Microbiology exam 4 homework and quiz study set

Antibodies are which biological molecule? Question 10 options: 1. carbohydrate 2. protein l3. ipid 4. nucleic acid 5. enzyme

2. protein

Which DOES NOT provide long-term immunity? (In this case, long-term refers to more than a few months.) Question 1 options: 1. getting the flu vaccine 2. injection with an immune serum containing anti-flu virus antibodies 3. contracting the flu virus 4. all of the above provide long term immunity 5. none of the above provide long term immunity

2. injection with an immune serum containing anti-flu virus antibodies

Adaptive defenses can be divided into the humoral response which is mediated by T-cells and the Cell-mediated response which is mediated by B-cells. Question 3 options: True False

False

Antigen and their cooresponding antibody are very loosely fit. A single antibody will bind many differently shaped and charged antigens. Question 11 options: True False

False

The normal flora of the upper portion of the respiratory tract closely resembles the normal flora of the large intestine in both species abundance and diversity. True False

False

Ten people in your Chemistry lab come down with H1N1 influenza in a 7 day period. This would be considered an epidemic. True False

False (It would be considered an outbreak)

Cytotoxic T-cells associate with antigen presented in a _________ molecule and secrete toxic chemicals to destroy the cell presenting that antigen. Helper T-cells associate with antigen presented in a ________ molecule and secrete chemokines to direct the immune response but do not kill the cell presenting the antigen. Question 6 options: 1. MHC I, MHC II 2. MHC II, MHC I

1. MHC I, MHC II

A _______ mother will have no trouble carrying a _________ fetus the first time, but her body may then produce antibodies and attack a second _________ fetus. Question 9 options: 1. Rh-, Rh+, Rh+ 2. Rh+, Rh-, Rh-

1. Rh-, Rh+, Rh+

Which areas of the body are typically colonized with normal flora? (Select all that apply.) 1.sinuses 2.liver 3.skin 4.intestines 5.teeth 6.spinal fluid

1.sinuses 3.skin 4.intestines 5.teeth

B-cells when sensitized or activated can become _____________ which can produce 2000 antibodies per second. Question 7 options: 1. T-cells 2. plasma cells 3. Helper T cells 4. Natural Killer cells 5. cytotoxic T-cells

2. plasma cells

Most people carry Candida albicans as part of their normal intestinal flora and do not exhibit signs of disease unless (select all that apply.) 1. They are exposed to a low infectious dose. 2. They are 55 years or older. 3. They have recently completed a course of antibiotics. 4. They are immune suppressed or compromised.

3. They have recently completed a course of antibiotics. 4. They are immune suppressed or compromised.

The practice of treating all patient samples as potentially dangerous and taking measures to avoid transmission to self, patients, and other health care workers is known as: 1. Incidence 2. Strict Isolation 3. universal precautions 4. Prevalence

3. universal precautions

If you contract Clostridium difficile while you are in the hospital being treated for a stroke, C. difficileis considered a nosocomial infection. True False

true

All of the following cells are antigen presenting cells and possess MHC II molecules. Question 4 options: 1. macrophages 2. B cells 3. Dendritic cells 4. T-cells 5. Natural Killer cells

1. macrophages 2. B cells 3. Dendritic cells

Someone with type A blood can receive a transfusion from which of the following? Question 8 options: 1. A or O 2. A or B 3. B or O 4. only A 5. only AB

1. A or O

Which areas of the body are sterile? (Select all that apply.) 1. blood 2. scalp 3. surface of the eye 4. lower portion of the lungs 5. brain 6. stomach

1. Blood 4. Lower portion of the lungs 5. brain

All nucleated cells have _______ which take an internal sample and present to Cytotoxic or Killer T-cells if compromised by a virus or cancer. Question 5 options: 1. MHC I 2. MHC II

1. MHC I

What is the infectious dose and what can it tell you about a microorganism? Would you develop an infection if you inhaled 1 Measles virus? What if you ingested 1 Vibrio cholera (Cholera) bacterium?

• The infectious dose is the estimated number of microorganisms that must be present to cause an infection. • The infectious dose can indicate how virulent the infecting microorganism is. Those with a relatively smaller infectious dose are much more virulent than those with a larger infectious dose • It only takes inhalation of 1 measles virus to produce infection • It takes 100,000,000 cells of Cholera to produce disease so ingesting one cell would not produce infection.

Why do you think that there is so much redundancy of action and so many interacting aspects of the immune response?

• The redundancy allows for multiple cells and immune responses to attack and rid the body of the MO so that if one immune cell or immune responder cannot do the job another can take over and finish the job. This is to ensure that the invading MO is unlikely to survive.

Describe how the third layer/line of defense (adaptive/acquired) is different from the first two lines of defense (innate.)

• The third layer is very specific rather than innate like layers 1 and 2, and antibodies are produced specifically against each different foreign invader whereas layers 1 and 2 produce the same immune response to every foreign MO. • The initial infection causes a slow response but each subsequent infection of the same organism will cause a more rapid response.

What is an opportunistic pathogen? Why are immunocompromised humans more susceptible to them?

•An opportunistic pathogen is a microbe that is part of normal flora in one part of our body, but when given the right circumstance (such as a weakened immune system) can penetrate the host defenses, invading and multiplying in other areas of our body that are considered sterile resulting in illness or disease. •immunocompromised humans are more susceptible to opportunistic pathogens because their immune system is compromised and not working properly. In this circumstance, normal flora can substantially over replicate and move into areas of the human body where they are not normally found which can then cause infection and or disease.

What is a nosocomial infection? Why do you think that urinary tract, lower respiratory tract, and surgical wounds are the most common sites of nosocomial infections?

• a nosocomial infection is a healthcare acquired infection (hospitals, dental offices, nursing homes) • Bacteria are everywhere, but in a hospital there are many sick patients. If good hand hygiene is not properly followed and enforced, then health care workers can unintentionally transfer a microbe from one patient on to the next patient introducing transient microbes to the second patient. Also good sanitation of hospital rooms and equipment is important in disinfecting and killing bacteria that may linger on these objects. This raises the risk of becoming colonized by the transient microbes. • Inserting urinary catheters raises the risk of introducing transient bacteria to the urinary tract, immunosuppression is a factor as well; Also, Poor patient hand hygiene and wiping after toileting can also introduce transient bacteria that may have been picked up from the hospital environment the patient is in. The genital area is an easy entry point for bacteria to enter and travel through the urinary tract causing infection (especially in women) • Many surgical site infections are caused by the patient's own bacterial flora. When a patient is surgically opened up underlying tissue is exposed to overlying native flora giving the native flora a route in which to invade foreign tissue. • Ventilators and respiratory devices can easily introduce transient bacteria into the respiratory tract giving transients an easy vehicle to invade foreign tissue • Generally, a hospitalized patient is immunosuppressed giving the patients normal bacterial flora an opportunity to overcome the normal host defenses and enter into other parts of the body that are not endogenous to these bacteria. These sites are the most common easiest sites for transients to invade.

Normal flora are important to humans because they: 1. assist in breaking down our food. 2. assist in the development of the immune system 3. assist in preventing pathogenic organisms from colonizing our body via microbial antagonism 4. all answers are correct 5. none of the answers are correct

4. all answers are correct

The plague bacterium, Yersinia pestis, is transmitted by fleas. The flea is an example of a: 1. zoonosis 2. carrier 3. sequelae 4. vector

4. vector

These bacteria are members of your normal flora that are acquired from your contact with the outside world. They are diverse and sometimes pathogenic. The abundance and diversity is closely related to hygiene: 1.exogenous pathogens 2.endogenous pathogens 3.transient flora 4.resident flora

4.resident flora

Why is a cesarean section necessary for cultivating axenic mammals like mice for study?

Because the mice need to remain germ free and are thus taken via C-section as a means of a controlled, aseptic delivery ensuring no microorganisms were unintentionally introduced to the axenic mice. (The uterus is an axenic environment)

What is the difference between transient microbiota and resident microbiota on the skin? Which ones are washed away during a normal handwashing routine of 2 minutes or less?

Resident microbiota also known as normal flora are established microbes that live all over your skin and in your body and are part of your own body's defense system fighting off other microbes from invading your body. The bodies normal flora does not produce disease under normal conditions. Resident microbes are not easily removed from the skin by mechanical friction or normal handwashing. Transient microbiota are organisms that do not normally live in or on the human body and usually only occupy space in or on the body for short periods. When Transient microbiota invade an individual by whatever means [ie. hand shaking or touching any object], they do not become firmly entrenched as resident microbiota does. Thus transient microbiota are more easily washed away during a normal handwashing routine of 2 minutes or less

In the T-independent humoral response, there is no contact with T-cells which secrete important cytokines, therefore there are no memory B-cells produced. Question 12 options: True False

True

The stem of the Y of an antibody molecule is the constant region and has binding sites for phagocytes and complement. Question 2 options: True False

True

Can healthy gut resident microbiota protect someone who has been infected with Clostridium difficile spores from developing C. difficile associated diarrhea? Why or why not?

Yes, a healthy population of normal flora microbes in your gut take up every available habitat. They physically occupy the space and they consume the nutrients produced. Clostridium difficile is a spore forming microbe. You can contract the spore anytime you are in contact with someone who is infected or anytime you touch something that has been contaminated with the spores. Remember that spores are used for survival when the bacterium senses that there are not enough nutrients present to support life and reproduction. So if you have a healthy gut population of normal flora microbes, you may be infected with the C. difficile spores, but they will remain as spores and not cause illness. If however, your gut flora is disrupted (for instance by antibiotic usage) then there will be nutrients available and the C. difficile will become vegetative and cause disease (C. difficile associated diarrhea.)

What is a biofilm? What does the text mean when it states that "Many of the interactions between the human body and microorganisms involve the development of biofilms?"

• A biofilm is an aggregate of microorganisms in which cells adhere to each other on a surface. • As the text states, microbes do not like to live in isolation. It would only be natural for the microbes residing in us [some estimate that normal flora outnumber our own cells of our bodies possibly 10:1] to form biofilms so that these microbes can utilize quorum sensing to communicate maximizing the metabolic and behavioral processes of the group as a whole. These direct microbe-microbe interactions and their use of our bodily space and resources help our normal flora to resist transient colonization. However, biofilms most often are harmful to humans and have been indicated in many microbial infections of the human body.

What does axenic mean? Are there any advantages to being axenic? Any disadvantages?

• Axenic refers to an environment that is free of microbes • In experiments with axenic mice there were advantages and disadvantages to being axenic: Axenic animals that remain in an axenic environment live longer, develop fewer diseases, and have less body fat than normal mice. This suggests that we do not need microbiota in order to survive; also the microbiota seem to be a source of pathogenesis. However, when axenic animals come in contact with normal animals or an un-axenic environment, they will eventually acquire resident flora. Further, the axenic animals have a low tolerance of microorganisms leaving them extremely susceptible (due to an immature immune system) to pathogenesis from normally harmless agents.

What do the terms: outbreak, epidemic, and pandemic describe?

• Epidemic: A community wide outbreak or dramatic increase of disease which happens suddenly and simultaneously • Outbreak: disease that occurs in a small geographical area or community exceeding normal expectations of disease prevalence. • Pandemic: an epidemic of an infectious disease that spreads across a wide geographic area and affects an exceptionally high proportion of the population

Explain why you alternately feel cold and shiver followed by feeling hot and sweating when you have a fever. Be specific and describe the physiology of fever.

• Injured tissue release chemicals that trigger an increase in temperature set point. Because of the higher temp set point, the regulatory mechanisms of the body will make you feel cold and further cause the body to shiver until the body reaches the new temperature set point. • When the tissue begins to heal, it stops releasing chemicals and resets the temperature set point to its normal range of about 98.6. The body is used to the higher set point and therefore the new lower set point makes the body feel as if it is really hot.... this is breaking of the fever

Describe the first and second layers or lines of defense your body has to protect itself against pathogens.

• Layer 1 is innate/not specific and consists of physical and chemical barriers to prevent foreign and harmful invaders from penetrating the bodies outer layer. • Layer 2 is innate/not specific and consists of leukocytes and all its different cells and the lymphatic system and the immune response which causes inflammation and fever. There are two main types of leucocytes: granulocytes and agranulocytes and each consist of several other cells.

Why would someone who has had lymph nodes removed from the groin suffer from edema in the leg?

• Lymph nodes filter fluid which can trap bacteria, viruses and foreign invaders, and destroy them via lymphocytes. If the lymph node is removed from the groin, fluid can build up in the leg of the side the node was removed causing lymphedema

Describe the action of each of the agranulocytes (include Dendritic Cells.)

• Lymphocytes are major players in the humoral immune system • B lymphocytes (Humoral immunity) when activated, make antibodies and prime pathogens for destruction and then make memory cells that can recognize specific pathogen causing MO that can spring into action at any time • T lymphocytes are important in cell-mediated immunity. When activated, they mediate immune functions and kill foreign cells • Monocytes: Chief phagocytes, largest of WBCs, circulate for 1 to 2 days then enter body tissue and differentiate into macrophages. • Dendritic cells are antigen presenting cells; trap pathogens. Can induce a primary immune response and take part in immune reactions

Describe the action of each of the granulocytes (include Mast Cells.)

• Neutrophils function by attaching to the walls of the blood vessels to block foreign invaders from accessing the blood. They kill germs via phagocytes that engulf and destroy bacteria. They are the earliest fastest responders to foreign invaders and tissue damage. • Eosinophils are extracellular killers. Eosinophils release toxins from their granules to kill MO such as parasites and worms and destroys antigen-antibody complexes. High counts of eosinophils are associated with allergic reactions. • Basophils are mobile in the blood stream. Releases anti-coagulants and histamine, which dilates the vessels to bring more immune cells to the area of injury. • Mast cells, like basophils, also release histamine but mast cells are not mobile and can be found bound to connective tissue

What are probiotics? What are prebiotics? What kinds of foods would you have to consume to get probiotics? Prebiotics?

• Probiotics are live microbes colonizing the human gut which imparts health benefits to the host. Probiotics are most notably found in active-culture yogurt or any fermented milk product or fermented vegetables. Kefir, kombucha, tempeh, kimchi, sauerkraut, pickles, etc... • Prebiotics are nondigestible fiber that serve as nutrients for probiotics in order for probiotics to grow and colonize the human gut. Resistant starch is one type of prebiotic Inulin is another type of prebiotic, a fiber found in bananas, onions, leeks, asparagus, and garlic

Describe what prompts a cell to produce interferon and the effects interferon has on the infected cells as well as surrounding cells.

• The cell produces interferon due to the presence of foreign, invading MO. • A cell that is infected will release Interferon which alerts the immune system to invading MO and triggers the activation of the immune response of different cells (t-cells, natural killer cells, macrophages). Interferon also amplifies antigen presentation to specific T cells and also promote production of second messengers.

What are the four signs of inflammation? Why is inflammation such a common reaction at the site of Influenza vaccination?

• The four signs of inflammation are redness, heat, edema, and pain. • Inflammation is a common response to many vaccines and are caused by the normal inflammatory response to a foreign invading substance at the site of the injection.