Exam #4 Micro
Vaccines
Explain several ways that immunity may develop.
· What is immunity?
Resistance from pathogens/infection
· What branch of the immune system helps develop long-term immunity?
Adaptive-Memory B & T-cells
· Identify passive vs. active and natural vs. artificial mechanisms of immunity:
| Natural | Artificial |
Passive |
Antibodies pass thru breast milk/placenta
| Receive treatment of purified antibodies from IV or injection |
Active |
Gained thru illness & recovery
|
Vaccine always activates & trains immune system as to what pathogen looks like |
Describe the different types of vaccines.
· What are the different considerations of a successful vaccine?
o Effective
§ Activates both humoral & cell-mediated
§ Long term memory response
§ Full protection
§ Minimum side effects
o Practical
§ Easy administration
§ Few doses, limited boosters
§ Affordable
§ Stable storage
§ Esay to manufacture & distribute
· Who was Edward Jenner? What contribution(s) did he make to the field of science?
English physician who developed first vaccine and built herd immunity
· Who was Maurice Hilleman? What contribution(s) did he make to the field of science?
American microbiologist who developed over 40+ vaccines mostly for children
· What are the different types of vaccines? (Note: you should be able to read a scenario and identify which type of vaccine is being used)
Vaccine Type | Explanation |
Live Attenuated Vaccines | Live, weakened/ less virulent form
|
Inactivated Vaccines |
Pathogen is dead, can’t replicate nor cause disease
|
Subunit Vaccines | Pathogen fragments illicit response
|
Toxoid Vaccines | Contains attenuated toxin
|
Nucleic Acid Vaccines | DNA/mRNA carry genes that encode for pathogen’s antigen protein, elicits immune response
|
· What is an adjuvant? What do you call a vaccine that has an added adjuvant?
Adjuvant- added ingredient to illicit stronger immune response known as a Conjugated vaccine
Provide an explanation for why vaccines are important.
Vaccines are important bc they provide protection for the immunocompromised and
Describe herd immunity and why it’s important.
· What is herd immunity?
Large portion of pop. is immune, indirectly protects unimmunized persons
· Who does herd immunity help to protect?
immunocompromised
· What influences herd immunity?
o Infectiousness
o Duration
· What is R0?
How many people will the individual infect based on type of pathogen
Describe the importance of boosters in vaccination schedules.
· What is a booster? Why do people need to receive boosters?
Extra dose of vaccine to bring immunity response back up
· Boosters are most commonly associated with what type(s) of vaccines?
inactivated
Explain the science behind the mRNA COVID vaccine
· How do the mRNA COVID-19 vaccines work?
Use genetic code of virus to have own cells reproduce the antigens so that the body recognizes it.
Antibiotics
· Where do antibiotics come from? Antibiotics are used to treat infections caused by what type of prokaryotes?
often come from compounds of other bacteria or fungi- medicines that fight against bacterial inf.
· What is the name of the assay imaged to the right?
Kirby Bauer
· The bacteria is most resistance to which antibiotic: A__
· The bacteria is most sensitive to which antibiotic: D
· What is the name of the clear circle around the antibiotic disk?
Zone of clearance
· Identify the mode of action and examples for each antibiotic:
Antibiotic | Mode of Action | Examples |
β – Lactams |
Inhibit cell wall synthesis Including transpeptidase | Penicillin, Carbapenem, Monobactam, Cephlasporin |
Glycopeptides | Inhibit cell wall synthesis
| Vancomycin |
Chloramphenicol |
| N/A |
Lincosamides |
|
|
Polymyxins | Disrupt cell membrane
| N/A |
Quinolones | Inhibits DNA synthesis
| N/A |
Rifamycin | Inhibits mRNA synthesis
| N/A |
Aminoglycosides | Inhibits biosynthesis of proteins
| Streptomycin |
Tetracyclines | Inhibit biosynthesis of proteins
| N/A |
· Mechanisms of Antibiotics
o β-Lactams à Penicillin
§ What type of bacteria does this antibiotic class target?
Gram +
§ What is the mechanism of action?
Bind to transpeptidase (enzyme instead)
§ How are bacteria resistant to penicillin?
Antibiotic hydrolysis: Beta-lactamase breaks down beta-lactam, allows transpeptidase to bind to peptidoglycan layer
o Glycopeptides à Vancomycin
§ What type of bacteria does this antibiotic class target?
Gram +
§ What is the mechanism of action?
Bind to cell wall (peptide chain, peptidoglycan layer) to inhibit transpeptidase
§ How are bacteria resistant to vancomycin?
Target Modification: change target of antibiotic so it can’t bind to it anymore
o Quinolones
§ What type of bacteria does this antibiotic class target?
Broad spectrum
§ What is the mechanism of action?
-DNA replication termination requires separation of chromosomes
-Gyrase- enzyme that cuts DNA backbone
· Define the following mechanisms of antibiotic resistance:
Mechanism | Definition | Example |
Antibiotic Hydrolysis |
Bacteria produces enzyme that chemically breaks bonds in antibiotic
| Beta-lactamase breaks beta-lactams |
Antibiotic Modification | Resistant bacteria enzymatically add a functional group to an antibiotic so that it does not function
| AMP added to streptomycin to inactivate |
Membrane Modification | Resistant bacteria prevent antibiotic from getting into/staying in cytoplasm
| Different LPS so antibiotic (polymyxin) can’t bind to it |
Target Modification | Rsestant bacteria can change target of antibiotic so it doesn’t recognize it and can’t bind to it anymore
| Instead of D-Ala-D-Ala, cells modify to D-Ala-D-Lactate so vancomycin can’t bind |
Probiotics
Define probiotic
· What is the difference between a probiotic and prebiotic?
Probiotic is live microbiota whereas prebiotic is food that nourishes gut flora
· Who is Élie Metchnikoff?
Father of Innate Immunity, discovered connection between fermented foods and better health
· What are some examples of probiotic strains?
o Bifidobacterium infantis
§ Isolate form breast fed baby feces
o Lactobacillus bulgaricus
§ Isolated from yogurt
o Lactobaillus acidophilus
§ Infant feces
o Sacchiaromyces boulardi
§ Lychee & mangosteen peels (fruit)
Describe the rationale and science behind probiotics and their purported health benefits
· How do probiotics confer health benefits?
1. Competitively exclude pathogens
a. No room for them to attach to epi layer
2. Stimulate immune system
3. Enhance epithelial barriers
a. Tighter junctions
· What is the gut-brain axis?
Research has shown that there is a correlation between depression and less diverse gut flora
Explain probiotics regulations
· Explain the implications of probiotics being considered a dietary supplement.
They have not been FDA approved
· Why should people be cautious about taking probiotics?
o They are live organisms and can impact everyone differently
o Not covered by insurance
Other Types of Treatments
Describe antiviral and antifungal targets.
· What are the targets of antifungals?
Cell wall (chitin) synthesis
· Why are antifungals difficult to develop?
Hard to target fungi specific structures bc they are eukaryotes too
· What are the targets of antivirals?
Parts of viral cycle
· Why are antivirals difficult to develop?
Mutations, limited number of virus specific targets to attack, & side effects
Understand the concept of Fecal Microbiota Transplantation (FMT).
· What are symptoms of CDI? What is recurrent CDI (rCDI)?
o Produces exotoxin leading to host inflammation
§ Watery diarrhea
§ Blood in stool
§ Abdominal pain
§ Nausea and vomiting
§ fever
Recurrent CDI: the likelihood that the infection will return after primary exposure
· What is the main treatment of CDI?
Antibiotics (Vancomycin)
· What are Fecal Microbiota Transplants (FMTs)
Microbes from healthy donor’s feces are transplanted into patient with CDI in order to introduce healthy gut flora back into the environment.
· What are the benefits of FMTs?
o Restores diverse healthy gut flora
o 80-90% cure rate
Evaluate the safety and risks of FMT
· What are the limitations of FMTs?
o Mech is unknown, poor understanding-don’t know what dosage to give or when to give it
o Safety concerns with live organisms-potentially introduce pathogen as well
o Patient comfortability
Discuss the application of phage therapy
· What are bacteriophages?
Viruses that attack and kill bacteria
· What is phage therapy?
The process of using bacteriophages to kill hardy/antibiotic resistant bacteria
· What are the benefits of phage therapy?
o Kill antibiotic resistant bacteria
o SPECIFIC, doesn’t harm good flora
o inexpensive
· What are the limitations of phage therapy?
o Uncertain side effects
o Potential to develop phage resistance?
o Immune system interference?
o Not enough data-hasn’t been tested on humans
· When is phage therapy in the US available?
In cases of compassionate use, or when all other treatment methods have been tried with no result
What is the difference between preventative and responsive therapy/treatment?
Preventive= intends to stop the infection from occurring
Responsive= intends to treat symptoms