2. CONTENTS
• Introduction
• History
• Terminologies
• Oral cavity as microbial habitat
• Development of residual
microflora
2
• Oral Microbiota In Various Sites At
Different Stages Of Human
Development
• Factors affecting growth of
microorganisms
• Conclusion
• References
3. INTRODUCTION
• Human beings harbour a wide range of
microorganisms.
• Mouth is the gateway of the body to the external
world
• Easily accessible part of the body and acts as a major
site of entry.
• Mouth has its own natural microflora.
Ref :Marsh and Martin :Oral microbiology 6 Edition
3
4. • Most of the microorganisms in the oral
cavity are oppurtunistic.
• Diseases occur as a result of imbalance in
the normal microflora.
4
5. HISTORY
• W. D. Miller - Father Of Oral Microbiology.
• Louis Pasteur- Father Of Bacteriology.
• Anton von Leeuwenhoek (1683) - First to observe microbes in saliva and teeth.
• K. Clark (1924) - studied coccus from a caries lesion – S. mutans.
• Leon Williams (1897) - showed microorganisms attached to tooth sections.
• G. V. Black (1898) - Term microbial plaque.
• Refernce :Anant Narayan- 5th edition, textbook of microbiology
5
7. Interaction Between Normal Microbiota And Host
• Symbiosis: “Living together”.
• Commensalism: One organism benefits, the other is not affected (+/0).
• Mutualism: Both organisms benefit from living together (+/+).
• Parasitism: One organism benefits, the other is harmed (+/-).
7
8. • Oral microflora has a characteristic composition and is existing in a
harmonious relationship with the host.
• The relationship can breakdown in mouth and disease can occur when:
a. Major changes to biology of mouth from exogenous or endogenous
sources.
b. The presence of microorganisms at sites not normally accessible to them
8
9. • Most endogenous bacterial disease are Opportunistic Infections.
• Commonest clinical manifestations include: Dental caries and Periodontal
diseases.
• Dental caries is the dissolution of enamel and dental plaque is associated with
the etiology of periodontal disease.
9
10. NORMAL FLORA
BENEFICIAL EFFECT
1. Synthesize & excrete vitamins
2. Prevent colonization by
pathogens
3. Antagonize other bacteria
4. Stimulate development of
certain tissues
5. Production of antibodies.
HARMFUL EFFECTS
1. Bacterial synergism
2. Competition for nutrients
3. Induction of low-grade toxemia
4. May be agents of disease
5. Transfer to susceptible host.
10
Reference :KMK Masthan- 1st edition, textbook of oral microbiology
13. Resident flora
• Species that are almost
always present in high
numbers (>1%) in a
particular site;
supragingival plaque/
surface of the tongue.
• Don’t compromise the
host survival.
• Oral flora is dominated
by anaerobic &
facultative bacteria
which exhibit optimal
growth at about 37°C .
Intermidiate
flora
• Comprises species that
are nearly always
present, but in low
numbers (<1%)
• May become
indigenous if
environment changes.
• Eg.lactobacillus
species.
Transient flora
• Comprise organism
“just passing through
the host”
• At a given time a
particular species may
or may not be present
in the flora.
• Bacteria present in
food or drink may be
temporarily established
in the mouth.
• Quickly disappear.
13
15. • Study indicated that neonates can acquire strict anaerobes, such as C. difficile,
within the first 2 days of stay on a neonatal ward.
• Breast-fed infants have predominant populations of bifido bacteria in their stools
and formula-fed neonates had a more complex mixture of organisms
• By 2 years of age, children have a similar complexity and range of microbes as a
adults.
Ref :Ullah S, Rahman K, Hedayati M. Hyperbilirubinemia in Neonates: Types, Causes, Clinical Examinations, Preventive Measures and Treatments: A
Narrative Review Article. Iran J Public Health. 2016 May;45(5):558-68. PMID: 27398328; PMCID: PMC4935699.
15
16. • Microbes find suitable environments, either on outer or inner body surfaces, quickly
multiply and establish themselves.
• Each part of human body with its special environmental conditions, has its own
particular mixture of microbes.
16
17. DEVELOPMENT OF ORAL FLORA
• The process begins with the colonization of habitat by pioneer microbial
populations.
• In oral cavity of newborns, streptococci are the pioneer organisms.
• They fill the niche of the new environment and modify the habitat and new
population develops.
• When no additional niche is available for new population, a stable
assemblage of bacterial population is achieved called as climax community.
Reference Marsh & Nyvad,2008 p.165
17
19. PIONEER COMMUNITY & MICROBIAL SUCESSION
• Predominant pioneer organisms are streptococci and in particular, S. Salivarius, S.
mitis and S. oralis.
• Their metabolic activity modifies the environment:
(a) Changing the local pH
(b) Modifying or exposing new receptors on surfaces for attachment
(c) Generating novel nutrients
• Microbial succession eventually leads to a stable situation (climax community).
19
20. WINDOW OF INFECTIVITY
• “Time period in which the initial acquisition of streptococcus mutans takes
place on either primary or permanent tooth”
• Caufield (1993) monitored oral cavity levels from birth to 5 years.
• Where he noted initial acquisition of streptococcus mutans.
• As the primary teeth erupt into the oral cavity, they provide a completely
virgin habitat.
• Thus window of infectivity in deciduous teeth is established by 7-31
months.
22
21. • Krass et al (1967) and Edrman et al (1975) - at 2-6 yrs of age is less
susceptible to acquire MS.
• Klock & Kroske (1977) - “Second window of infectivity” present in
permanent dentition between 6-12 years of age.
• 90% of teenagers have MS colonization while others found only 3% of
adults (mothers).
23
22. • Children aquire additional strain of MS as they get older & new teeth emerge but remain
undetected since they are low in numbers.
24
23. Vertical Transmission
• Vertical transmission is the transmission of microbes from caregiver to child. The
major reservoir from which infants acquire MS is their mothers.
• Colonization may be related to several factors –
frequency of small dose inoculations,
a minimum infective dose.
Study reported that,
• when mothers harbored greater than 105 CFUs of MS per mL of saliva, the
frequency of infant infection was 58%.
• While at 103 CFUs of MS per mL of saliva or more, the frequency was 6%.
These data clearly demonstrate that
mothers with dense salivary
reservoirs of MS are at high risk for
infecting their infants early in life.
Berkowitz et al. Mutans Streptococci: Acquisition and Transmission. Pediatric Dentistry – 28:2 2006
25
24. Horizontal Transmission
• The presence of matching genotypes of S mutans among children attending
one nursery school strongly suggests horizontal transmission.
• Van Loeveren and colleagues reported data which bacteriocin typed isolates
of MS obtained from children 5 years of age and their parents.
• The results showed that, even when a child acquires MS after the age of 5,
there may be similarity between MS in mother, father, and child—indicating
that horizontal transmission can occur between family members.
Berkowitz et al. Mutans Streptococci: Acquisition and Transmission. Pediatric Dentistry – 28:2 2006
26
25. Currently drafted recommendations for dental providers addressing the issue:
1. Reduce the MS reservoir in the mother, sibling(s), and all of the infant’s
caretaker(s) by eliminating active dental caries lesions and using agents such as
fluorides and chlorhexidene.
2. Alter saliva-sharing activities, such as tasting food before feeding and sharing
toothbrushes.
3. Twice daily tooth-brushing of the dentate infant with an appropriate amount
of an ADA-approved fluoridated toothpaste.
4. Avoid decay-promoting feeding behaviors.
5. Oral health evaluation of the infant by a dental professional should occur
before the first birthday. 27
27. The Composition Of The Oral Microbiota In Various Sites At
Different Stages Of Human Development.
Infant
• At birth, the oral cavity is essentially sterile and the number of
organisms appear to remain low for the first 6 hours.
• From 6-10 hours following birth there is a rapid increase in the
number of detectable organisms.
• However, at least one organism can be detected culturally with
some degree of regularity, Streptococcus salivarius.
• Zinner et al using immunofluorescence techniques - salivarius
was found in 80% of infants at approx. one day of age and
remained high consistently thereafter.
29
28. Infant….
• S. salivarius normally resides on the tongue. It is not dependent upon the
teeth for survival.
• On the other hand, one would not expect to detect spirochetes in the
edentulous infant since the gingival crevice, its primary ecologic niche, is
absent.
• Also, one may detect organisms such as S. mutans or lactobacilli since they
are constantly being introduced to the infant,
30
29. An evolutionary change occurs during & after tooth eruption enamel / hard-tissue &
gingival crevice .
• Organism prefer hard tissue colonization – s. mutans, s. sanguis & actinomyces.
• Gingival crevice colonization by: Prevotella, Porphyromonas and spirochaetes
Child and Adolescent
The presence of teeth would provide surfaces for the
attachment of organisms best adapted to this niche.
The dominant flora of oral cavity –
• Before eruption of teeth – facultative aerobes in nature
• After eruption – Increase in anaerobic forms
31
30. • Spirochetes also appear to increase in
incidence with age and are universally
present in adults.
Adult
• The cultivable microbiota of the gingival
crevice, dental plaque, dorsum of the
tongue, and saliva of the adult has been
fairly well described.
32
31. • The presence of nutrients, epithelial debris and secretions makes the mouth a
favorable habitat for a great variety of bacteria.
• Oral bacteria include streptococci, lactobacilli, staphylococci and
corynebacteria, with a great number of anaerobes, especially bacteroides.
• The mouth presents a succession of different ecological situations with age,
and this corresponds with changes in the composition of the normal flora.
33
33. THE ORAL
ECOSYSTEMS
Buccal epithelium
Dorsum of the tongue
Supragingival tooth surface
Subgingival tooth and
crevicular epithelial surfaces
Nasopharynx
• S. pneumoniae
Vestibular mucosa
• S. vestibularis
Buccal mucosa
• S. mitis
• mitis group
• anginosus group
Tonsils
• S. sanguis
• S. mitis
• S. mutans
• mitis group
• anginosus group
Tooth surface
• mitis group
• mutans group
• anginosus group
Saliva
• S. salivarius
• S. mitis
• S. oralis
• mitis group
• anginosus group
Tongue
• S. salivarius
• S. mitis
35
Ref :Marsh and Martin :Oral microbiology 6 Edition
34. • The buccal epithelium has gram positive streptococci in contrast to tongue
which has more of gram positive filaments.
• The subgingival region is anaerobic as compared to the
supragingival region.
• Mutans streptococci (S. mutans, S. sorbinus, S. cricetus, S. rattus) and S.
Sanguis are found in large number on teeth.
• S. Salivarius is isolated mainly from the tongue.
• S. mutans and S. sanguis appear only after eruption of teeth.
36
39. GRAM POSITIVE BACTERIA
• Streptococci constitute the largest group.
• Streptococcus mutans – most important role in dental caries.
• Lactobacilli are widely present.
• Saliva has lactobacilli count of 70,000/ml.
• 27 recognized species of the genus.
41
40. STREPTOCOCCI
• Most important organism to initiate dental caries.
• This name of this genus means "pliant berry.”
• S.species have spherical cells that may be oval or
elongated to short rods.
• The cells are nonmotile and do not form endospores.
• Some species produce hyaluronic acid or
polysaccharide capsules.
42
41. • Streptococci – gram positive cocci
• Arranged in chain or pairs.
• Billroth (1874) - Cocci in chains first seen in
erysipelas & wound infection;
Streptos – twisted or coiled.
• Ogston (1881) isolated them from acute
abscesses.
• Rosenbach (1884) – isolated the cocci from
human suppurative lesions & gave them name
streptoccoccus pyogens
43
43. • Colonial morphology varies between species and ranges from 0.5 to 1 mm,
convex, smooth to 5 to 10 mm, low convex, flecked, with radial and
concentric striations.
• Oral streptococci are major components of supragingival dental plaque and
are also found in subgingival plaque.
45
45. I. MUTANS-GROUP
• Originally isolated from human carious teeth by
Clarke in 1924.
• Cells can lose their coccal morphology and often
appear as short rods.
• Nine serotypes have been identified( a-h , and k)
• Recovered exclusively from hard, non – shedding
surfaces in the mouth.
• Can act as opportunistic pathogens.
• Regularly isolated from dental plaque but
prevalence is low on sound enamel.
S. mutans S. sobrinus
47
46. VIRULENCE FACTORS
• Specific adherence to tooth surface using antigen I/II adhesin and GTF
(glycosyl transferase)
• Rapid metabolism of sugars to lactic acid and other organic acids
• Lower the pH to below 5.5, the critical pH.
• Able to maintain microbial growth and continue acid production at low pH
values.
• Accumulation of intracellular polysaccharides (carbon/energy reserve)
48
47. II. SALIVARIUS GROUP
• Strains of S.salivarius commonly isolated from different
areas of mouth.
• Preferably, colonizes the mucosal surfaces especially the
tongue.
• S.vestibularis isolated mainly from the vestibular
mucosa.
• Produce urease and hydrogen peroxide and inhibit other
bacteria.
S.
salivarius
S. vestibularis
49
48. III. ANGINOSUS GROUP
• Sometimes also referred to as the milleri group.
• Readily isolated from dental plaque and mucosal surfaces.
• Important in causing serious, purulent maxillo-facial infections.
S.constellatus S.intermedius
S.anginosus S.pharyngis
50
49. IV. MITIS GROUP
• Typically small, round, blue colonies about 0.2–0.5
mm in diameter.
• Colonize hard surfaces in the oral cavity and also
mucous membranes.
• Contribute to plaque formation and also can break
down starch.
• Non - motile, do not form spores and lack group -
specific antigens.
S. sanguis S. gordonii
51
50. Composition Of The Oral Streptococcal Flora In
Healthy Children
• To identify the predominant streptococcal species in the mouths of healthy children
and to investigate the composition of the oral streptococcal flora over a period of
4 months.
• The predominant species were Streptococcus salivarius, S. oralis and S. mitis.
• No significant variation in the composition of the oral streptococcal flora.
• Within a few hours bacteria may be isolated from the oral cavity e.g. streptococci,
lactobacilli and Veillonella.
Reference :Journal of Dentistry : Volume 28, Issue 1, January 2000 52
51. Prevalence Of Different Streptococci Species In The
Oral Cavity Of Children And Adolescents
• S.salivarius was isolated from infants 18 hours after birth and from 75% of children
aged 1 to 5 years.
• With age, this microbiota differentiates, although the species S.salivarius continues
to predominate on the tongue and oral mucosa.
• The prevalence of Streptococci in saliva were: S. salivarius (89.31%) and S.
mutans (73.28%) by the standard method.
• The tongue depressor method showed S. mutans (62.59%) and S. salivarius
(77.86%).
Reference :Braz J Oral Sci. January/March 2013 - Vol. 2 - Number 4
53
53. LACTOBACILLI
• Anaerobic Gram positive bacilli; alpha hemolytic or non hemolytic.
• Found commonly in normal mouth and comprise less than 1% of total
microflora.
• Highly acidogenic and aciduric.
• Associated with advanced caries lesions and carious dentin.
L. casei L. rhamnosus L. acidophilus L. oris
55
54. • Lactobacilli are absent from the oral cavity of newborns and appear during
the first year of the life.
• McCarthy et al. observed the presence of this species in 50% of newborns
during their first year with a rate from 200 to 30000 bacteria/sample.
• The higher the DMF index, the higher the number of children harboring a
high Lactobacillus count.
• Among children, the presence of lactobacilli in coronal caries is
incontestable. Among adults, lactobacilli are found in root caries.
Reference :lactobacilli and the oral cavity
the open microbiology journal, 2008, volume 2
56
55. GRAM NEGATIVE BACTERIA
• Anaerobic gram negative bacilli are another important group.
• 5 genera of these bacteria frequently seen in oral cavity:
• Veilonellae account for about 10% of microflora on tongue & saliva.
Bacteroide
s
Fusobacterium Leptotrichia Veilonella Selenomonas
57
56. GRAM NEGATIVE RODS & FILAMENTS
ACTINOMYCES
• Actinomyces are facultatively
anaerobic or strictly anaerobic.
• They have been associated with root
surface caries and gingivitis.
• The most representative species in
plaque is A.naeslundii.
58
57. • A. israelli can act as opportunistic pathogen & causes actinomycosis.
• A. viscosus and A. naeslundii differ in both the host age at which they
establish in the human mouth and their preferences for colonizing various
intraoral sites
• Catalase-negative isolates resembling A. naeslundii were found to colonize
most infants.
• A. odontolyticus & A. meyeri have also been reported occasionally.
59
58. Most Important Gram Negative Bacteria
• Porphyromonas: P. gingivalis major periodontal pathogen and causes
significant bone loss.
• Prevotella: P. intermedia a periodontal pathogen pregnancy gingivitis.
• Actinobacillus/Aggregatibacter: A.actinomycetemcomitans associated with
aggressive periodontitis
• Treponema: group important in acute periodontal conditions i.e ANUG
60
59. • F.nucleatum - most regularly occuring in the gingival crevices and
subgingival plaque.
• 4 species of Haemophilus are usual inhabitants of oral cavity.
• H.segnis - recently recognized as causative organism of dental plaque.
• Seven species of oral Spirochaetes are common in gingival crevices.
61
62. 1. Temperature
• Human mouth - constant temperature - 35-36°C.
• Periodontal pockets with active disease - higher temp. 39°C
• Rise in temperature - alter bacterial gene expression and possibly the
competitiveness of individual species
64
63. 2. Redox Potential (Eh)
• It is an oxidation - reduction potential.
• Majority of organisms are either facultatively anaerobic or obligately
anaerobic.
• Oxygen concentration - limits the growth of obligately anaerobic bacteria
• Anaerobic species require reduced conditions for their normal metabolism
It is a degree of oxidation reduction at a site that governs the survival and
relative growth of these organisms 65
64. 3. pH
• Many organisms require a pH around neutrality for growth
• pH of most surfaces of mouth is regulated by saliva.
• After sugar consumption pH in plaque can fall rapidly below 5.0 by production of
acids by bacterial metabolism
pH of Palate - 7.34
pH of tongue - 6.8
Floor of mouth - 6.5
Buccal mucosa - 6.3
66
65. • pH of the gingival crevice can become alkaline during the host inflammatory
response in periodontal disease
• pH of healthy gingival crevice - approx. 6.90
• Rises during disease - 7.2 and 7.4
67
66. 4. Nutrients
• Populations within a microbial community are dependent solely on the
habitat for the nutrients essential for their growth.
• Two types of nutrients :-
Endogenous
Exogenous
68
67. Endogenous Nutrients
• Persistence and diversity of the resident oral microflora is due to primarily
the metabolism of endogenous nutrients.
• Main source - saliva
• Gingival crevice is supplied - GCF contains novel nutrients
69
68. Exogenous Nutrients
• Complex array of foodstuffs ingested periodically in the diet
• Fermentable carbohydrates are the only class of compound markedly
influence the ecology of mouth
• Carbohydrates can be broken down acids
• Sucrose by bacterial enzymes Glucans
Fructans
70
69. • Frequent consumption of dietary carbohydrates is associated with a shift in the
proportions of microflora and dental plaque
• Xylitol is a sugar substitute that has been added to some confectionery -
- can’t be metabolised by oral bacteria
- inhibit growth of streptococcus mutans
Level of acid tolerating species
(mutans streptococci and lactobacilli)
growth of acid sensitive species
is inhibited
71
70. 5. Host Defences
• Health of the mucosa is dependent on the integrity of the mucosa - acts as
physical barrier to prevent penetration by micro-organisms or antigens
• In maintaining the integrity of these oral surfaces, many of which have more
than one function.
• Defences are divided into non-specific and specific factors
Innate
immunity Adaptive
immunity 72
71. Innate Immunity
When saliva flow is blocked in sedated patients in intensive
care, there will be shift in the composition of oral microflora
Chewing and natural flow of saliva - remove micro-
organisms not firmly attached to an oral surface
Micro-organisms are unable to maintain themselves by cell
division alone.
73
72. Adaptive Immunity
• Specific host defences are found on and within the mucosa
• Predominant immunoglobin in the healthy mouth - IgA
• IgA is considered to be first line of defense
• Other components can be found in saliva
74
73. 6. Host Genetics
• Gender and race can influence disease susceptibility, and possibly also affect the
microflora.
• The reasons for this are unknown, but may reflect some variation in the local
immune response.
• IgG2 is elevated in some forms of periodontal disease, and levels of this
immunoglobulin have been related to host genetics.
• Genetic polymorphisms associated with interleukin-1 (IL-1), or other cytokines, can
increase the likelihood of detecting certain key periodontal pathogens and
predispose individuals to periodontitis.
75
74. Benefits Of Normal Oral Microflora
• Prevent the invasion of body by pathogens.
• Synthesize vitamins especially vitamin k.
• Raise the overall immune status of the host.
• Produce bacteriocins & endotoxins and thus help in defense mechanism.
• The presence of a resident microflora prevents disease by reducing the
chance of colonization by exogenous species.
76
75. • AN UNDERSTANDING OF RELATIONSHIP BETWEEN ORAL MICROFLORA
AND HOST IS NECESSARY FOR DIAGNOSING ORAL INFECTION
• ORAL INFECTION USUALLY INVOLVE THE COMMENSAL MICROFLORA
• ANTIMICROBIAL PROPHYLAXIS SHOULD BE GIVEN CAUTIOUSLY
77
CONCLUSION
76. References
• Philip D Marsh-5th edition, oral microbiology
• Anant Narayan- 5th edition, textbook of microbiology
• Shafer’s-6th edition, textbook of oral pathology
• Shobha Tandon – 2nd edition, textbook of Pedodontics
• Damle -5th edition, Text Book Of Pediatric Dentistry
78
Oral microflora
S mutans
Window of infectivity
Lactobacilli in dental caries
Harbour : that can cause disease to spread
Microrogranisms found in human oral cavity
Before 2 Oral cavity is proximal part of both alimentary & respiratory tracts. Mouth is principal portal of entry of infectious agents & allergens into human body.
Hence, it is essential to understand the interaction of human beings & their pathogen prsnt in the environment, where mouth has its own microflora.
Oppurtunstic-microorganisms that has potential to cause disease when harmonous relation with host is alter
Koch's postulates were developed in the 19th century as general guidelines to identify pathogens that could be isolated with the techniques of the day.
Associate
Isolate
Inoculate
Reisolate
AEROBIC Microorg. that require O2 for growth. eg. mycobact. Tubrculosis
ANAEROBIC Microorg. that don’t require O2 for growth. eg. actinomyces, clostridium
CAPNOPHILIC Microorg. that require CO2 for growth. eg. hemophilus influenzea
OBLIGATORY Microorg. that require a specific environment for growth. E.g. obligatory anaerobes - clostridium
FACULTATIVE Microorg. that can grow in the presence or absence of a specific environment E.g. facultative aerobes
HABITAT Site where the microorg. grow
Symbiosis : is defined as condition where two dissimilar organisms living together in an intimate associate that seems both organisms benefit .
Before Microbial colonization of all environmentally exposed surfaces of the body begins at birth.
Commensalism: Eg. Many microbes live off secretions and dead cells and do not benefit or harm host.
Mutualism: Eg. E. coli synthesizes vitamin K and some B vitamins.
Parasitism: Eg. Most disease causing bacteria.
Exo: are micorgoransims are introduced by external world .endo : infection caused by normal flora under certain condition
a. eg: EXO - antibiotic t/t or frequent intake of fermentable carbs; ENDO - alterations in integrity of host defences following drug therapy
b. eg: when oral bact. enter bld stream following tooth extraction or other traumas n are disseminated to distant organs, where they can cause abscesses or endocarditis.
Endogenous- disease dat r produced by nrml flora in their host.
1.Micro-organisms with the potential to cause disease at exceptional circumstances - ‘Oppurtunistic Pathogens’. Hiv virus
Normal flora are the microroganisms that live on another living organisms or object without causing disease
The mixture of organisms regularly found at any anatomical site
Bacteria, fungi, protozoa, and viruses - derive from their host a steady supply of: Nutrients, stable environment, protection, transport
The host obtains from normal flora : nutritional & digestive benefit, stimulation of development, activity of immune system, protection against colonization
(When the number of resident normal flora is greatly reduced, opportunistic microbes can easily cause infections in these areas e.g. Candida albicans that cause candidiasis.)
Later on the slide - 1. Enteric secrete vit k, b12; 2. compete for attachment site 3. thru production of substance which kill non indigenous species. 4. cecum of germ free animal.
Indigenous : living or growing in theplace whee it can originally origin
Transient flora Nisseria, streptococcus pnemonia 4. As these transients normally do not have mechanisms for persisting in the crowded oral environment
Foetus in the womb is normally sterile.
Passive transfer occurs from the mother.
Mouth is highly selective for microorganisms even during the first few days of life.
Bifidobacterium is a genus of gram-positive, nonmotile, often branched anaerobic bacteria. They are ubiquitous inhabitants of the gastrointestinal tract though strains have been isolated from the vagina and mouth of mammals, including humans
UBIQUTIOUS : seeming to be everywhere or in several places at a same time .
pioneer species /: The first microorganisms to colonize are termed pioneer species, and collectively they make up the pioneer microbial community.
Pioneer organisms also called as disaster taxon. Organisms that populates a region after a natural diaster ,mass extincatrion or any other events that kills most of the life of that region
An ecological niche is the role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces.
A species' niche includes all of its interactions with the biotic and abiotic factors of its environment.
----the progressive development of a pioneer community (containing few species) through several stages in which the number of microbial groups increases, until an equilibrium is reached; this is termed the climax community
The oral cavity of the newborn contains only epithelial surfaces for colonization. The pioneer populations consist of mainly aerobic and facultatively anaerobic species. In full-term babies, a range of streptococcal species have been recovered during the first few days of life, and S. oralis, S. mitis biovar and S. salivarius were numerically dominant.
the diversity of the streptococcal microflora increases with time; after one month, all babies were colonized by at least two species of Streptococcus, with S. salivariu.
pioneer species /: The first microorganisms to colonize are termed pioneer species, and collectively they make up the pioneer microbial community.
the progressive development of a pioneer community (containing few species) through several stages in which the number of microbial groups increases, until an equilibrium is reached; this is termed the climax community
4. Which enables the MS to colonize the oral cavity
Cfu-colony forming unit
Cfu is the measure of viable coloonogenic cell in per cfu/ml
little evidence of father infant (or father–mother) transmission of mutans streptococci was observed, although horizontal transmission between spouses, and vertical transmission within family units, can occur with some periodontal pathogens, such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans.
Knowledge regarding the natural history of an infectious disease facilitates a more comprehensive approach toward its prevention.
Crest Pro-Health Gel Toothpaste - Clean Mint,
S salivarius –birth
-S mitis -7
S mutans -
Before 1 Immediately after birth (<5 mins) - the bact. communities +nt in diff. habitats of the newborn (oral, nasopharyngeal, skin, and intestines) are very similar to each other.
After 2 Great variability appears to exist in the bacterial composition for the first few days of life. For example, one can detect several species of streptococci, pneumococci, micrococci, enterococci, staphylococci, veillonella, c . Most of these organisms are found sporadically,
Around 5 months of age, infants already show a distinct oral microbiota from the mother, due to environmental exposure that occurs in the first months of life, particularly through the ingestion of food, contact with other adults and children, contact with domestic animals, hygiene habits, (At this stage, the most frequent colonizers of the oral cavity are Gram-positive cocci, including Streptococcus and Staphylococcus)
After 1 Thus the mucous membranes of the infant oral cavity are ideal for this organism to proliferate.
After 3 but one would not expect to find them in significant proportions because conditions in the oral cavity at this time are not conducive for their maximal retention and growth.
It should be noted that "anaerobic“ genera can be found although in low numbers in the oral microbiota of the child less than one year of age. Thus, Nocardia, Actinomyces and Veillonella are found with increasing regularity in the infants mouths up to one year of age.
Summarize Oral flora in the child’s first year, consists of :
Streptococcus, staphylococcus, neisseriae & Lactobacilli.
Anaerobes such as veillonella & fusobacterium.
(Anaerobic fusiform bacilli – present in mouths younger than 2 months & infants before eruption of incisors.
Fusiform bacilli – inc. in number during the 4-8 months.
Peptostreptococcus appears in 5 months older infants)
After 1 . For example, the incidence of S. mutans increases significantly as infants grow older.
In adolescence
With the eruption of permanent teeth, there is increase in the anaerobic forms.
Like bacteriodes, leptotrichia, fusobacteria, spirocheates and vibrio
Before everything The proportions of the predominant cultivable organisms from the gingival crevice area of the preschool child appear to generally resemble that of the adult with the exception that spirochetes and Bacteroides melaninogenicus were not present in all children
The incidence of B. melaninogenicus in children about 5 years of age ranges from 18-40%, however by 13-16 years of age essentially all individuals harbour this organism.
reason for the late establishment not clear.
Possibly conditions essential not be provided
For example, heme and a 2 globulin might not be available in abundance due to a "normal" gingival sulcus. In addition, it is likely that repeated transmission is necessary for these organisms to become established particularly for the spirochetes which are uniquely sensitive to oxygen and are liable to be killed on exposure to air
Adult shall discuss it in part 2
oral MICROFLORA CHANGES WITH AGE
Four major ecosystems are present in the oral cavity
Buccal mucosa – predom. – S. mitior, with S. sanguis n salivarius.
Hard palate – (resembles buccal mucosa) predom. - streptococci.
Soft palate- Harbours resp. tract bact. - Corynebacterium, Neisseria, Haemophilus.
Tongue - Is an ideal site for retention of microorg d/t its keratinized dorsal surface. S. salivarius –50% of the total. S. mitior - also common.
Teeth and artificial hard surfaces - Fissures and deep grooves in the teeth, especially with regard to the occlusal surfaces of posterior teeth, provide ideal conditions for the formation and build-up of dental plaque. As these areas are seldom in direct contact and mechanical friction, which also removes bioflim from these surfaces.
Gingival crevice - most numerous bact. population among all sites d/t absence of dislodging forces and GCF acting as a rich nutrient medium.
The clinical significance of their presence in the oral cavity is that they are responsible for the plaque formation d/t their interaction with each other and the tooth surface. (Discussed in part 2)
1884- Christian Gram- helps in the classification and differentiations of microorganisms.
Gram positive- some of the bacteria are able to retain the voilet, blue and some are decolorized by alcohol
The cell walls of gram positive bacteria have a thick layer of protein-sugar complexes called peptidoglycan and lipid content is low. Decolorizing the cell causes this thick cell wall to dehydrate and shrink, which closes the pores in the cell wall and prevents the stain from exiting the cell.
Gram negative bacteria, cell wall also takes up the CV-Iodine complex but due to the thin layer of peptidoglycan and thick outer layer which is formed of lipids, CV-Iodine complex gets washed off. When they are exposed to alcohol, decolorizer dissolves the lipids in the cell walls, which allows the crystal violet-iodine complex to leach out of the cells. Then when again stained with safranin, they take the stain and appears red in color.
Procedure of gram staining heat fixed smear crystal violet iodine acetone/alc safranine
Hemolysis occur into 5 % horse agar
Based on their haemolytic properties: 3 types of rxns seen on bld agar medium
Alpha viridans grp of strep. N pneumococcus
Beta most pathogenic strep. Mainly s. pyogenes (majority of human infections); s. pyogenes further classified based on their surface proteins (M) into 80 Griffith serotypes
The species most frequently isolated from the oral cavity are Streptococcus salivarius, Streptococcus sanguis, Streptococus mitis, and mutans Streptococci
S. mutans polymerizes the glucose and the fructose moieties of sucrose to synthesize glucans and fructans, which are two types of extracellular polymers.
The enzymes responsible for the synthesis of extracellular glucans and fructans are called glucosyl- and fructosyl transferases, respectively.
Synthesis of glucans from sucrose has been considered for several years to be the essential glue in S. mutans attachment to enamel and subsequent plaque formation.
Primary pathogen in:
Enamel caries in children and young adults
Root surface caries in the elderly
Nursing caries in infants
After 1S. salivarius, becomes well established within 2 days of birth.
After 2 Produce large quantities of an unusual extracellular fructan from sucrose.
S.intermedius strains produce a protein toxin, intermedilysin.
Normal inhabitants of the mouth, throat and nasopharynx.
Usually an etiologic agent in odontogenic infections and endocarditis.
The prevalence and proportions of a wider range of streptococcal species were reported from a group of infants before and after tooth eruption.
Acidogenic – produces great amt of acids
Aciduric- can tolerate acidic enviornments.
LAST Some species have been associated with dental caries although these bacteria are normally symbiotic in humans and are found in the gut flora.
A strong correlation has been established between the saliva Lactobacillus count and dental caries,
More than 40 species of Bacteroides have been identified.
Before everything Actinomyces from Greek word "actis" ray, beam and "mykes" mucus, fungus.
Initially assumpted to be a fungus.
Individual bacteria are rod-shaped, morphologically Actinomyces colonies form fungus-like branched networks of hyphae.
A. viscosus and A. naeslundii have been implicated in the etiology of periodontal disease.
Fusobacterium: F. nucleatum periodontal pathogen
Extrinsic temperature
Intrinsic ph redox potentintial
The human mouth is kept at a relatively constant temperature (35–36°C) which provides stable conditions suitable for the growth of a wide range of microorganisms.
Periodontal pockets with active disease (inflammation) have a higher temperature up to 39°C) compared with healthy sites. Even such relatively small rises in temperature can significantly alter bacterial gene expression, and possibly the competitiveness of individual species.
A rise in temperature down-regulated expression of some of the major proteases as well as the gene coding for the major subunit protein of fimbriae
Enzymatic reactions are oxidation – reduction reactions in which one compound is oxidized and another compound is reduced
Eh is the measurement of the ease in which it gains or loose the electron
Oxidation reduction potential is nothing but is the ratio of total oxidizing (electron accepting) power to the total reducing power (electron donateing)power of substance.
Oxygen concentration is the main factor limiting the growth of obligately anaerobic bacteria.
after 4 line ---It is the commonest and most readily reduced electron acceptor in the majority of microbial habitats, and its presence results in the oxidation of the environment..
1. And are extremities of acid and alkali
After sugar consumption, the pH in plaque can fall rapidly to below pH 5.0 by the production of acids (predominantly lactic acid) by bacterial metabolism
the pH then recovers slowly to resting values.
Depending on the frequency of sugar intake, the bacteria in plaque will be exposed to varying challenges of low pH.
Many of the predominant plaque bacteria that are associated with healthy sites can tolerate brief conditions of low pH, but are inhibited or killed by more frequent or prolonged exposures to acidic conditions.
These latter conditions are likely to occur in subjects who commonly consume sugar-containing snacks or drinks between meals
This can result in the enhanced growth of, or colonization by, acid-tolerant (aciduric) species, especially mutans streptococci and Lactobacillus species which are normally absent or only minor components in dental plaque at healthy sites
Such a change in the bacterial composition of plaque predisposes a surface to dental caries.
Before everything ---Exogenous nutrients are the process in substances entering the body from the enviorment .
After 2 line ----Ingested food is broken down into comparatively simple chemical compound which are absorbed and then used to build tissues and organs to regulate functions .
carbohydrates can be broken down to acids while, additionally, sucrose can be converted by bacterial enzymes (glucosyltransferases, GTF, and fructosyltransferases, FTF) into two main classes of exopolymer (glucans and fructans) which can be used to consolidate attachment or act as extracellular nutrient storage compounds.
.
The levels of acid-tolerating species, especially mutans streptococci and lactobacilli, increase while the growth of acid-sensitive species (for example, some strains of Streptococcus sanguinis and S. gordonii) is inhibited, and they decrease. The metabolism of plaque changes so that the predominant fermentation product becomes lactate. Such alterations to the microflora and its metabolism can predispose a site to dental caries.
Lastly ------Dairy products (milk, cheese) have some influence on the ecology of the mouth. The ingestion of milk or milk products can protect the teeth against caries. This may be due to the buffering capacity of milk proteins or due to decarboxylation of amino acids after proteolysis since several bacterial species can metabolise casein
2. For eg: chemical properties of salivary mucins result in the formation of hydrophilic, viscoelastic gels function as protective barrier as well as bacterial aggregating factors.
3. they are termed as innate immunity and adaptive immunity
After 1 line ----because they are lost at an even faster rate by swallowing. Although saliva contains between approximately 10*8 viable microorganisms ml−1, these organisms are all derived from dental plaque and the oral mucosa, especially the tongue.
2.Produced by plasma cell in salivary gland.
3. by virtue of its local dispersal of environment antigens
4. but are derived from GCF it contains leukocytes
