1. NORMAL FLORA
Dr. S.Harshad

2. INTRODUCTION
• THE TERM NORMAL MICROBIAL FLORA DENOTES THE POPULATION OF
MICROORGANISMS THAT INHABIT THE SKIN AND MUCOUS MEMBRANE OF
NORMAL HEALTHY INDIVIDUALS.
• THE ORGANISMS ARE PRESENT IN THOSE PARTS THAT ARE EXPOSED TO OR
COMMUNICATE WITH THE EXTERNAL ENVIRONMENT.
• MICROBES THAT HAVE THE ABILITY TO CAUSE SERIOUS DISEASES ARE
NORMALLY FOUND IN AND ON THE HUMAN BODY
• VIRUSES AND PARASITES ARE NOT CONSIDERED.
• IT IS MORE OR LESS COMMON IN ALL THE MAMMALIAN SPECIES.
• DIVIDED INTO RESIDENTS AND TRANSIENTS.

3. FUNCTIONS OF RESIDENT FLORA
• Maintains protected environment
• Production of proteolytic enzymes
• Synthesize vitamins and other biological
products like biotin, riboflavin, vitamin K etc.
• Colicins produced by some bacteria of normal
flora prevent harmful effects of some bacteria.

4. Microbial flora of mouth
• Among all micro-organism present in the
mouth bacteria are most predominant.
• These includes both aerobic and anaerobic
bacteria

5. cocci
GRAM POSITIVE COCCI
• Strep.mutans
• Strep.sanguis
• Strep.salivarius
• Strep.mitior
• Strep.milleri
• Enterococcus sps
• Peptostreptococcus aps
• Micrococcus sps
• Staphylococcus sps

6. GRAM NEGATIVE COCCI
• Veillonella sps
• Neisseria sps
• Branhamella sps

7. Bacilli
GRAM POSITIVE BACILLI
• Lactobacillus sps
• Actinomycetes sps
• Propionibacterium sps
• Arachnia sps
• Bifidobacterium sps
• Bacterionema sps
• Eubacterium sps

8. GRAM NEGATIVE BACILLI
• Actinobacillus sps
• Fusobacterium sps
• Bacteroids sps
• Capanocytophaga sps
• Leptotrichina sps
• Treponema sps
• Haemophilus sps
• Selenomonas sps
• Eikenella sps
• Wollinella sps

9. • Of all bacteria present in mouth, streptococci are
predominant group.
• Various species of Streptococci are encountered in
mouth.
• Most of these are alpha-haemolytic streptococci,
collectively named as viridians streptococci

10. Lactobacilli are frequently found in mouth.
They are imp bacteria to promote the progress
of carious lesion after the initiation of dental
caries by Strep mutans

11. • Veilonella is the most common among Gram-
negative bacteria.
• Fusobacterium nucleatum is the most
commonly occurring Gram-negative anaerobic
bacillus
• Other anaerobes such as Bacteroids,
Leptotrichia, Selenomonas etc have also been
found to be an imp group

12. • Oral treponema(T.vincenti,T.denticola,T.orale) are
common inhabitants of gingival crevice & sub
gingival area
• Due to their presence in subgingival plagues, they
have been imp role in causing gingivitis and most
forms of periodontitis.

13. Acquisition Of Normal Flora Of Mouth
• The mouth of newborn at birth is usually
microbiologically sterile.
• Within few hours of birth Streptococci
establish themselves in the mouth.

14. Acquisition Of Normal Flora Of Mouth
– Cont’d
• Among Streptococci, Strep. salivarius is
dominant at this stage.
• During the first year of life other species of
Streptococci,Staphylococci,Neisseriae,Veilonell
a,Actinomyces,Lactobacilli and Fusobacteria
also colonize.

15. Acquisition Of Normal Flora Of Mouth
– Cont’d
• With the eruption of teeth, solid surfaces in
the oral cavity are available for colonization.
• Strep mutans, Strep sanguis establish
themselves on these hard surfaces.
• Simultaneously, there is also increase in
number of obligate anaerobes

16. RESPIRATORY TRACT
• DIVIDED INTO
1.UPPER AIR WAYS (NARES AND NASOPHARYNX)
2.MIDDLE AIRWAYS ( OROPHARYNX AND
TONSILS)
3.LOWER AIRWAYS ( TRACHEA, LARYNX,
BRONCHI AND LUNGS)

17. NARES AND NASOPHARYNX
• NARES ARE INHIBITED BY
1. STAPHYLOCOCCUS SPS
2. CORYNEBACTERIUM SPS
3. PEPTOSTREPTOCOCCUS SPS
4. FUSOBACTERIUM SPS
• NASOPHARYNX, PREDOMINANCE OF
1. STREPTOCOCCI SPS
 STREPTOCOCCUS SALIVARIUS
 STREPTOCOCCUS PARASANGUIS
 STREPTOCOCCUS PNEUMONIAE
2. NEISSERIA SPS 3. GRAM-VE COCCOBACILLI
 N. MENINGITIDIS i) MORAXELLA CATARRHALIS
 N. SUBFLAVA ii) KINGELLA SPS
 N. SICCA 4. HAEMOPHILUS INFLUENZAE
 N.MUCOSA (UNCAPSULATED STRAINS)
 N. LACTAMIA

18. OROPHARYNX AND TONSILS
• ANAEROBES > AEROBES (100:1)
• PEPTOSTREPTOCOCCUS SPP
• VEILLONELLA
• ACTINOMYCES
• FUSOBACTERIUM
• STREPTOCOCCUS
• NEISSERIA
• STOMATOCOCCUS MUCILAGINOSUS
• GEMELLA SPECIES

19. TRACHEA, LARYNX, BRONCHI & LUNGS
• TRANSIENT COLONIZATION
• LONG TERM COLONOZATION OCCUR WHEN
CILIATED EPITHELIAL CELLS ARE DAMAGED OR
ALTERED IN DISEASE PROCESS

20. GASTROINTESTINAL TRACT
• DIVIDED INTO
1. ESOPHAGUS
2. STOMACH
3. JEJUNUM & UPPER ILEUM
4. DISTAL SMALL INTESTINE
5. LARGE INTESTINE

21. ESOPHAGUS
• TRANSTIENT COLONIZATION BY
OROPHARYNGEAL BACTERIA AND YEAST IS
KNOWN TO OCCUR.

22. STOMACH
• HYDROCHLORIC ACID AND PEPSINOGEN
• VERY SPARSE MICROBIAL FLORA
• LACTOBACILLUS SPP
• STREPTOCOCCUS SPP
• HELICOBACTER PYROLI

23. JEJUNUM AND UPPER ILEUM
• PREDOMINANTLY ANAEROBIC
• LACTOBACILLUS
• PEPTOSTREPTOCOCCUS
• STREPTOCOCCUS
• PORPHYROMONAS
• PREVOTELLA

24. DISTAL SMALL INTESTINE
• SPARSE AMOUT OF ACID-TOLERANT BACTERIA
• PREDOMINANCE OF ANAEROBES

25. LARGE INTESTINE
• ANAEROBIC > AEROBIC
• BIFIDOBACTERIUM SPS
• BACTEROIDES FRAGILIS
• EUBACTERIUM SPP
• ENTEROCOCCUS SPP
• E COLI
• STREPTOCOCCUS SPP
• ACTINOMYCES
• PEPTOSTREPTOCOCCUS
• FUSOBACTERIUM
• PORPHYROMONAS
• PREVOTELLA
• CANDIDA AND PROTOZOA

26. GENITOURINARY TRACT
• EXCEPT FEMALE URETHRA AND VAGINA THE GUT IS GENERALLY STERILE
• LACTOBACILLI
• STREPTOCOCCAL SPECIES
• BIFIDOBACTERIUM
• PEPTOSTREPTOCOCCUS
• PORPHYROMONAS
• PREVOTELLA
• ACTINOMYCES
• STAPHYLOCOCCUS
• STREPTOCOCCUS
• CORYNEBACTERIUM
• GARDNERELLA VAGINALIS
• NEISSERIA
• HAEMOPHILUS
• TREPONEMA

27. BODY SURFACE
• HIGHER DENSITIES OF MICROBES IN MOIST AREA
• ANAEROBIC > AEROBIC
• GRAM +VE > GRAM –VE
• STAPHYLOCOCCUS
• MICROCOCCUS
• CORYNEBACTERIUM
• PEPTOSTREPTOCOCCUS
• PROPIONIBACTERIUM

28. CONJUNCTIVA
• FLUSHING ACTION AND LYSOZYMES IN TEARS
MAKE THE CONJUCTIVA FREE OF BACTERIA
• C. XEROSIS
• MORAXELLA SPP
• S. AUREUS
• NON HAEMOLYTIC STREPTOCOCCI

29. THANK YOU