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
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
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
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
