Microbiology Unit 2 Mastering
Complications associated with S. pyogenes infection
In some streptococcal infections, the bacteria spread rapidly once they enter the body: entering the connective bands of fascia that surround muscles, fat, and other structures. The damage caused by the immune system's response to the M protein and other pathogenic responses can be swift and severe, resulting in bacterial shock, organ damage, and large scale tissue death and damage.
Describe Rashes and lesions
In the most basic terms, a skin lesion denotes any skin abnormality. There are a wide variety of skin lesions, from abnormalities as small as tiny discolorations of the skin, to large raised ulcers and bullae. There are several different ways to characterize rashes and lesions that may accompany a microbial disease of the skin. Review the illustration to differentiate some common skin lesions.
Molecular action of CPE
Increasing levels of sodium, potassium, bicarbonate, and chloride ions, as well as water, are secreted as toxin concentrations are increased from 25, 50, 100, and 150 units. Histological observation indicates that morphological alteration and sloughing of epithelial cells occurs up to a maximum of 1000 units. Protein levels within the ileum loop fluid are increased up to 1000 units of toxin. Excess toxin does not increase ion loss, fluid loss, or tissue damage beyond a certain point.
Which of the following is true concerning systemic anaphylaxis?
Injected antigens combine with IgE antibodies on the surface of certain cells, causing them to release histamines and other inflammatory mediators.
Includes cilia, mucous membranes, dendritic cells
Innate immunity
While we usually think of fever as a bad thing, a fever is actually signifying that an immune response is progressing! Overall, which of the following cytokines would be most involved in increasing Caleb's fever response?
Interleukin-1
Why is vasodilation important to tissue repair?
It allows for an increased delivery of oxygen, nutrients, and phagocytes to the site of damage.
Acne is the result of the inflammatory response. In this case, the inflammation is resulting in acne that is very painful (physically and emotionally) for Scott. However, inflammation is a critical component of a normal immune response. What are the main functions of the inflammatory response?
"walling off" the site of injury or infection repairing tissue damage resulting from inflammation destroying and eliminating the invading pathogen
What is the correct sequence of events for activation of a B cell by a T-dependent antigen?
(1) Immunoglobulin receptors on the B cell recognize and bind the antigen. (2) An antigen fragment in complex with MHC class 2 is displayed on the B cell's surface. (3) The MHC-antigen complex binds a receptor on a TH cell. (4) The TH cell secretes cytokines that activate the B cell.
How does the protozoan Trypanosoma evade detection by the immune system?
It can change the surface antigens frequently, preventing the immune system from tracking it.
Which of the following statements concerning necrotizing fasciitis is TRUE
It is often associated with streptococcal toxic shock syndrome. Some cases require limb amputation. It may be caused by several different organisms, but Streptococcus pyogenes is the most common.
Why is methicillin-resistant Staphylococcus aureus (MRSA) methicillin resistant?
It produces a modified version of the molecule that is targeted by the drug.
Arrange in the correct order the following pathologic events in cystic fibrosis lung disease.
1. CFTR defect results in production of dehydrated thick mucus. 2. thick mucus results in impaired ciliary clearance. 3. bacteria become trapped in mucus, resulting in a chronic bacterial infection. 4. As a result of bacterial infection, a chronic neutrophilic inflammatory response ensues. 5. Inflammation results in bronchiectasis and fibrosis of lung bronchial walls.
Disease research and epidemiology bring together many different facets to help us better understand disease pathology and spread. Which of the following statements are true?
1. Some pathogens are able to cause disease within a host without penetrating the body. 2. Bacterial exotoxins can be altered to create toxoids, which can be used to produce protective immunity in a host. 3. The interactions that occur between a microbe and host influence the evolution of both.
The earliest vaccinations were against smallpox. Which of the following statements about the history of smallpox vaccinations is true
1. The earliest vaccinations were called variolations and protected people from smallpox by inoculating them with smallpox matter. 2. Edward Jenner inoculated people with cowpox in an attempt to protect them from smallpox. 3. Chinese physicians prevented smallpox disease by having children inhale dried smallpox scabs.
The physical symptoms of cholera present only after a specific series of events has taken place. What is the most likely sequence of events in the pathogenesis of V. cholerae?
1. V. cholerae is ingested via contaminated water, 2. V. cholerae survives passage through the stomach and enters the intestine, 3. V. cholerae attaches via pili, 4. V. cholerae produces cholera toxin, 5. The host intestinal cells are destroyed, resulting in a profuse watery diarrhea, 6. v. cholerae exits the host via the feces
Kelly learns that the diagnosis of HPV may rely on the presence of viral DNA. Other infectious agents can be diagnosed based on immunologic responses. Which of the following represents an immunologic-based diagnostic test?
1. precipitation reactions 2. fluorescent-antibody techniques 3. agglutination reactions
Arrange the statement of events below in the order that best describes the sequence of events in the pathology of Clostridium perfringens poisoning once contaminated food has been ingested.
1. sporulation and lysis of vegetative cells result in the release of CPE. 2. CPE binds to claudin receptors of the tight junctions of intestinal epithelia. 3. Absorption of fluid and ions across the epithelia is inhibited. 4. Formation of the CPE-claudin complex results in active pore formation. 5. Calcium ion influx results in activation of calpain. 6. Cellular death and loss of epithelial layer of intestinal villi result in fluid secretion into lumen and diarrhea. 7. Increased myoelectrical activity of intestine leads to severe cramping.
Which is the correct sequence of events regarding the stages of tooth decay? 1. Dentin decay 2. Enamel decay 3. Plaque 4. Pulp decay
3-2-1-4
What is a blood blister
A blood blister is a fluid-filled lesion (the fluid is blood). Often these types of lesions will appear red, purple, or blackish. You may hear the term hemorrhagic used to denote the presence of blood for this type of lesion.
Left shift
A left shift indicates that there are higher numbers of immature leukocytes (predominantly neutrophils) in the blood than normal. The young neutrophils can be referred to as band cells because of their unsegmented nuclei. The presence of a left shift indicates an overwhelming infectious process, as the bone marrow supplies new leukocytes as quickly as possible.
Cystic fibrosis is an autosomal recessive disease.
A recessive gene is expressed only when two copies of genes are present. A person who has only one copy of the gene is a carrier.
Which of the following would be an example of disease transmission via INDIRECT contact?
A student sneezes on her test booklet. The instructor grades it and catches her cold.
Which of the following is true regarding systemic anaphylactic reactions?
A systemic reaction can be fatal in only a few minutes. Systemic reactions are commonly associated with injected antigens. Systemic reactions can result in a dramatic decrease in blood pressure.
Assuming Rh compatibility is present, which of the following individuals would be able to receive donor blood from any of the four blood types (A, B, AB, and O)?
AB
As we progress through the immune response, we hope to activate more "specialized" cells in our arsenal. However, this requires specific and regulated interactions between cells. This occurs as we transition from innate responses to adaptive responses by processing or displaying antigen to adaptive players. This is called
Adaptive immune cell and an antigen presenting cell
__________ reactions are used to detect antibodies for relatively large pathogens, such as bacteria. For these tests, the antigen is mixed with the test sample at various dilutions. Reaction mixes are then monitored for the formation of visible aggregates.
Agglutination
Which of the complement pathways employs properdin?
Alternative pathway
Which of the following choices correctly matches the class of antibiotic and its mode of action?
Aminoglycosides and tetracyclines are inhibitors of protein synthesis. Sulfonamides inhibit the synthesis of essential metabolites
Which of the following would be an example of an infection initiated via the parenteral route?
An individual contracts hepatitis B from an accidental stick with a contaminated needle.
Which of the following is a characteristic of tuberculosis infection?
An individual could become infected by standing next to an infected person who is coughing. Treatment requires a minimum of 6 months of antibiotic therapy. The adaptive immune response is mostly cell mediated, because Mycobacterium tuberculosis lives and reproduces inside macrophages.
Which of the following best describes vaccination?
An individual is exposed to a killed pathogen, an inactivated pathogen, or a component of a pathogen. The individual is protected from subsequent exposures to the pathogen because the adaptive immune system is stimulated to produce memory B cells and memory T cells, which protect from subsequent exposures.
If this particular antigen attempts to re-infect Caleb, it's in for a bigger fight. By getting activation of adaptive immune cells such as B-cells and T-cells, the body generates an extra layer of protection. What is a critical advantage for Caleb the next time he encounters this antigen?
Anamnestic (memory) responses and future vaccinations to augment the response
Although cholera can be treated with antibiotics, data suggest that antibiotic treatment alone is NOT the most effective therapy. Which of the following statements describes the most likely reason for supplementing antibiotic therapy?
Antibiotic therapy addresses only the growth of V. cholerae; it doesn't address the extreme dehydration suffered by a person infected with V. cholerae.
After listening to Caleb's lungs, Dr. Bell determines that Caleb most likely has a lower respiratory infection and prescribes the antibiotic azithromycin. After listening to Caleb's lungs, Dr. Bell determines that Caleb most likely has a lower respiratory infection and prescribes the antibiotic azithromycin
Antibiotic therapy is started with a broad-spectrum antibiotic because broad-spectrum antibiotics are effective against many gram-positive and many gram-negative bacteria
The antibiotic balancing act
Antibiotics will kill off beneficial bacteria. Antibiotics have side effects. Antibiotics can weaken the immune system. Using antibiotics can accelerate drug resistance in Staph.
What is meant by the term arbovirus?
Arboviruses get their name because they are typically arthropod-borne viruses that remain in nature because of biological transmission between susceptible hosts by blood-feeding arthropods, such as mosquitoes.
Which statement regarding the infectiveness and pathogenicity of HIV is TRUE?
Attachment of HIV to the target cell depends on the glycoprotein spike (gp120) combining with the CD4+ receptor. Some cells that do not carry the CD4 molecule can become infected with HIV. The ability of the HIV to remain as a provirus shelters it from the immune system.
__________________ stimulated with ___________ differentiate into __________, which secrete antibodies into the bloodstream.
B-cells, antigen, plasma cells
B. pseudomallei culture
B. pseudomallei is not fastidious, and will grow on a variety of media. For selective isolation Ashdown's media or blood agar with gentamicin can be used.
Buffered charcoal-yeast extract agar
Buffered charcoal yeast extract agar is the best medium for the growth of Legionella pneumophila. This medium supplies the bacteria with the cysteine and iron the bacteria need for growth.
In the classical pathway, which of the following directly activates cellular responses?
C3a, C5a, and C5bC6C7
Which complement protein is used as an opsonin?
C3b
The absence of C5 means that the molecule is not present to be activated. What happens in normal serum when C5 is "activated"?
C3b is a part of enzyme that splits C5 into two fragments, C5a and C5b.
Fragment C5b initiates the binding of the terminal complement proteins that form the membrane-attack complex (MAC). Which of these proteins associates with the MAC?
C7
Which statement regarding cancer immunotherapy is TRUE
Cancer vaccines may be either therapeutic or prophylactic. Monoclonal antibodies are a promising tool for cancer treatment delivery. Cancer immunotherapy is preferable to radiation therapy because it does not involve causing damage to healthy cells.
How can capsules enable bacteria to evade the immune system?
Capsules block the complement biding sites on the surface of the pathogen.
Which of the following can release histamines?
Cells from damaged tissues and the complement pathway
Which of the following statements concerning cellular immunity is FALSE?
Cellular immunity involves cells that recognize antigens and make specific antibodies against them.
True
Certain accessory digestive structures lie outside the gastrointestinal (GI) tract and convey their secretions via ducts.
What complement result involves the use of phagocytes?
Chemotaxis and opsonization
Which of the following would you likely see on the surface of a human dendritic cell following phagocytosis of a bacterium?
Class I MHC with dendritic cell antigens and Class II MHC with engulfed bacteria
What would a virally infected skin epithelial cell have on its cell surface?
Class I MHC with skin cell antigens
Pathogenic staphylococci
Coagulase-negative strains of staphylococci are generally less pathogenic than coagulase-positive strains. Staphylococcus aureus
If a person could not form C2, which result of complement would be affected?
Cytolysis, chemotaxis, inflammation, and opsonization
Which of the following are likely to be found on an MHC-I protein?
Damaged mitochondrial fragment
Phagocytes that engulf anything foreign. eventually display epitope to helper T cells using MHC I or II
Dendritic cells
Differential media
Differential media can be used to identify bacteria based upon their usage of a specific type of media (culture conditions). Some common examples of differential media are MacConkey Medium, which is used to culture and differentiate bacteria based upon their ability to ferment lactose, as well as blood agar, which is used to culture and differentiate hemolytic organisms.
Why does Dr. Bell start Caleb on HIV therapy in addition to the antibiotics used to treat the tuberculosis?
Dr. Bell prescribes Caleb HIV therapy because the virus is not affected by the antibiotics used to treat tuberculosis.
Which of the following is an example of the symbiotic relationship known as mutualism?
E. coli within the large intestine
Which of the following is the most likely possible diagnosis for Caleb? The symptoms are localized to his head and there's no nasal discharge discernable. Fever is a prominent sign.
Ear infection
The brain tissue of the birds indicated the possibility of encephalitis. What is encephalitis, and why should this type of infection cause concern among health care professionals?
Encephalitis is an inflammation of the brain tissue. It is a concern to health care professionals because an infection in the brain means the virus has breached protective measures.
A patient exhibits hemorrhagic colitis and is treated via intravenous rehydration. The pathogen is a gram-negative rod. It is isolated and differentiated from related organisms based on its inability to ferment sorbitol. Which of the following is a likely diagnosis?
Escherichia coli gastroenteritis
Which of the following statements about lysogenic conversion is true?
Exotoxin production by bacteria is frequently the result of a lysogenic infection.
I have a new test for determining whether a patient is infected with the influenza virus. It is very specific but not very sensitive. What does this mean?
False-positives will be rare, but false-negatives may happen frequently.
The name Propionibacterium is derived from the fact that the organism produces propionic acid during fermentative metabolism. Which of the following statements about fermentative metabolism is true?
Fermentation produces significantly less ATP than aerobic respiration; however it generates NAD+, which can be used in glycolysis.
How does cytolysis occur via the complement pathway?
Formation of the MAC in invading cells, killing them
Organisms associated with skin disease
Frequently, skin-related diseases result when bacteria that are normally commensal are able to pass through the skin's barrier. These bacteria are very common, and the probability that they are present when skin is broken or invaded is high. Once inside the body, some types of these commensal bacteria will produce harmful enzymes and toxins that trigger the outward symptoms of skin disease. The presence of certain organisms may not seem significant because they are part of the normal skin microbiota.
Which of the following conclusions are supported by the current research data regarding Burkholderia cepacia
Genomovars III and II appear to be the most virulent or transmissible to humans Burkholderia cepacia complex appears to be very diverse in its habitat and distribution. It would appear that the environment may serve as a reservoir for acquiring Burkholderia cepacia complex strains.
Streptococcus pneumoniae
Gram + coccus; typical pneumonia
Mycoplasma pneumoniae
Gram - pleomorph; atypical pneumonia
Mycobacterium tuberculosis
Gram - rod; tuberculosis
Bordetella pertussis
Gram - rod; whooping cough
Haemophilus influenzae
Gram- rod; pneumonia
H. influenzae culture
H. influenzae is known as a "fastidious" bacterium, meaning that it has complex growth requirements. In particular, H. influenzae requires blood in its culture medium, as well as cofactors and parts of the cytochrome sequence that the bacterium requires for respiration, but is unable to synthesize itself.
You are conducting a viral hemagglutination inhibition test. Which of the following indicates that a patient's serum has antibodies against influenza virus?
Hemagglutination occurs in a mixture of influenza virus and erythrocytes but does not occur when the patient's serum is added.
Hematocrit
Hematocrit is an essential measure for any CBC. To ascertain a hematocrit, heparinized blood (blood that will not coagulate) is centrifuged until the different blood elements separate out into distinct layers. The topmost layer (usually yellowish in color) is plasma, which is followed by a thin layer of white blood cells (leukocytes and thrombocytes), followed by a layer of red blood cells (erythrocytes). Hematocrit is calculated as the percentage of the volume of whole blood that is made up of red blood cells. A low hematocrit value can indicate anemia, bleeding, the destruction of red blood cells, and/or malnutrition among other conditions.
____________ antibodies are found in mucosal secretions and help to protect the respiratory system from infection.
IgA
Arrange the following statements in the order that best represents the chronological order of events in generating an anaphylactic reaction.
IgE molecules bind to mast cells and basophils. 2. Antigen molecules cross-link adjacent IgE molecules. 3. Degranulation occurs. 4. Chemical mediators such as histamine are released. 5. Capillary permeability and smooth muscle contractions increase. 6. Neutrophils and eosinophils move to the site.
Which of the following mediators are involved in anaphylactic reactions?
IgE, basophils, mast cells
If a patient has been exposed to an antigen for the first time, which class of immunoglobulin appears first?
IgM
Use BCR's to recognize epitope. First step in clonal selection
Immature B. Cells
Which of the following best describes graft-versus-host disease?
Immune cells in transplanted bone marrow attack the cells of the host
Which of the following is a characteristic of rheumatoid arthritis?
Immune complexes of IgM, IgG, and complement are involved.
Measures of organ function
Kidney function can be assessed in a variety of ways. Abnormal serum values such as low calcium and albumin, or the presence of products that are normally removed from circulation by kidney filtration can indicate a pathological condition.
________________ is/are always present in an individual's blood. However, in the absence of infection, it is in an inactive form.
Kinins
L. pneumophila culture
L. pneumophila is traditionally detected by culture on agar that can supply the cysteine and iron the bacterium needs to grow. For example, BYCE agar is a good source of both.
Which of the following is the best mode of controlling the spread of West Nile infections?
Limit exposure to mosquitoes to prevent the transmission of West Nile virus.
Which statement regarding the lymphatic system is true?
Lymphatic capillaries possess one-way valves. These valves permit the uptake of fluid from the body but do not allow the fluid to flow back out of the capillaries into the intracellular spaces.
Which of the following virulence factors could directly prevent phagocytosis and/or phagocytic degradation?
M proteins capsules waxy lipids
What does MRSA stand for?
MRSA stands for methicillin-resistant Staphylococcus aureus. Your patient is infected with a strain of S. aureus that is resistant to penicillin, but still sensitive to methicillin.
Which of the following contribute to drug resistance in M. tuberculosis?
Many individuals fail to complete their entire regimen of antibiotics. Some physicians prescribe the wrong medication, the wrong dosage, or the wrong length of time for treating tuberculosis. In many areas, tuberculosis antibiotics are unavailable or of poor quality.
Who gets legionellosis
Men over the age of 50 are the most likely to contract legionellosis, especially if they are heavy smokers or drinkers. There are other factors that involve travel and pathogen exposure that are associated with a high rate of legionellosis transmission as well.
What are leukocidins?
Molecules that are capable of destroying phagocytes
Which of the following statements about adherence is true?
Most bacterial adhesins are glycoproteins or lipoproteins.
which of the following organisms exhibits antigenic variation?
N. gonorrheae
necrotizing fasciitis
Necrotizing fasciitis is frequently associated with streptococcal toxic shock syndrome, and your patient's hemorrhagic bullae, in combination with her elevated serum creatine kinase levels, give you good reason to suspect that she may have some potentially dangerous tissue damage.
Infants may acquire a serious form of conjunctivitis during birth if they are born to a mother infected with __________.
Neisseria gonorrhoeae
Meningitis and gonorrhea are caused by
Neisseria species
The 'grainy' appearance of the cytoplasm and the structural appearance of the nucleus are key identifiers of this type of cell as opposed to other immune cell phenotypes.which could likely be identified as a:
Neutrophil
Why would a body cell that is not a phagocyte need to present antigens?
Non-phagocytic body cells can become infected with a virus.
Which statement regarding endotoxins is true?
One consequence of endotoxins is the activation of blood-clotting proteins.
If a person lacked the ability to form C5, what direct result of complement could still occur?
Opsonization
Place the following statements in the chronological order that best describes the sequence of events leading to the appearance of acne
Overproduction of sebum leads to an accumulation on the follicle. 2. P. acnes metabolizes glycerol in sebum, forming free fatty acids. 3. Free fatty acids stimulate the release of proinflammatory cytokines within the follicle. 4. The blood vessels surrounding the follicle dilate and become more permeable. 5. Immune cells such as neutrophils and phagocytes move into the follicle to try to eliminate P. acnes. 6. The building of dead cells, bacteria and body fluids causes a raised pustule to appear on the skin surface.
Which of the following statements concerning pathology, infection, and disease is true?
Pathology refers to the study of structural and functional changes that occur in the body as a result of a disease.
Suppose that Charlie and Rachelle have a C3 deficiency rather than a C5 deficiency. What would be one consequence for innate immunity to microbes if these siblings lack C3 in their blood?
Phagocytes could not attach as easily to invading microbes.
Which structure do antigen presenting cells utilize to directly help them present bacterial antigens?
Phagolysosome
Produce and secrete antibodies
Plasma Cells
Sally decides to go through the desensitization program recommended by her doctor. What is the overall purpose/goal of this process?
Repeated exposure to wasp venom antigen will increase the amount of IgG produced by Sally's immune system.
Part of the reason for Scott's acne is the overproduction of sebum. Scott's initial instinct is that shutting down production of sebum would be the quickest route to eliminating his acne; however, sebum actually plays an important role in maintaining the skin as a first line of defense against pathogens. Which of the following best describes the role of sebum as a component of the first line of defense?
Sebum forms a protective layer over the skin. Sebum helps to keep the pH of the skin low, which inhibits the growth of microorganisms.
In mice, the LD50 for staphylococcal enterotoxin is 1350 ng/kg, and the LD50 for Shiga toxin is 250 ng/kg. Which of the following statements is true?
Shiga toxin is more lethal than staphylococcal enterotoxin.
What does it mean when a patient goes into "shock"?
Shock refers to any life-threatening decrease in blood pressure. Shock caused by bacteria is called septic shock.
Which of the following are necessary conditions for natural selection to occur within a population of Staphylococcus aureus?
Some individuals in the population reproduce more than others. Traits are hereditary Traits that permit an individual to survive at least until reproduction will increase in frequency over time. Individuals in the population vary from one another.
Ways to group staphylococci
Species of staphylococci can be grouped a number of ways. For instance, staphylococci can be grouped by their growth on selective media, the color of their colonies, their hemolytic activity, and/or their ability to reduce nitrates. For almost all clinical purposes, however, staphylococci are divided into species that produce coagulase and those that do not. One of the most important phenotypic features that can be used to differentiate among Staph species is their ability to produce , an enzyme that causes blood clot formation.
Bacterial diseases of the skin
Staphylococcus Streptococcus
A child presents with large red patches of skin. The top layers are peeling off. Because the parents report that the child hasn't been burned, you suspect that the lesions are due to infection with
Staphylococcus aureus
ohn went to a picnic. He took some leftover chicken and rice home, heated it on the stove, ate it, and got sick two hours later. John thought the heating made his food safe because it would have killed any bacteria present. He didn't know that __________ produces a heat-stable toxin.
Staphylococcus aureus
Which statement regarding the skin is true?
Sweat contains an enzyme called lysozyme, which breaks down the cell walls of some bacteria. The outer layer is composed of dead cells. It is waterproof.
Which type of T cell is involved in activating macrophages and stimulating development of cytotoxic T cells?
TH1 cells
Lymphocytes that activate B cells and CTLs.
Th cells
In cystic fibrosis, a defective gene and its protein product lead to the production of thick and dehydrated mucus because of __________.
The CFTR protein functions as an anion channel transport molecule. defective secretion of chloride ions and excess absorption of sodium
Which of the following findings are key to the cause of the outbreak?
The Clostridium perfringens food poisoning at the July 4 celebration most likely could have been prevented if appropriate measures had been taken. Large quantities of meat were prepared and kept warm for a long time before they were served. The sauce was prepared on an overcrowded steam table and, as a result, did not reach an appropriate temperature to kill any organisms.
The IgG molecules that are produced during desensitization function as blocking antibodies. These antibodies are extremely effective in providing protection from a hypersensitivity reaction. Why are blocking IgG antibodies so effective at protecting Sally from another anaphylactic response to wasp venom?
The blocking IgG antibodies "outnumber" the IgE antibodies and bind to wasp venom before the IgE antibodies can bind.
How does a capsule help certain bacteria evade detection by the immune system?
The capsule is composed of polysaccharides that are similar to those found in the host; thus, the immune system does not recognize it as foreign.
Which of the complement pathways was discovered first?
The classical pathway
Coagulase test
The coagulase test is used to differentiate coagulase-positive organisms from coagulase-negative organisms. In a slide coagulase test, coagulase-positive activity is detected by a clumping reaction in a drop of plasma relative to a negative control. In a tube coagulase test, a sample of the unknown bacteria are added to a tube of rabbit plasma and then incubated. If the plasma clumps, it indicates a coagulase-positive organism; while if the plasma remains solid it indicates a coagulase-negative organism.
Drugs for Legionella pneumophila infection
The drugs of choice for infection by Legionella pneumophila are macrolide antibiotics. erythromycin
Why does Dr. Turner change Chloe's initial antimicrobial therapy? Which of the following are valid reasons why Chloe's antimicrobial therapy should be changed?
The isolate is confirmed to be Burkholderia cepacia. Results of antimicrobial susceptibility testing were conflicting.
Which of the following statements concerning immunological memory is true?
The memory response is due to production of long-lived cells that can respond very rapidly upon second exposure.
Koch's postulates established criteria for proving that a specific organism causes a specific disease. Which of the following is NOT one of the criteria given by Koch's postulates?
The pathogen must be isolated from inoculated animals and must be different from the original organism.
An individual presents with a pinkish red rash and a red sore throat. Gram-positive cocci are cultured from a throat swab. The cocci are growing in chains. Which of the following is the most likely conclusion?
The patient has scarlet fever
Which of the following statements about the development of infectious diseases is correct?
The period of convalescence is the time during which the person regains health and fully recovers (back to the pre-disease state).
he pathology of cepacia syndrome is often complex and due to multiple factors. All of the following factors may contribute to the development of cepacia syndrome
The severity of Burkholderia cepacia infection is due in part to the microbes' ability to form biofilms, which are resistant to penetration by antimicrobials. The defective CFTR protein leads to increased mucus and viscosity, which allow the organism to persist. The patient's clinical status does not improve, and progressive respiratory impairment and failure follow. Patients who are colonized and/or infected with Burkholderia cepacia genomovar III are most likely to develop cepacia syndrome.
Which statement correctly describes the normal microbiota of the skin?
The skin's normal microbiota are capable of growth at elevated salt concentrations.
If mosquitoes are the mode of transmission for West Nile virus, why did the students in Bill's virology class focus on finding the virus in the dead birds rather than collecting mosquitoes to examine?
The students tried to isolate and identify West Nile virus from birds because they are an amplifying host for the virus, making it more likely that the virus can be isolated from these animals.
Which statement regarding normal microbiota of the human respiratory system is true?
The trachea normally may contain a few bacteria. The ciliary escalator in the bronchial tubes keeps the lower respiratory tract nearly sterile. Potentially pathogenic microorganisms are present in nonsterile portions of the respiratory tract but usually do not cause disease.
Consider a helminthic infection in which an individual is colonized by a parasitic worm. The worm is too big to be engulfed by a phagocytic cell. How does the immune system respond?
The worm gets coated with antibodies, which activate other cells in the immune system to secrete chemicals that kill it.
Dangerous complications of microbial infections of the skin
There are several complications of microbial infections of the skin that can be very dangerous. For example, necrotizing fasciitis, toxic shock (streptococcal or staphylococcal), Reye's syndrome, and herpes encephalitis, among other diseases, can be highly lethal.
Which of the following are functions of lectins?
They act as opsonins for phagocytosis, they attach to carbohydrates on some bacterial and viral surfaces, and they activate C2 and C4.
What direct effect do histamines and leukotrienes have on capillaries?
They allow capillary walls to open and become leaky.
How are immune cells able to detect foreign pathogens?
They are able to detect structures on the surfaces of foreign cells that are not found in the host
Which of the following is NOT a reason why monoclonal antibodies (Mabs) are useful?
They are always highly sensitive.
What do hyaluronidase and kinase have in common?
They are both enzymes involved in evading host defense.
Which of the following statements concerning antigen-presenting cells is true?
They are involved in activating T cells
Which of the following is TRUE concerning type II (cytotoxic) hypersensitivity reactions?
They are responsible for transfusion reactions. IgM and IgG antibodies bind to antigens on foreign cells. Macrophage activity my lead to additional cellular damage
Which of the following is NOT an advantage of using live attenuated vaccines?
They are usually safer than other types of vaccines.
How do superantigens enable pathogens to hide from the immune system if they actually stimulate the immune system?
They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen
How do phagocytes communicate to other cells what they have captured?
They present antigens from engulfed foreign cells.
Why is it necessary to give the HPV vaccine in multiple doses?
Three doses of the HPV vaccine are given to elicit both a humoral and a cell-mediated response
Thrombocytopenia
Thrombocytopenia is a relative decrease in the number of platelets in the blood. Platelets are involved in hemostasis (the cessation of bleeding), leading to the formation of clots.
Some studies have indicated that the ID50 for Vibrio cholerae can be as high as 108 organisms. Which of the following most likely explains the requirement for this relatively high ID50?
To establish infection, V. cholerae must survive the host immune response and the acidic environment of the stomach
Tom has a genetic disorder in which he does not synthesize class I MHC proteins or functional NK cells. Which of the following statements would be true for Tom?
Tom would not be able to destroy virally-infected cells
Which of the following microorganisms actually grows inside the macrophage?
Tuberculosis bacterium
The examination led to a diagnosis of otitis media (OM), or an ear infection. The picture on the left demonstrates a swollen, red eardrum with a fluid buildup behind the membrane. The immune processes most involved in the inflammation seen behind Caleb's eardrum would be attributed to:
Vasodilation of capillaries and accumulation of immune cells, fluid or pus
Which of the following are properties of exotoxins?
Very small amounts of exotoxin can be lethal, Exotoxins are protein molecules, Exotoxins target specific cellular structures or molecules.
Which of the following toxins does NOT match the description?
Vibrio enterotoxin: a superantigen that destroys epithelial cells
Why is it more difficult to treat viral infections than it is to treat bacterial infections?
Viruses use the host cell's processes to carry out their own reproduction
As a health care worker, I am keenly aware of how important it is to avoid harming my patients. I worry about inadvertently transmitting an infectious disease to an already compromised individual. According to the CDC, what is the MOST important thing I can do to avoid this?
Wash my hands before interacting with any patient.
What features of West Nile virus make it an emerging disease of special concern?
West Nile virus is an arthropod-borne virus transmitted by mosquitoes. West Nile virus has a high mortality rate in immunosuppressed humans and infects many species of birds in southern Europe, the Mediterranean basin, and North America. West Nile virus is maintained in nature through biological transmission between susceptible hosts by blood-feeding arthropods.
Which of the following best describes why West Nile Virus is considered to be an emerging infectious disease?
West Nile virus outbreaks have increased in number and affected areas since 1937.
You have a culture of bacteria that you suspect is either Staphylococcus aureus or Streptococcus pyogenes. Is there any morphological difference between the two?
Yes. S. aureus tends to grow in clusters, whereas S. pyogenes tends to grow in chains.
What is an adjuvant?
a chemical additive that increases the effectiveness of vaccines
When the wasps stung Sally, the injection of venom initiated a type I hypersensitivity reaction called anaphylaxis. Which of the following best describes a hypersensitivity reaction?
a reaction that occurs in a sensitized individual resulting in tissue damage rather than immunity
The bacteria appear to be in clusters, as opposed to chains. This suggests that your patient has ______.
a staphylococcal infection
left ship
active inflammation or infection
Phagocytosis is a process for engulfing large particles (>1μm). Which feature of antibodies will help to make particles larger, therefore enhancing phagocytosis?
agglutination
Treatment approaches to inflammatory acne
an oral antibiotic such as erythromycin topical treatment with a product containing benzoyl peroxide Clear Light, a nonchemical, light-based system
Selecting the best drug to treat Staphylococcus aureus infections can be difficult because some strains of the bacteria have developed
antibiotic resistance
Which of the following are best described as short chains of amino acids that are very stable and can have a variety of different antimicrobial activities, such as forming pores in bacterial plasma membranes and inhibiting cell wall synthesis?
antimicrobial peptides
You know that Streptococcus pyogenes is both beta-hemolytic and capable of causing toxic shock syndrome; however, you also know that Staphylococcus aureus can be beta-hemolytic, and also cause its own variant of the same syndrome. What are some ways you can differentiate between these two genera?
arrangement of cocci ability to produce coagulase presence of M protein
decreased hematocrit
blood loss, red blood cell destruction hemolysis
How do antifungal drugs such as miconazole and amphotericin B function?
by disrupting the plasma membrane
Legionella pneumophila
can cause both Pontiac fever and legionellosis.
Immunological response that kills infected host cells
cellular immunity
Genes for beta-lactamase are present in Burkholderia cepacia but are not normally expressed unless they are induced. Exposure to which of the following agents most likely induced the expression of beta-lactamase resistance in Burkholderia cepacia?
cephalexin
Which disease would be potentially propagated in an environment without functional plumbing and in which drinking water is contaminated with sewage?
cholera
You are very concerned that your patient's fever, rash, desquamation, and hemorrhagic bullae could be indicative of the late stages of a variant of toxic shock syndrome. You review your patient's vitals and see that she is hypotensive (low blood pressure) and her pulse is elevated. These signs are ______.
consistent with the symptoms of toxic shock
Kill(s) infected host cells
cytotoxic T cells
Pus is comprised of
dead phagocytes.
Predict which of the following outcomes would result from taking an antihistamine.
decreased histamine-based stimulation of cells decreased permeability of blood vessels decreased mucus secretions
Direct fluorescent-antibody techniques are frequently used to __________.
detect microorganisms in a clinical sample
In macrophages and dendritic cells (so-called antigen-presenting cells) some small parts of the phagocytosed particle are presented to other cells of the immune system. If you were to draw an arrow leading to "antigen presentation" as described above, from which word would it extend?
digestion
You note that the body temperature of one of your patients is starting to increase. As a result, you can infer that all of the following may be occurring in this patient EXCEPT __________.
dilation of blood vessels
Which of the following is caused by infection of the upper respiratory tract?
diphtheria, streptococcal pharyngitis, scarlet fever. NOTE:Whooping cough is not an infection of the upper respiratory system.
Malaria is an infectious disease caused by infection with a protozoan. In certain tropical regions, malaria is constantly present. We would say that malaria is a(n) _________ disease in these regions.
endemic
If one is examining a blood smear from a patient with a parasitic worm infection, which of the following leukocytes would be found in increased numbers (as opposed to a blood smear from a normal patient NOT infected with worms
eosinophils
The development of multi-drug resistance in Staphylococcus aureus is a classic example of ______.
evolution
Which type of bacterial enzyme helps spread Streptococcus pyogenes by digesting blood clots?
fibrinolysin
Sulfanilamides interfere with __________.
folic acid synthesis in bacteria
he ability of Vibrio cholerae to cause disease depends on a number of factors. Which of the following are requirements for causing disease within a host?
gaining access to the host via a portal of entry; evasion of host defenses; adherence to host tissues
Mechanisms of action of antibiotics and benzoyl peroxide, side effects?
gastrointestinal problems resulting from a reduction/elimination of normal intestinal flora excessive drying of the skin
Legionella pneumophila
gram - rod; Legionnaire's disease
If penicillin G is chosen as the best treatment for a given infection, what microorganisms are most likely the cause?
gram-positive bacteria
The development of vaccines is considered the single most important application of immunology. What are the benefits associated with vaccinations?
herd immunity control of viral disease eradication of disease protection during travels
Immunological response brought about by antibody production
humoral immunity
The following choices list several types of diseases, along with factors that may contribute to their emergence. Which disease and associated factor match?
increased incidence of malaria: global warming, spread of cholera to new regions: modern travel, Increased incidence of Lyme disease: increases in deer populations
Which of the following are outcomes of activating complement pathways?
inflammation cytolysis opsonization
Which of the following is an event that ultimately results in activation of complement C3 by splitting it into C3a and C3b?
interaction of mannose-binding lectin with mannose molecules on a bacterium
Antigen processing and presentation
is a way for a cell to give information about its activities.
Toxic shock
like other forms of septic shock, is a condition in which the body's response to infection or intoxication triggers a life-threatening decrease in blood pressure.
Common sources of legionellosis outbreaks
long-term care, senior, or assisted living facility (e.g. nursing home, rehab facility) a hospital (besides his current stay) a mall or other large enclosed shopping venue a pool, hot tub, jacuzzi or whirlpool spa recreational misters a decorative fountain grocery stores with misters for fruit and vegetables a hotel a humidifier a shower (away from home) a doctor's or dentist's office construction or projects affecting, plumbing and/or water lines a steam room or sauna any form of respiratory therapy equipment (e.g. sleep apnea, asthma devices)
Because C5 is absent in their sera, which of the protective effects of complement activation does not occur in response to infection with Neisseria meningitidis?
lysis of infecting microbes
In which intracellular compartment would you expect most of the digestive enzymes involved in pathogen destruction to be found?
lysosome
Differentiated B cells that are stored in lymph nodes to provide protection against future infections by same pathogen
memory cells
Which of the following is an antiprotozoan drug that interferes with anaerobic metabolism?
metronidazole
A driving force of this sort of evolution is _____ , which is sometimes colloquially referred to as the "survival of the fittest."
natural seclection
An individual may be exposed to a pathogen and become infected without actually getting sick. This is known as a subclinical infection. Even in subclinical infections, the individual's adaptive immune system can generate memory for the pathogen. What type of adaptive immunity is this?
naturally acquired active immunity
The flu virus mutates fairly frequently. Its adhesive proteins change such that we have different "strains" of influenza each year. When a particular flu virus mutates such that its adhesive proteins change, which function of antibodies is disrupted?
neutralization
Below is a view at 1000X magnification of a Gram stain of the cerebrospinal fluid. What type of white blood cell predominates in Charlie's CSF?
neutrophil
Mycobacterium tuberculosis is an intracellular pathogen of humans. After being ingested by a macrophage, it prevents formation of the ___________ by preventing fusion of the phagosome with the ___________________.
phagolysosome, lysosome
low serum platelet count
possible coagulation pathology
low serum albumin and calcium, increased creatinine and BUN
possible organ failure
Increased serum creatine kinase
possible tissue damage
Which of the following bacterial pneumonias would you treat with tetracycline?
psittacosis, chlamydial pneumonia, mycoplasmal pneumonia Tetracyclines are not used to treat H. influenzae pneumonia.
Because Chloe is complaining of stomachache and is refusing food, Dr. Turner orders tests to evaluate Chloe for pancreatic insufficiency. Which of the following test results would indicate pancreatic insufficiency?
reduced pancreatic elastase levels detection of fat in the feces, which indicates that fats are not being digested and appropriately absorbed in the intestine
Which of the following is a fungal zoonosis that can be transmitted by direct contact?
ringworm
Characteristics of Clostridium perfringens food poisoning
severe abdominal cramping short incubation period sudden onset of diarrhea
Which of the following is classified as a latent disease?
shingles
Bacteria present in the __________ can be phagocytosed by Paneth cells.
small intestine
If Caleb's strain of M. tuberculosis is sensitive to antibiotic treatment, which of the following could be used to treat his infection?
streptomycin, isoniazid and ethambutol, rifampin
Which of the following correctly lists the current distribution of HIV infection and AIDS in order of DECREASING prevalence?
sub-Saharan Africa, Latin America, Western Europe, Australia / New Zealand
Which of the following is a basic type of vaccine?
subunit vaccine; live, attenuated vaccine; nucleic acid vaccines
Measles viruses are capable of inactivating host defenses by
suppressing the immune system
Consider a Kirby-Bauer disk-diffusion assay. If you put penicillin and streptomycin disks adjacent to one another, the zone of inhibition is greater than that obtained by either disk alone. This is an example of __________.
synergism
Antibodies from cellular immune responses are used in
the classical pathway.
Which of the complement pathways was discovered first?
the classical pathway.
Which description of melioidosis is correct?
the disease may appear as pneumonia, as septic shock, or as abscesses that resemble necrotizing fasciitis. The organism is commonly found in soil.
Diapedesis is
the migration of phagocytes through blood vessels to the site of tissue damage.
Which of the following is a xenograft?
the replacement of a human's heart valve with a pig's heart valve
Western blotting is best used for which of the following?
to detect a specific protein in a mixture
What is the purpose of conjugated vaccines?
to enhance the immune response of children to polysaccharide antigens
In which of the following cases would the Limulus amebocyte lysate (LAL) assay be used?
to ensure that a sterilized medical device is free of endotoxin
Over the course of an average life span, approximately 25 tons of food pass through the gastrointestinal (GI) tract.
true
The digestive system includes the mouth and pharynx.
true
Which cytokines are believed to contribute to autoimmune disease, such as rheumatoid arthritis?
tumor necrosis factor (TNF)
Which type of hypersensitivity is allergic contact dermatitis?
type IV reaction
