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Presentation on theme: "Dr.T.V.Rao MD NORMAL HUMAN FLORA DR.T.V.RAO MD 1."— Presentation transcript:


2 HUMAN MICROBIOME DR.T.V.RAO MD 2 The human microbiome (or human micro biota ) is the aggregate of microorganisms that reside on the surface and in deep layers of skin, in the saliva and oral mucosa, in the conjunctiva, and in the gastrointestinal tracts. They include bacteria, fungi. Some of these organisms perform tasks that are useful for the human host. However, the majority have no known beneficial or harmful effect. Those that are expected to be present, and that under normal circumstances do not cause disease, but instead participate in maintaining health, are deemed members of the normal flora

3 More bacterial than human cells in the body More bacterial than human cells in the body provide some nutrients (vitamin K) stimulate immune system, immunity can be cross-reactive against certain pathogens Prevent colonization by potential pathogens (antibiotic-associated colitis, Clostridium difficile ) NORMAL BACTERIAL FLORA DR.T.V.RAO MD 3

4 OVERVIEW OF HUMAN-MICROBIAL INTERACTIONS Microbial flora of the healthy human host 1) The reasons for understanding the normal flora of the healthy human body ▶ Normal flora vs. human body ▶ Some normal flora: opportunistic pathogens when injury occurred, when resistance of body decreased, when moved to another site 2) Origin of the normal flora 3) Relationship between normal flora and human host 4) Distribution and occurrence of the normal flora DR.T.V.RAO MD 4


6 INTRODUCTION OF NORMAL FLORA 1.A diverse microbial flora => Human body Area: the skin and mucous membranes Time: shortly after birth until death Number: 10 14 bacteria =>10 13 host cells 2. Normal flora may: a. Aid the host b. Harm the host (in sometimes) c. Exist as commensals (no effect to the host) 3.Viruses and parasites NOT normal microbial flora 3.Viruses and parasites => NOT normal microbial flora Most investigators consider that they are not commensals and do not aid the host. DR.T.V.RAO MD 6

7 Colonization vs. Infection Colonization: establishment of a site of reproduction of microbes on a person without necessarily resulting in tissue invasion or damage. Infection: growth and multiplication of a microbe in or on the body of the host with or without the production of disease. Outcomes of exposure to a microorganism: 1.Transient colonization 2. Permanent colonization 3.Disease Normal Flora and Pathogenesis DR.T.V.RAO MD 7

8 SIGNIFICANCE OF NORMAL FLORA 1.The normal flora influences the anatomy, physiology, susceptibility to pathogens, and morbidity of the host. 2. The effect of the normal flora on the host was not well understood until germ-free animals became available. Cesarean Section => Germ-free animals => Isolators w/o detectable pathogens (viruses, bacteria & others) 3. Two interesting observations: a. the germ-free animals lived almost twice as long as their conventionally maintained counterparts. b. the major causes of death were different in the two groups. DR.T.V.RAO MD 8

9 1.Local Environment (pH, temperature, redox potential, O2, H2O, and nutrient levels…). 2.Diet 3.Age 4.Health condition (immune activity…) 5.Antibiotics,…..etc FACTORS INFLUENCING NORMAL FLORA DR.T.V.RAO MD 9

10 Significance of Normal Flora Normal flora may aid the host in several ways: Aid in digestion of foodAid in digestion of food Help the development of mucosa immunityHelp the development of mucosa immunity Protect the host from colonization with pathogenic micrProtect the host from colonization with pathogenic microbes. Normal flora may aid the host in several ways: Aid in digestion of foodAid in digestion of food Help the development of mucosa immunityHelp the development of mucosa immunity Protect the host from colonization with pathogenic micrProtect the host from colonization with pathogenic microbes. 10 6 pathogenic microbes GI infection w/ normal flora GI infection w/ reduced flora after Streptomycin treatment w/ reduced flora after Streptomycin treatment 10 pathogenic microbes DR.T.V.RAO MD 10

11 COMPOSITION OF THE NORMAL FLORA DR.T.V.RAO MD 11 The normal flora of humans are exceedingly complex and consist of more than 200 species of bacteria. The makeup of the normal flora may be influenced by various factors, including genetics, age, sex, stress, nutrition and diet of the individual. Three developmental changes in humans, weaning, the eruption of the teeth, and the onset and cessation of ovarian functions, invariably affect the composition of the normal flora in the intestinal tract, the oral cavity, and the vagina, respectively. However, within the limits of these fluctuations, the bacterial flora of humans is sufficiently constant to a give general description of the situation

12 DR.T.V.RAO MD 12

13 A human first becomes colonized by a normal flora at the moment of birth and passage through the birth canal. In utero, the fetus is sterile, but when the mother's water breaks and the birth process begins, so does colonization of the body surfaces. Handling and feeding of the infant after birth leads to establishment of a stable normal flora on the skin, oral cavity and intestinal tract in about 48 hours. WHEN WE GET COLONIZED WITH NORMAL FLORA DR.T.V.RAO MD 13

14 The composition of a child’s bacterial flora is dependent on the mother’s micro flora, since she is the primary source for the child’s bacteria at the outset A NEW BORN CHILD'S FLORA IS DEPENDENT ON MOTHER DR.T.V.RAO MD 14

15 It has been calculated that a human adult houses about 10 12 bacteria on the skin, 10 10 in the mouth, and 10 14 in the gastrointestinal tract. The latter number is far in excess of the number of eukaryotic cells in all the tissues and organs which comprise a human. The predominant bacteria on the surfaces of the human body are listed in Table 3. Informal names identify the bacteria in this table. DENSITY OF NORMAL FLORA IN HUMANS DR.T.V.RAO MD 15

16 Resident flora Reflects sex of person Normal Flora DR.T.V.RAO MD 16


18 HUMANS AS HABITATS Colonization (and infection) frequently begin at mucous membranes These are found throughout the body. Consist of single or multiple layers of epithelial cells, tightly packed cells in direct contact with the external _____________________________. Bacteria may associate loosely or firmly Breaches in the _______________ barrier can result in infection (pathogenesis)by opportunistic pathogens DR.T.V.RAO MD 18


20 COMMON SKIN BACTERIUM MAY BE NEW OPPORTUNISTIC PATHOGEN* Helococcus kunzii is a recently identified bacterium that is thought to be a nonpathogenic member of normal human skin flora and is rarely associated with skin infections. In the study though, the researchers report the isolation of the organism from an infected cyst on the breast of a 57-year-old immunocompromised woman. Finding provides further support for the opportunistic role of H. kunzii in causing infection in both immunosuppre ssed and immunocompetent patients," say the researchers. A.H. Chagla, A.A. Borczyk, R.R. Facklam, and M. Lovgren. 1998. Breast abscess associated with Helocococcus kunzii. Journal of Clinical Microbiology. 36:2377-2379.) DR.T.V.RAO MD 20

21 we do not fully understand its ecological relationship with humans E. coli is the best known bacterium that regularly associates itself with humans, being an invariable component of the human intestinal tract. Even though E. coli is the most studied of all bacteria, and we know the exact location and sequence of 4,288 genes on its chromosome, we do not fully understand its ecological relationship with humans ASSOCIATIONS BETWEEN HUMANS AND THE NORMAL FLORA DR.T.V.RAO MD 21

22 Sometimes the relationship between a member of the normal flora an its host cannot be deciphered. Such a relationship where there is no apparent benefit or harm to either organism during their association is referred to as a commensal relationship. Many of the normal flora that are not predominant in their habitat, even though always present in low numbers, are thought of as commensal bacteria. However, if a presumed commensal relationship is studied in detail, parasitic or mutualistic characteristics often emerge. COMMENSAL RELATIONSHIP. DR.T.V.RAO MD 22

23 NORMAL FLORA ARE MUTUALISTIC DR.T.V.RAO MD 23 Much is not known about the nature of the associations between humans and their normal flora, but they are thought to be dynamic interactions rather than associations of mutual indifference. Both host and bacteria are thought to derive benefit from each other, and the associations are, for the most part, mutualistic. The normal flora derive from their host a steady supply of nutrients, a stable environment, and protection and transport. The host obtains from the normal flora certain nutritional and digestive benefits, stimulation of the development and activity of immune system, and protection against colonization and infection by pathogenic microbes.

24 NORMAL FLORA OF THE GASTROINTESTINAL TRACT (GIT) In bottle-fed infants Bifidobacteria are not predominant. When breast-fed infants are switched to a diet of cow's milk or solid food, bifidobacteria are progressively joined by: 1.Enterics 2.Bacteroides 3.Enterococci 4.Lactobacilli 5.Clostridia DR.T.V.RAO MD 24

25 NORMAL MICROBIAL FLORA OF THE GASTROINTESTINAL TRACT Functions and Products of Intestinal Flora Intestinal microbes carry out a variety of essential metabolic reactions that produce various compounds The type and amount produced is influenced by the composition of the intestinal flora and the diet Compounds produced include vitamins B 12 and Kvitamins B 12 and K gasgas DR.T.V.RAO MD 25

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27 THE FLORA OF THE LARGE INTESTINE (COLON) 1.Enterococci 2.Clostridia 3.lactobacilli 4.Bacteroides 5.Bifidobacterium ( Bifidobacterium bifidum ) 6. Escherichia coli 7.Methanogenic bacteria 8. Viridans streptococci 9. Staphylococcus sp. 10. Proteus sp. 11. Candida albicans (Yeast) 12. Mycoplama sp. DR.T.V.RAO MD 27

28 NORMAL FLORA OF THE RESPIRATORY TRACT A) The nares (nostrils) 1. Staphylococcus epidermidis 2.Corynebacterium 3.Staphylococcus aureus 4. Neisseria sp. 5. Haemophilus sp 6. Streptococcus pneumoniae DR.T.V.RAO MD 28

29 NORMAL FLORA OF THE RESPIRATORY TRACT B) The upper respiratory tract (nasopharynx). 1.Non-hemolytic streptococci 2.Alpha-hemolytic streptococci 3. Neisseria sp. 4. Streptococcus pneumoniae 5. Streptococcus pyogenes 6. Hemophilus influenzae 7. Neisseria meningitidis DR.T.V.RAO MD 29

30 NORMAL FLORA OF THE RESPIRATORY TRACT C) The lower respiratory tract (trachea, bronchi, and pulmonary tissues): Usually sterile. The individual may become susceptible to infection by pathogens descending from the nasopharynx e.g. H. influenzae S. pneumoniae ). DR.T.V.RAO MD 30

31 NORMAL FLORA OF THE HUMAN ORAL CAVITY Oral bacteria include: Viridans streptococci 1. Viridans streptococci 2.Lactobacilli 3.Staphylococci ( S. aureus and S. epidermidis ) 4. Corynebacterium sp. 5. Bacteroides sp. 6. Streptococcus sanguis (dental plaque) 7. Streptococcus mutans (dental plaque) 8. Actinomyces sp. DR.T.V.RAO MD 31

32 SITES OF HUMAN BODY THAT THE NORMAL FLORA MICROBES COLONIZE Respiratory tract and head outer ear, eye, mouth, oropharynx, nasopharynx Sterile sites: sinuses, middle ear, brain, lower respiratory tract (trachea, bronchiole, lung) Gastrointestinal tract esophagus, stomach, small intestine, large intestine Genitourinary system anterior urethra, vagina Sterile sites: bladder, cervix, uterus Skin DR.T.V.RAO MD 32

33 Especially in hosts rendered susceptible by: 1. Immuno-suppression (AIDS & SCID) 2. Radiation therapy & Chemotherapy 3. Perforated mucous membranes 4. Rheumatic heart disease…etc. NORMAL FLORA MAY ACT AS OPPORTUNISTIC PATHOGENS DR.T.V.RAO MD 33

34 Sterile tissues In a healthy human, the internal tissues such as: blood brain muscle cerbrospinal fluid (csf.) are normally free of microorganisms. Normal Flora absent in … DR.T.V.RAO MD 34

35 1. They constitute a protective host defense mechanism by occupying ecological niches. Importance of The Normal Flora (Advantages) DR.T.V.RAO MD 35

36 NORMAL FLORA OF THE SKIN The most important sites are: 1.Axilla 2.Groin 3.Areas between the toes DR.T.V.RAO MD 36

37 The oral flora contribute to immunity by inducing low levels of circulating and secretory antibodies that may cross react with pathogens. IMPORTANCE OF THE NORMAL FLORA (ADVANTAGES) DR.T.V.RAO MD 37

38 1. They can cause disease in the following: a) When individuals become immunocompromised or debilitated. b) When they change their usual anatomic location. IMPORTANCE OF THE NORMAL FLORA (DISADVANTAGES) DR.T.V.RAO MD 38

39 FECAL BACTERIOTHERAPY DR.T.V.RAO MD 39 Fecal bacteriotherapy, which is now officially and scientifically known as fecal micro biota transplantation and is also referred to as fecal micro biota therapy, fecal transfusion, fecal transplant, stool transplant, fecal enema or human probiotic infusion ( HPI ), is a medical treatment for patients with pseudomembranous colitis (caused by Clostridium difficile ), or ulcerative colitis that involves restoration of colon homeostasis by reintroducing normal bacterial flora from stool obtained from a healthy donor.

40 Fecal micro biota transplantation (FMT) -- also known as fecal bacteriotherapy, among other names -- is an effort to calm a troubled bowel by reintroducing the vast diversity of collaborative bowel inhabitants after the usual mix has been disturbed. More than 1,000 different strains of bacteria co- exist peacefully in the typical healthy bowel. But when the delicate balance is altered, by antibiotics or other causes, a few strains can become dominant, leading to severe diarrhea, inflammation and tissue damage. FECAL MICRO BIOTA TRANSPLANTATION DR.T.V.RAO MD 40

41 Like an organ transplant, fecal microbiota transplantation begins with finding a donor, often a family member. The treatment team collects a fresh stool sample, at least 200 to 300 grams. The sample is mixed with salt water in a blender and filtered to remove particulate matter. It can be administered to the recipient through a colonoscopy, as an enema, or -- when the inflamed region is higher in the colon -- through a naso-gastric tube. MICROBIOTA TRANSPLANTATION DR.T.V.RAO MD 41

42 Programme created by Dr.T.V.Rao MD for Medical and Paramedical students in the Developing World DR.T.V.RAO MD 42

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