Microbiology Review #4

Define the following terminology: a.) Microbiome b.) Human microbiome c.) Microbiota d.) Normal Microbiota

A microbiome is the functional collection of different microbes in a particular environmental system. Just as the human microbiome is the massive assemblage of microorganisms colonizing the human body. Microbiota is a reference to the types of organisms present in an environmental habitat such as the human skin or gastrointestinal tract. The normal microbiota are the microorganisms that are found in healthy body tissue.

Briefly describe how an AB toxin interacts with a cell.

AB toxins consist of two subunits (A and B), the B component binds to a host cell surface molecule, facilitating the transfer of the A subunit across the cytoplasmic membrane where it damages the cell.

Compare B cells and T cells. What do they do? What type of immunity does each produce? Why does an adaptive immune response need specificity, memory, and tolerance?

Adaptive immunity is the function of antigen-reactive leukocytes called lymphocytes. B lymphocytes (B Cells) specialize in the production of antibodies that interact with and protect against extracellular antigens conferring antibody-mediated (humoral) immunity to the host. T lymphocytes (T Cells) express antigen-specific receptor proteins on their surfaces that defend against intracellular pathogens such as viruses and certain bacteria conferring cell-mediated (cellular) immunity. Specificity: to interact with particular antigens Memory: to respond more quickly to second exposures to an antigen Tolerance: to produce an immune response to particular antigen

What is the pathogenicity of a pathogen? What are the virulence factors? When a pathogen's virulence is decreased, or loss is called?

All pathogen have unique properties that contribute to their ability to cause disease known as its pathogenicity. To measure pathogenicity is called virulence, the relative ability of a pathogen to cause disease. These are not uniform properties and vary between strains of the same bacteria. Host damage in an infectious disease is mediated through virulence factors, toxic or destructive substances produced by the pathogen to enhance invasiveness. The virulence of a pathogen can change by decreasing or a loss of virulence known as attenuation.

Compare natural active and passive immunity. Compare artificial active and passive immunity. Provide an example for each one.

An immune response either active, an actual exposure to the antigen or passive, the transfer of antibodies or immune cells from an immune individual to a nonimmune one. Natural active immunity is the exposure to antigens through infection and generates protective immunity from both antibodies and T cells. In contrast, natural passive immunity acquiring cells or antibodies through natural transfer from an immune person such between mother and child. Artificial active immunity is conferred by vaccination (immunization), to inoculate a host with inactive or weakened pathogens or products to stimulate active immunity such as memory. Artificial passive immunity is receiving antibodies from an immune individual through injection of an antiserum, but the memory is conferred as the antibodies disappear from the body. Examples include tetanus or rabies, but also bites from venomous animals.

What does the cholera enterotoxin cause? How is it treated?

Another AB type exotoxin, the cholera enterotoxin is produced by Vibrio cholerae to cause waterborne disease cholera. Cholera is characterized by massive fluid loss from the intestines, resulting in severe diarrhea, life threatening dehydration, and electrolyte depletion. Cholera begins by ingesting V. cholerae cells from food or water contamination with human feces where the organism travels to the small intestine and colonizes and secrete the toxins. Individuals without treatment can die, but it fluids are replaced the toxin is neutralized and the individual will return to normal a few days.

Hemolysins are an example of what type of exotoxin? How does exposure to the superantigen from Staphylococcus aureus cause toxic shock syndrome? The lipopolysaccharide (LPS) is what type of toxin? Which part of LPS is toxic?

Both cytolytic and superantigen exotoxins function by destroying host cells. Cytotoxins are soluble proteins secreted by the pathogen that damage the cytoplasmic membrane causing cell lysis and death. An example is the lytic activity of red blood cells called hemolysis, done by the toxins called hemolysins. Superantigens are produced mainly from Staphylococcus aureus and Streptococcus pyogenes. Reactions to superantigen poisoning are severe and can even be fatal in some individuals. Toxic shock syndrome (TSS) is exposure to the toxin, but S. aureus TSS is localized and S. pyogenes is systemic causing bacteremia or septicemia and tissue damage. Mortality rates are higher in S. pyogenes. TSS triggered an overblown immune response causing widespread inflammation, hypotension, organ failure, and systemic shock. Endotoxins are the toxic lipopolysaccharide (LPS). Remember there are three components to LPS: the O polysaccharide, core polysaccharide, and lipid A. Lipid A is the toxic part of LPS, but not alone and requires the other components to be toxic.

What is the function of the following protein or complex in the complement system: C3a C3b C5a Membrane attack complex (MAC)

C3a leads to inflammation and C3b causes opsonization, which coats the pathogens with antibodies or C3b to enhance phagocytosis. C3b binds to convertase to form C5 that cleaves into C5a used in inflammation and C5b that binds to other complement proteins to form membrane attack complex (MAC) that forms a pore of the pathogen causing cell lysis.

Compare chickenpox and shingles in symptoms and who is affected. What is the vaccine for chickenpox/shingles?

Chicken Pox (varicella) is a common childhood disease cause by the varicella-zoster virus (VZV), a double stranded DNA herpesvirus. VZV is a mild but highly contagious disease and is transmitted by infectious droplets and direct close contact. The virus enters the respiratory tract, multiplies, and is quickly disseminated through the bloodstream, results in a systemic rash that heals quickly scarring if not scratch. The vaccine (Varivax) has reduce the incidence of chicken pox. VZV establishes a lifelong latent (permanent) infections in nerve cells. The virus can remain dormant but migrates to the skin surface in later years causing painful shingles (zoster). The vaccine can be given to the eldery to reduce the migration of the virus to the skin cells.

The enzyme coagulase can be found in what organism and what is its activity? The enzyme hyaluronidase can be found in what organism and what is its activity? The enzyme collagenase can be found in what organism and what is its activity?

Coagulase can be found in the organism Stapylococcus aureus and its activity induces fibrin clotting; allows bacterial cells to remain at site of infection (prevents access to pathogens by cells of the immune response) Break down nucleic acids or lipids. Hyaluronidase can be found in the organism streptococcus pyogenes and its activity dissolves hyaluronic acid in connective tissues; allows bacterial cells to spread (enhances pathogen invasion). Dissolves fibrin clots; allows bacterial cells to spread. Collagenase can be found in the organism Clostridium perfringens and its activity breaks down collagen (a protein), allowing the bacterium to spread to other tissues. Breaks down proteins.

List some examples that cause delayed-type hypersensitivity (DTH). What is immediate hypersensitivity?

Contact dermatitis from poison ivy, jewelry, cosmetics, and latex. Allergy is an antibody-mediated immediate hypersensitivity release substances that either increase or decrease blood pressure or heart rate. Reactions occur within minutes after exposure to an allergen which can be mild or life threatening called anaphylaxis.

Where do HIV-1 replicate? Why is this necessary? Individuals with AIDS die from what?

HIV-1 replicates in macrophages and T cells of the human immune system. This leads to the destruction of key immune system cells, eliminating the host immune response. Death from AIDS is usually the result of a secondary infection.

Compare herpes simplex virus 1 (HSV-1) and herpes simplex virus 2 (HSV-2).

Herpes simplex 1 virus (HSV-1) infects the epithelial cells around the mouth and lips, causing cold sores or fever blisters. Lesions heal in 2-3 weeks but remember herpesviruses are latent infections and can reoccur. Herpes simplex 2 virus (HSV-2) infect the genital region causes painful blister on the penis of males or on the cervix, vulva, or vagina of females. Transmission by direct sexual contact with blisters present or absent. These are no curable but some medications are used to control the blisters.

Is IBD or IBS caused by a pathogen? Define dysbiosis.

IBD is not due to specific pathogenic microbe but to an imbalance between the immune system and the normal gut microbiota called dysbiosis. IBD syndromes of Crohn's disease and ulcerative colitis are associated with a T-cell response to intestinal commensal bacteria. The western diet also plays a role in producing products that initiate an immune response, a plant based diet is a preferred to prevent leaky gut and gut inflammation.

Define colonization and invasion. Define the following terms: Bacteremia Septicemia Viremia

If a single pathogenic cell or virus attaches to its specific host tissue, it alone is insufficient to cause disease; the pathogen must establish residence there and multiply known as colonization. Invasion is the ability of a pathogen to enter into host cells or tissues, spread, and cause disease. When bacteria enters the blood, this is called bacteremia, but this is self-limiting as bacterials cells do not grow in the bloodstreams and the immune system quickly removes them. Symptoms are mild to none. In contrast is the condition known as septicemia where bacteria multiply in the bloodstream and spreads while producing toxins and other substances. Septicemia begins as an infection at a specific organ and spreads throughout the body from there. Viruses present in the bloodstream, and measles is called viremia.

Define immunity. Briefly compare innate and adaptive immunity. Describe a natural host resistance.

Immunity is the ability of an organism to resist infection. There are two defenses against pathogens in the human immune system. Innate immunity is the built in capacity to target common pathogens regardless of their identity while the adaptive immunity is triggered by exposure to specific pathogens that cannot be eliminated from the body by the innate immunity. A natural host resistance or competitive exclusion is where pathogens cannot compete with the normal microbiota by limiting available nutrients and site for infection. This is not part of the immune response.

Why are compromised hosts more susceptible to pathogens than healthy individuals? What are nosocomial infections?

Individual that are more susceptible to infection are called compromised hosts in which one or more resistance mechanisms are inactive and have little to do with the virulence of the pathogen. Many hospital patients with noninfectious diseases (cancer or heart disease) acquire more microbial infections because they are compromised. Nosocomial infections are healthcare-associated infections through invasive medical procedures like catheters, hypodermic injection, biopsy, and surgery may introduce microbes to the patients. The trauma of surgery and anti-inflammatory drugs that reduce pain and swelling also reduce host resistance.

Why is early exposure essential for early life? What are the consequences of excessive hygiene?

It is known that the immune system does not work properly in the absence of microbial stimulation and that early life exposure to a variety of microorganisms is essential for developing tolerance to beneficial microorganisms and recognizing pathogens as foreign. The consequences of excessive hygiene in an infant's development may be a poorly trained immune system that is more likely to attach beneficial organisms with an inflammatory response. It is thought this immune status would promote autoimmune conditions, allergies, asthma, and inflammatory bowel diseases later in life.

What is the bacterium that causes the following diseases? MRSA Pneumonia Strep Throat Diphtheria Pertussis (Whooping cough) Tuberculosis Leprosy Meningitis/meningococcemia Gonorrhea Syphilis Chlamydia

MRSA-Staphylococcus aureus Pneumonia-Streptococcus pneumoniae Strep Throat-Streptococcus pyogenes Diphtheria-Corynebacterium diphtheriae Pertussis (Whooping cough)-Bordetella pertussis Tuberculosis-Mycobacterium tuberculosis Leprosy-Mycobacterium leprae Meningitis/meningococcemia-Neisseria meningitidis or meningococcus Gonorrhea-Neisseria gonorrhoeae Syphilis-Treponema pallidum Chlamydia-Chlamydia trachomatis

How do phagocytes recognize potential pathogens? How do they interact with pathogens? This interaction leads to what cellular process? Describe the pathway of phagocytosis, include the phagosome and lysosome in your answer.

Macrophages are stimulated by invading pathogens and secrete chemokines that create a gradient chemoattractants that recruit neutrophils and T cells to the site of infection initiating neutrophil-mediated inflammatory response. With inflammation allows neutrophils, the most numerous circulating phagocytes, to migrate quickly along the chemotactic gradient. Once there neutrophils adhere to the inner wall of blood capillary called margination. The neutrophils that move from the bloodstream to surrounding infected tissues is called extravasation. Activation of the phagocyte causes the phagocyte membrane to envelop and engulf pathogens called phagocytosis. Eventually pinching off inwardly for a phagosome, a vacuole containing the engulfed pathogen moves to the cytoplasm and fuse with a membrane -bound inclusions called lysosomes to form a phagolysosome that contains toxic chemical and enzymes combined to kill and digest the pathogen.

What is the family name for the following viruses? RNA or DNA? Plus or Minus sense? Measles Rubella Mumps Chicken Pox/Shingles Common Cold HPV

Measles affects susceptible children as an acute, highly infectious, often epidemic disease. The measle virus is a paramyxovirus, a single-stranded minus-sense RNA virus that is passed through airborne transmission. Rubella or German measles is a single-stranded positive-sense RNA virus. Symptoms resemble those of measles but restricted to the upper torso and is less contagious. Mumps paramyxovirus, a single-stranded minus-sense RNA virus. Chicken Pox (varicella) is a common childhood disease cause by the varicella-zoster virus (VZV), a double stranded DNA herpesvirus. The common cold is from the family Rhinoviruses that are single-stranded plus-sense RNA viruses. Human papillomaviruses (HPV) is a double-stranded DNA virus of more than 100 different strains, 30 are sexually transmitted. About 20 million people in U.S. are infected with 6 million people are acquiring new infections.

In the oral cavity, what defenses are present to reduce microbial growth? However, how do microbes persist?

Mucous membranes secrete mucin, forming the mucus later that retains moisture and inhibits microbial attachment. Invaders are usually swept away from swallowing or sneezing, but some can adhere to the epithelial surface and colonize. Saliva contains low concentrations of microbial nutrients and antibacterial substances like lysozymes that are not good for microbial growth. Food particles and cell debris provide high concentration of nutrients near surfaces such as teeth and gums, creating favorable conditions for extensive microbial growth, tissue damage, and disease.

What are natural killer (NK) cells? Briefly, how do NK cells initiate apoptosis? What is the function of interferons?

Natural killer cells (NK cells) are cytotoxic lymphocytes that are distinct from T cells and B cells. The role NK cells is to seek out and destroy compromised cells that are infected by migrating close proximity and release granules from their cytoplasm to the infected cell. These granules are perforins and proteases (ganzymes) that create pores and enter the cell causing apoptosis (cell death). NK cells do not recruit more immune cells and holds not memory. NK cells use major histocompatibility complex (MHC), surface proteins found on host cells. Another defense is interferons, small proteins related to cytokines that prevent viral replication by stimulating the production of antiviral proteins in uninfected cells. Host cells produce and secrete interferons in response to viral infection or exposure to inactivated viruses or viral nucleic acids (RNA or DNA).

What is necrotizing fasciitis?

Necrotizing fasciitis is a rapid and progessive disease for the destruction of tissue, muscle, and fat giving the term "flesh-eating bacteria."

What is obesity to the gut microbiota? How much daily energy do volatile fatty acids provide to the host? What is the change in microbes that cause fat accumulation? What role do methanogens play in fat accumulation?

Obesity: is a significant health risk that contributes to secondary health issues such as high blood pressure, cardiovascular disease, and diabetes. Minor changes in gut energy metabolism has a significant long-term effect of the accumulation of body fat. The intestinal microbiota is to break down and ferment dietary fibers into volatile fatty acids (VFAs) including acetate, propionate, and butyrate where the host absorbs these acids which is about 10% of daily energy. Obsese mice have 50% fewer Bacteroidetes, an increase in Firmicutes, and a increase in Archaea methanogens. Methanogens increase the efficiency of fermentation by removing H2 that are available for absorption by the host.

How often do individuals get the common cold compare to the flu?

On average a person in the U.S. get about three colds per year compared to one case of influenza per year.

Compare and contrast probiotics and prebiotics.

Probiotics: are live microorganisms administered in adequate amounts as a health benefit to the host. The most common microbe in a probiotics is Bifidobacterium and Lactobacillus. The can be delivered by the ingestion of fermented milk products like yogurt. Prebiotics: are the ingestion of plant nutrients to promote healthy development or nurture the bacterial species associated with healthy colons that are currently present. Some yogurts can have both a probiotic and prebiotic.

How are males and females different when infected with gonorrhea? Know what happens during primary, secondary, tertiary syphilis.

Symptoms differ between male and females. In females can be asymptomatic or cause mild vaginitis that is difficult to distinguish from other organisms. Complication in females can lead to pelvic inflammatory disease (PID) which can cause sterility. In men is painful causing puslike urethral discharge. Primary syphilis: Localized infection Secondary syphilis: Generalized skin rash Tertiary syphilis: Serious and fatal infections

Be able to differentiate the function of the following T helper cell: Th1, Th2, Th17, and Treg cells.

T-cytotoxic (Tc) cell or cytotoxic T lymphocytes (CD8 T cells) are lymphocytes that interact with MHC-1 complexes through T cell receptors and produces cytotoxins that kill the interacting target cell. Th1 cells or T helper cells promote the growth and activation of other T cells, specifically macrophages. Th2 cells activate B cells and antibody production. Th17 cells activate dendritic cells to attract neutrophils. Treg cells shut down the immune response and inhibit inflammation to control immune responses to self antigen and preventing autoimmunity.

What does the MMR vaccine treat? How are mumps different from measles and rubella?

The attenuated MMR vaccine is highly effective in preventing disease for mumps, measles, and rubella (MMR).

Compare and contrast botulism and tetanus toxins (including organism, function, and diseases).

The bacteria Clostridium botulinum and Clostridium tetani are endospore forming soil bacteria causing botulism and tetanus that produce AB toxins that act as neurotoxins. They both block of the release of neurotransmitters but in different ways. The botulism toxin binds to the terminal end of a neuron preventing the release of acetylcholine for muscle contraction, called flaccid paralysis. This can cause death by preventing the diaphragm muscles to contract causing suffocation. The tetanus toxin bind to the terminal end of inhibitory interneurons that work to releasing an inhibitory neurotransmitter to stop the release of acetylcholine.By blocking this function and the continual release of acetylcholine cause the muscles to stay contract and prevent muscle relaxation. This is called spastic paralysis, this can cause lockjaw or death by prolonged contraction of the diaphragm causing asphyxiation.

What is the complement? What are the names of the mechanisms to complement? All mechanisms produce which enzyme?

The complement system or complement is a group of sequentially interacting proteins that boost the efficiency of both innate and adaptive responses like phagocytosis, inflammation, and lysis of invading cells. There are three mechanisms of complement: 1.Classical Pathway 2.Mannose-Binding Lectin Pathway 3.Alternative Pathway All mechanisms produce the enzyme C3 convertase

Describe the differences in the gut microbiota of a newborn infant between vaginal birth and a C-section. When does an infant's gut have the composition of an adult? What two genera are found in infants that are breastfed?

The gut microbiota of a child delivered by C-section is significantly different from that of the mother. About 41% species match those of the mother while in vaginally delivered infant's share 72% of species with the mother. The infant's gut does not reach an adultlike composition until about 3 years old. Breast-fed infants have increased levels of taxa commonly found in probiotics including Lactobacillus and Bifidobacterium.

What is the relationship between the host and gut microbiota? What is the core microbiome of the gastrointestinal microbiota?

The host and the gut microorganisms share the easily digestible nutrients. The core microbiome consist of Bacteroidetes, Firmicutes, Actinobacteria, Fusobacteria, and Proteobacteria.

Define infection and disease. What is the first step of infection? How do pathogens adhere to host cells? What structures are associated with adherence?

The infection is used to imply the growth of microorganisms on or in the host whereas the term disease is actual tissue damage or injury that impairs host function. If a pathogen gains access to the specific tissues in infects, disease will occur only if it first adheres to those tissues, multiplies to yield many cells or viral particles, and then proceeds to damage tissues by the release of toxic or invasive substances. Adherence is the first step required to initiate disease, but not sufficient to cause a disease. Adherence is the enhanced ability of a microorganism to attach to a cell or a surface. Pathogens adhere to epithelial cells through interactions between molecules of the pathogens and the host tissues. Pathogens can adhere to each other by forming biofilms. These molecules on pathogens are called adhesins like glycoproteins or lipoproteins. Other adherence structures include: ●Fimbriae ●Pili ●Flagella ●Capsule

What is the significance of the Shiga toxin?

The last AB type enterotoxin is the Shiga toxin that causes bloody diarrhea and dehydration. The toxin is most notable because it is the sam between Escherichia coli, Shigella, and Salmonella enterotoxins possibly obtained through horizontal gene transfer.

What major pathogen causes dental caries in the oral cavity? What disorder does the genus Propionobacteroium associate with? How can the dysbiosis of the vaginal microbiota be measured?

The major pathogen is Streptococcus mutans to cause caries and colonizes tooth surfaces. The bacterial genus Propionibacterium is associated with acne, a cutaneous inflammatory disease of the skin and affect 85% of the world's adolescents. Dysbiosis of the normal vaginal microbiota is associated with either an inflammatory infection (vaginitis) or a less severe clinical form (vaginosis) that is asymptomatic with maloder and discharges. This can occur with the overgrowth of Candida (yeast), but is measured by the decrease in Lactobacillus.

What are the three beneficial genera present in the oral cavity? Where do they colonize? How are they beneficial to the host? What happens if they are reduced or eliminated?

The most abundant genera in the oral cavity include Streptococcus, Haemophilus, Veillonella, Actinomyces, and Fusobacterium. The bacteria in the mouth when teeth are absent are aerotolerant anaerobes, but when teeth appear anaerobes colonized the surface of teeth and gingival crevices in using biofilms. Streptococcus colonize clean tooth surfaces while Veillonella and Fusobacterium habit below the gum line. All three contribute to the health of the host by keeping pathogenic bacteria in check by preventing them from adhering. Tooth decay, gum inflammation, and periodontal disease are manifestations of a breakdown of these mutualisms.

Compare how leprosy develops on the face to the extremities.

The most severe form is lepromatous leprosy with folded, bulblike lesions on cooler parts of the body like the face and extremities. These lesions are M. leprae growing in skin Schwann cells that insulate the nerves that when left untreated leads to muscle atrophy and motor function is impaired in the face. On the extremities there is the loss of sensation and loss of bone calcium leading to shrinking of digits.

What are the precursor cells that differentiate into different immune cells and blood cells?

The precursor cells produced in the bone marrow that differentiate into different blood cells are called hematopoietic stem cells.

What is the significance of microbes in the human microbiome compared to the human cells? The human microbiome plays a role in what development?

The significance of microbes in the human microbiome is it estimated that the microbes in the human microbiome number 10^13 and 10^14, which is roughly the same as ten times the total number of human cells in a single person. The human microbiome plays a role in the development of the immune system, overall health in life, and predisposition to disease.

What is the function of the skin? What conditions make the skin microbiota diverse? What are the three main sites for diversity on the skin? Give an example of these sites and include the primary bacterial family at each location. What are environmental and host factors that influence the composition of the skin microbiota?

The skin is a complex human organ that functions to prevent the loss of moisture and restrict entry of pathogens. The skin microbiota associate with the host's hormonal, nervous, and immunological systems. There are about 10^10 of skin microorganisms covering the average adult. Less than the oral and gut communities, but diverse in bacteria and fungi. The habitat consist of varying temperature, pH, moisture, sebum content, and surface characteristics. Sweat is high in salt and other antimicrobial substances such as fatty acids and peptides for controlling diversity. Environmental and host factors influence the composition of the normal skin microbiota. ●Weather: may cause an increase in skin temperature and moisture ●Age: young children have more varied skin microbiota and potential pathogens ●Personal Hygiene: poor hygiene have higher microbial population densities

Spasmodic coughing to inhale deep breaths to obtain sufficient air is known as what? What does the DTaP vaccine prevent?

The spasmodic coughing gives its name inhaling deep breaths to obtain sufficient air. Both are treated with a highly effective toxoid vaccine (the same vaccine), the DTaP vaccine for diphtheria, tetanus, and pertussis.

Which part of the respiratory tract is frequently exposed to microbes? What is the function of ciliated epithelial cells in the lungs?

The upper respiratory tract includes the throat/tonsils, nasopharynx, oral cavity, oropharynx, and larynx. Microbes live in secretions of the mucous membranes, some bacteria are introduced through breathing while most are trapped in the mucus of the nasal and oral passages. The lower respiratory tract includes the trachea, bronchi, and lungs where in healthy individuals are absent of bacteria. Covered in ciliated epithelial cells pushing bacteria upward to the upper respiratory tract or to the esophagus to send contents to the stomach.

Why is inflammation necessary at the site of infection? Why is a fever necessary?

Various cells even damaged ones produce the activator and chemoattractant molecules, proinflammatory cytokines and chemokines. Though it is an immune response that trigger the release of molecules and recruits neutrophils, inflammation isolates and limit tissue damage by initiating the destruction of pathogens and removal of damage cells. The cytokines increase vascular permeability causing swelling (edema) and redding, and local heating. The swelling serves to force fluids away from blood vessels and into the lymphatic systems to increase the immune response and prevent pathogens from entering the bloodstream. Certain cytokines released during inflammation can induce fever, a condition of elevated body temperature. Although uncomfortable to the host a moderate fever is beneficial because the rise in temperature inhibits growth of most pathogens, minimizing tissue damage and workload of immune cells.

Which bacterium was found to survive the acidic environment of the stomach? How is it transmitted? Why is prolonged exposure to this microbe alarming? What domains are present in the large intestine?

When H. pylori is pathogenic and is transmitted orally between family members and can persist for decades in the gastric mucosa. Infected individuals will suffer from upper gastrointestinal tract symptoms during their lifetime. Infection is often asymptomatic, chronic inflammation is considered a major risk factor for the development of ulcers and gastric malignancies recognizing H. pylori as a carcinogen in 1994. In the large intestines where Bacteria and Archaea(methanogens) are present in large numbers.

What is the consequence of taking antibiotics? What is the consequence of an infant taking antibiotics? Which gut microorganism becomes pathogenic when stimulated by antibiotics, and how is it pathogenic?

When antibiotics is take orally it kills or inhibits to at least some extent the normal microbiota as well as the targeted pathogens. After antibiotic therapy the gut microbiota is not always reestablished spontaneously in adults. The use of antibiotics in the first few months of life is a particular problem by disrupting the normal development of the microbiota leading to IBS, allergies, or increase in weight. Antibiotic resistant opportunistic pathogens become pathogenic when exposed to antibiotics. Clostridium difficile is toxin and is present in small amounts in a healthy person, when an antibiotic is added growth increase producing more toxins that cause diarrhea, abdominal pain, and fever.

Compare the functions of cytokines and chemokines.

When microbial invasion cause trauma to host, resident phagocytes and damaged host cells release cytokines, which are proteins that function in communication between different cell of the body, activating a signal pathway for transcription and protein synthesis. A specific class of cytokines are chemokines, that specifically recruit other immune cells to site of injury.

List the sites of the human that are inhabited by microorganisms. (there are eight). Besides the location of the sites, how are these sites different?

●Mouth ●Nasal cavities ●Throat ●Stomach ●Intestines ●Urogenital tracts ●Skin Vagina The sites have different types of bacteria than other locations