Mastering Microbiology Exam 3

Which of the following microorganisms actually grows inside the macrophage? Tuberculosis bacterium Shigella Leishmania Streptococcus pneumoniae Legionella

Tubercolosis bacterium

Which of the following are properties of exotoxins? Select all that apply. Exotoxins are extremely heat stable. Very small amounts of exotoxin can be lethal. Exotoxins are released from the cell during death or replication. Exotoxins are protein molecules. Exotoxins target specific cellular structures or molecules. Exotoxins are produced primarily by gram-negative bacteria.

Very small amounts of exotoxin can be lethal. Exotoxins are protein molecules. Exotoxins target specific cellular structures or molecules.

On a global scale, the most important waterborne bacterial pathogens are __________. Vibrio cholerae and norovirus Salmonella enterica serovar Typhi and Escherichia coli Vibrio cholerae and Legionella pneumoniae Vibrio cholerae and Salmonella enterica serovar Typhi

Vibrio cholerae and Salmonella enterica serovar Typhi

Why is it difficult to find good chemotherapeutic agents against viruses? There is no effective way to deliver the drug to the virus. Viruses are not cells, and therefore not sensitive to such compounds. Viruses infect both bacteria and human cells. Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected.

Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected.

A pathogen must __________ in order for it to cause disease. secrete a toxin attach enter a host attach and multiply

attach and multiply

R-plasmids are most likely acquired via Check all that apply. transformation. translation. transduction. bacterial conjugation.

bacterial conjugation

The presence of microbes in the bladder is __________. likely to lead to a UTI used to prime the immune response more likely to occur in men than women normal

likely to lead to a UTI

The typical progression of symptoms for an acute infection would be __________. infection-acute period-incubation-decline period-convalescence incubation-acute period-infection-decline period-convalescence incubation-infection-acute period-decline period-convalescence infection-incubation-acute period-decline period-convalescence

infection-incubation-acute period-decline period-convalescence

Which of the following is most likely to cause disease? injection of 101 cells of a highly virulent bacterial species into a mouse injection of 106 cells of a low virulent bacterial species into a mouse injection of 105 cells of a highly virulent bacterial species into a mouse injection of 103 cells of a moderately virulent bacterial species into a mouse

injection of 105 cells of a highly virulent bacterial species into a mouse

The most important rickettsial diseases in humans include __________. Q fever Lyme disease typhus fever West Nile fever

typhus fever

The common methods to control the spread of West Nile virus include __________. using insect repellents wearing loose-fitting clothes when outside a vaccine for humans providing water in yards for birds to drink

using insect repellents

Certain traits that allow pathogens to create infection and cause disease are termed streptokinases. collagenases. virulence factors. hyaluronidases

virulence factors

As an epidemiologist, Dr. Thompson is interested in determining the frequency with which a specified event occurs within a particular population at a certain instant or during a particular period. This measure is known as a rate. In epidemiologic practice, an attack rate is the most commonly used method of determining the extent or frequency with which a disease is experienced by a population of individuals. In this instance, Dr. Thompson is interested in knowing what percentage of the individuals who attended the July 4 celebration became ill. What is the attack rate of food poisoning among the group who attended the July 4 celebration? 40/65(100)= 61.5% 65/105(100)= 61.9% 40/150(100)= 26.6% 105/150(100)= 70.0%

105/150(100)= 70.0%

According to the animation, surgical infections account for what percentage of nosocomial infections? 15% 11% 8% 40% 20%

20%

Which of the following correctly orders the successful application of epidemiology to control the emergence of SARS? 1. Sales restriction of civets and other wild food sources. 2. Containment and infection-control of virus in healthcare settings 3. Source of SARS traced to bats and civets. 4. Travel restricted to and from endemic areas. 5. Initial outbreak of SARS identified. 5, 4, 1, 3, 2 4, 5, 3, 2, 1 5, 3, 2, 4, 1 3, 5, 4, 2, 1

5, 3, 2, 4, 1

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? The production of cholera toxin helps V. cholerae resist antibiotic treatment. Antibiotic therapy addresses only the growth of V. cholerae; it doesn't address the extreme dehydration suffered by a person infected with V. cholerae. Because V. cholerae is a gram-negative organism, it is not very effectively treated with antibiotics. As with V. cholerae, the acidic environment of the stomach can have a negative impact on antibiotic activity.

Antibiotic therapy addresses only the growth of V. cholerae; it doesn't address the extreme dehydration suffered by a person infected with V. cholerae.

How might a patient who is not being treated with an antibiotic still be exposed to an antibiotic? Antibiotics can be used in aerosols, thereby entering the environment. Health care workers being treated with antibiotics may pass the antibiotic on to the patient. Visitors currently being treated with antibiotics can pass them on to the patient.

Antibiotics can be used in aerosols, thereby entering the environment.

Why are antibiotics often ineffective in treating food poisoning (food intoxication)? Oral antibiotics are degraded by stomach acid and, therefore, do not work well in the digestive tract. Pathogens in food pass through the digestive tract too rapidly to be targeted by antibiotics. Food poisoning is caused by viruses, which are not targeted by antibiotics. Antibiotics target bacteria; they do not damage toxins.

Antibiotics target bacteria; they do not damage toxins.

What type of nosocomial infection is likely to arise from intravenous catheterizations? Bacteremia Urinary tract Lower respiratory Surgical Cutaneous

Bacteremia

Penicillin and other β-lactam antibiotics inhibit cell-wall synthesis. What makes them effective at killing bacterial cells? Bacteria are generally hypertonic relative to their environment, so they desiccate when their cell wall is weakened by the action of these antibiotics. Bacteria are generally hypotonic relative to their environment, so they burst when their cell wall is weakened by the action of these antibiotics. Bacteria are generally hypertonic relative to their environment, so they burst when their cell wall is weakened by the action of these antibiotics. Bacteria may burst or desiccate when their cell wall is weakened by the action of these antibiotics.

Bacteria are generally hypertonic relative to their environment, so they burst when their cell wall is weakened by the action of these antibiotics.

All of the following are Gram-positive genera typically found on the skin EXCEPT __________. Propionibacterium Bacteroides Staphylococcus Corynebacterium

Bacteroides

Which of the following explains why treatment of symptomatic tetanus requires an antitoxin and an antibiotic? It is always better to use multiple treatments to elicit a stronger response. Because the toxin is within the cell wall of the bacteria, it can only be eliminated by killing the bacteria. Because C. tetani bacteria excrete tetanus toxin, it is important to neutralize the toxin while also killing the bacteria that are producing more. The tetanus toxin binds irreversibly, causing damage to axons. The only way to heal the axons is with an antitoxin.

Because C. tetani bacteria excrete tetanus toxin, it is important to neutralize the toxin while also killing the bacteria that are producing more.

Which of the pairs below are matched correctly for these clostridial pathogens involved in food poisoning? C. perfringens: produces enterotoxin C. botulinum: produces endotoxin C. perfringens: requires only a small number of cells to produce toxin C. botulinum: must grow in the body to produce toxin

C. perfringens: produces enterotoxin

How can capsules enable bacteria to evade the immune system? Capsules block the complement biding sites on the surface of the pathogen. Capsules can bind up IgA, rendering it inactive. A capsule is a superantigen that distracts the immune system.

Capsules block the complement biding sites on the surface of the pathogen.

What is meant by selective toxicity? Chemotherapeutic agents should work on certain types of pathogens. Chemotherapeutic agents should act against the pathogen and not the host. Chemotherapeutic agents should have only one mode of action. Chemotherapeutic agents should work on many different targets on a pathogen.

Chemotherapeutic agents should act against the pathogen and not the host.

Everyone, but particularly individuals who are farmers, gardeners, foresters, or others who spend significant time outdoors, are urged to adhere to a tetanus booster vaccinations schedule, receiving a booster if planning to travel and cannot remember when his or her last one. Why? Clostridium tetani typically causes infection when a wound is contaminated with soil, it's natural habitat. Accidental ingestion of Clostridium tetani toxin would lead to rapid onset of symptoms and an inability to call for help. Clostridium tetani typically causes infection when it produces quick-acting exotoxins that affect the nervous system. Quick treatment would not be available to victims who succumb far from help. There are no antibiotics available to treat this bacterial infection.

Clostridium tetani typically causes infection when a wound is contaminated with soil, it's natural habitat.

Quinolones and fluoroquinolones act against what bacterial target? Metabolic pathways unique to bacteria Cell membranes Bacterial ribosomes Cell walls DNA gyrase

DNA gyrase

When an individual has severe diarrhea, as can occur with cholera, rehydration solution with glucose, salt, sodium bicarbonate, and potassium chloride can be administered. Why is it important to use a solution like this rather than simply giving the individual water? Hints The salt helps to reduce bacterial contamination and spoilage of the rehydration fluids. This type of solution is hypertonic to human body fluids and, therefore, causes water to flow into cells. It is not necessary; water would be equally effective. Patients suffering from diarrhea loose mainly water through their stools, and dehydration is dangerous. Diarrhea causes the loss of electrolytes, not just fluids. It is important to replace the electrolytes as well as the water.

Diarrhea causes the loss of electrolytes, not just fluids. It is important to replace the electrolytes as well as the water.

Why will the microbiota in the vagina of a woman of reproductive age differ from that of the same woman before puberty and after menopause? During the reproductive years, bacterial community in the vagina changes every month due to menstruation. Before puberty and after menopause, the vagina is colonized primarily by Lactobacillus acidophilus, which creates an acidic environment through fermentation. During the reproductive years, bacteria are introduced to the vagina during intercourse and colonize the mucosa. Before puberty and after menopause the vagina is sterile. During the reproductive years, the vagina contains significant amounts of glycogen that is fermented by Lactobacillus acidophilus to produce lactic acid, creating an acidic environment. Glycogen is absent before puberty and after menopause. During the reproductive years, the vagina is colonized only by Lactobacillus acidophilus, which produces lactic acid by fermentation, creating an acidic environment. Before puberty and after menopause the vagina is alkaline.

During the reproductive years, the vagina contains significant amounts of glycogen that is fermented by Lactobacillus acidophilus to produce lactic acid, creating an acidic environment. Glycogen is absent before puberty and after menopause.

Place the stages of maturation of the light organ in Euprymna scolopes in the correct order. A. migration to light organ B. monoculture of bacteria established C. reproduction of bacteriaD. mature light organE. mucus secretion by squid E, A, C, B, D E, C, A, B, D E, B, C, A, D E, B, A, C, D

E, B, A, C, D

Membrane transport proteins are required for which mode(s) of antibiotic resistance? Efflux pumps Modification of a porins Modification of a metabolic enzyme Beta-lactamases Efflux pumps, beta-lactamases, and modification of porins all utilize membrane transport proteins.

Efflux pumps, beta-lactamases, and modification of porins all utilize membrane transport proteins.

Clostridium tetani is an obligate anaerobe that can cause tetanus. When it enters the human body, it can produce tetanus toxin. Considering that C. tetani is an obligate anaerobe, which of the following explains how it can survive and cause disease in the human body? Especially in deep wounds, C. tetani can sometimes survive in areas with damaged tissue that have become anoxic because of poor-to-no blood flow. It doesn't survive but instead simply releases toxin as it dies. C. tetani can't access atmospheric oxygen, so it can grow as long as it stays on the surface of the skin rather than in well-oxygenated deeper tissues. C. tetani can only survive when other bacteria are available to consume oxygen and to keep oxygen levels low.

Especially in deep wounds, C. tetani can sometimes survive in areas with damaged tissue that have become anoxic because of poor-to-no blood flow.

West Nile Virus is an arbovirus that can be transmitted by birds because they develop viremia when infected. In contrast, infected humans cannot spread the disease because they do not develop viremia. Why is viremia associated with the ability to transmit the disease? Direct contact with blood is required for infection. If there are no viral particles in the blood, then infection can't occur using this mechanism. Because white blood cells are found in the blood, any virus in the blood would be attacked by the immune system. With no viral particles available for the immune system to attack, the virus cannot be spread. The virus is only found within red blood cells if there is no viremia, so it cannot be spread by mosquitoes that do not consume those cells. If there are no (or only very few) viral particles in the blood, then they are not picked up by vectors feeding on the blood in sufficient amounts to cause infection.

If there are no (or only very few) viral particles in the blood, then they are not picked up by vectors feeding on the blood in sufficient amounts to cause infection.

Antibiotic resistance is a major concern as microbes can rapidly develop resistance when antibiotics are not used appropriately. Which of the following examples best describes how this occurs? Microbes respond to the presence of antibiotics by deliberately developing resistance mechanisms. Exposure to too much of an antibiotic causes resistance. Antibiotics are mutagenic. They cause mutations, like other mutagenic chemicals. In any population of microbes, some individuals may have resistance genes. When exposed to an antibiotic, there is selection for the microbes that have these genes.

In any population of microbes, some individuals may have resistance genes. When exposed to an antibiotic, there is selection for the microbes that have these genes.

From the preliminary analysis, it would appear that individuals who consumed barbecue with Bubba-Qs sauce had the highest attack rate, followed by the dry-rubbed barbecue. Some of the individuals who said they ate the barbecue with the sauce did not become ill. Which one of the following is the most likely explanation for such an occurrence? Not everyone who was questioned may accurately remember which foods they consumed. Individuals who did not become ill are genetically less susceptible to the food poisoning agent. Some individuals may have immunity to the illness because they have been previously exposed. Individuals who became ill may have consumed larger quantities of the food than individuals who did not become ill.

Individuals who became ill may have consumed larger quantities of the food than individuals who did not become ill.

Why is polymyxin only used on the skin? It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead. It has no effect on bacteria that live in the GI tract. It is sensitive to degradation by acid, making oral delivery unsuitable. It can disrupt the metabolic pathways found in humans.

It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead.

How does the protozoan Trypanosoma evade detection by the immune system? It produces a capsule which is composed of polysaccharides similar to those found in the host. It can change the surface antigens frequently, preventing the immune system from tracking it. It prevents phagosome-lysosome fusion. It can resist oxidation inside macrophages.

It can change the surface antigens frequently, preventing the immune system from tracking it.

Eosin-methylene blue agar inhibits the growth of gram-positive organisms while allowing gram-negative organisms to grow. Colonies of lactose fermenters turn a blackish color while nonfermenters are colorless. How would you classify EMB? Is EMB a differential medium or a selective medium? Think about the meaning of the terms differential and selective to choose your answer. It is a differential medium and a selective medium. It is a selective medium only. It is neither differential nor selective. It is a differential medium only.

It is a differential medium and a selective medium.

How does the bobtail squid select only Aliiovibrio fischeri for colonization of the light organ? It produces nitric oxide in the mucus only. It produces nitric oxide in the mucus and light organ. It produces mucus that aggregates gram-negative bacteria. Aliiovibrio fischeri is present in very high numbers in marine environments, so it isn't necessary to select for it.

It produces nitric oxide in the mucus and light organ.

Which of the following antibiotics are properly matched with their target of action? macrolide-30S ribosomal subunit Platensimycin-lipid biosynthesis aminoglycoside-50S ribosomal subunit tetracycline-50S ribosomal subunit

Platensimycin-lipid biosynthesis

Lactose-fermenting bacteria turn eosin-methylene blue medium from colorless to black or red. What causes this change? Lactose fermentation allows pyruvate to build up. This excess of pyruvate causes the color change. Lactose fermentation generates lactic acid. Lactic acid lowers the pH of the medium, causing the medium to change colors. Lactose fermentation generates lactate, making the medium more alkaline and causing the color change. Lactose fermentation generates alcohol. The alcohol reacts with chemicals in the medium to cause the color change.

Lactose fermentation generates lactic acid. Lactic acid lowers the pH of the medium, causing the medium to change colors.

Water supplies are treated with chlorine to kill pathogens. Chlorine reacts well with many other chemicals and bacterial cells because it is a strong oxidant. However, Legionella pneumophila can sometimes evade killing by residual chlorine. How does it do this? Legionella can detoxify chlorine by metabolizing it. Legionella tends to be found in warm waters and in aerosols, both situations in which the chlorine readily evaporates and, thus, is in lower concentration in the water. Legionella tends to form biofilms and infect other microbial cells as intracellular pathogens. Legionella produces cations that bind up the negative chloride ions, thus inactivating them.

Legionella tends to form biofilms and infect other microbial cells as intracellular pathogens.

Antifungal medications are often used topically. Why is this the case? Like human cells, fungal cells are prokaryotic. To develop systemic fungal medications requires finding specific characteristics of fungal cells that can be targeted, such as the ergosterol in fungal cell membranes. Like human cells, fungal cells are eukaryotic. To develop systemic fungal medications requires finding specific characteristics of fungal cells that can be targeted, such as the ergosterol in fungal cell membranes. It is not possible for fungi to cause systemic infections, so only topical treatments are needed. Fungi force cells to help them reproduce, making it difficult to target them without harming the host.

Like human cells, fungal cells are eukaryotic. To develop systemic fungal medications requires finding specific characteristics of fungal cells that can be targeted, such as the ergosterol in fungal cell membranes.

What are leukocidins? Molecules that can degrade IgA Molecules that destroy the complement proteins Molecules that are capable of destroying phagocytes

Molecules that are capable of destroying phagocytes

Meningitis and gonorrhea are caused by Neisseria species. Pseudomonas species. measles virus.

Neisseria species.

Bacteria that are resistant to sulfonamide have enzymes that have a greater affinity for what? PABA Sulfonamide Tetrahyrdrofolic acid Tetracycline

PABA

A clinical lab was not able to isolate any pathogenic bacteria from a patient suffering from a high fever and elevated white blood cell count. The physician suspects a viral infection may be to blame. What detection assay may the lab want to try next? PCR followed by a nucleic acid hybridization technique to detect viral DNA or RNA an agglutination test immunofluorescence an immunoblot (Western blot) assay

PCR followed by a nucleic acid hybridization technique to detect viral DNA or RNA

Which antibiotic is overcome by beta-lactamases? Tetracycline Sulfonamide Penicillin Tetracycline, Penicillin, and Sulfonamide are all affected by beta-lactamase.

Penicillin

How can health care workers reduce the occurrence of nosocomial infections? Administer all medications orally instead of through injections Practice more stringent aseptic techniques Limit the number of visitors who can see the patient Reduce the number of times they visit a patient

Practice more stringent aseptic techniques

How might efflux pumps increase antibiotic resistance in bacteria? Resistant bacteria may have a greater number of efflux pumps on their cell surfaces. Some bacteria can decrease the specificity of their efflux pumps, increasing the number of different antibiotics the pumps can eliminate. Some bacteria can change the chemical structure of the antibiotic. Efflux pumps can never be modified to increase antibiotic resistance. Resistant bacteria can have more efflux pumps, and can have less specific efflux pumps.

Resistant bacteria can have more efflux pumps, and can have less specific efflux pumps.

Native peoples often experience an increase in the incidence of dental caries after they are introduced to imported processed foods. This finding could be explained by the fact that __________. Sucrose and other purified sugars cause pitting of the tooth surfaces. Sucrose is required for the production of adhesive dextran by Streptococcus mutans. Lactobacilli require sucrose in order to form biofilms on tooth surfaces. Only purified sucrose and fructose can be fermented or produce acids in the oral cavity.

Sucrose is required for the production of adhesive dextran by Streptococcus mutans.

What is meant when a bacterium is said to become "resistant" to an antibiotic? The antibiotic kills or inhibits the bacterium. The antibiotic is metabolized by the bacterium, providing more energy for growth of the cell. The bacterium is neither killed nor inhibited by the antibiotic. The antibiotic mutates in a way that benefits the bacterium.

The bacterium is neither killed nor inhibited by the antibiotic.

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. Capsules allow the bacteria to stick together, creating a larger mass that is too big for immune cells to engulf. The capsule makes the bacterium too sticky to be phagocytosed by the immune cells. Capsules have the ability to destroy antibodies secreted 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.

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? Select all that apply. The interactions that occur between a microbe and host influence the evolution of both. Some pathogens are able to cause disease within a host without penetrating the body. Intoxications result from a bacterial infection in which a large amount of bacterial toxin is produced. The ID50 value refers to the number of microbes needed to cause half of an infected population to die. Bacterial exotoxins can be altered to create toxoids, which can be used to produce protective immunity in a host. The terms pathogenicity and virulence can be used interchangeably to describe the severity of an infection.

The interactions that occur between a microbe and host influence the evolution of both. Some pathogens are able to cause disease within a host without penetrating the body. Bacterial exotoxins can be altered to create toxoids, which can be used to produce protective immunity in a host.

If a human is bitten by an animal that has rabies, then it is recommended that the human receive immune globin (human rabies antibodies) and a rabies vaccination (with inactive virus) as well. Which of the following is the best (and most specific) explanation for why both are recommended in this case? Hints The rabies vaccination is relatively new and ineffective, so it is important to give the immune globin as well to make certain that the viruses cannot cause disease. Because rabies is such a serious illness, using antibodies and a vaccine provides the strongest possible immediate protection. Both antibodies and the vaccine provide a rapid immediate response to prevent illness from developing. Using both is needed because an individual who has received this type of bite is more likely than someone else to receive another bite. While the immune globin is sufficient to prevent rabies infection, the vaccination helps to prevent the individual from the risk of a future bite. The rabies antibodies provide a rapid response but short-lived response while the vaccination provides slower but longer-lasting protection.

The rabies antibodies provide a rapid response but short-lived response while the vaccination provides slower but longer-lasting protection.

The yellow fever virus replicates in lymph nodes and in other immune system cells. How does it arrive in lymph nodes? It is injected there by the mosquitoes that carry the disease. The yellow fever virus is phagocytosed by white blood cells, and then travels through the lymph vessels. Lymph nodes contain white blood cells and filter lymph as it moves through the lymph vessels. White blood cells with yellow fever virus can become established there. Some viruses, like the yellow fever virus, can replicate inside of white blood cells like those in lymph nodes. The virus is carried to the lymph nodes by the blood stream. It is attracted to the lymph nodes by chemoattractants.

The yellow fever virus is phagocytosed by white blood cells, and then travels through the lymph vessels. Lymph nodes contain white blood cells and filter lymph as it moves through the lymph vessels. White blood cells with yellow fever virus can become established there. Some viruses, like the yellow fever virus, can replicate inside of white blood cells like those in lymph nodes.

Collectively, metagenomic studies of the human microbiome have shown ALL BUT one of the following statements are true. There is no general pattern of similarity in the microbiomes of humans; they are unpredictable. Microbial diversity in the human microbiome is so great that no one microbial species is present in the greatest abundance in all individuals. Similarities in microbial diversity between individuals are more evident at higher bacterial taxonomic levels (such as phyla). Certain microbial genes appear to be linked to certain human body sites.

There is no general pattern of similarity in the microbiomes of humans; they are unpredictable.

Why are invasive procedures likely to increase the risk of nosocomial infections? Invasive procedures must use antibiotics. These procedures allow microbes from the skin to enter the bloodstream of the patient. Invasive procedures require long term hospital stays, thereby increasing the number of visitors seen by the patient. These procedures are carried out by health care workers, who carry resistant microbes.

These procedures allow microbes from the skin to enter the bloodstream of the patient.

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. They can compare the DNA sequences from the foreign cells to host DNA. They detect foreign, unfamiliar chemical substances released by the invading cells.

They are able to detect structures on the surfaces of foreign cells that are not found in the host.

Considering that they require an oxygen-free environment, how do obligate anaerobes survive in the human body? They are able to use enzymes to convert reactive oxygen species to harmless molecules. They live inside of organelles, such as peroxisomes. They are able to survive in places where aerobic organisms quickly use the available oxygen. They can also survive in areas with impaired blood flow (reducing oxygen availability). Obligate anaerobes are unable to survive in the human body.

They are able to survive in places where aerobic organisms quickly use the available oxygen. They can also survive in areas with impaired blood flow (reducing oxygen availability).

How do fibrinolysins enhance a pathogen's virulence? They destroy the molecules that hold cells together. They destroy the fibers that are found at the base of superficial tissues, allowing for deeper penetration by the pathogen. They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin.

They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin.

How do superantigens enable pathogens to hide from the immune system if they actually stimulate the immune system? They cause fever, which destroys the complement proteins. They cause the immune system to destroy IgA antibodies. They cause the immune system to turn on itself. They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen.

They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen.

A researcher wanted to determine the LD50 (lethal dose that kills 50% of the infected hosts) for a newly isolated bacterial pathogen. Mice were inoculated with diluted cultures containing between 101 and 107 cells. After two days, all of the mice had died EXCEPT for the uninoculated controls. Which of the following is the most likely explanation? Mice are not good model animals for this pathogen. The pathogen has become attenuated. This pathogen is highly virulent in mice. The pathogen has a very high LD50.

This pathogen is highly virulent in mice.

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? V. cholerae does not produce enough virulence factors to overcome the host response and cause disease. Because V. cholerae cells are relatively small compared to host cells, thousands of bacteria must infect each cell to cause disease. Because the major virulence factor of V. cholerae is cholera toxin, large numbers of bacteria are required to produce enough toxin to cause disease. To establish infection, V. cholerae must survive the host immune response and the acidic environment of the stomach.

To establish infection, V. cholerae must survive the host immune response and the acidic environment of the stomach.

What is the role of epidemiology? To learn which organisms cause disease. To learn which medicines are effective at killing pathogens. To learn how to treat and prevent various diseases. To learn what diseases can be caused by respiratory pathogens.

To learn how to treat and prevent various diseases

Reheating food to a temperature sufficient to kill bacteria is helpful in making food safer. However, is there a way that one can get food poisoning despite food having been reheated? No, it is not possible to develop food poisoning if all of the bacteria have been killed. Toxins may be heat-stable above temperatures that kill bacteria. Even if only a few bacteria survive, those bacteria may be sufficient to start an infection and produce toxins. Even if the toxins have been denatured, they can return to a functional form after cooling.

Toxins may be heat-stable above temperatures that kill bacteria.

Vibrio cholerae is a human pathogen that causes cholera. It has an unusual shape distinctive of its genus. Considering that it does not have one of the most common bacterial shapes, what is the shape of this species? a rigid spiral shape a spherical shape a curved rod a straight rod

a curved rod

A patient reported a headache, chills, vomiting, and diarrhea that occurred 12 hours after having a meal at home that included chicken. The physician suspected which type of organism? norovirus a food infection, most likely Enterohemorrhagic E. coli or Shigella a food infection, most likely Salmonella a food intoxication, most likely from Staphylococcus

a food infection, most likely Salmonella

Which of the following is predicted to result in the largest disease outbreak? a pathogen with a high R0 in an immunologically naïve population a pathogen with a high R0 in an immunized population a pathogen with a low R0 in an immunologically naïve population a pathogen with a high R0 in an immunized population

a pathogen with a high R0 in an immunologically naïve population

An animal disease transmitted to humans by direct contact, inhalation of aerosols, or bites is called __________. epizootic a zoophyte enzootic a zoonosis

a zoonosis

An unknown bacterium was isolated from a patient with pneumonia. To determine the minimum inhibitory concentration of the chosen drug to use to treat the respiratory infection, the doctor must take into account __________. pH of growth medium all of the listed responses are correct time of incubation concentration of amino acids in the medium

all of the listed responses are correct

Deaths because of infectious disease are more common in developing countries, such as Africa, compared to the Americas because of __________. all of the listed responses are correct limited access to clean water limited immunization programs inadequate sanitation

all of the listed responses are correct

The distribution of disease can change very quickly. An increase in emerging diseases can be attributed to __________. more people being immunized more people moving away from cities unchanging climate an increase in international travel

an increase in international travel

When the human papillomavirus (HPV) vaccine was first introduced to help prevent cervical cancer as well as anal warts and cancers, it was only recommended for 11- or 12-year-old girls. However, the CDC later expanded its HPV vaccination recommendations to include 11- and 12-year-old boys. By including males, the public health officials hoped to do all of the following EXCEPT __________. decrease the incidence of cervical cancer in women protect men from anal warts and cancer increase herd immunity to HPV decrease the basic reproductive number (R0) of HPV

decrease the basic reproductive number (R0) of HPV

The emergent H5N1 strain of avian influenza can occasionally be transmitted from birds to humans with a resulting 60% mortality rate (compared with a 2.5% mortality rate for the 1918 pandemic influenza). In 2012, after a single dead chicken in a wholesale market in Hong Kong tested positive for H5N1, all 17,000 chickens in the market and surrounding area were culled. This was an attempt to__________. quarantine . prevent migration. eliminate a vector. eliminate a reservoir.

eliminate a reservoir

A disease that is constantly present in a population at low numbers is a(n) __________. pandemic outbreak endemic epidemic

endemic

When treating a fungal infection, the best target for selective toxicity would be __________. ergosterol synthesis cell division proteins polypeptide elongation lipid synthesis

ergosterol synthesis

C. difficile infections are on the rise, both in elderly hospitalized patients receiving antibiotics and in younger populations having no previous contact either with a hospital environment or antibiotics. What is the most effective treatment for chronic C. difficile infections? high doses of antibiotics medical management with intravenous fluids to prevent dehydration and shock fecal transplants from a healthy donor surgical removal of the colon if antibiotic therapy fails

fecal transplants from a healthy donor

Illness that results from ingestion of pathogen-contaminated food is __________. foodborne disease food infection food poisoning food intoxication

food infection

The 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? Select all that apply. gaining access to the host via a portal of entry depleting the host of nutrients at the site of infection adherence to host tissues direct damage of host tissues evasion of host defenses production of exotoxins

gaining access to the host via a portal of entry adherence to host tissues evasion of host defenses

Staphylococcus aureus is a particularly dangerous organism when in food due to the enterotoxins some species produce. These toxins are dangerous because they are __________. acid-tolerant heat-stable superantigen toxins heat-stable, acid-tolerant superantigen toxins

heat-stable, acid-tolerant superantigen toxins

For many years the CDC focused its seasonal influenza vaccination efforts on those groups in the population who suffered the highest influenza mortality rates, including the elderly aged 65 years and older. However, starting in 2008 the CDC shifted their focus to school-aged children and began recommending the vaccine for everyone aged at least 6 months. Research had shown no evidence for any protective effect of the vaccine in the elderly. By changing the recommendations for who should be vaccinated, the CDC planned to better protect the elderly by means of__________. vaccination. herd immunity. direct contact. acquired immunity.

herd immunity

Which of the following enzymes breaks down the "glue" that holds cells together? Hyaluronidase Streptokinase Fibrinolysin Collagenase

hyaluronidase

Helicobacter pylori is a bacterium found in the stomachs of roughly half of the human population. It is considered to be a pathogen because __________. it can cause chronic inflammation when present, it accounts for the vast majority of stomach microbial biomass it is the only bacterium found in the human stomach it is found in the stomach mucosa rather than the lumen

it can cause chronic inflammation

Borrelia burgdorferi is an interesting spirochete that is unusual when compared to other bacteria. Which of the following is the reason that it is so unusual? it has a cell wall it has ribosomes it has flagella it has a linear chromosome

it has a linear chromosome

Which of the following was a downfall of the Human Microbiome Project? lack of subject diversity lack of subject numbers too few sample sites lack of female participants

lack of subject diversity

Staphyloccocus aureus is an important cause of food poisoning. Several gene-encoding exotoxins are associated with S. aureus food poisoning, including SEA, an exotoxin encoded by a viral gene. What sort of life cycle must this phage have? lytic cytocidal infections budding lysogenic

lysogenic

After tuberculosis, malaria causes more annual deaths worldwide than any other single disease. Recent research has attempted to control the spread of malaria by genetically-modifying a bacterium (Pantoea agglomerans) commonly found in the guts of mosquitos to produce a toxin that kills the malaria parasite Plasmodium falciparum. If this project is effective it could significantly decrease the incidence of malaria because__________. malaria is a vectorborne disease. the mosquitoes will die. Pantoea agglomerans would be killed. malaria is a person-to-person disease.

malaria is a vectorborne disease.

Which of the following symptoms is LEAST characteristic of Clostridium perfringens food poisoning? sudden onset of diarrhea short incubation period moderate vomiting and fever severe abdominal cramping

moderate vomiting and fever

The incidence of disease in a population is termed the __________. prevalence morbidity mortality outbreak

morbidity

In the first reported epidemiological study in 1854, John Snow attempted to discover the source of a London cholera epidemic by going house-to-house and recording deaths. When he mapped the results, he was able to identify the Broad Street water pump as the likely source of contaminated water. The data collected in this study was__________. morbidity. incidence. prevalence. mortality.

mortality

In the search for new antimicrobial drugs, to minimize resistance developing scientists should focus on __________. combinations of current antimicrobial compounds new targets of action found only in bacteria new targets of action found only in eukaryotes modifications of current antimicrobial compounds

new targets of action found only in bacteria

Identification of a pathogen in a patient can be done without having to culture the pathogen using __________. none of the listed responses are correct PCR testing if a host specific genetic sequence is known PCR testing if a pathogen specific genetic sequence is not known PCR testing if growing the pathogen in the lab is common

none of the listed responses are correct

Nearly 90% of all foodborne illnesses are associated with __________. norovirus, Salmonella, Clostridium perfringens, and Campylobacter jejuni norovirus, Salmonella, Clostridium perfringens, and Toxoplasma Salmonella, Clostridium perfringens, Campylobacter jejuni, and Listeria monocytogenes Staphylococcus aureus, Salmonella, Clostridium perfringens, and Campylobacter jejuni

norovirus, Salmonella, Clostridium perfringens, and Campylobacter jejuni

One advantage of a monogastric digestive system is that __________. more microbes are present digestion occurs more slowly digestion occurs in compartments nutrients are easily accessible to the microbes that aid in digestion and vitamin production

nutrients are easily accessible to the microbes that aid in digestion and vitamin production

Legionella pneumophilia can grow in water and is transmitted in aerosols. Which of the following has NOT been linked to an infection? spas hot water tanks ocean water swimming pools

ocean water

The ability to cause disease is __________. virulence pathogenicity colonization infection

pathogenicity

Which of the following is an important virulence factor for dental caries? siderophores endotoxin polysaccharide adhesion pili

polysaccharide adhesion

H5N1 avian influenza is widely considered to be the most serious global pandemic threat today and is the target of much worldwide surveillance. The human H5N1 infections thus far have resulted in a mortality rate of almost 60%, underscoring the danger of this virus. Currently, the virus is not readily passed person to person, but reports that the virus may have recently entered (or re-entered) the swine population are of concern because of __________. possible antigenic drift humans typically come into more frequent contact with swine than with birds possible reassortment of the influenza genome with swine and human strains influenza more easily passing from pig to human than from human to human

possible reassortment of the influenza genome with swine and human strains

During the 2002-2004 emergence and epidemic of Severe Acute Respiratory Syndrome corona virus (SARS-coV) the virus was found to be highly contagious, with an observed reproductive number (R) of 3.6. For this reason many rigorous means of infection control were instituted by the countries experiencing SARS outbreaks, including__________. culling of chickens. vaccination. quarantine and isolation. application of DDT to kill mosquitoes.

quarantine and isolation

The lowest number of pathogens or pathogen produced products that can be detected is a measure of __________. sensitivity specificity discrimination selectivity

sensitivity

Which of the following mutations would not result in antibiotic resistance? Missense mutation Nonsense mutation Silent mutation Frameshift insertion Frameshift deletion

silent mutation

Which of the following virulence factors would be found in Staphylococcus aureus? Hyaluronidase Collagenase Streptokinase Staphylokinase

staphylokinase

Measles viruses are capable of inactivating host defenses by producing leukocidins. producing superantigens. destroying complement proteins. suppressing the immune system.

suppressing the immune system

Termites are capable of digesting cellulose and hemicellulose due to the presence of __________. enzymes that digest these compounds symbiotic bacteria in their gut endosymbiotic bacteria none of the listed responses

symbiotic bacteria in their gut

Saliva contains relatively few microbes compared to other body sites, because __________. the concentration of lipids limits their growth the temperature of saliva does not support microbial growth the concentration of antimicrobial enzymes limits their growth the pH is too low

the concentration of antimicrobial enzymes limits their growth

When a patient is treated with antibiotics, __________. mutations occur in all of the bacterial cells sensitive bacterial cells multiply uncontrollably the drug will kill or inhibit the growth of all of the sensitive bacterial cells the drug will kill or inhibit the growth of all of the resistant bacterial cells mutations will occur in the sensitive bacterial cells, but not in the resistant bacterial cells

the drug will kill or inhibit the growth of all of the sensitive bacterial cells

During the early 20th century, pandemics typically took months to years to span the globe, while the 2009 H1N1 swine flu spread globally within weeks and had affected most countries within 6 months. This difference in the rate of spread is mainly due to__________. more human contact with wild and domestic animals worldwide. the increased virulence of the pathogens. the increased volume and speed of global transportation. the emergence of antibiotic resistance.

the increased volume and speed of global transportation.

The ingestion of a large number of Vibrio cholerae cells is necessary for infection. Why is such a large concentration of bacteria needed? to ensure enough survive the low pH in the stomach to establish infection to ensure enough bacteria survive the enzymes in our mouth because a large number of bacteria are required to overcome the specificity of our immune system because they must compete with bacteria in our intestines

to ensure enough survive the low pH in the stomach to establish infection

Among the recommendations from the Centers for Disease Control and Prevention to limit the development of antibiotic resistance are __________. to treat with the oldest, effective antimicrobial to treat with broad spectrum drugs to stop taking the antimicrobial as soon as symptoms disappear to treat with the newest, effective antimicrobial

to treat with the oldest, effective antimicrobial

The process of acquiring antibiotic resistance by means of bacteriophage activity is called transduction. R-plasmid acquisition. point mutation. transformation.

transduction

It is difficult to attain good selective toxicity with antiviral drugs because of the fact that __________. viruses can hide in an envelope from the host cell viruses are not living organisms viruses are not cells viruses require host cells to replicate themselves

viruses require host cells to replicate themselves

A patient is brought to the hospital with severe gastrointestinal distress, including cramps, dehydration and diarrhea. Which of the following symptoms would indicate that the pathogen is Vibrio cholerae? occasional diarrhea but no blood in the stool frequent vomiting voluminous watery diarrhea bloody, foul smelling diarrhea

voluminous watery diarrhea

Epidemiology is defined as the study of how a disease is transmitted. where and when a disease occurs, and how it is transmitted. where a disease occurs. when a disease occurs.

where and when a disease occurs, and how it is transmitted.

Rickettsia are obligate intracellular parasites that are transmitted by arthropods. In which of the following places would you most likely find the parasites living in the host organism during the course of infection? within the blood plasma on the surface of heart cells on the outer surface of the skin within macrophages

within macrophages

Of the arthropod-borne diseases, there is a vaccine to prevent __________. West Nile fever yellow fever Lyme disease dengue fever

yellow fever

Bacillus anthracis is an endospore-forming bacterium. Which of the following is most likely? B. anthracis uses spores to reproduce, which develop into new offspring capable of causing anthrax. B. anthracis spores require a moist environment in order to stay dormant for an extended time. These spores will germinate and be capable of causing anthrax when they dry out. B. anthracis spores can remain dormant for hundreds of years without needing nutrients, remaining capable of causing anthrax when they germinate. B. anthracis spores can be killed by boiling water or ultraviolet light, so these can be used to prevent anthrax.

B. anthracis spores can remain dormant for hundreds of years without needing nutrients, remaining capable of causing anthrax when they germinate.

Which bacteria involved in food infections produce toxins to cause host damage? Listeria and Escherichia coli Listeria and Salmonella Campylobacter and Escherichia coli Escherichia coli and Salmonella

Escherichia coli and Salmonella

Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug? Bacteria are especially sensitive to these compounds. Humans and other animal hosts lack peptidoglycan cell walls. The drugs also work against DNA gyrase.

Humans and other animal hosts lack peptidoglycan cell walls.

Immunoassays are techniques that use immunology to determine the presence of antigens, antibodies, or both. In one type of enzyme-linked immunoassay test, antibodies are attached to a matrix (such as the bottom of a microtiter plate). Next, the sample to be tested (such as patient serum) is added. An antibody-enzyme complex is then added. Finally, the enzyme substrate is added. The enzyme must catalyze a reaction that is visible (such as a color change), meaning that it is possible to see if the antibodies were present by seeing if there is a color change. The development of the colored product is proportional to the concentration of antibody. What would this sort of test be useful for? It would be useful for detecting whether a patient had antibodies for a particular pathogen. The second antibody (attached to the enzyme) is able to bind because it is specific for the antigen. It would be useful for detecting a virus in a patient's blood, as the antibody on the matrix would bind to the virus. The second antibody (attached to the enzyme) is able to bind because it is specific for the first antibody. It would be useful for detecting whether a patient had antibodies for a particular antigen. The second antibody (attached to the enzyme) is not necessary as the enzyme can react directly with the antigen if the antigen is present. It would be useful for detecting a virus in a patient's blood, as the antibody on the matrix would bind to the virus. The second antibody (attached to the enzyme) is able to bind because it is specific for the antigen.

It would be useful for detecting a virus in a patient's blood, as the antibody on the matrix would bind to the virus. The second antibody (attached to the enzyme) is able to bind because it is specific for the antigen.

Why would an efflux pump for penicillin located on a bacterial cell membrane not be effective at providing resistance to the drug? The efflux pumps would not stop penicillin from blocking metabolic pathways. There are fewer efflux pumps on the cell membrane. The cell membrane is the target of penicillin. Penicillin disrupts the cell wall, which is located outside of the cell membrane.

Penicillin disrupts the cell wall, which is located outside of the cell membrane.

One way to test if someone has immunity to a particular pathogen is to measure the antibody titer. What does it mean if someone has a positive antibody titer? Previous exposure to the pathogen (or through a vaccination) has caused B cells to produce memory B cells. When re-exposed to the pathogen, they rapidly produce antibodies against the antigen (resulting in a positive antibody titer). They must not have been exposed to the pathogen previously, meaning that they were able to rapidly produce antibodies. They must not have been exposed to the pathogen previously, meaning that they were not able to rapidly produce antibodies. Previous exposure to the pathogen has caused T cells to attack the pathogen, leading to a more rapid response by T cells upon repeat exposure.

Previous exposure to the pathogen (or through a vaccination) has caused B cells to produce memory B cells. When re-exposed to the pathogen, they rapidly produce antibodies against the antigen (resulting in a positive antibody titer).

When a child begins to get its first teeth, what happens to the microbiota in the oral cavity? The teeth are rapidly colonized by anaerobes, in particular Streptococcus, that are specifically adapted to growth in biofilms in the gingival crevices. The teeth are rapidly colonized by obligate anaerobes, in particular Fusobacterium, that are specifically adapted to growth in biofilms on the surfaces of the teeth. The teeth are rapidly colonized by aerobes, in particular Streptococcus, that are specifically adapted to growth in biofilms on the surfaces of the teeth. The teeth are rapidly colonized by anaerobes, in particular Streptococcus, that are specifically adapted to growth in biofilms on the surfaces of the teeth.

The teeth are rapidly colonized by anaerobes, in particular Streptococcus, that are specifically adapted to growth in biofilms on the surfaces of the teeth.

Wild rodents are the major reservoir of the plague organism, Yersinia pestis, but pandemic plagues were historically associated with crowded, unsanitary urban areas. Why is this the case? Yersinia pestis can be transmitted by fleas from wild rodents to urban rats, which quickly die of the disease. Humans are accidental hosts due to fleas seeking out blood meals after most rats have succumbed to the disease. Wild rodents tended to have high plague mortality rates, but most urban rats survived infection. This allowed the disease to be passed on to nearby humans by the vector. At one time, it was fashionable for city dwellers to keep rats as pets, bringing humans into close contact with these plague hosts. Crowded urban areas have more garbage and filth, allowing plague to spread more easily due to unsanitary conditions.

Yersinia pestis can be transmitted by fleas from wild rodents to urban rats, which quickly die of the disease.

Lyme disease and syphilis are similar in that they __________. are both chronic infections that involve the nervous system are both contracted by person-to-person contact are both caused by spirochetes and are chronic infections that involve the nervous systems are both caused by spirochetes

are both caused by spirochetes and are chronic infections that involve the nervous systems

A person who tests positive for the human immunodeficiency virus but shows no symptoms of AIDS would be termed a __________. vector carrier reservoir vehicle

carrier

Gram-negative, rod-shaped bacteria that are facultative anaerobes, are non-spore formers, and ferment lactose to acid and gas are __________. fecal bacteria pathogens coliforms indicator organisms

coliforms

Obligate anaerobes are likely to be found in the __________. mouth urogenital tract nasal cavity colon

colon

All students that ate in the school dining hall on Monday developed stomach cramps and diarrhea. The student clinic was overwhelmed with patients. However, by Thursday the number of patients seen in the clinic was back to normal. This could have been caused by a __________. host-to-host epidemic common-source epidemic infectious disease vector-borne disease

common-source epidemic

In 2011, the CDC reported a 28-state outbreak of Listeria monocytogenes that killed 33 people in the United States. The victims were found to have eaten portions of whole cantaloupe melons originating from a single farm in Colorado. The FDA traced the source of bacterial contamination to a piece of used equipment that had been recently purchased to wash the melons, nearby puddles of water, and a truck that hauled spoiled melons to a field to be fed to cattle. This would be an example of __________. zoonotic reservoir water-borne transmission person-to-person transmission common-source transmission

common-source transmission

The colon has been described as a living fermentation vessel. Which type of culture system would it most resemble? immobilized cell culture batch culture continuous culture None of the listed responses is correct.

continuous culture