microbiology orally

1. Dr.Iman Qoraan
Spring 2020
The Resident Oral Microflora

2. Diversity of resident flora
Synergic
metabolic
interactions by
microorganisms
Dental
plaque
biofilms
Diversity
of
nutrients
supplied

3. Microbial
classification
schemes
Conventional
Morphological
and
Physiological
Chemical
properties :
enzymes ,
carbohydrate ,
amino acid, etc...
Serological :
antigen-­
antibody
reactions
Molecular
16S
ribosomal
RNA gene
amplification

4. -­Simple
-­Quantitative
-­Sensitivity tests
-­Rapid(serological tests)
-­Some tests can be done
directly on clinical samples
(other than culture)
-Pure culture is needed
-­Not all microorganisms can
be cultured(e.g: treponema)
Conventional Identification Methods
Advantages
Disadvantages

5. Around 700
microorganism
present in the oral
cavity
Only 50% can be
cultured

6. Molecular Identification Methods
*Accurate
*Rapid
*Sensitive
*Provide information about non
culturable microorganisms
*Data sequences is limited
*Antimicrobial sensitivity is not
possible
Pros
Cons

7. Oral
Microorganisms
Bacteria
Gram
positive
(cocci,
bacilli)
Gram
negative
(cocci,
bacilli)
Obligate
anaerobes
Mycoplasma
Fungi Protozoa
Archea Viruses

8. Gram Positive Cell Wall

9. A. Mutans streptococcus Group
Mutans(different shapes): cocci, coccobacilli,bacilli
Extracellular soluble/insoluble glucan, mutan (insoluble
glucan), fructan ,and intracellular polysaccharides
Release signaling molecules that induce genetic transformation
and acid tolerance
Facultative anaerobic , acidophilic,acidogenic
AntigenI/II subunit vaccine

10. 1. S. mutans
c,e,f,k human
serotypes
Favors hard non
shedding
surfaces
(teeth, denture)
Opportunistic
(dental caries,
endocarditis)

11. Streptococcus mutans
Gram stain Colonies on blood agar

12. 2.
S. sobrinus
Inhibited by bacitracin
d,g serotypes are human specific
AntigenI/II is also present (SpaA)
Associated with dental caries
Produce extracellular and intracellular
polysaccharides

13. B. Anginosus Group
S.anginosus
• Isolated from
purulent
infections like
maxillofacial and
other body sites
• Don’t produce
extracellular
polysaccharides
S.intermedius
• Produce
intermedilysin
affect neutrophil
function in
abscess formation
• Don't produce
extracellular
polysaccharides
• isolated from
brain and liver
abscesses
S.constellatus
• Derived from
purulent
infections
• Don’t produce
extracellular
polysaccharides

14. Anginosus Group
S. anginosus may be B-hemolytic or none

15. • Isolated from vestibular mucosa of
mouth
• Produce urease and H2O2 which
inhibit competing bacteria
• Do not produce extracellular
polysaccharides
• Opportunistic endocarditis and
bacteremia
S.vestibularis
• Colonize mucosal surfaces mainly the
tongue ,rarely cause disease
• Produce extracellular fructan, glucan
and levanase
• Levan (extracllular fructan) make
mucoid colonies on sucrose containing
agar
S. salivarius
C. Salivarius group

16. D.Mitis group
S.sanguinis
Colonize
tooth
surface
Produce
extracellular
glucan
Cleave
arginine
and
generate
ammonia
Produce
IgA
prtoease
S.gordonii
Colonize
tooth
surface
Produce
extracellular
glucan
Cleave
arginine and
generate
ammonia
Cleave starch
using salivary
alpha
amylase(binding
to amylase
protect it from
host) defenses-­
host mimicry
S.oralis
produce
neuraminidase
enhance
adherence by
cleaving sialic
acid from mucin
Produce IgA
protease
Competent for
natural genetic
transformation
S.mitis
Opportunistic
pathogen
misidentified as
S.pneumoniae
Cause infective
endocarditis
Competent for
natural genetic
transformation

17. Nutritionally variant streptococci
ØGranulicatella adiacens(S.adiacens):
ü Require cysteine ,pyridoxal(vitamin B6) for growth
ü Exhibit satellitism with other bacteria that provide
cofactors
ØAbiotrophia defectiva

18. Other Gram positive cocci
Ø Enterococcus faecalis : isolated from immunocompromised
patients, treatment failed periodontal pocket
Ø S.pyogenes: isolated from saliva of patients with sore throat
Ø Staphylococcus and Micrococci: Transient flora, isolated from
denture plaque
Ø Peptostreptococcus stomatis: anaerobic,isolated from dental
abscesses,infected pulp chambers,root canals and advanced
forms of periodontal disease

19. Gram Positive Rods and Filaments

20. A. Actinomyces
A.naeslundii
Major portion of
dental plaque,
colonize mouth at
infant age
produce fructan,
urease,neuraminidase
have fimbriae for
coaggregation and
cell-­surface
interaction
A.israelii
opportunistic
pathogen cause
actinomycosis
produce protective
granules that help
bacteria evade
immune system
and antibiotic
treatment and
disseminate into
body
A.odontolyticus
form red
pigment
colonize mouth
at infant age

21. B. Eubacterium
Gram variable,filamentous , obligate anaerobe, non
culturable
Asaccharolytic
Form dentoalveolar abscesses

22. C. Lactobacillus species
Some
species
are cocci
Acidogenic
and acid
tolerant
There salivary
levels are
useful to
monitor
patient's
dietary
behavior
(carbohydrate
intake) and
cariogenic
potential of a
mouth
Isolated
from
advanced
caries
lesions

23. Lactobacillus

24. Other Gram Positive Rods
qPropionibacterium spp.:obligate anaerobic, found in
dental plaque
qBifidobacterium dentium:isolated from dental plaque
qRothia mucilaginosa: produce extracellular
polysaccharides,isolated exclusively from the
tongue
qCorynebacterium matruchutii: short fat cell and long
filament growing out( whip-­handle cell)
Corynebacterium matruchutii

25. Gram Negative Cell Wall and Stain

26. Gram Negative Cocci
Neisseria
• Consume
oxygen
creating
anaerobic
environment
during plaque
formation
Moraxella catarrhalis
• opportunistic
pathogen
• B-­lactamase producer
Veillonella
• Strict
anaerobic
• unable to
metabolize
carbohydrates
• Convert lactic
acid to
weaker acid
preventing
enamel
dissolution

27. Gram Negative Rods
q Haemophilus
Ø H.parainfluenzae: Require NAD
(nicotinamide adenine dinucleotide )
q Aggregatibacter
Ø A.actinomycetemcomitans
Ø Capnophilic (require 5-­10% CO2)
Ø Opportunistic pathogen produce collagenase, IgG
protease
Ø Cause aggressive periodontitis in adults

28. Obligately Anaerobic Genera
qBlack pigmented anaerobes:
Ø Prevotella and Porphyromonas
Ø Produce brown-­black pigment on Blood agar
Ø Require X-­factor (hemin)
Ø Isolated from subgingival sites of dental plaques
qFusobacterium
Ø Pleomorphic,long filamentous
Ø Asaccharolytic Use amino acids as energy source
Ø Some species isolated from normal gingival crevice others are
associated with periodontal disease

29. Black pigmented anaerobes

30. Fusobacterium

31. Obligately Anaerobic Genera
qHelicobacter pylori
Ø Associated with gastritis, peptic ulcers and gastric
cancer
Ø Transiently found in the mouth following reflux from
the stomach

32. Obligately Anaerobic Genera
qSpirochaetes
Ø Isolated from subgingival plaque
Ø Their number is diagnostic for necrotizing ulcerative
periodontitis
Ø Characterized by endoplasmic flagella(axial filaments)
Ø Difficult to be cultured, need dark field microscope,
molecular methods
Ø Treponema denticola
ü Proteolytic: degrade collagen and gelatin
ü Can be cultured

33. Spirochetes Cell wall and Gram stain

34. Fungi
Present in
small
proportion
Imperfect
yeast
(divide
asexually)
like candida
are
common
flora
Perfect
(divide
sexually)
yeast are
transient in
healthy
individuals
Perfect
molds like
Aspergillus ,
Mucor,
Geotrichum
present in
AIDS
patients

35. 1. Candida albicans
is the main oral fungal
flora
2. C. glabrata, C. krusei,
C. tropicalis,
C.guilliermundii,
Rhodotorulla,
Saccharomyces
are present
3. Isolated mainly from
dorsum of the tongue and
increased with presence of
intra-­oral devices like
dentures or orthodontic
appliances
4. Carriage rate increases
at middle and old age
Fungi

36. Mycoplasma
Disease associated
M.orale, M. salivarium associated with salivary gland
hypofunction
Isolation
mucosal surfaces
RT,UT
Saliva
M.salivarium
M.pneumonaie
Oral mucosa
M.buccale
M. orale
Growth media
Need enriched media with
protein
Elevated CO2
Shape and size
Lack cell wall
Gram negative pleomorphic
Smallest free growing
cells<1um

37. Mycoplasma structure

38. Viruses
1. Herpesviridae
Herpes simplex virus type1 (HSV1)
• Most virus isolated from saliva
and orofacial areas
• Persist within oral tissues
• Cause cold sores
• Remains latent in trigeminal
nerve ganglion
• Reactivated by stress or UV light
• Mainly recovered by molecular
methods
Cytomegalovirus(CMV)
• Isolated from saliva
• Latent
• persistent
• Portal entry to oral cavity
is unknown

39. Cytomegalovirus infection

40. Viruses
2. Coxakievirus A
Coxakievirus A serotypes
2,4,5,6,8,9,10,16 isolated from oral
epithelium and saliva
Disease
Herpangina( hand,foot,mouth
disease)

41. Coxakievirus

42. Viruses
3.Human papilloma virus(HPV)
more than 100 type
2,4,6,11,16 detected in
oral lesions of AIDS
Isolated from tissues
with hyperplastic warty
like lesions
(verruca vulgaris)

44. Viruses
Hepatits B &HIV
HBV
Present in saliva
of carriers
Cross infection
threat
HIV
Present in
saliva
Cross infection
threat(rare)

45. Hepatitis B HIV

46. Other Viruses
qMumps and measles in oral lesions
qBacteriophage
ü Viruses for which bacteria are the natural hosts
ü Bacteriophage specific for S.mutans, Lactobacillus,
Actinomyces, Veillonella and Aggregatibacter sp.
ü Isolated from saliva and dental plaque samples

48. Protozoa
microscopic
unicellular
eukaryotes
Their life cycle
consist of
trophozoite
the motile,
feeding form)
and cyst
(protective form)
Some are motile by
flagella , cilia or
pseudopodia while
others are non
motile
Reproduce
asexually by
binary
fission,
(apicomplexa
reproduce
sexually

49. Protozoa
Trichomonas tenax
Commensal in oral cavity
Heterotrophic (acquire
carbon through ingestion
of other microorganisms ,
organic matter and
leucocytes)
Motile by flagella and
undulating membrane
Increase in patients with
periodontal disease
Entamoeba gingivalis
First ameobae isolated
from human
Heterotrophic
Motile by pseudopodia
found in the gingival
pocket(abnormal depth of
the gingival sulcus

50. Trichomonas tenax