Exam 3

Question 1

What is the difference between “bactericidal” and “bacteriostatic”? Give a specific example of each approach.

Answer 1

The difference between bactericidal and bacteriostatic drugs is that bactericidal drugs kill the bacteria cells and can eradicate an infection while bacteriostatic drugs suppress an infection but do not eradicate it. An example of a bactericidal antibiotic is penicillin a beta-lactam that inhibits the production of peptidoglycan promoting cell lysis. A bacteriostatic antimicrobial drug is sulfa drugs which inhibit folic acid synthesis. These drugs inhibit but don’t kill bacterial infections however they can be combined with other drugs (synergy) to be more effective and be bactericidal with the other drug.

Question 2

Define “sterilization” and give two examples of ways things are sterilized.

Answer 2

Sterilization is completely removing all endospores, vegetative cells and viruses from a certain object or area. One way things are sterilized is by dry heat, like a Bunsen burner to burn the loop after inoculation. Another way is by ionizing radiation like gamma rays and X-rays, which can be used for sterilizing heat sensitive materials like pharmaceutical drugs and medical equipment.

Question 3

Compare and contrast “sterilization” and “pasteurization”. Provide two ways the processes are similar, and two ways they are different.

Answer 3

terilization and pasteurization are both processes used to eliminate harmful microorganisms in various substances, but they differ in the degree of microbial reduction achieved and the method used to achieve it.

Two ways sterilization and pasteurization are similar:

Both processes aim to eliminate microorganisms: Both sterilization and pasteurization aim to eliminate microorganisms, including bacteria, viruses, fungi, and spores. They are used to prevent spoilage, extend shelf life, and improve the safety of various products, including food, pharmaceuticals, medical devices, and laboratory equipment.

Both processes use heat: Heat is the most common method used in both sterilization and pasteurization. High temperatures can kill or inactivate microorganisms by denaturing their proteins, disrupting their cell membranes, or causing other forms of cellular damage.

Two ways sterilization and pasteurization are different:

Degree of microbial reduction: Sterilization aims to eliminate all microorganisms from a substance, achieving a 100% reduction in microbial count. In contrast, pasteurization aims to reduce the number of microorganisms to a level that is considered safe for consumption or use, usually by at least 99.9% or more. Pasteurization does not eliminate all microorganisms but rather reduces the number of pathogenic microorganisms to a safe level.

Method of application: Sterilization typically involves the use of more extreme conditions than pasteurization. Sterilization methods include exposure to high temperature (e.g., autoclaving), chemicals (e.g., ethylene oxide), radiation (e.g., gamma rays), or filtration (e.g., through a membrane with small pores). Pasteurization, on the other hand, typically involves heating a substance to a specific temperature for a specific duration, with variations such as high-temperature short-time (HTST) pasteurization or ultra-high temperature (UHT) pasteurization.

Question 4

Why can you sterilize things more quickly (and at lower temperatures) in an autoclave than in a dry-heat oven?

Answer 4

Moist heat is generally more effective than dry heat in destroying microorganisms, and it can achieve sterilization at lower temperatures and shorter exposure times. This is because moist heat works by denaturing and coagulating enzymes and proteins within the microbe, leading to its death. The presence of moisture in the environment helps to transfer heat more efficiently to the microorganisms and disrupt their cellular structures. Examples of moist heat methods include boiling, autoclaving, and pasteurization.

In contrast, dry heat works by slowly dehydrating the microbe and damaging its cellular structures. Dry heat sterilization requires much higher temperatures and longer exposure times than moist heat methods to achieve the same level of microbial destruction. This is because dry heat does not transfer heat as efficiently as moist heat, and without the presence of moisture, the microorganisms are more resistant to heat. Examples of dry heat methods include incineration, hot air ovens, and dry heat blocks

Question 5

What is the effect of DNA damage done to bacteria by UV light? Does irradiation of food make the food radioactive? Explain.

Answer 5

UV light damages DNA by creating pyrimidine dimers in DNA strands, and this can lead to genetic mutations that could lead to impaired cell functions and cell death.

Irradiating food does not make food radioactive. The material would need high atomic elements, which food generally does not contain, and if extreme doses of radiation were used to attempt to make food radioactive, it would more likely destroy the food via thermal or chemical damage.

Question 6

How does filtration work, and when is it appropriate to use filtration?

Answer 6

Filtration works via a semi-porous filter that only allows things that are smaller than the pores through and blocks everything else that is bigger than the pores. It is appropriate to use filtration when you want to isolate heat-sensitive products such as proteins, viral particles, phages, etc.

Question 7

List two different disinfectants that you might find in a surgical suite and explain how they work.

Answer 7

Bisphenol hexachlorophene is a disinfectant which is the active ingredient of pHisoHex, which is a cleansing detergent often used for handwashing in hospital settings. pHisoHex is effective against gram-positive bacteria, such as microbes causing staphylococcal and streptococcal skin infections.

Phenol is made up of a benzene ring with an -OH group, phenolics are compounds that have this group as their chemical structure. Phenolics like thymol eucalyptol come from plants, however other phenolics can from creosote which is a from coal tar. Phenolics tend to be more stable less toxic and persist on surfaces. They denature proteins and disrupt membranes of
microbes.

Question 8

How are handwashing with soap and hand-sanitizers different? Explain how each method works. Be specific about chemistry.

Answer 8

Soaps are salts of long-chain fatty acids and have both polar and nonpolar regions, allowing them to interact with polar and nonpolar regions in other molecules. They can interact with nonpolar oils and grease to create emulsions in water, loosening and lifting away dirt and microbes from surfaces and skin. Soaps do not kill or inhibit microbial growth and so are not considered antiseptics or disinfectants.

While hand sanitizers, work by rapidly denaturing proteins, which inhibits cell metabolism by disrupting membranes, which leads to cell lysis.

Question 9

What is the natural purpose for the production of antibiotics in microorganisms? Use an example to illustrate.

Answer 9

Some microorganisms produce antimicrobial substances that reduce competition from other microbes. One such example is streptomycin which is produced by soil bacteria of the genus Streptomyces.

Question 10

What are semisynthetic and synthetic drugs? Use penicillins or cephalosporins as examples to comment on what attributes can be optimized by chemically modifying drugs (drug generations).

Answer 10

Semisynthetic drugs are chemically modified drugs that occurs in a lab after isolation from natural resources. Meanwhile synthetic drugs are anti microbial compounds that are synthesized in a lab through chemical reactions.

Question 11

You are a scientist developing new antibiotics. List THREE different characteristics that you would like to engineer into new antibiotics (in addition to their ability to kill bacteria!).

Answer 11

3 different beneficial characteristics could be:

1. Ensuring a low toxicity/minimizing the amount of strain the medications put onto the organs of human body.
2. Somehow engineering antibiotics that DON’T lead to increased antibiotic resistance would be pretty convenient.
3. Increased specificity of the antibiotics to target exactly what they’re designed to, nothing more, nothing less.

Question 12

What is selective toxicity? What is the therapeutic index (TI)? Is it good to have a high or a low TI? Use a specific drug to explain.

Answer 12

1. selective toxicity is the ability of a drug to target certain types of cells or organisms, while leaving surrounding cells unharmed. The more selective a drug can be the safer it is to use.
2. Therapeutic index is a measure of a drugs safety margin. It is the ratio of the dose that produces a therapeutic effect to the dose that produces toxic effects.
3. A high therapeutic index = a safer drug, as the therapeutic dose is much lower than the toxic dose. A low therapeutic index = a narrow safety margin, where even small deviations from the the TD can cause toxicity.
4. Ibuprofen is a good example of a drug that has a high TI. As one of the NSAIDS it is a common anti-inflammatory and pain reliever. The therapeutic dose for ibuprofen is 200-400 mg while the toxic dose is much higher at 1200 mg or more. Excessive doses of ibuprofen lead to severely negative effects that can cause gastrointestinal or kidney damage.

Question 13

Do drugs targeting bacterial cell walls have high or low selective toxicity? Briefly explain.

Answer 13

Drugs that target bacterial cell walls have high selective toxicity, because human cells do not make peptidoglycan.

I think if the drug just targets the bacterial cell wall, it’s actually low selective toxicity. The reason is the indiscriminate killing of both the pathogen and the natural microbiota within our body would cause harm to the body since the presence of the natural microbiome is essential for human health.

Question 14

What enzyme/protein does penicillin target? What is the function of this enzyme? (Hint: this enzyme has two names. What do the two names indicate?)

Answer 14

Penicillin targets the bacteria’s crosslinking transpeptidase enzyme, which is an enzyme that connects amino acids between peptidoglycan monomers and produces the cell wall.

Another name for this enzyme is Penicillin-binding proteins.

This enzyme/protein is inhibited by Penicillin’s beta-lactam ring.

Penicillin binds to the active site of PBPs (Penicillin-binding proteins) and inhibit their function. This leads to the formation of weakened cell walls that are unable to withstand the high internal pressure of the bacterial cytoplasm, resulting in bacterial lysis and cell death.

The names penicillin-binding protein and transpeptidase both refer to the enzyme’s ability to bind penicillin and catalyze the transpeptidation reaction that links peptidoglycan chains in the bacterial cell wall.

Question 15

What is a β-lactam ring? What enzyme gives some bacteria resistance to the class of drugs that have a β-lactam ring? This enzyme has two names. What do the two names indicate?

Answer 15

The β-lactam ring is responsible for the antibacterial activity of these drugs (such as penicillins, cephalosporins, and carbapenems) by interfering with bacterial cell wall synthesis. The β-lactam ring binds to and inhibits the enzymes that cross-link the peptidoglycan chains that make up the bacterial cell wall and leading to bacterial cell death.

The class of enzymes that give some bacteria resistance to β-lactam antibiotics are called β-lactamases. These enzymes are able to break the amide bond in the β-lactam ring. β-lactamases are produced by bacteria. Some bacteria may produce multiple types of β-lactamases and make them resistant to a broad range of β-lactam antibiotics.

The two names of the enzyme that gives some bacteria resistance to β-lactam antibiotics are β-lactamases and penicillinases. These two names indicate that the enzyme is capable of breaking down the β-lactam ring in β-lactam antibiotics such as penicillins. Penicillinases are a specific type of β-lactamase that are capable of inactivating penicillin antibiotics, rendering them ineffective. The β-lactamase is more commonly used as it encompasses a wider range of enzymes that can inactivate multiple classes of β-lactam antibiotics, including penicillins, cephalosporins, and carbapenems.

Question 16

Choose a drug that targets the small subunit (30S) of the ribosome and comment on its mechanism of action and potential side effects.

Answer 16

Drug Name: Streptomycin

Mechanism of action: causes mismatches between codons and anticodons, leading to faulty proteins that insert into and disrupt cytoplasmic membrane

Side effects: nephrotoxic (damage to kidneys), neurotoxic (damaging to nervous system), ototoxic (damage to ear)

Question 17

Choose a drug that targets the large subunit (50S) of the ribosome and comment on its mechanism of action and potential side effects.

Answer 17

Chloramphenicol

1st broad-spectrum antibiotic that was approved by the FDA
Produced by Streptomyces venezuelae
MoA: Inhibition of peptide bond formation
Historically used to treat: meningitis, typhoid, fever, and conjunctivitis
Side effects: gray baby syndrome, suppression of bone marrow production, and anemia

Question 18

Do drugs targeting metabolism have high or low selective toxicity/TI? Briefly explain. What does it mean to say that Sulfa drugs and TMZ have synergistic effects?

Answer 18

Some drugs targeting metabolism have high selective toxicity. Sulfa drugs and trimethoprim target the folic acid synthesis pathway. These drugs are selectively toxic to bacteria because humans get folic acid from food instead of synthesizing it intracellularly. You could say that these two drugs work together synergistically because the combined effect of the drugs is greater than the sum of their effects separately.

Question 19

Why is polymyxin B not used in an oral form? Does it have high or low TI?

Answer 19

Since the mechanism of action for polymyxin B is to target the membrane, this unfortunately makes it not selectively toxic. These drugs also target and damage the membrane of cells in the kidney and nervous system when administered systemically. Because of these serious side effects and their poor absorption from the digestive tract, polymyxin B is used in over-the-counter topical antibiotic ointments.

Question 20

Why are broad-spectrum antibiotics sometimes dangerous in treating infections? What is superinfection?

Answer 20

Broad-spectrum antibiotics can be dangerous because they are more likely to lead to drug resistant bacteria and can cause damage to the normal microbiota, which increases the risk of a superinfection. A superinfection is a second infection occurring on top of a preexisting infection. A superinfection usually occurs when an antibiotic kills the protective microbiota, which allows another antibiotic resistant pathogen to thrive and reproduce.

Question 21

Describe the urinary organs, defenses and normal biota.

Answer 21

The basic structures of the urinary tract are common in males and females however locations of these structures may be unique. Below is a common structure found in both males and females. The kidneys carry out the urinary system’s primary functions of filtering the blood and maintaining the water and electrolyte balance. The kidneys are composed of millions of filtration units called the nephrons. Fluids, electrolytes and molecules from the blood passes from the glomerulus (a capillary bed) into the nephron which creates a filtrate that becomes urine. Urine that is collected in each kidney empties through a ureter and drains to the urinary bladder which stores the urine. Urine is then released from the bladder to the urethra which transports it to be excreted from the body through the opening of the urethra called urinary meatus.

The flushing action of urine is the main defense of the urinary organs. This includes the kidneys, ureters, and urinary bladder. Urine passing out of the body washes out transient microorganisms and preventing them from taking up residence.

The normal microbiota of males is found primarily within the distal urethra and it includes bacterial species that are commonly associated with the skin microbiota. The normal microbiota of women is found within the distal one third of the urethra and the vagina. The normal microbiota of the vagina becomes established shortly after birth and is a complex and dynamic population of bacteria that fluctuates in response to environmental changes. Members of the vaginal microbiota plays an important role in the nonspecific defense against vaginal infections and sexually transmitted infections by occupying cellular binding sites and competing for nutrients. The production of lactic acid by members of the microbiota provides an acidic environment within the vagina that also serves as a defense against infections.

Question 22

Why is it more common for women to get UTIs? Use the anatomy difference to explain.

Answer 22

It is more common for women to get UTIs because the urethra is shorter than a male urethra, making it easier for bacteria to travel through and enter the urinary tract. It is also so close to the vagina and anus that there is a higher chance of bacteria.

Question 23

Give two signs and symptoms of urinary tract infections (UTIs)? Use the prefixes and suffixes in Table 15.1Links to an external site. to explain what each term means. (Note: each student should only talk about two; this question is designed for multiple students to discuss.)

Answer 23

Two signs and symptoms of a UTI are urethritis and cystitis. The suffix -itis means inflammation and the prefix cyst- means bladder, so cystitis is inflammation of the bladder. The prefix urethr/o- represents urethra and the suffix -itis means inflammation, so urethritis is inflammation of the urethra.

Question 24

What are some characteristics of K. pneumoniae? If K. pneumoniae is one of your unknown bacteria, what test results would you get?

Answer 24

K. pneumoniae is a gram-negative bacteria. It is rod shaped bacteria, capsule producing, lactose fermenter, nonmotile, and facultative anaerobic.
an image of K. pneumoniae colonies on MacConkey Agar. It may be beneficial to consider which characteristics of K. pneumoniae contribute to what you see on the plate based on what you know about MAC.

Question 25

How is UTI transmitted? Who is more at risk for developing UTI?

Answer 25

UTIs can be transmitted through catheterization or fecal bacteria entering from the urethra and travels to the bladder and then to the urinary tract. Women are more at risk for UTIs because in women the urethra is closer to the anus making them prone to transmission of bacteria. UTIs are common in elderly because they have weaker immune systems.

Question 26

How is UTI usually diagnosed? What is a clean catch?

Answer 26

UTIs are usually diagnosed by analyzing urine samples, like a urinalysis, just a regular urine culture or using OTC dipsticks. A clean catch is a method used to collect the urine sample to prevent any bacterias from getting into the sample.

Question 27

Why are there fewer antifungal, antiprotozoal and antiviral drugs? Briefly explain

Answer 27

Viruses rely on the host cell to reproduce and also have a protective coat that can protect from antiviral drugs. Fungi and protozoa are eukaryotic. The cells are similar to humans making it selectively toxic

Question 28

What are some drug targets of antifungal drugs? Why are these targets exploited (Hint: do these properties make the drugs having high or low TI)?

Answer 28

The most common targets are fungal RNA synthesis and the fungal cell wall and cell membrane. It eliminates fungal pathogens from a host with minimal toxicity to the host.

Question 29

Do you know how nucleoside analog drugs work as antivirals? Use an example to explain.

Answer 29

Nucleoside analogs are variations of nucleosides (specifically of the purine or pyrimidine bases) which "jump into" the DNA or RNA replication process of the virus and halt elongation of the genome. Acyclovir, used for herpes infections (e.g. coldsores), is an example of a G (guanosine) analog. Acyclovir is an example of a nucleoside analog that is used to treat herpes infections by inhibiting viral DNA replication. By mimicking the structure of the guanosine nucleoside, acyclovir can be incorporated into the viral DNA by viral enzymes, but it lacks the necessary 3' hydroxyl group for further elongation of the DNA chain, leading to termination of the viral DNA replication process. This selective targeting of viral enzymes and inhibition of viral replication makes acyclovir effective against herpes simplex virus and varicella-zoster virus infections.

Question 30

Give two examples of common drugs for influenza and explain how they work.

Answer 30

Amantidine: target hemagglutinin (H), prevent viral escape from endosome (uncoating and biosynthesis) Neuraminidase inhibitors: target neuraminidase (N), prevent viral release

Question 31

Give two examples of common drugs for HIV and explain how they work.

Answer 31

Azidothymidine/Zidovudine (AZT) selectively inhibits reverse transcriptase, an enzyme found in retroviruses that converts the RNA genome carried in the retrovirus particle into double-stranded DNA. Causing HIV-infected cells to produce fewer viruses. Ritonavir is a protease inhibitor that block the processing of viral proteins and prevent viral maturation. This helping out to slow the progression of HIV.

Question 32

List three strategies (mechanisms) that have evolved in bacteria that provide protection against antibiotics.

Answer 32

Cell wall uses penicillin to protect against antibiotics Protein synthesis has aminoglycosides to bind to 30s to protect from antibiotics Nucleic acid synthesis has quinolones inhibit DNA gyrase for protection

Question 33

List a few things under the “responsible antibiotic use” category. Why would some of the behaviors contribute to the antibiotic resistance problem?

Answer 33

Responsible antibiotic use would be like taking antibiotics when prescribed by a doctor, taking the full and complete course as directed, and not sharing/overusing the antibiotics. Some of these behaviors when done incorrectly could lead to an antibiotic resistance problem. For instance not being consistent in taking prescribed antibiotics could allow time for bacteria to survive and adapt. Similarly using antibiotics when they aren't needed, such as for a viral infection, could lead to antibiotic resistance.

Question 34

Use an example of a common infectious disease (flu, COVID, etc.) to discuss signs and symptoms of it.

Answer 34

Firstly a symptom is a manifestation that only the patient can perceive, and sign is a manifestation that a physician can also perceive and likely measure. I will use the flu as my example as its early symptoms can be very general classic symptoms, making it hard to differentiate from other illnesses such as the common cold. Infectious diseases can be contagious during all five of the periods of disease (incubation P, prodromal P, P of illness, P of decline, and P of convalescence) Signs: Vomiting, Swollen lymph nodes, sudden and extreme fever higher than common cold most of the time, diarrhea. Symptoms: Nausea, loss of appetite, chills, extreme fatigue and lack of energy/motivation, sore muscles, sore throat, headaches, sweating. Some signs and symptoms are related, for example nausea is a symptom, but vomiting is a sign.

Question 35

Use an example of a common infectious disease to discuss the five phases of the disease. Patients in which phases of your disease are contagious?

Answer 35

In the case of the flu, influenza, these are the five phases of the disease: 1) Incubation phase: 1-4 days, when the virus first enters the host body and begins to spread; no symptoms presented yet. 2) Prodromal phase: 1-2 days. Symptoms begin to appear but not yet fully developed. Symptoms include: fever, fatigue, cough, sore throat. 3) Acute phase: 3-7 days. The disease is at its peak in this phase. Symptoms are fully developed. High fever, body aches, dry cough. 4) Recovery phase: several days to over a week. Active immunity response by the body has begin. Symptoms will begin to gradually decrease. 5) Convalescent phase: several days to a few weeks. This is when the body has fully recovered from the infection and symptoms have disappeared. For influenza, the person may still feel weak and fatigued during this phase. In the case of influenza, it is contagious during almost all phases, but especially during the Acute phase; even during the convalescent phase, there may still be some viral material shed by the infected person.

Question 36

Use an example of a common infectious disease to discuss how Koch’s postulates (KPs) can be used to link the pathogen to the disease?

Answer 36

Cholera can be used as an example to link the pathogen to the disease using Koch's postulate as Vibrio cholerae is a definitive pathogen. One can isolate the pathogen from an infected host, then culture it in vitro, reintroduce it into a healthy host, observe for changes to see if it matches the signs of the previous infected host, then proceed to isolate the pathogen and identify it again. Vibrio cholerae can grow in vitro and is pathogenic, thus fits the requirement for KP.

Question 37

What are some limitations to KPs (choose one)? Give an example of how the limitation can hinder the establishment of a disease pathogen

Answer 37

The presence of H. pylori in the normal microbiota of some individuals could be considered a limitation to Koch's first postulate, which states that the suspected pathogen must be found in every case of the disease and not be found in healthy individuals. This postulate would be challenged, as H. pylori is a common cause of gastritis or peptic ulcers. Another limitation is Koch's postulate 3 assumed that animals could serve as reliable models for human disease. HIV only causes disease in humans so animals would not be a reliable model. Also H. pylori was found to not cause stomach ulcers in animal test subjects, so animals can not be a reliable model for every pathogen. I wanted to add Koch's second faulty assumption that all healthy test subjects are equally susceptible to disease. Individuals are not equally susceptible to diseases. Individuals are unique because of their microbiota and the state of their immune system at any given time. The makeup of the resident microbiota can influence an individual’s susceptibility to an infection. Members of the normal microbiota play an important role in immunity by inhibiting the growth of transient pathogens.

Question 38

EHEC was used as an example to illustrate molecular Koch’s postulates (MKPs). Can you come up with another example to use MKPs to establish a disease pathogen?

Answer 38

MKPS & COVID-19 SARS-CoV-2 should be consistently detected in individuals diagnosed with COVID-19 using RT-PCR or viral genome sequencing. Studies show that SARS-CoV-2 can be isolated and identified from respiratory samples of COVID-19 patients. SARS-CoV-2 should be successfully isolated and cultured in the laboratory. SARS-CoV-2 has been successfully isolated and cultured in the laboratory, fulfilling this postulate. SARS-CoV-2 should be capable of causing COVID-19 when experimentally inoculated into healthy individuals. SARS-CoV-2 should be re-isolated from the experimentally infected hosts and its genetic identity should match that of the original virus isolated from COVID-19 patients. This can be confirmed using techniques such as RT-PCR or genome sequencing to compare the viral genomes. By fulfilling these four criteria, we can establish SARS-CoV-2 as the causative agent of COVID-19, following the principles of molecular Koch's postulates.

Question 39

What are some signs and symptoms of the flu? Do you know how to tell whether it is a common cold or a flu?

Answer 39

Symptoms of the flu include a fever, headache, fatigue, nausea, aches and pain. Common colds tend to have a lower fever and less severe headaches than the flu. Sneezing and nasal congestion are very common in common colds but less common with the flu. The flu also usually has more severe fatigue, aches and pain than the common cold.

Question 40

What is the causative agent for the flu, and what kind of genome does it have?

Answer 40

The flu is caused by the virus, influenza. It is in the Orthomyxoviridae family, and has a single stranded RNA genome. I just wanted to add that influenza has a circular genome. Also, there are four main families of influenza viruses: A, B, C, D. Scientists create vaccines by predicting what the next strain may be based on trends. If they guess correctly, the vaccine will work really well, if not, the vaccine will have a dramatically decreased effect. Surprisingly, the global flu pandemic is only caused by the A strain.

Question 41

Do you know the function of H and N spike proteins?

Answer 41

Hemagglutinin protein, H spike protein, plays a role in attachment. It binds to receptors on the surface of host cells, This facilitates endocytosis of the viral particle. Once inside the host cell, the negative strand viral RNA is replicated by the viral RNA polymerase to form mRNA, which is translated by the host to produce viral proteins. Additional viral RNA molecules are transcribed to produce viral genomic RNA, which assemble with viral proteins to form mature virions. Release of the virions from the host cell is facilitated by viral neuraminidase, N spike protein, which cleaves sialic-acid receptors to allow progeny viruses to make a clean exit when budding from an infected cell.

Question 42

Do you know the viral life cycle?

Answer 42

Attachment: Influenza virus becomes attached to a target epithelial cell. Penetration: The cell engulfs the virus by endocytosis. Uncoating: Viral contents are released. Biosynthesis: Viral RNA enters the nucleus, where it is replicated by the viral RNA polymerase. Assembly: New Phage particles are assembled. Release: New viral particles are made and released into the extracellular fluid. the cell, which is not killed in the process, continues to make new virus.

Question 43

What are antigenic drift and antigenic shift?

Answer 43

Antigenic drift is small changes due to genetic mistakes that create a slightly new virus. These are the changes that make the yearly variations in the influenza viruses. A genetic shift is a significant change due to genetic changes that arise from multiple viruses infecting the same host and creating a new virus with a very different genome. These shifts are responsible for epidemics like the Spanish Flu epidemic.

Question 44

How is the flu diagnosed, prevented and treated?

Answer 44

Diagnosis: To diagnose the flu, doctors often rely on symptoms such as fever, cough, sore throat, body aches, and fatigue. Sometimes, they may perform a rapid influenza diagnostic test (RIDT), which involves taking a swab from the back of the throat or nose to test for the presence of the virus. However, this test may not always be accurate, and the diagnosis may also be based on symptoms alone. Prevention: Preventing the flu involves getting vaccinated annually, practicing good hygiene, and avoiding contact with infected individuals. Vaccines are the most effective way to prevent the flu and are recommended for everyone over the age of 6 months. Good hygiene practices include frequent hand washing with soap and water or using hand sanitizer, covering your mouth and nose when coughing or sneezing, and avoiding close contact with people who are sick. Treatment: Treatment for the flu typically involves rest, hydration, and medication to relieve symptoms. Over-the-counter pain relievers such as acetaminophen or ibuprofen can help reduce fever and relieve body aches. Antiviral medications such as Tamiflu may also be prescribed to shorten the duration of the illness and reduce the severity of symptoms, but these medications work best when started early in the course of the illness.

Question 45

A 13-year-old male Ethan is admitted to the pediatric intensive care unit. Ethan has a history of mental retardation and cerebral palsy following an anoxic injury as an infant. He was admitted two months earlier due to aspiration pneumonia, necessitating a lengthy hospital stay, mechanical ventilation, and intravenous antibiotics. His caregiver reports another aspiration event two days prior. For the past 24 hours, Ethan has been lethargic with a frequent cough producing thick sputum. Upon presentation to the hospital, he is noted to have a fever, low oxygen saturations, and low blood pressure. Upon arrival to the intensive care unit, the patient is cool, pale, and has poor pulses and capillary refill. Following administration of intravenous fluid boluses, it is determined that Ethan needs central venous access for fluid and medication administration. You the RN prepare for the sterile procedure. To reduce the patient's risk of infection, you assist the physician with applying PPEs prior to the procedure. What does PPE stand for? What kind of PPE should you apply? Give two examples. Prior to placement of the central venous line, Ethan’s skin is scrubbed with chlorhexidine. What microorganisms are targeted by this chemical agent? Give a comprehensive list. How does chlorhexidine work to control microbial numbers? If chlorhexidine is unavailable for the procedure, which chemical agent(s) would also be appropriate as a topical antiseptic? Explain the mechanism of action of the alternative agent.

Answer 45

A. PPE stands for Personal Protective Equipment. Gloves and masks would be the kind of PPE I would use. Gloves to reduce the risk of contamination and to wear a mask because of droplet isolation precaution, since Ethan is coughing and his caregiver reported that he had another aspiration pneumonia two days prior his arrival to the hospital. I would have Ethan wear a mask as well to reduce dissemination of respiratory secretion. B. Chlorhexidine targets gram-positive and gram-negative bacterias as well as yeast, fungi and viruses. C. Chlorhexidine disrupts microbial cell membranes and is bacteriostatic at lower concentrations or bactericidal at higher concentrations, in which causes the cells’ cytoplasmic contents to congeal. It also has activity against enveloped viruses. D. A 2% Iodine will be another alternative as a topical antiseptic because it works by oxidizing cellular components, including sulfur-containing amino acids, nucleotides, and fatty acids, and destabilizing the macromolecules that contain these molecules. It is also commonly used as a hand scrub by medical personnel before surgery and used for topical antisepsis of a patient’s skin before incisions.

Question 46

Use an example of an infectious disease to describe the five stages of pathogenesis.

Answer 46

Pathogenesis of the Flu (Influenza) Incubation period: The incubation period marks the time between exposure to the virus and onset of symptoms The incubation period for the flu is typically 1-4 days. During this stage, the virus is replicating within the body, but the person does not yet feel sick. Prodromal stage: This stage is when a symptoms are normally felt and are generally non-specific such as fever, fatigue, muscle aches, and cough. The prodromal stage usually lasts for 1-2 days. Acute stage: This is the peak of the illness and includes the most severe symptoms, including high fever, cough, sore throat, headache, and body aches. The acute stage usually lasts for 3-5 days, but can be longer, depending on the case Recovery stage: During this stage, the person begins to feel better as their immune system fights off the virus. Symptoms gradually subside, and the person may still feel tired or weak. The recovery stage can last for several days to a week or more. Convalescence stage: This is the final stage of pathogenesis, during which the person has fully recovered from the illness. However, they may still experience lingering symptoms such as fatigue or cough for several weeks.

Question 47

Use an example of an infectious disease to discuss the infectious dose of the pathogen and the implication for how easy or hard it is to get the infection.

Answer 47

We talked about Pseudomonas aeruginosa in class today. This linkLinks to an external site. to the Merck Manual, a reputable and dependable source for clinical information, lists several different modes of transmission of the bacteria. External ear infections from swimming, epidermal infections from sitting in a hot tub (hot tub folliculitis), soft tissue infections (from contaminated , dressings during surgery, stepping on a nail, existing wounds becoming infected by various means) and blood stream infections (from contaminated needles during IV drug use) are some of but not all modes of transmission of this bacteria. Another common mode of transmission is ingesting contaminated water. In this case, the infectious dose is between 108-109. While it is rather infectious and can be spread in various ways, it should be noted that it is famously a nosocomial pathogen and very opportunistic. So, while it is easy to contract, it should be specified that it tends to successfully invade the immunocompromised.

Question 48

Does attachment always lead to colonization? Does colonization always lead to disease? Use an example to explain.

Answer 48

Colonization means germs are on the body but do not make you sick. People who are colonized will have no signs or symptoms. Infection means that germs are in or on the body and make you sick, which results in signs and symptoms such as fever, pus from a wound, a high white blood cell count, diarrhea, or pneumonia. Colonization means germs are on the body but do not make you sick.

Question 49

Use a specific bacterium to talk about an exoenzyme it has that contributes to the pathogenicity. Which stage of pathogenesis does it affect?

Answer 49

DNAse produced by Staphylococcus aureus helps degrade DNA that is released by dying cells that can trap the bacteria and helping them spread. This affects the fourth stage of pathogenesis which is causing the disease which is a focal type of infection since the pathogen is being spread throughout the body.

Question 50

Use a specific bacterium to talk about an exoenzyme it has that contributes to the pathogenicity. Which stage of pathogenesis does it affect?

Answer 50

Some pathogens produce extracellular enzymes, or exoenzymes, that enable them to invade host cells and deeper tissues. Exoenzymes have a wide variety of targets. Some general classes of exoenzymes and associated pathogens are listed in Table 15.8. Each of these exoenzymes functions in the context of a particular tissue structure to facilitate invasion or support its own growth and defend against the immune system. For example, hyaluronidase S, an enzyme produced by pathogens like Staphylococcus aureus, Streptococcus pyogenes, and Clostridium perfringens, degrades the glycoside hyaluronan (hyaluronic acid), which acts as an intercellular cement between adjacent cells in connective tissue (Figure 15.11). This allows the pathogen to pass through the tissue layers at the portal of entry and disseminate elsewhere in the body

Question 51

Compare exotoxins with endotoxin.

Answer 51

Exotoxins and endotoxins are both harmful substances produced by bacteria. Exotoxins are proteins secreted by certain living bacteria, usually gram-positive, such as C. tetanus. Exotoxins can be released as a part of the bacteria's normal metabolism, or can also be released following cell death. Exotoxins are usually heat labile and can be neutralized by antibodies. Exotoxins are also specific in their target, using receptor-mediated mechanisms. Endotoxins are lipopolysaccharides (LPS) that are on the outer membrane of gram-negative bacteria, such as E. coli. If the cell is lysed, destroyed, or dies, then the cell will start to degrade and break apart, leading to these endotoxins being released into the host. Endotoxins are heat stable, and are not neutralized by antibodies. Symptoms can include general systemic fever and shock, as endotoxins do not target specific cells or tissues. It is important to note that exotoxins are much more dangerous as they can be lethal at lower doses compared to endotoxins. exotoxins can be grouped into three categories based on their target which are: intracellular targeting: are composed of two components: A for activity and B for binding. The B component is responsible for the cellular specificity of the toxin and it mediates the initial attachment of the toxin to the specific cell surface receptors. membrane disrupting: are exotoxins that affect cell membrane function either by forming pores or by disrupting the phospholipid bilayer in host cell membranes. superantigens: these are exotoxins that trigger an excessive, nonspecific stimulation of immune cells to secrete cytokines

Question 52

How do A-B toxins work? Use an example to explain.

Answer 52

The intracellular targeting toxins are made up of 2 parts, A-B exotoxins. A for activity and B for binding, B is responsible for the cellular specificity of the toxin and also mediates the initial attachment of the toxin to specific cell surface receptors. Once the A-B toxin is bound it enters the cell through endocytosis it entraps in a vacuole. Then as the vacuole acidifies, the A-B subunits separate. Finally, the subunit A enters the cytoplasm of the cell and disrupts the cellular functions it can target. Examples: diphtheria, cholera, botulinum, and tetanus toxins

Question 53

How do botox and tetanus toxins work? What neurons do they target and what neurotransmitters do they inhibit?

Answer 53

Tetanus neurotoxin acts mainly at the CNS synapse, while the seven botulinum neurotoxins act peripherally. Clostridial neurotoxins share a similar mechanism of cell intoxication: they block the release of neurotransmitters. They are composed of two disulfide-linked polypeptide chains. Ultimately, tetanus toxin blocks the release of the inhibitory neurotransmitters glycine and GABA. Glycine is the neurotransmitter for primary inhibitory interneurons such as the Renshaw cell; GABA is the inhibitory transmitter for descending pathways.

Question 54

What kind of enzymes are membrane-disrupting toxins? Briefly explain

Answer 54

Two types of membrane-disrupting exotoxins are hemolysins and leukocidins, which form pores in cell membranes, causing leakage of the cytoplasmic contents and cell lysis.

Question 55

How do superantigens work?

Answer 55

Superantigens are bacterial proteins that generate a powerful immune response by binding to Major Histocompatibility Complex class II molecules on antigen-presenting cells and T cell receptors on T cells.

Question 56

Use influenza to explain antigenic variation. How are antigenic drift and antigenic shift different?

Answer 56

Antigenic drift creates influenza viruses with slightly modified antigens, while antigenic shift generates viruses with entirely new antigens

Question 57

Define key terms such as incidence, prevalence, mortality, morbidity, epidemic and pandemic.

Answer 57

Incidence - number or proportion of new cases in a period of time. Prevalence - number, or proportion, of individuals with a particular illness in a given population at a point in time. Mortality - population that has died from a disease. Morbidity - state of being diseased. Epidemic - larger than expected number of cases occurs in a short time within a geographic region. Pandemic - an epidemic on a worldwide scale.

Question 58

Do you know how to calculate the rates of prevalence, incidence, and mortality?

Answer 58

Prevalence: ( # of individuals afflicted with the disease from survey sample ÷ total survey sample ) * 100 = prevalence % Incidence: ( new cases ÷ population ) * 100,000 = x amount of new cases per 100,000 population Mortality: ( deaths due to disease ÷ population ) * 100,000 = x amount of deaths per 100,000 population What is R sub zero? What is an effective reproduction number? Use examples to illustrate them.

Question 59

What is herd immunity? Who does it protect the population from infectious diseases?

Answer 59

Herd immunity is also known as community immunity, and it occurs when a high enough percentage community achieves immunity either through vaccination or previous infection, it makes it harder for the disease to spread person to person. This helps protect those who are not immune, and also those who are more vulnerable.

Question 60

What is herd immunity? Who does it protect the population from infectious diseases?

Answer 60

“Herd immunity,” also known as “community immunity,” happens when enough of the community is immune to a particular disease, either because of vaccination or natural infection, that it makes it less likely to spread from one person to another.

Question 61

Differentiate between direct droplet transmission and indirect airborne transmission

Answer 61

They may also fall on surfaces and then be transferred onto someone's hand who then rubs their eyes, nose or mouth. Airborne transmission occurs when bacteria or viruses travel in droplet nuclei that become aerosolized. Healthy people can inhale the infectious droplet nuclei into their lungs.

Question 62

What are some differences between mechanical vs biological transmissions?

Answer 62

Biological vectors, such as mosquitoes and ticks may carry pathogens that can multiply within their bodies and be delivered to new hosts, usually by biting. Mechanical vectors, such as flies can pick up infectious agents on the outside of their bodies and transmit them through physical contact.

Question 63

What are nosocomial infections? What are iatrogenic infections?

Answer 63

Improper or excessive medication, spreading of an infection by patients, redundant surgery, and neuroses engendered by a psychiatrist are all examples of iatrogenic diseases. Nosocomial illness has a similar meaning to iatrogenic and refers in particular to the hospital environment.

Question 64

What are emerging and re-emerging diseases? Give some examples.

Answer 64

Emerging diseases are newly identified infectious diseases that are increasing in incidence or geographic range in humans, animals or both. They may be caused by new or previously unknown pathogens or known pathogens that have evolved to become more virulent, drug-resistant or able to infect new hosts. Re-emerging diseases are known infectious diseases that have reappeared after a significant decline in incidence or control measures. This can happen due to several factors, including changes in the environment, genetic mutations in the pathogen, or lapses in control measures. Examples of emerging diseases include: COVID-19 (caused by the SARS-CoV-2 virus) Ebola virus disease Zika virus disease Chikungunya virus disease Middle East Respiratory Syndrome (MERS) Severe Acute Respiratory Syndrome (SARS) Examples of re-emerging diseases include: Tuberculosis Measles Cholera Dengue fever Yellow fever Poliomyelitis (polio)

Question 65

What is salmonellosis, and what are some signs and symptoms? What are some characteristics about Salmonella?

Answer 65

Most people with Salmonella infection have diarrhea, fever, and stomach cramps. Symptoms usually begin six hours to six days after infection and last four to seven days. However, some people do not develop symptoms for several weeks after infection and others experience symptoms for several weeks.

Question 66

What are some virulence factors of Salmonella? How do they work?

Answer 66

Virulence factors in Salmonella Typhi are involved in the various stages of infection, namely: the production of toxins (LPS) endotoxin, enterotoxin, cytotoxin), colonization, adhesion and invasion, as well as survival inside the host cells

Question 67

How is salmonellosis transmitted? How is it usually diagnosed? What about treatment and prevention?

Answer 67

Salmonellosis is transmitted by ingesting contaminated food, touching eggshells, or exposure to certain animals like pet reptiles and amphibians. It is usually diagnosed by a culture from feces, blood, urine, or bone marrow. The culture is is followed with serotyping and DNA fingerprinting if necessary. Many people don't go to doctors to get diagnosed though because it is usually self-limiting. Treatment includes rehydration therapy and very rarely antibiotics are used for immunocompromised patients. Prevention include hand washing, avoid eating raw eggs and making sure eggs and poultry are fully cooked to safe temperatures before ingesting.

Question 68

How is K. pneumoniae infection treated? Is it known to be antibiotics-resistant? What are some resistance mechanisms?

Answer 68

Klebsiella pneumoniae is a difficult infection to treat because of the organism's thick capsule. Klebsiella is best treated with third- and fourth-generation cephalosporins, quinolones, or carbapenems. Monotherapy is just as effective as a combination treatment in Klebsiella pneumoniae because newer agents are used. It has a variety of antibiotic resistance mechanisms and is a common pathogen causing hospital-acquired surgical wound infections, digestive tract infections, and community-onset infections, which can cause outbreaks of nosocomial infection K. pneumoniae has been observed to develop resistance to antibiotics more easily than most bacteria through the production of enzymes such as Extended Spectrum β-Lactamase (ESBLs) and Carbapenemase [1–3]. The most important risk factor of AMR is antibiotic exposure.

Question 69

What does the acronym "PPE" stand for?

Answer 69

Personal Protective Equipment

Question 70

Match the description with each biosafety level.

Answer 70

BSL-1 Microbes are not known to cause disease in healthy hosts and pose minimal risks to workers and the environment. BSL-2 microbes are typically indigenous and and are associated with diseases of varying severity. They pose moderate risk to workers and the environment. BSL-3 microbes are indigenous or exotic and cause serious or potentially lethal diseases through respiratory transmission BSL-4 microbes are dangerous and exotic, posing a high risk of aerosol-transmitted infections, which are frequently fatal without treatment or vaccines. Few labs are at this level

Question 71

What are the advantages of pasteurizing foods and beverages? Mark all correct answers.

Answer 71

to increase the shelf life of a food or beverage to kill pathogenic microbes

Question 72

Which of the following terms is used to describe the time required to kill all of the microbes within a sample at a given temperature?

Answer 72

thermal death time

Question 73

Which chemical disinfectant works by methylating enzymes and nucleic acids and is known for being toxic and carcinogenic?

Answer 73

formaldehyde

Question 74

Which of the following peroxygens is widely used as a household disinfectant, is inexpensive, and breaks down into water and oxygen gas?

Answer 74

hydrogen peroxide

Question 75

A scientist discovers that a soil bacterium he has been studying produces an antimicrobial that kills gram-negative bacteria. She isolates and purifies the antimicrobial compound, then chemically converts a chemical side chain to a hydroxyl group. When she tests the antimicrobial properties of this new version, she finds that this antimicrobial drug can now also kill gram-positive bacteria. The new antimicrobial drug with broad-spectrum activity is considered to be which of the following?

Answer 75

semisynthetic

Question 76

Which of the following combinations would most likely contribute to the development of a superinfection?

Answer 76

long-term use of broad-spectrum antimicrobials

Question 77

Which of the following does not bind to the 50S ribosomal subunit?

Answer 77

tetracyclines

Question 78

One of the choices below is true for all of the following: penicillins, cephalosporins, monobactam, and carbapenems.

Answer 78

Is the presence of Beta lactam ring

Question 79

Which of the following is not an appropriate target for antifungal drugs?

Answer 79

cholesterol

Question 80

Which of the following is an appropriate target for antifungal drugs?

Answer 80

(1→3) glucan ergosterol chitin

Question 81

Which of the following is a target for an antifungal drug? Check all that apply.

Answer 81

Cell membrane Chitin synthesis Ergosterol synthesis Mitochondria (ETC)

Question 82

MRSA (Methicillin Resistant Staphylococcus Aureus), develops resistance to Methicillin (low affinity PBP) through this process.

Answer 82

Target modification

Question 83

Which of the following types of drug-resistant bacteria do not typically persist in individuals as a member of their intestinal microbiota?

Answer 83

MRSA

Question 84

What are some factors that determine the size of a zone of inhibition in Kirby-Bauer disk diffusion test? Check all that apply.

Answer 84

drug solubility the nature of the bacteria the thickness of the agar medium

Question 85

What is an example of a chronic disease?

Answer 85

Hepatitis B

Question 86

Which of the following would be a sign of an infection?

Answer 86

fever

Question 87

What are Koch's postulates used for?

Answer 87

To determine the cause of a new disease

Question 88

Pathogen A has an ID50 of 50 particles, pathogen B has an ID50 of 1,000 particles, and pathogen C has an ID50 of 1 × 106 particles. Which pathogen is most virulent?

Answer 88

pathogen A

Question 89

What is the excessive number of bacterial toxins in the blood known as?

Answer 89

toxemia

Question 90

What is excessive activation of the immune system and severe response that can lead to life threatening fever, inflammation, and shock, are caused by?

Answer 90

Superantigens

Question 91

Match the concept with its correct definition:

Answer 91

Sporadic diseases that are seen only occasionally, and usually without geographic concentration Epidemic diseases for which a larger than expected number of cases occur in a short time within a geographical region Endemic diseases that are constantly present (often at a low level) in a population within a geographical region Pandemic and epidemic that occurs on a world wide scale

Question 92

The way that COVID-19 is spreading is called:

Answer 92

propagated spread

Question 93

A disease that has a steady frequency over time in a particular geographic location is

Answer 93

endemic

Question 94

A blanket from a child with chickenpox is likely to be contaminated with the virus that causes chickenpox (Varicella-zoster virus). What is the blanket called?

Answer 94

Fomite

Question 95

When hiking in Northern California around the Russian River, Mary was bitten by a tick. The tick transmitted the bacteria Borrelia burgdorferi to Mary’s leg tissues while it was obtaining a blood meal. This bacteria is found in certain species of hard-bodied ticks around the USA such as the Deer Tick. The Borrelia bacteria completes part of its life cycle in the ticks. Because the bacteria completes part of its life cycle in the tick, the tick is considered a _______ for the bacteria.

Answer 95

Biological vector

Question 96

Why are emerging diseases with very few cases the focus of intense scrutiny?

Answer 96

They are increasing and therefore not controlled

Question 97

Match the Lyme disease symptom to the stage of the disease.

Answer 97

Bull’s eye (erythema migrans) early localized stage Facial paralysis early disseminated stage Meningitis late stage

Question 98

Which of the following is true of Borrelia burgdorferi? Check all that apply.

Answer 98

it has internal flagella It is gram-negative It is a spirochete

Question 99

Which of the following represents a difficulty of diagnosing Lyme disease? Check all that apply.

Answer 99

Many symptoms resemble those of other diseases Only 70-80% patients develop the bull’s eye rash

Question 100

Which of the following is not a characteristic of the normal biota of the female reproductive tract during childbearing years?

Answer 100

Vaginal pH is neutral

Question 101

Match the following virulence factors of K. pneumoniae with their function.

Answer 101

Capsule avoid phagocytosis LPS cause systemic symptoms such as fever fimbrial adhesins attachment to host cells Siderophores sequester iron for survival

Question 102

Why would a urine culture be informative in diagnosing UTI? Check all that apply.

Answer 102

The lack of growth of bacteria or fungi could indicate a viral infection. The lack of growth of bacteria or fungi could indicate other conditions such as cancer. The growth of bacteria would confirm a bacterial caused UTI. The growth of fungi would confirm a yeast infection.

Question 103

What is the mortality rate of the 2013 bird flu (H7N9) epidemic?

Answer 103

33%

Question 104

Which of the following is a component of the influenza virus? Check all that apply.

Answer 104

Neuraminidase (N) spike M2 ion channel Capsid proteins

Question 105

Match the H and N spikes with the steps they are involved in.

Answer 105

Involved in attachment H spike Involved in release N spike Cleaves sialic acid receptors to make a clean exit N spike Binds sialic acid receptor to facilitate entry H spike

Question 106

Which of the following make up feces? Check all that apply.

Answer 106

Undigested food Epithelial cells Mucus Microbes

Question 107

The part of the gastrointestinal tract with the largest natural microbiota is the:

Answer 107

Large intestine or colon

Question 108

Why does the CDC think that the 1 million cases of salmonellosis per year is an underestimate? Check all that apply.

Answer 108

Because most infections are mild and self-limiting Because many patients do not seek medical help

Question 109

Which of the following is not a criteria for determining the Biosafety Level of a particular microbe?

Answer 109

whether it is gram positive or gram negative

Question 110

Match the controlling microbial growth term with the correct definition.

Answer 110

Disinfection reduces or destroys microbial load of an inanimate item through application of heat or antimicrobial chemicals Sterilization completely eliminated all vegetative cells, endospores, and viruses from an inanimate item Antisepsis reduces microbial load on skin or tissue through application of an antimicrobial chemical Degerming reduces microbial load on skin or tissue through gentle or firm scrubbing and use of mild chemicals

Question 111

When flaming the loop in the lab this is an example of __.

Answer 111

dry-heat sterilization

Question 112

Which of the following microbial control methods does not actually kill microbes or inhibit their growth but instead removes them physically from samples?

Answer 112

filtration

Question 113

Soaps are classified as disinfectants.

Answer 113

False

Question 114

Which of the following best describes the mechanism of action iodophor?

Answer 114

oxidizes cellular material

Question 115

Bacteriostatic ______________________________________.

Answer 115

Causes a reversible inhibition of growth of the target bacteria

Question 116

One of the bacteria that is notorious of causing superinfection is:

Answer 116

Clostridium difficile

Question 117

Which one is the antimicrobic that does not inhibit the cell wall synthesis?

Answer 117

Gentamicin

Question 118

Which of the following antimicrobials inhibits the activity of DNA gyrase?

Answer 118

Ciprofloxacin

Question 119

Which of the following is not an appropriate target for antifungal drugs?

Answer 119

cholesterol

Question 120

There are fewer drugs (Antifungal, antiprotozoan, antihelminthic) available to treat other microbes than bacteria, because____________________________.

Answer 120

They are so similar to human cells that selective toxicity is difficult to achieve

Question 121

Which of the following resistance mechanisms describes the function of β-lactamase?

Answer 121

drug inactivation

Question 122

Why have the United States and Europe banned the use of human antibiotics in animal feed?

Answer 122

Because it has been connected to drug resistant problem

Question 123

What are some reasons why the development of new antibiotics has slowed down? Check all that apply.

Answer 123

developing new drugs is a lengthy process developing new drugs is expensive pharmaceutical companies can make more money developing drugs for chronic conditions

Question 124

What is an example of a chronic disease?

Answer 124

Hepatitis B

Question 125

During an oral surgery, the surgeon nicked the patient’s gum with a sharp instrument. This allowed Streptococcus, a bacterium normally present in the mouth, to gain access to the blood. As a result, the patient developed bacterial endocarditis (an infection of the heart). Which type of disease is this?

Answer 125

iatrogenic

Question 126

The number of pathogen cells or particles required to cause active infection in 50% of inoculated animals is _______________________.

Answer 126

Median Infectious Dose (ID50)

Question 127

Pathogen A has an ID50 of 50 particles, pathogen B has an ID50 of 1,000 particles, and pathogen C has an ID50 of 1 × 106 particles. Which pathogen is most virulent?

Answer 127

pathogen A Order the following events when superantigen attacks. 1 superantigen stimulates immune cells 2 excess release of cytokines (cytokine storm 3 high fever and low blood pressure 4 multi-organ failure and death

Question 128

Some of the following are membrane disrupting toxins. Mark all that apply.

Answer 128

Bacterial phospholipases Leukocidins Hemolysins

Question 129

If I said there were 43,103 confirmed cases of the Novel Coronavirus worldwide on February 11, 2020, I would be talking about the ________________ of the disease.

Answer 129

Prevalence

Question 130

Match each pioneer of epidemiology with his or her contribution.

Answer 130

John Snow determined the source of a cholera outbreak in london Joseph Lister showed that surgical wound infection rates could be drastically reduced by using carbolic acid to disinfect the surgical tools, bandages, and surgical sites Florence Nightingale compiled data on the cause of mortality in soldiers, leading to innovations in military medical care Robert Koch developed a methodology conclusively determining the etiology of a disease

Question 131

Match the term with its description.

Answer 131

common source spread there is a single source for all the individuals infected point source spread the common source operates for a short time continuous common source spread the commons source occurs for and extended time period intermittent common source spread infection occurs, stop and begins again

Question 132

Toxoplasmosis is caused by a protozoan parasite called Toxoplasma gondii. This parasite reaches sexual maturity in cats and the intermediate host is usually a rat or a bird. It can cause aberrant behavior in the prey organisms it infects, such as making the scent of cat urine appealing to rodents. Humans can become infected and affected by this eukaryotic single-celled organism, but the organism does not reproduce sexually in human tissues nor is it transmitted to other organisms by humans. In this scenario, a human would be what to the Toxoplasma gondii organism?

Answer 132

Dead-end host

Question 133

Toxoplasmosis is caused by a protozoan parasite called Toxoplasma gondii. This parasite reaches sexual maturity in cats and the intermediate host is usually a rat or a bird. It can cause aberrant behavior in the prey organisms it infects, such as making the scent of cat urine appealing to rodents. Humans can become infected and affected by this eukaryotic single-celled organism, but the organism does not reproduce sexually in human tissues nor is it transmitted to other organisms by humans. In this scenario, a rodent would be what to the Toxoplasma gondii organism?

Answer 133

Intermediate host

Question 134

Why are emerging diseases with very few cases the focus of intense scrutiny?

Answer 134

They are increasing and therefore not controlled

Question 135

Which of the following is true of antigenic variation? Check all that apply.

Answer 135

Can evade immune detection Renders antibodies ineffective Plays a role in causing chronic disease

Question 136

Match the tick stage with the host they feed on.

Answer 136

Larvae Mice Nymphs Mice and humans Adults deer, occasionally humans

Question 137

Order the stages of the tick life cycle.

Answer 137

1 eggs 2 larvae 3 nymphs 4 adults

Question 138

The following are conditions that can establish homeostasis due to the normal microbiota of the vagina. Mark all that apply.

Answer 138

Levels of estrogen Production of lactic acid Low pH It is established shortly after birth

Question 139

The urinary tract defenses in both males and females consists of mechanical factors such as ________, and chemicals like ________, to prevent the growth of pathogens in the system.

Answer 139

the flushing action of urine; lysozyme

Question 140

Why would a urine culture be informative in diagnosing UTI? Check all that apply.

Answer 140

The lack of growth of bacteria or fungi could indicate a viral infection. The growth of fungi would confirm a yeast infection. The lack of growth of bacteria or fungi could indicate other conditions such as cancer. The growth of bacteria would confirm a bacterial caused UTI.

Question 141

What kind of bacterium is Klebsiella pneumoniae? Check all that apply.

Answer 141

Lactose fermenter Capsule producing

Question 142

Do you know how to tell the difference between a common cold and the flu?

Answer 142

mild fatigue common cold severe fatigue flu nasal congestion rare flu nasal congestion common common cold

Question 143

Compare and contrast the 2013 bird flu (H7N9) pandemic and the 1918-1919 flu (H1N1) pandemic.

Answer 143

Capable of person to person transmission 1918-19 pandemic incapable of person to person transmission 2013 pandemic Caused by re-assortment of RNA strands from different strains both Caused by antigenic shift both

Question 144

Arrange the steps of influenza viral life cycle in the correct order.

Answer 144

1 attachment 2 penetration (endocytosis) 3 uncoating 4 biosynthesis 5 assembly 6 release

Question 145

Natural defenses of the GI tract include mechanical factors, such as peristalsis, and chemical factors, such as secretory IgA on the surface of the intestines.

Answer 145

True

Question 146

The normal __________ provides an additional barrier to infection via a variety of mechanisms. For example, these organisms outcompete potential pathogens for space and nutrients within the intestine. This is known as ___________. Members of the microbiota may also secrete protein toxins known as __________ that are able to bind to specific receptors on the surface of susceptible bacteria.

Answer 146

The normal microbiota provides an additional barrier to infection via a variety of mechanisms. For example, these organisms outcompete potential pathogens for space and nutrients within the intestine. This is known as competitive exclusion. Members of the microbiota may also secrete protein toxins known as bacteriocins that are able to bind to specific receptors on the surface of susceptible bacteria.

Question 147

Which of the following is used for salmonellosis diagnosis? Check all that apply.

Answer 147

Serological tests such as ELISA Culture of bacteria

Question 148

Which biosafety level is appropriate for research with microbes or infectious agents that pose moderate risk to laboratory workers and the community, and are typically indigenous?

Answer 148

BSL-2

Question 149

Match the temperature with the following treatments.

Answer 149

Freezer -20 °C Refrigeration 4 °C Pasteurization 72 °C Boiling 100 °C Autoclave 121 °C Dry oven 171 °C

Question 150

Which of the following methods when used properly is capable of sterilization?

Answer 150

ionizing radiation

Question 151

Which of the following is not a heavy metal disinfectant used to control growth of microbes?

Answer 151

chlorine

Question 152

Which chemical disinfectant works by methylating enzymes and nucleic acids and is known for being toxic and carcinogenic?

Answer 152

formaldehyde

Question 153

Bacteriostatic ______________________________________.

Answer 153

Causes a reversible inhibition of growth of the target bacteria

Question 154

One of the bacteria that is notorious of causing superinfection is:

Answer 154

Clostridium difficile

Question 155

Which one is the antimicrobic that does not inhibit the cell wall synthesis?

Answer 155

Gentamicin

Question 156

Which of the following terms refers to the ability of an antimicrobial drug to harm the target microbe without harming the host? Check all that apply.

Answer 156

selective toxicity therapeutic index

Question 157

Distinguish the drugs treating influenza vs. HIV infections.

Answer 157

Inhibit neuraminidase influenza treatment Inhibit reverse transcriptase HIV treatment Inhibit protease HIV treatment Inhibit integrase HIV treatment Inhibit viral escape from endosome influenza treatment

Question 158

Which of the following is a target for an antifungal drug? Check all that apply.

Answer 158

Chitin synthesis Ergosterol synthesis Mitochondria (ETC) Cell membrane

Question 159

Match the following drug resistance mechanism with its example.

Answer 159

Drug modification / inactivation beta-lactamase / penicillinase Target modification modification of PBP active site Prevention of cellular uptake or efflux reducing porin concentration on the outer membrane Target mimicry TB bacteria producing a protein that mimics DNA structure

Question 160

What are some of our practices that contribute to the rapid evolution of antibiotic resistance in bacteria? Check all that apply

Answer 160

over the counter access to antibiotics overuse or misuse of antibiotics (prescribing antibiotics for cold or flu) share antibiotics with family members feeling better before the full course of antibiotics and stopping therapy early

Question 161

Which of the following is one of the most common difficulties in finding new antibiotics?

Answer 161

Ability to grow new-found bacteria (microbes) in lab environment

Question 162

What is a symptom?

Answer 162

Is a condition that is observed and experienced by the patient

Question 163

A communicable disease that can be easily transmitted from person to person is which type of disease?

Answer 163

contagious

Question 164

What are Koch's postulates used for?

Answer 164

To determine the cause of a new disease

Question 165

A(n) __________ infection is a small region of infection from which a pathogen may move to another part of the body to establish a second infection.

Answer 165

Focal

Question 166

What is excessive activation of the immune system and severe response that can lead to life threatening fever, inflammation, and shock, are caused by?

Answer 166

Superantigens

Question 167

What is the excessive number of bacterial toxins in the blood known as?

Answer 167

Toxemia

Question 168

The total number of deaths in a population due to a disease is the ________ rate.

Answer 168

mortality

Question 169

Toxoplasmosis is caused by a protozoan parasite called Toxoplasma gondii. This parasite reaches sexual maturity in cats and the intermediate host is usually a rat or a bird. It can cause aberrant behavior in the prey organisms it infects, such as making the scent of cat urine appealing to rodents. Humans can become infected and affected by this eukaryotic single-celled organism, but the organism does not reproduce sexually in human tissues nor is it transmitted to other organisms by humans. In this scenario, a rodent would be what to the Toxoplasma gondii organism?

Answer 169

Intermediate host

Question 170

Cattle are allowed to pasture in a field that contains the farmhouse well, and the farmer’s family becomes ill with a gastrointestinal pathogen after drinking the water. What type of transmission of infectious agents would this be?

Answer 170

vehicle transmission

Question 171

Which of the following factors can lead to reemergence of a disease?

Answer 171

A period of decline in vaccination rates

Question 172

Lyme disease is transmitted by:

Answer 172

ticks

Question 173

Which of the following is true of antigenic variation? Check all that apply.

Answer 173

Plays a role in causing chronic disease Can evade immune detection Renders antibodies ineffective

Question 174

Why would a differential blood count be informative in distinguishing UTI from other conditions? Check all that apply.

Answer 174

An increased number of lymphocytes may indicate a viral infection. A high percentage of neutrophils may indicate bacterial infection. A high WBC count may indicate infection, immune disorders or allergic responses. An increased number of eosinophils may indicate allergic responses

Question 175

Why would a differential blood count be informative in distinguishing UTI from other conditions? Check all that apply.

Answer 175

An increased number of eosinophils may indicate allergic responses. An increased number of lymphocytes may indicate a viral infection. A high WBC count may indicate infection, immune disorders or allergic responses. A high percentage of neutrophils may indicate bacterial infection.

Question 176

In diagnosing UTI, what will the doctor look for in the urine analysis test? Check all that apply.

Answer 176

The presence of bacteria The presence of red blood cells (RBCs) The presence of white blood cells (WBCs)

Question 177

Female's urethra is shorter than male's, and closer to the anus, making it easier for fecal bacteria such as K. pneumoniae to cause UTI Do you know how to tell the difference between a common cold and the flu?

Answer 177

low fever common cold high fever flu mild muscle pain common cold sneezing common common cold severe muscle pain flu sneezing rare flu

Question 178

Which of the following is true about the rapid influenza diagnostic test (RIDT) tests? Check all that apply.

Answer 178

Tend to produce false-negative Lack sensitivity

Question 179

Which of the following are common signs and symptoms of salmonellosis? Check all that apply.

Answer 179

Nausea Vomiting Watery diarrhea

Question 180

Why do doctors not prescribe antibiotics for many diarrhea patients? Check all that apply.

Answer 180

Because in bacterial diarrhea, sometimes using antibiotics can delay the excretion of bacteria Because in bacterial diarrhea, sometimes using antibiotics can cause the release of toxin and make the condition worse Because for diarrhea, rehydration therapy is more important