VBS Exam 3 - flash cards
Lec 1
Active immunity involves the body's adaptive immune response, triggered by exposure to an antigen, leading to long-lasting protection with memory cells. Passive immunity occurs when antibodies are transferred, either naturally (e.g., through breast milk) or artificially (e.g., via injections), providing immediate but temporary protection without memory cell formation.
Variolation involved collecting smallpox material from patients to protect others, while smallpox vaccination, discovered by Edward Jenner, used cowpox to induce immunity against smallpox, providing a safer alternative.
An attenuated vaccine is a live virus that has been weakened but can still replicate in the body, such as the polio vaccine. The rVSV-ZEBOV vaccine against Ebola is a hybrid virus engineered to express Ebola's surface protein, eliciting an immune response without causing disease.
Toxoid vaccines contain inactivated toxins and are used against diseases caused by bacterial toxins, like Tdap for tetanus, diphtheria, and pertussis.
IPV (inactivated polio vaccine) is used in countries where polio is controlled, while OPV (oral polio vaccine) is crucial in areas with circulating wild poliovirus. OPV carries a risk of vaccine-derived poliovirus, especially in under-vaccinated populations.
Immunocompromised individuals cannot receive attenuated vaccines because the weakened virus may cause illness, and pregnant women should avoid them due to potential harm to the fetus.
Boosters are necessary for subunit vaccines to enhance the immune response, as they may not stimulate strong and lasting immunity on their own.
Adjuvants like aluminum hydroxide are sometimes necessary to boost the body's immune response to vaccines, making them more effective.
Conjugate HiB vaccine combines polysaccharides with proteins, stimulating a better immune response than capsule-based vaccines alone, especially in children.
RNA vaccines work by introducing mRNA into the body, which instructs cells to produce viral proteins, triggering an immune response. They offer advantages in rapid development and production compared to traditional vaccines.
Various types of vaccines are being developed for COVID-19, including DNA, RNA, subunit, inactivated, chimeric, and attenuated vaccines.
Clinical vaccine trials progress through phases from preclinical testing in animals to human trials (Phase 1-4), assessing safety, immune responses, and efficacy. Preclinical trials are necessary to evaluate vaccine candidates before testing in humans.
Both RNA and adenovirus-based COVID-19 vaccines enter cells and instruct them to produce viral proteins, eliciting an immune response that leads to antibody production and memory cell formation, providing future protection against the virus.
LEC 2
How are antibiotics administered to livestock like chickens and turkeys?
Livestock receive antibiotics through injections, pills, or by mixing them into drinking water or feed, primarily administered to cattle when they are sick or at high risk of illness.
Describe some ways antibiotics given to people, pets, or livestock can circulate in the environment.
Antibiotics can enter the environment through improper disposal, such as being thrown into landfills or flushed down drains, leading to contamination of waterways and soil.
How can antibiotic resistance spread within a health care system, between people, and between bacteria?
Resistance can spread within healthcare settings through contaminated hands or equipment, between individuals via poor hygiene, and among bacteria through mechanisms like conjugation.
How did the Veterinary Feed Directive (2017) change antibiotic use in the US?
The directive eliminated the growth promotion label for medically important antibiotics, requiring prescriptions from veterinarians for their use, thus aiming to reduce unnecessary antibiotic use in livestock.
Does reducing antibiotic usage always reduce antibiotic resistance?
No, because resistance can still spread through various mechanisms even with reduced antibiotic usage, making the spread of resistant strains and genes the primary driver of resistance.
Compare/contrast non-medically important, medically important, and critically important antibiotics.
Non-medically important antibiotics are not used in human medicine, while medically important ones are, and critically important antibiotics should not be used in animals due to the risk of transmission to humans.
Why did the use of virginiamycin decline while bambermycin increased in turkey production?
Virginiamycin's decline was due to its status as a medically important drug, while bambermycin's increase was because it was not medically important.
Describe the process of co-selection involving bacterial plasmids and its implications for antibiotic resistance.
Co-selection occurs when resistance genes for antibiotics and metals are linked on the same plasmid, allowing the selection of multiple resistances. Cleaning a barn with disinfectant may select for bacteria resistant to both disinfectant and antibiotics due to this phenomenon.
Define terms such as APEC, ExPEC, FUTI, and COPs.
APEC causes avian colibacillosis, ExPEC causes disease outside the gut, FUTI is a foodborne urinary tract infection, and COPs colonize opportunistic pathogens.
Explain how a foodborne E. coli could cause a urinary tract infection (UTI).
Ingesting contaminated food can introduce E. coli into the gut, where it may eventually reach the urinary tract through unsanitary practices, leading to a UTI.
What is the evidence that some UTIs are caused by E. coli from food?
Genetic similarity between E. coli strains found in humans with UTIs and those in food suggests a link between foodborne E. coli and UTIs.
Generally speaking, what is the difference between recent and older Salmonella Reading strains?
Recent Salmonella Reading strains, unlike older ones, contain new mutations making them more resistant and causing more serious disease outbreaks.
Lec 3
Why isn’t Lyme disease contagious? Can you think of another example of a non-contagious disease?
Lyme disease can't spread from person to person; it's transmitted only through tick bites. Other non-contagious diseases include asthma and diabetes.
Why doesn't exposure to a pathogen always result in disease?
Factors like proper hygiene, innate and acquired immunity, and the absence of a suitable entry point for the pathogen can prevent disease even after exposure.
What is the difference between symptoms and signs of a disease?
Symptoms are feelings experienced by the patient, like nausea, while signs are measurable observations, such as fever or a rash.
How can a primary infection lead to a secondary infection?
A primary infection, like the flu, can damage protective mechanisms in the body, leading to a secondary infection, such as pneumonia, caused by opportunistic pathogens.
When do opportunistic pathogens cause disease?
Opportunistic pathogens cause disease when the immune system is weakened, normal microbial balance is disrupted, or they enter areas of the body where they're not usually found.
What are some ways that our normal microbiota protect us from disease?
Normal microbiota protect us by competing for resources, producing antimicrobial substances, and occupying sites where pathogens could attach.
What factors influence host immunity?
Host immunity is influenced by factors like age, nutrition, sleep, smoking, and lifestyle choices.
What are virulence factors, and how do they increase pathogenicity?
Virulence factors are mechanisms that enhance a microorganism's ability to cause disease, such as enzymes that spread through tissues, toxins that cause severe illness, or adhesins that help bacteria attach to host cells.
How does Mycobacterium tuberculosis evade the immune system?
Mycobacterium tuberculosis evades the immune system by having a thick, waxy cell wall that resists digestion by immune cells, allowing it to multiply within human cells.
How do some bacteria evade the complement system?
Some bacteria evade the complement system by producing elastase to inactivate complement proteins or by having long polysaccharide chains in their cell wall to prevent complement activation.
How does the prodromal period of disease differ from the symptomatic period?
The prodromal period precedes the symptomatic period and presents with early, vague symptoms, while the symptomatic period is characterized by specific signs and symptoms of the disease.
What is a latent infection, and can it be transmitted?
A latent infection occurs when a microbe remains in the body without causing symptoms, but it can reactivate later. Some latent infections, like certain sexually transmitted diseases, can be transmitted to others.
Lec 4
What types of virulence factors help a pathogen spread through the body, evade the host immune defenses, or cause damage to the host?
Virulence factors include toxins, adhesins, flagella, enzymes, and other mechanisms that aid in attachment, multiplication, invasion, evasion of host defenses, and tissue damage.
If you only stay home during the symptomatic phase of illness, will you avoid infecting other people?
Staying home during the symptomatic phase can reduce transmission, but some illnesses can still spread before symptoms appear, so complete prevention may not be guaranteed.
What is the difference between an asymptomatic carrier and a person with a latent infection?
Asymptomatic carriers carry and shed pathogens without showing symptoms, while latent infections are dormant and may reactivate later to cause disease.
What is a fomite?
A fomite is an inanimate object that can transmit pathogens or viruses, such as towels, doorknobs, or microphones.
What types of microorganisms are transmitted directly?
Microorganisms like shigella, treponema pallidum (syphilis), and Neisseria gonorrhea are transmitted directly through activities like touching or through respiratory droplets.
What is the difference between a microbial intoxication and a microbial infection?
Microbial intoxication occurs when toxins are ingested, while microbial infection involves the multiplication of bacteria in the body.
What are some examples of when Koch’s postulates could not be satisfied?
Koch's postulates may not be satisfied when organisms can't be cultured, multiple organisms cause the disease, or animal hosts aren't available.
What is herd immunity and how does it protect unvaccinated members of the population?
Herd immunity occurs when a high percentage of the population is immune to a disease, reducing its spread and protecting unvaccinated individuals.
How does the value of R0 influence vaccination strategies?
R0 influences vaccination strategies by determining the percentage of the population that needs to be vaccinated to achieve herd immunity.
How long do you think we should practice social distancing during the COVID-19 pandemic? Why?
Social distancing should continue until enough people are vaccinated or have immunity to achieve herd immunity and prevent further spread of the virus.
Lec 5
Definition of Outbreak: An outbreak is defined as the occurrence of a disease above what would normally be expected to happen.
Most Common Source of Foodborne Illness: Fresh produce is the most common source of foodborne illness.
Most Common Cause of Foodborne Illness: Norovirus is the most common cause, followed by bacterial pathogens like Salmonella, Clostridium perfringens, Campylobacter, and Staphylococcus aureus. Among the most dangerous are Listeria, Clostridium botulinum, E. coli, and Vibrio.
Bacteria Causing Serious Foodborne Illness: Listeria, Clostridium botulinum, E. coli, and Vibrio are the bacteria that cause the most serious forms of foodborne illness.
FDA and USDS-FSIS Inspection: FDA inspects most food products except meat, poultry, and egg products, which are inspected by USDS-FSIS.
Definition of Outbreak and Outbreak Strain: An outbreak is a number of cases above the expected number. An outbreak strain refers to isolates of the same species that are both epidemiologically and genetically related, indicating a common source of infection.
Investigating Foodborne Illness Outbreaks: Investigation involves identifying the index case, gathering information on affected individuals, identifying the microbe causing the illness, and tracing its source in the food supply chain.
Definition of "O", "H", and "K" Antigens: These antigens are associated with bacterial classification and are used for strain identification. Gram-negative bacteria have these antigens.
Resolution in Distinguishing Strains: Whole genome sequencing has the highest resolution, followed by Pulsed-Field Gel Electrophoresis (PFGE), and antigenic typing has the lowest resolution.
Hypotheses in Grocery Store Chicken Experiment: The experiment aims to test if conventional chicken contains more multi-drug resistant isolates and if E. coli causes urinary tract infections (UTIs).
Questions from Whole Genomic Sequence: Whole-genome sequencing helps identify virulence and antibiotic-resistance genes, O or H antigen type, and sequence type.
Definition of GenomeTrakr: GenomeTrakr sequences pathogens from various sources to build a database, aiding in tracing the origin of outbreaks.
Role of Whole-Genome Sequencing in Epidemic Control: Whole-genome sequencing helps establish microbial leads, prevent contaminated food from reaching consumers, and improves understanding of bacterial pathogens for better control measures.
Quick Check:
Gold Standard Technique: Whole Genome Sequencing (WGS)
Government Agencies Inspecting Food: FDA and USDA
lec 6
Definition of an EID: An EID is a disease that is either new within a particular population or an old disease that has rapidly increased in incidence or geographic range.
Types of EIDs and Examples:
Old diseases, but returning or detected with new forms of surveillance: Example - Plague in prairie dogs. This fits the definition because it's an old disease reemerging with new surveillance methods.
Old diseases, but new geographic range (travel, climate change): Example - Mosquito-borne diseases like Zika and yellow fever virus in the US. This fits because the diseases are old but are now appearing in new areas due to factors like travel and climate change.
Old diseases, but agents have increased virulence/drug resistance: Example - E. coli containing Shiga Toxin. This fits because although the disease is old, it has evolved to become more virulent or resistant to drugs.
New diseases through spillover events: Example - SARS-CoV-2. This fits because it's a new disease resulting from a spillover event, likely originating from animals.
Most Common Cause of EIDs: RNA viruses, due to their high mutation rates and reassortment during viral replication.
Comparison of Zoonosis and EID: Zoonosis refers to diseases acquired directly or indirectly from animals, while EIDs can be caused by animals but are not always sustained through animal interaction. Reverse zoonosis refers to diseases transmitted from humans to animals.
SARS-CoV-2 as an EID of Animal Origin: SARS-CoV-2 is considered an EID of probable animal origin because close relatives of the virus have been found in bats.
Causes of Spillover Events: Contact with animals, particularly domestic animals, which can lead to infections in humans.
Difference Between Natural and Transmission Hosts: Natural hosts are the first hosts within an infectious disease and are asymptomatic, while transmission hosts acquire the infection from natural hosts and show symptoms.
Coronavirus EIDs and Hosts: MERS (natural host: bats, transmission host: camels) and SARS-CoV-1 (natural host: bats, transmission host: animal markets).
Reasons Why Bats Carry Many Viruses Without Showing Signs: Bats have higher levels of interferons, limited innate immune responses, high body temperatures during flight, and flight-induced cellular damage.
Bat Elimination as a Solution: No, because not all EIDs come from animals.
Reasons for Increase in EIDs of Animal Origin: Human encroachment on animal habitats, development reducing biodiversity, wildlife trade, and species mixing in markets.
Common HAIs/Nosocomial Infections: Central line bloodstream-associated infection, catheter-associated urinary tract infection, surgical site infection, ventilator-associated pneumonia.
Spread of HAIs/Nosocomial Infections: Through patients and staff via contaminated equipment and lack of handwashing, as well as airborne transmission.
Reasons for Persistence of Bacteria Like Acinetobacter in HAIs: Contain persistors and resistors, with biofilms, resistance to desiccation, high mutation rates, and efflux pumps contributing to their persistence.
lec 7
Distribution of Bacteria on Tooth Surface: Bacteria on the tooth surface are not randomly distributed but highly organized based on oxygen demands.
Organs of the Upper GI Tract: The upper GI tract includes the oral cavity, salivary glands, esophagus, and stomach.
Saliva's Protective Mechanisms: Saliva protects against bacterial infection through components like IgA, lactoferrin, and lysozyme, which inhibit bacterial growth. It also acts as a barrier, buffering agent, and promotes wound healing. Additionally, cell shedding helps remove potential pathogens.
Salivary Microbiome: The salivary microbiome is individualized, stable within orally healthy individuals, and reflects bacteria associated with dental caries and periodontitis. Streptococcus is the most predominant species in saliva.
Formation of Plaque and Tartar: Plaque forms when salivary proteins adhere to teeth, forming pellicles, which bacteria then colonize to form a biofilm. Mineral salt deposits lead to the formation of dental calculus or tartar.
Role of Streptococcus mutans in Tooth Decay: Streptococcus mutans adheres to pellicles and, in the presence of sucrose, produces acids that demineralize enamel, leading to tooth decay.
Impact of Sugary Carbonated Drinks on Teeth: Sugary carbonated drinks are harmful to teeth because they contribute to acidity, along with the breakdown of sucrose. Frequent sugar intake leads to an ecological shift favoring acid-producing microbes like Streptococcus mutans, which weaken enamel.
Prevention of Dental Caries: Dental caries can be prevented by practicing good oral hygiene, drinking fluoridated water, and reducing sucrose intake and frequency.
Development of Periodontitis: Prolonged gingivitis can lead to periodontitis, where gums recede, allowing plaque and tartar to accumulate between the tooth and gum tissue.
Bacteria Causing Periodontitis and Role of Flossing: Anaerobic, periogenic bacteria cause periodontitis. Flossing helps prevent periodontitis by removing plaque biofilm and introducing oxygen, which is harmful to anaerobic bacteria.
Causative Agent and Characteristics of ANUG: ANUG, also known as "trench mouth," is caused by Treponema and other anaerobic bacteria. More cases may be seen recently due to associations with methamphetamine use.
Causes and Characteristics of Cold Sores: Cold sores are caused by Herpes Simplex Virus 1, and they develop when the virus infects and damages cells. They cannot be cured as the virus remains latent in the body, leading to recurrent outbreaks.
lec 8
1. Basic Organ Functions in Lower Digestive Tract: The small intestine absorbs nutrients and water, while the liver and pancreas secrete bile and pancreatic enzymes for digestion. In the large intestine, water and vitamins are absorbed, and chyme is converted into feces.
2. Gut Microbiome Changes: The gut microbiome becomes more diverse as you move from the gut to the colon and is influenced by environmental factors in early childhood until fully colonized at around one year. Over time, dietary changes can alter the types of microbes present.
3. Functions of Gut Microbiome: The gut microbiome acts as a physical barrier, modulates the immune system, aids in gut maturation, secretes vitamins, and digests complex carbohydrates to release short-chain fatty acids, which decrease inflammation.
4. Lower GI Tract Protection from Infection: Various mechanisms protect the lower GI tract from infection, including the gut microbiome acting as a barrier, the presence of antimicrobial compounds in the intestine, and the shedding of infected cells.
5. Comparison of Gastroenteritis, Diarrhea, and Dysentery: Gastroenteritis is inflammation of the stomach and intestines, diarrhea involves loose, watery stools, and dysentery includes bloody diarrhea with pus, typically associated with large intestine infection.
6. Bacterial Infection Mechanisms in Lower GI Tract: Bacteria infect the lower GI tract through attachment to epithelial cells, production of toxins (enterotoxins, cytotoxins, neurotoxins), and invasion of host cells. Examples include Vibrio cholerae, which produces an AB enterotoxin causing profuse watery diarrhea.
7. Treatment of Bacterial Gastroenteritis: Most cases are treated with oral rehydration therapy (ORT) to prevent dehydration. Antimicrobial drugs are rarely used due to the risk of disrupting the gut microbiome and promoting antimicrobial resistance.
8. Vibrio cholerae Disease Mechanism and Prevention: Cholera causes profuse watery diarrhea by producing a toxin that dysregulates ion transport, leading to water loss. Prevention involves sanitation, vaccination, and improved food and water hygiene.
9. Disease Mechanism of Shigella sp.: Shigella causes disease by surviving stomach acidity, invading host cells, and producing toxins, resulting in dysentery. Unlike cholera, Shigella has a low infectious dose and invades cells directly.
10. Features and Development of E. coli Strains: E. coli strains causing diarrhea share similarities in producing toxins and invading the small intestine but differ in colonizing the large intestine and toxin production. Horizontal gene transfer allows for the development of diverse E. coli strains.
11. Disease Caused by E. coli STEC Strains: E. coli STEC strains cause bloody diarrhea due to Shiga toxin production. Antimicrobial drugs are not used because they can release more bacterial toxins, worsening the illness.
12. Similarities and Differences between Salmonella and Campylobacter: Both bacteria cause similar symptoms and rarely require antimicrobial treatment due to antimicrobial resistance. However, Campylobacter is more likely to result in dysentery, while Salmonella severity depends on the strain.
13. Disease Mechanism of C. difficile: C. difficile causes disease by producing toxins that kill intestinal cells, leading to a strong immune response and diarrhea. It is a common cause of healthcare-associated diarrhea, with symptoms ranging from mild to life-threatening.
14. Common Themes in Lecture: Microbes are ubiquitous and can contaminate various foods. Infection likelihood depends on factors like infectious dose, microbe virulence, and host immunity. Microbes can rapidly change through horizontal gene transfer, leading to diverse strains like V. cholerae and E. coli STEC.
lec 9
1. Viral Causes of Hepatitis: Hepatitis can be caused by five viruses, with Hepatitis A, B, and C being the most common.
2. Hepatitis A, B, and C Comparison: Hepatitis A is transmitted via the fecal-oral route, while Hepatitis B and C are transmitted via bodily fluids. Hepatitis A causes acute infection, whereas B and C can lead to chronic infection, cirrhosis, or cancer. Hepatitis A and B have vaccines, and B and C can be treated with antiviral medication.
3. Recent Hepatitis A Outbreaks: Recent outbreaks of Hepatitis A have been associated with factors like homelessness, drug use, and contaminated food. Outbreaks are increasing due to low vaccination rates and poor sanitation.
4. CDC Recommendations for Hepatitis C Screening: The CDC recommends screening all adults for Hepatitis C due to high rates of chronic infection without symptoms and the serious consequences of untreated infection. Pregnant women are screened to identify those who could benefit from treatment and to prevent perinatal transmission.
5. Selective Toxicity of Anti-Hepatitis C Drugs: Anti-Hepatitis C drugs target viral proteins like RNA-dependent RNA polymerase and protease, which are essential for viral replication. They are selectively toxic to the virus, resulting in a high cure rate.
6. Comparison of Rotavirus and Norovirus: Rotavirus can cause serious disease in children and has a vaccine. Norovirus is more common, has a low infectious dose, and causes more widespread outbreaks.
7. Importance of Boiling Water When Camping: Boiling or filtering water is important to prevent infection with Giardia cysts, which have a low infectious dose and are resistant to environmental conditions.
8. Causes of Milwaukee Cryptosporidium Outbreak: Milwaukee had a large Cryptosporidium outbreak in 1993 due to water contamination. Cryptosporidium is resistant to water treatment methods like chlorine and can bypass filters.
9. Features of Protozoa for Transmission: Protozoa like Giardia and Cryptosporidium have a low infectious dose and are highly resistant, making transmission likely through contaminated water sources.
10. Most Common Foodborne and Waterborne Illnesses: The most common foodborne illnesses include Norovirus, Salmonella, and Campylobacter, while the most common waterborne illnesses are Norovirus, Giardia, and Cryptosporidium.
Quick Check:
Chronic infection: Hepatitis C
Fecal-oral route transmission: Hepatitis A
lec 10
1. CNS vs. Peripheral Nervous System (PNS): The CNS comprises the brain, meninges, and spinal cord, while the PNS consists of sensory and motor neurons connecting the CNS to the body.
2. CNS Protection: The CNS is protected by bony structures and three layers of membranes called meninges (dura, arachnoid, pia).
3. Definitions of CNS Conditions: Meningitis is inflammation of the meninges, encephalitis is inflammation of brain tissue, myelitis is inflammation of the spinal cord.
4. Blood-Brain Barrier (BBB): The BBB allows nutrients and gases to pass but blocks cells, antibodies, and some antibiotics, protecting the brain from microbial invasion.
5. Cerebral Spinal Fluid (CSF): CSF provides cushioning, nutrients, and waste removal for the CNS and circulates through the ventricles and subarachnoid space.
6. Microbial Entry into CNS: Microbes can enter the CNS via nerves (e.g., Rabies), hematogenous spread (e.g., Streptococcus pneumoniae), surgery/trauma, or adjacent infected sites (e.g., sinusitis).
7. CNS Infection Detection: CNS infections are detected by analyzing CSF collected via lumbar puncture, which reveals white and red blood cell counts and bacterial presence.
8. Bacterial vs. Aseptic Meningitis: Bacterial meningitis is more serious and typically sourced from the respiratory tract, while aseptic meningitis is usually viral and self-limiting, sourced from the fecal-oral route.
9. Symptoms of Meningitis: Symptoms include severe headache, neck stiffness, fever, photophobia, nausea, and vomiting.
10. Neonatal Bacterial Meningitis: Neonates are susceptible due to underdeveloped immune systems and lack of maternal IgG protection, prevented by Group B Strep vaccination.
11. Meningitis Vaccines: Hib vaccine prevents bacterial meningitis, while viral meningitis is often caused by enteroviruses via fecal-oral transmission.
12. Meningococcal Meningitis: Caused by Neisseria meningitidis, vaccinated against serogroups A, C, W, and Y; serogroup B infection is possible.
13. Pneumococcal Meningitis: Common in the elderly, caused by encapsulated Streptococcus pneumoniae strains.
14. Bacterial Meningitis Virulence Factors: Entry into the bloodstream, lack of vaccine, and inflammatory response contribute to severity.
15. Immune Response in Bacterial Meningitis: Inflammatory response leads to vasodilation, fluid buildup, nerve damage, neutrophil invasion, clotting, tissue swelling, and CSF obstruction.
16. Listeria monocytogenes and Listeriosis: Listeriosis risk is higher for pregnant, elderly, and immunocompromised individuals, causing flu-like symptoms or severe consequences like meningitis or miscarriage.
17. Encephalitis Causes and Prevention: Typically viral, caused by HSV or arboviruses; prevention includes vector control and supportive care.