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Normal Microflora of Human body

This will tells the importance microorganisms present in various parts of our body

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Normal Microflora of Human body

  1. 1. Presented by NISHANTH S 2016601106Department of Agricultural Microbiology
  2. 2. Normal microflora and its groups • The term “normal microbial flora” denotes the population of microorganisms that inhabit the skin and mucous membranes of healthy normal persons. • The skin and mucous membranes always harbor a variety of microorganisms that can be arranged into two groups: Resident flora: The resident flora consists of relatively fixed types of microorganisms regularly found in a given area at a given age; If disturbed, it promptly re-establishes itself. 1. Resident flora 2.Transient flora
  3. 3. Examples of Resident biota
  4. 4. Transient flora: • The transient flora consists of non-pathogenic or potentially pathogenic microorganisms that inhabit the skin or mucous membranes for hours, days, or weeks. • It is derived from the environment, does not produce disease, and does not establish itself permanently on the surface. • Generally of little significance so long as the normal resident flora remains intact. • However, if the resident flora is disturbed, transient microorganisms may colonize, proliferate, and produce disease.
  5. 5. • Normal flora are microorganisms that are frequently found in a particular site in normal healthy individual, they are mostly bacteria and it doesn't cause any illness. • Normal flora is divided into different types: Commensals Natural relationship with host Residents Present for a long time Transients Present for a short time Carrier state This type is different from the other – potential pathogenic Ex: Streptococcus pneumoniae
  6. 6. The most comprehensive analysis - 27 distinct body sites and revealed the presence of 22 bacterial phyla, with most sequences (92.3%) related to just four phyla:  Actinobacteria :36.6%  Firmicutes :34.3%  Proteobacteria :11.9%  Bacteroidetes :9.5% Actinobacteria 36.6% Firmicutes 34.3% Proteobacteria 11.9% Bacteroidetes 9.5% Common group of Microbiota in Human body
  7. 7. Actinobacteria Corynebacterium, Propionibacterium, Microbacterium, Micrococcus Firmicutes Staphylococcus Clostridium Proteobacteria Pseudomonas, Janthinobacterium, Serratia, Halomonas, Stenotrophomonas, Delftia, Comamonas Bacteriodetes Sphingobacterium, Cryseobacterium
  8. 8. • Members of the normal flora form part of the host and include: Saprophytes Commensals Facultative pathogens and True pathogens
  9. 9. Methanobrevibacter smithii Methanosphaera stadtmanae Candida species Malassezia species - skin Major group of microbes
  10. 10. Sterile organs in human body Internal organs except alimentary tract are STERILE at health. Sterility maintained by: 1. Local defense mechanisms 2. Chemical substances in serum & tissues. Ex: Antibodies. 3. Phagocytic activity of polymorphomononucleocytes (PMN) Areas of the body with normal flora: • Respiratory tract • Gastrointestinal tract • Genital tract • Skin • External auditory meatus
  11. 11. Newborn is sterile from normal flora in uterus. After birth, it will be exposed to many sources of normal flora Ex: mother’s genital tract and skin
  12. 12. Human body 1013 cells 1014 bacteria 10<1-3 109 102 103-6 105-7 103 109-11 106-7 105-6
  13. 13.  Largest organ – 2 m2 of area  Inhabits 102 - 104 organisms/sq. cm Unfavourable habitat for microorganisms – 1. has many areas subject to periodic drying 2. acidic pH 3. high sodium chloride concentration Most skin microbes are associated with glands  eccrine glands—dispersed sweat glands  apocrine glands—sweat glands activated during puberty (underarm, genital area, etc.)  sebaceous glands—with each hair follicle
  14. 14. Gland secretions contain water, amino acids, urea, salts, and fatty acids that can serve as nutrients Staphylococcus epidermidis- found in regions of high moisture SITE COMMON ORGANISMS LESS COMMON Cutaneous surfaces including urethra and outer ear Staphyloccocus epidermidis Staphyloccocus aureus, Corynebacteria (diphteroids) Streptococci, Anaerobes e.g. Peptostreptococci, Yeast (Candida sp.)
  15. 15.  S. epidermidis: Major inhabitant making up more than 90% of the flora  S. aureus: Nose, perineum, vulvar skin Occurrence in nasal passages varies with age being greatest in newborns, less in adults  Micrococci, Diphtheroids, Propionibacterium Eg. P. acnes = children younger than 10 years are rarely colonized with it
  16. 16. Variety of bacteria: low numbers present 1. High moisture 2. Blinking mechanically removes bacteria 3. Lachrymal secretions include lysozyme – peptidoglycan break Predominant organisms of the eyes are:  Moraxella sp  Diphtheroids  S. epidermidis  Moraxella sp  Non hemolytic streptococci
  17. 17. The nasopharynx of the infant is sterile at birth but in 2-3 days time it acquires the flora. The nasopharynx is a natural habitat of the common pathogenic bacteria causing infection of the nose, throat, bronchi and lungs. The flora of nose harbours • Diptheroids • Straphylococcus • Streptococcus • Haemophilus, and • Moraxella lacunata
  18. 18. Modes of protection: 1. continuous stream of flowing mucus produced by ciliated cells 2. phagocytic action of macrophages 3. production of lysozyme in mucus Major sections of the respiratory tract: Upper: nasopharynx, oral cavity, throat – This is colonized by a wide assortment of microorganisms (streptococci, staphylococci, Gram-negative cocci) including pathogens (Staphylococcus aureus, Streptococcus pyrogenes, S. pneumoniae, Corynebacterium diphtheriae) Lower: trachea, lungs – nearly sterile
  19. 19. Ecology and developmental stages 1. Birth: sterile mouth within 4-12 hours (lactobacilli, streptococci) 2. Neonate (Streptococcus salivarius, staphylococci, Neisseriae, Moraxella catarrhalis) 3. Teeth appear (Streptococcus mutans, Streptococcus parasanguis) 4. Gingival crevice area (Anaerobic species, yeasts) 5. Puberty (Bacteroides, spirochetes) 108 bacteria/mL of saliva; potentially >700 species
  20. 20. Helicobacter pylori - urease Bacterial fermentation chamber
  21. 21.  Mycobacterium smegmatis a harmless commensal is found in the secretions (smegma) of both males and females genitalia.  Gardnerella vaginalis, bacteroides and alpha streptococci have been found in penile urethra. The microbiology of the vagina is especially interesting: 1. Pre-puberty: no glycogen, High pH 2. After puberty: glycogen is used by microbes as food, fermented to lactic acid (especially, Lactobacillus acidophilus) and pH is acidic. 3. After menopause: returns to the glycogen-free, alkaline environment lacking lactic acid bacteria. due to the actions of circulating estrogens
  22. 22. Lactobacillus acidophilus and a vaginal squamous epithelial cell. Streptococcus mutans, the main bacterium implicated in dental caries Propionibacterim acnesStaphylococcus epidermidis
  23. 23. Neisseria species - throat.Clostridium difficile - large intestine Enterococcus faecalis ‐ intestineBifidobacterium bifidus
  24. 24. Escherichia coli Gram stain and colonies on EMB agar