Exam 3 Flashcards
What is the difference between “bactericidal” and “bacteriostatic”? Give a specific example of each approach.
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.
Define “sterilization” and give two examples of ways things are sterilized.
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.
Compare and contrast “sterilization” and “pasteurization”. Provide two ways the processes are similar, and two ways they are different.
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.
Why can you sterilize things more quickly (and at lower temperatures) in an autoclave than in a dry-heat oven?
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
What is the effect of DNA damage done to bacteria by UV light? Does irradiation of food make the food radioactive? Explain.
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.
How does filtration work, and when is it appropriate to use filtration?
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.
List two different disinfectants that you might find in a surgical suite and explain how they work.
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.
How are handwashing with soap and hand-sanitizers different? Explain how each method works. Be specific about chemistry.
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.
What is the natural purpose for the production of antibiotics in microorganisms? Use an example to illustrate.
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.
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).
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.
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!).
3 different beneficial characteristics could be:
- Ensuring a low toxicity/minimizing the amount of strain the medications put onto the organs of human body.
- Somehow engineering antibiotics that DON’T lead to increased antibiotic resistance would be pretty convenient.
- Increased specificity of the antibiotics to target exactly what they’re designed to, nothing more, nothing less.
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.
- 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.
- 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.
- 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.
- 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.
Do drugs targeting bacterial cell walls have high or low selective toxicity? Briefly explain.
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.
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?)
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.
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?
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.
Choose a drug that targets the small subunit (30S) of the ribosome and comment on its mechanism of action and potential side effects.
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)
Choose a drug that targets the large subunit (50S) of the ribosome and comment on its mechanism of action and potential side effects.
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
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?
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.
Why is polymyxin B not used in an oral form? Does it have high or low TI?
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.
Why are broad-spectrum antibiotics sometimes dangerous in treating infections? What is superinfection?
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.
Describe the urinary organs, defenses and normal biota.
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.
Why is it more common for women to get UTIs? Use the anatomy difference to explain.
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.
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.)
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.
What are some characteristics of K. pneumoniae? If K. pneumoniae is one of your unknown bacteria, what test results would you get?
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.
How is UTI transmitted? Who is more at risk for developing UTI?
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.
How is UTI usually diagnosed? What is a clean catch?
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.
Why are there fewer antifungal, antiprotozoal and antiviral drugs? Briefly explain
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
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)?
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.
Do you know how nucleoside analog drugs work as antivirals? Use an example to explain.
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.
Give two examples of common drugs for influenza and explain how they work.
Amantidine: target hemagglutinin (H), prevent viral escape
from endosome (uncoating and biosynthesis)
Neuraminidase inhibitors: target neuraminidase (N),
prevent viral release
Give two examples of common drugs for HIV and explain how they work.
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.
List three strategies (mechanisms) that have evolved in bacteria that provide protection against antibiotics.
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
List a few things under the “responsible antibiotic use” category. Why would some of the behaviors contribute to the antibiotic resistance problem?
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.
Use an example of a common infectious disease (flu, COVID, etc.) to discuss signs and symptoms of it.
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.
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?
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.
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?
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.
What are some limitations to KPs (choose one)? Give an example of how the limitation can hinder the establishment of a disease pathogen
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.
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?
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.
What are some signs and symptoms of the flu? Do you know how to tell whether it is a common cold or a flu?
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.
What is the causative agent for the flu, and what kind of genome does it have?
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.
Do you know the function of H and N spike proteins?
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.
Do you know the viral life cycle?
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.
What are antigenic drift and antigenic shift?
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.
How is the flu diagnosed, prevented and treated?
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.
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.
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.
Use an example of an infectious disease to describe the five stages of pathogenesis.
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.
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.
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.
Does attachment always lead to colonization? Does colonization always lead to disease? Use an example to explain.
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.
Use a specific bacterium to talk about an exoenzyme it has that contributes to the pathogenicity. Which stage of pathogenesis does it affect?
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.
Use a specific bacterium to talk about an exoenzyme it has that contributes to the pathogenicity. Which stage of pathogenesis does it affect?
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
Compare exotoxins with endotoxin.
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
How do A-B toxins work? Use an example to explain.
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
How do botox and tetanus toxins work? What neurons do they target and what neurotransmitters do they inhibit?
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.
What kind of enzymes are membrane-disrupting toxins? Briefly explain
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.
How do superantigens work?
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.
Use influenza to explain antigenic variation. How are antigenic drift and antigenic shift different?
Antigenic drift creates influenza viruses with slightly modified antigens, while antigenic shift generates viruses with entirely new antigens
Define key terms such as incidence, prevalence, mortality, morbidity, epidemic and pandemic.
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.
Do you know how to calculate the rates of prevalence, incidence, and mortality?
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.
What is herd immunity? Who does it protect the population from infectious diseases?
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.
What is herd immunity? Who does it protect the population from infectious diseases?
“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.
Differentiate between direct droplet transmission and indirect airborne transmission
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.
What are some differences between mechanical vs biological transmissions?
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.
What are nosocomial infections? What are iatrogenic infections?
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.
What are emerging and re-emerging diseases? Give some examples.
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)
What is salmonellosis, and what are some signs and symptoms? What are some characteristics about Salmonella?
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.
What are some virulence factors of Salmonella? How do they work?
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
How is salmonellosis transmitted? How is it usually diagnosed? What about treatment and prevention?
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.
How is K. pneumoniae infection treated? Is it known to be antibiotics-resistant? What are some resistance mechanisms?
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.
What does the acronym “PPE” stand for?
Personal Protective Equipment
Match the description with each biosafety level.
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
What are the advantages of pasteurizing foods and beverages? Mark all correct answers.
to increase the shelf life of a food or beverage
to kill pathogenic microbes
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?
thermal death time
