However, in areas where diets are high in plant polysaccharides and easily digestible nutrients are scarce, colonic fermentation could mean the difference between life and death.
There is also evidence that E. The colon is a very complex microbial environment that we are only beginning to understand. Relative to other microbial populations of the human body little is known about the normal flora of the vaginal tract.
The predominant bacterial species are Lactobacillus. As is the case in other areas of the body, the presence of normal flora in the vaginal tract appears to have a protective role since women taking antibiotics for acne or urinary tract infections who have reduced levels of Lactobacillus often develop yeast infections.
It is thought that Lactobacillus may prevent the growth of yeast by producing hydrogen peroxide, a bi-product of bacterial metabolism. The examples presented above describe a few examples of normal flora around the human body.
Maintaining a balance is crucial. Normal flora consists of communities of bacteria that function as microbial ecosystems.
If these ecosystems are disrupted the consequences can be unpredictable. Antibiotics, tissue damage, medical procedures, changes in diet, and the introduction of new pathogens are examples of changes that can affect your normal flora. We are only beginning to appreciate the complexity and function of normal flora in the human body.
Our understanding of microbial communities has been limited by our ability to culture microbes in the laboratory environment. Today, new technologies such as the polymerase chain reaction PCR , high-throughput DNA sequencing and DNA microarrays are starting to provide glimpses into these microbial ecosystems.
Advancing our understanding of normal flora will provide us with fundamental information about who we are. New York: Wiley. English MP. Microbiology: Diversity, Disease and the Environment. Bethesda Maryland: Fitzgerald Science Press. Todar K. The Normal Bacterial Flora of Animals. University of Wisconsin Department of Bacteriology. Hillman JD. Genetically modified Streptococcus mutans for the prevention of dental caries.
Antonie Van Leeuwenhoek 82 : Lynch NA. Helicobacter pylori and Ulcers: a Paradigm Revised. Federation of American Society for Experimental Biology. Relman DA, Falkow S. The meaning and impact of the human genome sequence for microbiology. Trends Microbiol 9 5 : August Microbes are everywhere. Microbes and You You are covered in microorganisms! Each of these areas of the body contain their own microenvironments and various inhabitants of microbes The human body provides many unique environments for different bacterial communities to live.
Life on the Surface, the Skin Human skin is not a particularly rich place for microbes to live. A Bacterial Sneeze, the Nose The human nose is home to the infamous Gram positive bacterium Staphylococcus aureus , best known for its role in hospitals where it is a major cause of surgical wound and systemic infection.
Braving Stomach Acid What kind of organism would live in a highly acidic pH environment like the stomach? Small Intestine vs. Vaginal Relative to other microbial populations of the human body little is known about the normal flora of the vaginal tract.
Bringing it All Together The examples presented above describe a few examples of normal flora around the human body. Bacteria perform physiological, nutritional and protective functions in the human body.
Additional Reading 1. Postgate JR. Microbes and Man. Guarner F, Malagelada JR. Gut flora in health and disease. Lancet : References 1. The skin microbes found in the most superficial layers of the epidermis and the upper parts of the hair follicles are Gram-positive cocci Staphylococcus epidermidis and Micrococcus sp. These are generally nonpathogenic and considered to be commensal, although mutualistic and parasitic roles have been assigned to them.
For example, staphylococci and propionibacteria produce fatty acids that inhibit the growth of fungi and yeast on the skin. But, if Propionibacterium acnes, a normal inhabitant of the skin, becomes trapped in hair follicle, it may grow rapidly and cause inflammation and acne.
Figure 4. Colonies of Propionibacterium acnes, found on skin and the conjunctiva. Normal Flora of the Respiratory Tract A large number of bacterial species colonize the upper respiratory tract nasopharynx. The healthy sinuses, in contrast are sterile. The pharynx throat is normally colonized by streptococci and various Gram-negative cocci. Sometimes pathogens such as Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and Neisseria meningitidis colonize the pharynx.
The lower respiratory tract trachea, bronchi, and pulmonary tissues is virtually free of microorganisms, mainly because of the efficient cleansing action of the ciliated epithelium which lines the tract. Any bacteria reaching the lower respiratory tract are swept upward by the action of the mucociliary blanket that lines the bronchi, to be removed subsequently by coughing, sneezing, swallowing, etc. If the respiratory tract epithelium becomes damaged, as in bronchitis or viral pneumonia, the individual may become susceptible to infection by pathogens such as H.
Normal Flora of the Urogenital Tract Urine is normally sterile, and since the urinary tract is flushed with urine every few hours, microorganisms have problems gaining access and becoming established. The flora of the anterior urethra, as indicated principally by urine cultures, suggests that the area my be inhabited by a relatively consistent normal flora consisting of S taphylococcus epidermidis, Enterococcus faecalis and some alpha-hemolytic streptococci.
Their numbers are not plentiful, however. In addition, some enteric bacteria e. The vagina becomes colonized soon after birth with corynebacteria, staphylococci, streptococci, E.
During reproductive life, from puberty to menopause, the vaginal epithelium contains glycogen due to the actions of circulating estrogens. Doderlein's bacillus predominates, being able to metabolize the glycogen to lactic acid. The lactic acid and other products of metabolism inhibit colonization by all except this lactobacillus and a select number of lactic acid bacteria.
The resulting low pH of the vaginal epithelium prevents establishment by most other bacteria as well as the potentially-pathogenic yeast, Candida albicans. This is a striking example of the protective effect of the normal bacterial flora for their human host. Figure 5. A Lactobacillus species, possibly Doderlein's bacillus, in association with a vaginal epithelial cell. Normal Flora of the Oral Cavity The presence of nutrients, epithelial debris, and secretions makes the mouth a favorable habitat for a great variety of bacteria.
Oral bacteria include streptococci, lactobacilli, staphylococci and corynebacteria, with a great number of anaerobes, especially bacteroides. The mouth presents a succession of different ecological situations with age, and this corresponds with changes in the composition of the normal flora.
At birth, the oral cavity is composed solely of the soft tissues of the lips, cheeks, tongue and palate, which are kept moist by the secretions of the salivary glands.
At birth the oral cavity is sterile but rapidly becomes colonized from the environment, particularly from the mother in the first feeding. The eruption of the teeth during the first year leads to colonization by S. These bacteria require a nondesquamating nonepithelial surface in order to colonize. They will persist as long as teeth remain. Other strains of streptococci adhere strongly to the gums and cheeks but not to the teeth. The creation of the gingival crevice area supporting structures of the teeth increases the habitat for the variety of anaerobic species found.
The complexity of the oral flora continues to increase with time, and bacteroides and spirochetes colonize around puberty.
Figure 6. Various streptococci in a biofilm in the oral cavity. The normal bacterial flora of the oral cavity clearly benefit from their host who provides nutrients and habitat. There may be benefits, as well, to the host. The normal flora occupy available colonization sites which makes it more difficult for other microorganisms nonindigenous species to become established. Also, the oral flora contribute to host nutrition through the synthesis of vitamins, and they contribute to immunity by inducing low levels of circulating and secretory antibodies that may cross react with pathogens.
Finally, the oral bacteria exert microbial antagonism against nonindigenous species by production of inhibitory substances such as fatty acids, peroxides and bacteriocins.
On the other hand, the oral flora are the usual cause of various oral diseases in humans, including abscesses, dental caries, gingivitis, and periodontal disease. If oral bacteria can gain entrance into deeper tissues, they may cause abscesses of alveolar bone, lung, brain, or the extremities. Such infections usually contain mixtures of bacteria with Bacteroides melaninogenicus often playing a dominant role.
If oral streptococci are introduced into wounds created by dental manipulation or treatment, they may adhere to heart valves and initiate subacute bacterial endocarditis. Figure 7. Colonies of E. You can change your ad preferences anytime.
Normal Human Flora. Upcoming SlideShare. Like this presentation? Why not share! Embed Size px. Start on. Show related SlideShares at end. WordPress Shortcode. Next SlideShares. Download Now Download to read offline and view in fullscreen. Download Now Download Download to read offline. Freelance clinical Microbiologist Follow. Normal flora. Normal flora of Skin. Microbial flora-of-the-human-body.
Human normal flora. Microbiology ppt. Normal microbial flora. Staphylococci 09 10 Med. Related Books Free with a 30 day trial from Scribd. Related Audiobooks Free with a 30 day trial from Scribd. Gayathri Sunitha. Sathish Sathish. Mydeen Beevi. Hanan Othman. Chhatwal Singh. Eric Muthama. Mharmhie Phranxex. Pankaj Patkhaulia. Show More. Views Total views. Actions Shares. No notes for slide. Normal Human Flora 1. RAO MD 1 2. 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. RAO MD 3 4. RAO MD 4 5. RAO MD 6. Exist as commensals no effect to the host 3. 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. RAO MD 7 8. The normal flora influences the anatomy, physiology, susceptibility to pathogens, and morbidity of the host.
RAO MD 8 9. Diet 3. Age 4. Health condition immune activity… 5. RAO MD 9 RAO MD 10 The makeup of the normal flora may be influenced by various factors, including genetics, age, sex, stress, nutrition and diet of the individual.
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