in health, gingivitis or edentulous

- Detected in tissues of LJP lesions



HostResponse

- Elevated serum/saliva Ab in LJP and AP

- Elevated local Ab LJP

VirulenceFactors

- Leukotoxin, collagenase, epitheliotoxin, fibroplastihibitory factor, bone resorption inducing factor,

induction of cytocaine production from microphages,modification of neutrophil function, degrdation of immunoglubulins

Invades epithelial cells in vitro

Animal

Studies

Induced disease in rats; subcutaneous abscesses

Eff t f P i d t l Th



Effects of Periodontal Therapy on

the Subgingival Microbiota

Supra-gingival plaque control;

• Improve periodontal status

• Reduce amount of subgingival plaque

• Reduce subgingival periodontal species




Scaling and Root Planing (SRP);

• Well documented clinical benefits

• Parallel microbiological changes;

Decrease in spirochetes and motile rods

Decrease in P. g., A. a., T. d.

Increase in cocci (S. mitis, S. gordoni) andnon-motile rods






Systemic Antimicrobial Therapy;



microbiology of periodontal diseasest

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