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The human body contains a large number of bacteria, most of them performing tasks that are useful or even essential to human survival. Those that are expected to be present, and that under normal circumstances do not cause disease, are termed normal flora. Image File history File links Broom_icon. ... Homo sapiens (Latin: wise man) is the scientific name for the human species. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ...

It is estimated that 5000 to 10000 different species of bacteria live in the human body (Sears, 2005). Bacterial cells are much smaller than human cells, and there are about ten times as many bacteria as human cells in the body (1000 trillion (10¹⁵) versus 100 trillion (10¹⁴); Sears, 2005). Though normal flora are found on all surfaces exposed to the environment (on the skin and eyes, in the mouth, nose, small intestine, and colon), the vast majority of bacteria live in the large intestine. In biology, a species is a kind of organism. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hook from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... In biology the small intestine is the part of the gastrointestinal tract (gut) between the stomach and the large intestine. ... For the article about the punctuation symbol, see Colon (punctuation). ... The large intestine, or the organ which is now more commonly referred to as the colon, is the last part of the digestive system: the final stage of the alimentary canal in vertebrate animals. ...

Many of the bacteria in the digestive tract, collectively referred to as gut flora, are able to break down certain nutrients such as carbohydrates that humans otherwise could not digest. The majority of these commensal bacteria are anaerobes, meaning they survive in an environment with no oxygen. For the Physics term GUT, please refer to Grand unification theory The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and... Escherichia coli, one of the many species of bacteria present in the human gut. ... Lactose is a disaccharide found in milk. ... This article does not cite its references or sources. ... In ecology, commensalism is an interaction between two living organisms, where one creature benefits and the other is neither harmed nor helped. ... An anaerobic organism or anaerobe is any organism that does not require oxygen. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ...

Many of the bacteria of the normal flora can act as opportunistic pathogens at times of lowered immunity. Opportunistic infections are infections caused by organisms that usually do not cause disease in a person with a healthy immune system, but can affect people with a poorly functioning or suppressed immune system. ... A scanning electron microscope image of a single neutrophil (yellow), engulfing anthrax bacteria (orange). ...

Escherichia coli is a bacterium that lives in the colon; it is an extensively studied model organism and probably the best understood organism of all. E. coli redirects here. ... A model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. ...

Certain mutated strands of these gut bacteria do cause disease; an example is E. coli O157:H7. Escherichia coli O157:H7 is an emerging cause of foodborne illness. ...

A number of types of bacteria, such as Actinomyces viscosus and A. naeslundii, live in the mouth, where they are part of a sticky substance called plaque. If this is not removed by brushing, it hardens into calculus (also called tartar). The same bacteria also secrete acids that dissolve tooth enamel, causing tooth decay. Species A. naeslundii Actinomyces is a genus of Gram-positive bacteria. ... Improper removal of plaque caused a build up of calculus (dark yellow colour) near the gums on almost all the teeth. ... Calculus (dark yellow colour) can be seen on almost all teeth near the gums In dentistry, calculus or tartar refers to hardened plaque on the teeth, formed by the presence of saliva, debris, and minerals. ... Tooth enamel is the hardest and most highly mineralized substance of the body , and with dentin, cementum, and dental pulp is one of the four major parts of the tooth. ... Types of teeth Molars are used for grinding up foods Carnassials are used for slicing food. ...

The vaginal microflora consist mostly of various lactobacillus species. It was long thought that the most common of these species was Lactobacillus acidophilus, but it has later been shown that the most common one is L. iners followed by L. crispatus. Other lactobacilli found in the vagina are L. delbruekii and L. gasseri. Disturbance of the vaginal flora can lead to bacterial vaginosis. Species L. acidophilus L. brevis L. delbrueckii subsp. ... Binomial name Lactobacillus acidophilus (Moro 1900) Hansen & Mocquot 1970 Lactobacillus acidophilus is one of several bacteria in the genus Lactobacillus. ... Bacterial vaginosis (BV) is the most common cause of vaginal infection (vaginitis). ...

Bacteria and human health

Color-enhanced scanning electron micrograph showing Salmonella typhimurium (red) invading cultured human cells

Bacteria are vital for the maintenance of human health, but some also pose a significant health threat by causing diseases. Large numbers of bacteria live on the skin and in the digestive tract. Their growth can be increased by warmth and sweat. Large populations of these organisms on humans are the cause of body odor and thought to play a part in acne. The more than 500 bacterial species present in the normal human gut are generally beneficial: they synthesize vitamins such as folic acid, vitamin K and biotin, and they ferment complex indigestible carbohydrates.^[1][2] Other beneficial bacteria in the normal flora include Lactobacillus species, which convert milk protein to lactic acid in the gut.^[3] The presence of such bacterial colonies also inhibits the growth of potentially pathogenic bacteria (usually through competitive exclusion) and some beneficial bacteria are consequently sold as probiotic dietary supplements.^[4] ImageMetadata File history File links Download high resolution version (2100x1761, 1696 KB) Color-enhanced scanning electron micrograph showing Salmonella typhimurium (red) invading cultured human cells Credit: Rocky Mountain Laboratories, NIAID, NIH Source: NIAID: File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to... ImageMetadata File history File links Download high resolution version (2100x1761, 1696 KB) Color-enhanced scanning electron micrograph showing Salmonella typhimurium (red) invading cultured human cells Credit: Rocky Mountain Laboratories, NIAID, NIH Source: NIAID: File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to... Binomial name Salmonella enterica Salmonella enterica is a species of Salmonella bacterium. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Bromhidrosis or body odor (also called bromidrosis, osmidrosis and ozochrotia) is the smell of bacteria growing on the body. ... Retinol (Vitamin A) For the record label, see Vitamin Records Vitamins are nutrients required in very small amounts for essential metabolic reactions in the body. ... Folic acid and folate (the anion form) are forms of the water-soluble Vitamin B9. ... Vitamin K1 (phylloquinone). ... Vitamin H redirects here. ... Lactose is a disaccharide found in milk. ... Species L. acidophilus L. brevis L. delbrueckii subsp. ... The competitive exclusion principle, sometimes referred to as Gauses Law of competitive exclusion or just Gauses Law, states that two species that compete for the exact same resources cannot stably coexist. ... Probiotics are dietary supplements containing potentially beneficial bacteria or yeast, with lactic acid bacteria (LAB) as the most common microbes used. ... A prescribed dietary supplement is intended to supply nutrients (vitamins, minerals, fatty acids or amino acids) that are missing or not consumed in sufficient quantity in a persons diet. ...

Although the vast majority of bacteria are harmless or beneficial, a few pathogenic bacteria cause infectious diseases. The most common bacterial disease is tuberculosis, caused by the bacterium Mycobacterium tuberculosis, which kills about 2 million people a year, mostly in sub-Saharan Africa. Pathogenic bacteria contribute to other globally important diseases, such as pneumonia, which can be caused by bacteria such as Streptococcus and Pseudomonas, and foodborne illnesses, which can be caused by bacteria such as Shigella, Campylobacter and Salmonella. Pathogenic bacteria also cause infections such as tetanus, typhoid fever, diphtheria, syphilis and leprosy. Tuberculosis (abbreviated as TB for Tubercle Bacillus) is a common and deadly infectious disease that is caused by mycobacteria, primarily Mycobacterium tuberculosis. ... Streptococcus, a genus of spherical, Gram-positive bacteria of the phylum Firmicutes. ... Species group P. aeruginosa P. alcaligenes P. anguilliseptica P. argentinensis P. citronellolis P. flavescens P. mendocina P. nitroreducens P. oleovorans P. pseudoalcaligenes P. resinovorans P. straminea group P. aurantiaca P. aureofaciens P. chlororaphis P. fragi P. lundensis P. taetrolens group P. antarctica P. azotoformans P. cedrina P. corrugata P. fluorescens... Species S. boydii S. dysenteriae S. flexneri Shigella are Gram-negative, non-motile, non-spore forming rod-shaped bacteria closely related to Escherichia coli and Salmonella. ... Species C. fetus C. jejuni Campylobacter is a genus of Gram-negative bacteria. ... Species Salmonella bongori Salmonella enterica Salmonella arizonae Salmonella enteritidis Salmonella typhi Salmonella typhimurium Salmonella is a genus of rod-shaped Gram-negative enterobacteria that causes typhoid fever, paratyphoid fever, and foodborne illness. ... Tetanus is a medical condition characterized by a prolonged contraction of skeletal muscle fibers. ... For a related disease which is caused by a different bacterium, see Paratyphoid fever. ... Syphilis is a sexually transmitted disease (STD) caused by spirochaete bacterium, Treponema pallidum. ... This article or section is in need of attention from an expert on the subject. ...

Koch's postulates, proposed by Robert Koch in 1890, are criteria designed to establish a causal relationship between a causative microbe and a disease. A pathogenic cause for a known medical disease may only be discovered many years after, as was the case with Helicobacter pylori and peptic ulcer disease. Kochs postulates (or Henle-Koch postulates) are four criteria designed to establish a causal relationship between a causative microbe and a disease. ... Robert Koch For the American lobbyist, see Bobby Koch. ... Binomial name Helicobacter pylori ((Marshall 1985) Goodwin 1989) Helicobacter pylori is a bacterium that infects the mucus lining of the stomach and duodenum. ... Electron micrograph of This is a timeline of the events relating to the discovery that peptic ulcer disease is caused by . ...

Each pathogenic species has a characteristic spectrum of interactions with its human hosts. Some organisms, such as Staphylococcus or Streptococcus, can cause skin infections, pneumonia, meningitis and even overwhelming sepsis, a systemic inflammatory response producing shock, massive vasodilation and death.^[5] Yet these organisms are also part of the normal human flora and usually exist on the skin or in the nose without causing any disease at all. Other organisms invariably cause disease in humans, such as the Rickettsia, which are obligate intracellular parasites able to grow and reproduce only within the cells of other organisms. One species of Rickettsia causes typhus, while another causes Rocky Mountain spotted fever. Chlamydia, another phylum of obligate intracellular parasites, contains species that can cause pneumonia, or urinary tract infection and may be involved in coronary heart disease.^[6] Finally, some species, such as Pseudomonas aeruginosa, Burkholderia cenocepacia, and Mycobacterium avium, are opportunistic pathogens and cause disease mainly in people suffering from immunosuppression or cystic fibrosis.^[7][8] Species S. aureus S. caprae S. epidermidis S. haemolyticus S. hominis S. lugdunensis S. saprophyticus S. warneri S. xylosus Staphylococcus (in Greek staphyle means bunch of grapes and coccos means granule) is a genus of Gram-positive bacteria. ... Streptococcus, a genus of spherical, Gram-positive bacteria of the phylum Firmicutes. ... Sepsis (in Greek Σήψις, putrefaction) is a serious medical condition, resulting from the immune response to a severe infection. ... Species Rickettsia felis Rickettsia prowazekii Rickettsia rickettsii Rickettsia typhi Rickettsia conorii etc. ... It has been suggested that this article or section be merged with Epidemic typhus. ... Binomial name Rickettsia rickettsii Wolbach, 1919 Wikispecies has information related to: Ixodidae Wikispecies has information related to: Rickettsia Rocky Mountain spotted fever is the most severe and most frequently reported rickettsial illness in the United States, and has been diagnosed throughout the Americas. ... Chlamydia is a common term for infection with any bacterium belonging to the phylum Chlamydiae. ... Pneumonia is an illness of the lungs and respiratory system in which the alveoli (microscopic air-filled sacs of the lung responsible for absorbing oxygen from the atmosphere) become inflamed and flooded with fluid. ... A urinary tract infection (UTI) is a bacterial infection that affects any part of the urinary tract. ... This article or section does not adequately cite its references or sources. ... Binomial name Pseudomonas aeruginosa (Schroeter 1872) Migula 1900 Synonyms Bacterium aeruginosum Schroeter 1872 Bacterium aeruginosum Cohn 1872 Micrococcus pyocyaneus Zopf 1884 Bacillus aeruginosus (Schroeter 1872) Trevisan 1885 Bacillus pyocyaneus (Zopf 1884) Flügge 1886 Pseudomonas pyocyanea (Zopf 1884) Migula 1895 Bacterium pyocyaneum (Zopf 1884) Lehmann and Neumann 1896 Pseudomonas polycolor... Burkholderia cenocepacia is a Gram-negative bacteria that is common in the environment and may cause disease in plants. ... Mycobacterium avium complex refers to infection by two species of bacteria, Mycobacterium avium and Mycobacterium intracellulare. ... Opportunistic infections are infections caused by organisms and usually do not cause disease in a person with a healthy immune system, but can affect people with a poorly functioning or suppressed immune system. ... Immunosuppression is the medical suppression of the immune system. ...

Bacterial infections may be treated with antibiotics, which are classified as bacteriocidal if they kill bacteria, or bacteriostatic if they just prevent bacterial growth. There are many types of antibiotics and each class inhibits a process that is different in the pathogen from that found in the host. For example, the antibiotics, chloramphenicol and puromycin inhibit the bacterial ribosome, but not the structurally-different eukaryotic ribosome, and so exhibit selective toxicity.^[9] Antibiotics are used both in treating human disease and in intensive farming to promote animal growth. Both uses may be contributing to the rapid development of antibiotic resistance in bacterial populations.^[10] Infections can be prevented by antiseptic measures such as sterilizating the skin prior to piercing it with the needle of a syringe, and by proper care of indwelling catheters. Surgical and dental instruments are also sterilized to prevent contamination and infection by bacteria. Disinfectants such as bleach are used to kill bacteria or other pathogens on surfaces to prevent contamination and further reduce the risk of infection. Most bacteria in food are killed by cooking to temperatures above 60°C (140°F). Staphylococcus aureus - Antibiotics test plate. ... A bacteriocide or bactericide is a substance that kills bacteria and, preferably, nothing else. ... Bacteriostatic antibiotics hamper the growth of bacteria by interfering with bacteria protein production, interfering with bacteria DNA production interfering with bacteria cellular metabolism Bacteriostatic antibiotics inhibit growth and repoduction of the bacteria, though do not kill it, while bactericidal antibiotics kill bacteria. ... HIV protease in a complex with the protease inhibitor ritonavir. ... Chloramphenicol is a bacteriostatic antibiotic originally derived from the bacterium Streptomyces venezuelae, isolated by David Gottlieb, and introduced into clinical practice in 1949. ... Puromycin is an antibiotic that is a potent inhibitor of translation. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... Intensive Farming Intensive agriculture is an agricultural production system characterized by the high inputs as relative to land area (as opposed to extensive farming). ... Antibiotic resistance is the ability of a micro-organism to withstand the effects of an antibiotic. ... An antiseptic solution of iodine applied to a cut Antiseptics (Greek αντί, against, and σηπτικός, putrefactive) are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction. ... Sterilization (or sterilisation) is the elimination of all transmissible agents (such as bacteria, prions and viruses) from a surface, a piece of equipment, food or biological culture medium. ... Disinfection The destruction of pathogenic and other kinds of microorganisms by physical or chemical means Disinfectants are chemical substances used to kill viruses and microbes (germs), such as bacteria and fungi. ... Commercial chlorine bleach To Bleach something is to remove or lighten its color, sometimes as a preliminary step in the process of dyeing; a bleach is a chemical that produces these effects, often via oxidation. ...

References

• Sears CL. 2005. A dynamic partnership: Celebrating our gut flora. Anaerobe, Volume 11, Issue 5, October 2005, Pages 247-251.

External links

• Medical Microbiology chapter 6 - Normal Flora