Exam 2 - Microbiology

A pathogen existing dormant in a person and periodically causing symptoms is termed A. pathogenicity. B. virulence factor. C. opportunistic infection. D. latency. E. none of the above.

A pathogen existing dormant in a person and periodically causing symptoms is termed D. latency.

ID50 is a measure of A. the amount of a substance needed to guarantee death in those who receive it. B. the amount of a substance needed to kill 50% of individuals who receive it. C. the amount of a substance needed to kill 50% of cells in an organism. D. the amount of a substance needed to infect 50% of individuals that receive it. E. none of the above.

ID50 is a measure of D. the amount of a substance needed to infect 50% of individuals that receive it.

Where do you intracellular parasites live? Where do you obligate parasites live?

In intracellular parasite lives within cells. And obligate parasite is unable to grow outside of a living host.

N meningitidis (other name, Who is affected, how was one infected, one of the symptoms)

Bacterial meningitis is it's more common name Asymptomatic presence in 40% of the population Transmitted through liquids like shared food or drink Because of the infection is rapid. Experience experience fever, sore throat, headache, vomiting, and convulsions

N gonorrheae (resistence, how one contracts it, immunity, gender differences)

Resist phagocytosis and can live inside ofNeutral files. Spread mostly by sexual contact. Very often it is painful for meals. Asymptomatic for females. No long-term immunity.

Resistance to ß-lactams most often occurs when bacteria A. develop thick cells walls that the antibiotic can't penetrate. B. produce large amounts of endotoxin. C. have already acquired resistance to other antibiotics. D. produce ß-lactamase.

Resistance to ß-lactams most often occurs when bacteria D. produce ß-lactamase.

S. Pneumoniae ( what it causes, resistance, where it is found)

Responsible for pneumonia sinusitis and meningitis Capsule inhibits phagocytosis Present in 75% of all healthy individuals in their upper respiratory

Describe S. Epidermidis (shape, gram category, where it is found, what it affects, what it is known to do)

Robust, salt tolerant, anaerobic, major component of skin flora and is usually not pathogenic. Became a problem for immune compromised individuals. Known to form biofilms on artificial surfaces like catheters.

S enterica (other name, affect on body, who it affects)

Salmonella. Grows well on eggs and poultry... and reptiles too Large doses lead to food poisoning. Intestinal epithelial cells phagocytize bacteria and can die. Can potentially pass into blood through this route. Usually runs it's course without severe complications and healthy adults.

Define selective media.

Selective media employ specific growth conditions (pH, salinity, minerals, etc.) that specific microbes are known to grow or not to grow in.

S. Pyogenes (its other name, sicknesses & way they avoid immune system)

Group A Strep Pharyngitis, scarlet fever, pyoderma, necrotizing fasciitis Capsule is resistant to phagocytosis, streptolysin to escape cells, erythrotoxin production (beta hemolytic)

S. Agalactiae (other name & Who does this affect)

Group B strep Primary concern is infections and newborns during birth. Many women carry the bacteria, but most births are fine. Testing is a precaution.

Enterococcus (other former name, gram, where it is found, resistance)

Group D strep (former name) Grow best in high salt concentrations that most strep cannot tolerate, Commonly found in the G.I. tract. Results in opportunistic infections at wound sites. Carry resistance to most antibiotics Carrie resistance genes in their plasmid

Do distant pathogen's have higher or lower ID50s?

Higher because they need to diffuse through the body

What are some ways that hosts can vary?

Hosts very widely in their susceptibility to different types of ways a parasite can enter host, multiply, and damaged tissues.

What does ID50 mean?

ID50 Means how much bacteria Hass to be there for 50% of the population to get sick.

The bacteria that infect macrophages of the lungs and result in large masses of bacterial and human cells forming in the lungs is A. Corynebacterium diptheriae. B. Clostridium botulinm. C. Clostridium tetani D. Mycobacterium tuberculosis

The bacteria that infect macrophages of the lungs and result in large masses of bacterial and human cells forming in the lungs is D. Mycobacterium tuberculosis

The causative agent in pertussis (whooping cough) is A. Neisseria meningitidis. B. Clostridium botulinm. C. Escherichia coli D. Salmonella enterica. E. None of the above.

The causative agent in pertussis (whooping cough) is E. None of the above.

What are transient microbes?

Transient microbes don't normally live on you. You can get them from touching an object, touching another person, we're going into a new environment. Transient microbes come and go.

T/F: A harmful bacteria could have harmless strains.

True

T/F: DNA sequencing is the only way to be absolutely certain that you can distinguish between different strains of the same species of bacteria.

True

T/F: Most pathogenic bacteria are opportunistic to some degree.

True

Describe pathologic.

pathologic is a state results when infection damages or disrupts tissues and organs. What this really means is that we don't notice infection until it causes symptoms

ß-lactam antibiotics represent a strong selection pressure for bacteria treated with them. What strategy do many of those bacteria evolve to combat the antibiotic?

ß-lactam antibiotics represent a strong selection pressure for bacteria treated with them. What strategy do many of those bacteria evolve to combat the antibiotic? Resistance through enzymatic degradation. ß-lactamase degrades the antibiotic, protecting the bacteria that express it, leading to the ß-latamase gene being favored by natural selection and increasing in frequency in bacterial populations.

. I showed you data suggesting that multiple sclerosis (MS) may be caused by A. untreated salmonella infections. B. endotoxins that result from e. coli infections. C. exotoxins produced by a specific strain of Clostriudium perifringens. D. excessive and repeated antiriot use to treat Staphylococcus aureus infections.

. I showed you data suggesting that multiple sclerosis (MS) may be caused by C. exotoxins produced by a specific strain of Clostriudium perifringens.

. In order to infect a tissue and multiply, parasites need a portal of entry. What are the most common portals, and how do host tissues try to combat infections there?

. In order to infect a tissue and multiply, parasites need a portal of entry. What are the most common portals, and how do host tissues try to combat infections there? The most common entry points are damaged skin (epidermis), GI epithelium, and respiratory epithelium. Skin is common because it has a high risk of being damaged, and the other two because they are thin, fragile epithelial layers that don't offer much protection. Host tissues try to avoid infection by having resident macrophages that permanently live in those tissues and screen for infection.

What is a chronic carrier?

A chronic carrier is a latent virus that stays with you even after you recover from your infection.

T/F: A media culture can be either selective or differential, but not both.

A media culture can be either selective or differential, but not both. False - they can be both.

A public health worker goes out into a community and hands out antibacterial hand sanitizer to randomly selected residents, and gives the other half a placebo with no antibiotic. They then mail questionnaires asking each person about recent illnesses. Is this an example of an epidemiological study? A. Yes. B. No. C. There is not enough information to tell.

A public health worker goes out into a community and hands out antibacterial hand sanitizer to randomly selected residents, and gives the other half a placebo with no antibiotic. They then mail questionnaires asking each person about recent illnesses. Is this an example of an epidemiological study? B. No.

What is a symbiosis?

A symbiosis is when a bacteria lives near or on someone. There are three different types of symbiosis.

What is a virulence factor?

A virulence factor is any characteristic or structure of the microbes that contributes to its virulence.

What thost factors influence susceptibility to infectious diseases?

Age, gender, medical interventions, mental and physical stress, nutrition, and resident Microbiota

What is an Aerobe?

An aerobe can use gaseous oxygen in its metabolism and possesses the enzyme needed to produce toxic oxygen products.

What is a facultative aerobe?

An aerobe that does not require oxygen for its metabolism and is capable of growth in the absence of it..

Describe the progression of an infection in Five stages.

An incubation period is where one is infected but has no symptoms. A prodromal stage is where one feels a little bit off but can't pinpoint what is wrong. The invasion. Is where symptoms worsen and the person feels bad. The stage of convalescence is where one starts to improve and eventually completely improves. This is also the stage where one could just potentially die. The next stage is only for some infections. Latency means that although the person has recovered, the pathogen stays inside of the person and periodically show symptoms.

When is bacteria called pathogenic?

Bacteria is called pathogenic when it causes symptoms. This means that tissues are damaged enough that you notice (pain, disruption, discomfort)

Bacteria may be killed by causing mutations in DNA through exposure to A. extreme heat. B. ultraviolet light. C. ß-lactam antibiotics. D. tetracycline antibiotics. E. all of the above.

Bacteria may be killed by causing mutations in DNA through exposure to B. ultraviolet light.

Blood agar is a medium on which nearly all pathogens can grow, but those that can lyse red blood cells produce a color change that can be observed by the experimenter. This is an example a medium that is A. selective B. differential C. selective and differential

Blood agar is a medium on which nearly all pathogens can grow, but those that can lyse red blood cells produce a color change that can be observed by the experimenter. This is an example a medium that is B. differential

Describe contamination.

Body surfaces and entrances are constantly exposed to microbes. This is called contamination.

T/F: Botulinum toxin causes passive paralysis by disrupting upper motor neurons in the cerebral cortex of the brain.

Botulinum toxin causes passive paralysis by disrupting upper motor neurons in the cerebral cortex of the brain. False, it disrupts neuromuscular junctions.

C. Botulinum (other name, what it does to body, symptoms, treatment)

Botulism Transmitted through ingestion or a wound Toxin produced inhibits acetylcholine release at NMJ Results in paralysis but can be corrected by anti-toxin

T/F: Broad spectrum antibiotics are less likely to cause side-effects than narrow spectrum antibiotics.

Broad spectrum antibiotics are less likely to cause side-effects than narrow spectrum antibiotics. False, reverse it.

Broad spectrum antibiotics present a risk to patients because they A. are often very toxic to host cells. B. are more likely to cause resistance. C. take a very long time to take effect. D. are more likely to kill normal microbiota along with the parasite.

Broad spectrum antibiotics present a risk to patients because they D. are more likely to kill normal microbiota along with the parasite.

Broad spectrum antibiotics should only be used when A. infections are identified early. B. infections are not identified early. C. a more narrow-spectrum antibiotic is not available. D. the identity of the bacteria causing the infection is precisely known.

Broad spectrum antibiotics should only be used when C. a more narrow-spectrum antibiotic is not available.

B. anthacis ( how you get it, what it does to your body, resistence)

Can we go through ingestion, inhalation, or cutaneous exposure. Capsule prevents phagocytosis Protein toxins are lethal and increase white blood cell lysis Responds well to antibiotics and vaccines

What are strict or obligate anaerobes?

Cannot tolerate any free oxygen in the immediate environment and will die if exposed to it

Why is researching resident microbes, especially in the G.I. tract, difficult?

Cause-and-effect is difficult to identify

C. Prefringens (symptoms, who it affects, what it does to body, treatment)

Causes cramps and diarrhea (food poisoning) Infects injury. Send on to kills tissue. It can lead to amputation. Sometimes treatment is oxygen exposure

Cell wall (peptidoglycan) synthesis is directly inhibited by A. tetracyclines. B. aminoglycosides. C. ß-lactams. D. macrolides. E. more than one of the above.

Cell wall (peptidoglycan) synthesis is directly inhibited by C. ß-lactams.

What is the downside of culturing?

Culturing takes time and delays treatment

What are resident microbes?

Resident microbes or on you and they're not leaving. Each site on a person has particular populations of normal non-pathogenic bacteria that are coming in can change over time.

Chemical agents that decrease the rate of bacterial reproduction A. bacteriocidal. B. bacteriostatic. C. fungicidal. D. fungistatic. E. none of the above.

Chemical agents that decrease the rate of bacterial reproduction B. bacteriostatic.

Clostridium difficile toxins A. bind directly to myelin and may be associated with MS. B. disrupts intestinal function by inactivating enzymes that control cytoskeletal formation in intestinal epithelial cells. C. directly inhibit the absorption of sodium in the intestine, leading to large amounts of water being drawn into the intestinal lumen. D. inactivate macrophages in the lungs, leading to widespread respiratory infections. E. none of the above.

Clostridium difficile toxins B. disrupts intestinal function by inactivating enzymes that control cytoskeletal formation in intestinal epithelial cells.

List the Graham negative Cocci and rods

Cocci: N meningitidis & N gonorrhoeae Rods: E. Coli

S. Mutans (where its found, what it causes, where it colonizes)

Common in throat and mouth Presence associated w dental cavities Colonizes in pits and crevices of teeth

C diphtheriae (where is it found, what it does to body, worse case scenario, treatment)

Commonly found in the general population. Opportunistic infections through the throat. Toxins inhibit ribosomes (translation), leading to local cell death. If toxins build up to high enough concentrations, can kill heart/nerve tissue Anti-toxin, vaccine (DPT) and antibiotics are all affective

Compare and contrast aminoglycosides, tetracylcines, and macrolides in their effects on ribosomal activity. All three classes of drug inhibit protein synthesis by interfering with bacterial ribosomes. Since ribosomes are large, compacted molecules, there are many different ways to interfere with their activity. Aminoglycosides accomplish this by slightly distorting the shape of the ribosome and causing translation errors. This causes bacteria to produce proteins with many errors, leaving them nonfunctional. Tetracyclines block tRNA binding like a competitive inhibitor would so translation is impossible. Macrolides binds ribosomes and prevents is from linking amino acids together.

Compare and contrast aminoglycosides, tetracylcines, and macrolides in their effects on ribosomal activity. All three classes of drug inhibit protein synthesis by interfering with bacterial ribosomes. Since ribosomes are large, compacted molecules, there are many different ways to interfere with their activity. Aminoglycosides accomplish this by slightly distorting the shape of the ribosome and causing translation errors. This causes bacteria to produce proteins with many errors, leaving them nonfunctional. Tetracyclines block tRNA binding like a competitive inhibitor would so translation is impossible. Macrolides binds ribosomes and prevents is from linking amino acids together.

Compare bactericidal agents to bacteriostatic agents.

Compare bactericidal agents to bacteriostatic agents. Bacteriostatic agents slow or stop bacterial growth, but do not actually kill cells. This means that when the bacteriostatic agent is removed, growth may start again. Bactericidal agents actually cause cell death.

Compare epidemiological studies to controlled scientific experiments. What kinds of questions does each answer?

Compare epidemiological studies to controlled scientific experiments. What kinds of questions does each answer? Epidemiology involves collecting information about an existing population and their behavior. This is essentially data collection (usually through surveys or field study), and those data are then analyzed for association with specific diseases or outcomes. A controlled experiment involves manipulating a variable, so you need to have an experimental and a control condition, and then measure the difference in outcome between the two groups. Experiments like this are ideal, but are often too expensive or unethical to perform, because they would involve giving people diseases on purpose.

Contamination and infection sit on a continuum. Explain why they are not the same thing, and what variables affect the transition from exposure to an infection.

Contamination and infection sit on a continuum. Explain why they are not the same thing, and what variables affect the transition from exposure to an infection. Just because a microbe is present on/in a person (contamination), does not mean that it will begin to multiply and eventually cause symptoms. The variables that affect the position on this continue are the virulence of the pathogen, and immune system of the host (affected by age, sleep, nutrition, genetics, etc...)

Describe infection.

Contamination leads to infection. Infection is where pathogenic organisms penetrate the host defenses, enter the tissues, and multiply. How fast they multiply is what matters most.

DNA sequencing is the most precise way to identify potentially harmful strains of microorganisms because A. virulence factors cause changes in DNA that affect how quickly bacteria spread. B. nearly all virulence factors are proteins, which must be encoded by DNA. C. DNA sequence determine the kind of cell wall a bacterium produces, and cells wall type is what determines how pathogenic the strain is. D. DNA sequence determine shape a bacterium is, and cell shape is what determines how pathogenic the strain is. E. none of the above.

DNA sequencing is the most precise way to identify potentially harmful strains of microorganisms because B. nearly all virulence factors are proteins, which must be encoded by DNA.

What are four portals of entries that microbes use to enter The tissues of the body?

Damaged skin, perforations in the G.I. epithelium, respiratory epithelium (very fragile and susceptible - alveoli) ,urogenital openings

Define ID50 and LD50. Are pathogens with higher or lower IDs more likely to cause infections?

Define ID50 and LD50. Are pathogens with higher or lower IDs more likely to cause infections? These values represent the numbers of cells (or viruses) required to infect/kill 50% of individuals exposed to them. Assuming that the number of cells/viruses you are exposed to is random, pathogens with lower ID/LD values are more infectious and lethal because there is a greater probability to being exposed to an infectious or lethal dose

Define latency, and give at least one example of a pathogen that demonstrates it.

Define latency, and give at least one example of a pathogen that demonstrates it. Latency is when a microbe remains in the host after the symptoms of an infection have passed. There is a period of time when the symptoms are absent, but then that pathogen can later reemerge to start dividing again and cause another round of symptoms. A well-known example of this is herpes simplex viruses causing recurring cold sores.

Define therapeutic index, and be able to calculate it if given an example.

Define therapeutic index, and be able to calculate it if given an example. Therapeutic index is the ratio of human toxicity : effectiveness. This is telling you that the actual amount of drug given is not important in itself, but the amount relative to the toxic dose. Having a very large TI gives you flexibility in giving a high enough dose to treat the infection without concern about over-dosing and harming the patient.

Describe common applications for UV light and desiccation as a means of sterilization.

Describe common applications for UV light and desiccation as a means of sterilization. UV light kills bacteria by damaging DNA, and works well for sterilizing whole rooms because the reaches small crevices and objects. It is also good for sterilizing food because there is no chemical residue left on the food when it is consumed.

Describe the four ways that we discussed to identify and name pathogens, and describe the benefits and downsides of each.

Describe the four ways that we discussed to identify and name pathogens, and describe the benefits and downsides of each. Selective and differential media are used to screen for the ability of an unknown pathogen to grow in a specific set of conditions (high salt contraption, acidic pH, etc...) or use markers that allow you to observe a change (usually a color change) if specific nutrients are able to be used. As long as you know which pathogens can/can't growth in each set of conditions, selective and differential media can be used to cross of possibilities of what a pathogen may be by prices of elimination. This is a relatively easy and cheap method, but it is not always accurate, and cannot distinguish different strains from each other within one species. DNA sequencing is exactly what is sounds like - you get the sequence of the bacterial genome (ACTG...). This by far the most precise way to identify bacteria because you get a complete picture of every gene it contains. The only downside is that it is expensive to do, but this is changing as sequencing becomes cheaper over time. Molecular cytology and mass spectrometry both involve identifying specific molecules (usually proteins) found in or an a bacterial cell. Since virulence factors are usually proteins, this is an effective way to detect them. Molecular cytology works by using a marker (often an antibody) that a researcher has found which sticks to a specific virulence factor on the pathogen, and you simply apply the marker and see if it sticks. This is can be difficult to develop in the first place, but easy to use once is has been developed. Mass spectrometry uses a device that measures the mass and charge of every molecule found inside a bacterial samples. Each molecule shows up as an individual peak on the graph that the mass spec sensor puts out. All outhouse peaks combine to give each pathogen a unique "signature" that can be used to identify it from an unknown sample in the future. Mass spec seems to be fairly accurate in identifying pathogens, and the only downside is that most hospitals don't have the equipment or a technician trained to use it (they are usually found only in research labs).

Describe the mechanism of action for ß-lactams, and why it such a good (specific) target for killing bacteria.

Describe the mechanism of action for ß-lactams, and why it such a good (specific) target for killing bacteria. ß-lactams inhibit peptidoglycan synthesis, which is needed for cell wall formation. They can be highly specific (high TI) because cell wall synthesis occurs exclusively in bacteria, and peptidoglycan is not a molecule that is even endogenously produced in humans, so toxicity is very low.

Define differential media.

Differential media use a visual marker (often a color change) to differentiate between different species.

What type of differences are the majority of differences between strains of bacteria?

Genetic

Distinguish between resident, transient, and opportunistic microbes.

Distinguish between resident, transient, and opportunistic microbes. Resident microbes get their name because they take up semi-permanent residence in/on a particular tissue. This means that they are not pathogenic, and may often even be beneficial to the host. Transient microbes are those that people come into contact with (through touching objects or other people), but do not colonize and become permanent residents. This also means that they are nonpathogenic. Opportunists are microorganisms that can be harmless at times, but may also become pathogenic when given the opportunity. Whether an opportunist becomes pathogenic or not partly depends on the immune status of the host that they are infecting.

What are aerotolerant anaerobes?

Do not utilize oxygen but consider Vive and grow to a limited extent in its presence

Endotoxins are produced by A. Gram negative bacteria. B. Gram positive bacteria. C. both Gram positive and negative bacteria.

Endotoxins are produced by A. Gram negative bacteria.

T/F:Epidemiological studies can never directly prove a cause-effect relationship between two variables.

Epidemiological studies can never directly prove a cause-effect relationship between two variables. True

T/F: Epsilon toxin has been conclusively shown to bind to and destroy myelin tissue in humans.

Epsilon toxin has been conclusively shown to bind to and destroy myelin tissue in humans. False, there is an association, but no hard evidence of cause and effect.

Exotoxins are produced by A. Gram negative bacteria and result in systemic inflammation. B. Gram positive and Gram negative bacteria and result in systemic inflammation. C. Gram negative bacteria and target specific cells within a tissue. D. Gram positive and Gram negative bacteria and target specific cells within a tissue.

Exotoxins are produced by D. Gram positive and Gram negative bacteria and target specific cells within a tissue.

Explain why ribosomal inhibitors are usually better targets for antibiotic drugs than DNA/ RNA polymerases.

Explain why ribosomal inhibitors are usually better targets for antibiotic drugs than DNA/ RNA polymerases. Bacterial ribosomes are different enough in structure compared to human ribosomes that drugs are more likely to be specific (high TI). Polymerases are relatively similar between bacteria and human, so drugs targeting those enzymes are more likely to cross-react with human polymerases (low TI).

T/F: An increase in ID50 for a pathogen would likely lead to greater virulence.

False, An decrease in ID50 for a pathogen would likely lead to greater virulence.

T/F: Molecular cytology and mass spectrometry look for a DNA sequence.

False, Molecular cytology and Miss Beck trauma do you look for a protein not A DNA sequence.

T/F: one either has an infection or not.

False, and infection is not all or nothing. Contamination, infection, and pathologic states are a continuum that the body may stop at any point without you even noticing

T/F: Molecular cytology can identify bacteria by detecting specific genes within their chromosome.

False. Molecular cytology can identify bacteria by detecting specific proteins on their surface.

E coli (where it is found, what it primary causes, what pathogenic strains produce)

Found in the G.I. tract of asymptomatic individuals, also most common cause of urinary tract infection. Pathogenic strains produce toxins.

What is a manitol salt agar?

It is a culture that is both selective and differential. It is used in an attempt of in identifying virulence Factors. On one side there is a high salt content that allows only salt tolerant species to grow. The medium changes color if the peach becomes acidic. If the culture turns yellow, it means that the microbe can ferment manitol.

What are the pros and cons of testing genetic sequencing to identify virulence factors?

It is expensive but fast and very precise for characterizing the pathogen as specifically as possible. Remember that virulence factors are almost always proteins, and therefore coded for by genes in DNA

What are some plus sides to using mass spectrometry?

It is very fast and precise but expensive so only large research hospitals use it.

What are the pros and cons of mass spectrometry?

It requires expensive equipment and training, very fast and accurate. New methods are even capable of detecting specific strains.

What organ/tissue was thought to be sterile?

It was thought that the uterus was sterile during pregnancy. However, your pathogens inside of the uterus during gestation. This helps to develop the babies immune system.

What is the goal of PCR amplification of DNA?

It's goals to amplify small amount of DNA into a very large amount. PCR uses DNA polymerase (which is the enzyme that copies DNA during the S phase of cell division in eukaryotes). It tricks DNA polymerase into replicating DNA in a test tube.

Therapeutic index formula

LD50 / ED50 (median lethal dose / median effective dose)

What is an anaerobe?

Lacks the metabolic systems for using oxygen and respiration

What is latency?

Latency is a dormant state.

What is LD?

Lethal dose

Do local pathogen's have higher or lower ID50s?

Lower

Mass spectrometry can be used to A. identify pathogens by sequencing their DNA. B. identify pathogens by generating a unique signature based on proteins the pathogen produces. C. inactivate virulence factors by removing them fro the blood. D. inactivate virulence factors by deleting them from a bacterial genome.

Mass spectrometry can be used to B. identify pathogens by generating a unique signature based on proteins the pathogen produces.

S sonnei

Most common species found in the US. Transmitted fecal oral poor hygiene. Most common in children.

What are the three types of symbiosis?

Mutualism, commensalism, and parasitism Mutualism is when organisms live in an obligatory that mutually beneficial relationship Commensalism the member called the commensal Receives benefits, while it's coin have a tent is neither harmed nor benefited Parasitism a relationship in which the host organism provides the parasitic microbe with nutrients and a habitat

C. Difficile (virulence, what it does to body)

Normal G.I. species that can over grow after broad-spectrum anabiotic treatment and damage G.I. epithelium

Not all individual cells in a bacterial population are equally virulent. Explain why this variability exists.

Not all individual cells in a bacterial population are equally virulent. Explain why this variability exists. Virulence factors are genetically coded, and variation in bacterial genetics leads to variation in virulence. Two strains of a bacterial species can be identical except for a single virulence factor, leaving one strain harmed and the other very dangerous. All of the virulence factors we discussed in class are examples of this.

How does one experiment with epidemiology?

One cannot really experiment with epidemiology. One needs to interview and survey people and see if they got sick. One cannot simply experiment by giving someone HIV. It is not ethical.

Describe S. areus (type of pathogen, who it affects more, what it targets, how it is spread, what it produces, and prevention)

Opportunistic pathogen carried by 20% of the population and that is much higher in hospital staff. Frequently become pathogenic residents of skin. respiratory tract, G.I. tract, heart, lungs, and bone. Disease is spread by direct contact. Handwashing, hospital surfaces. Produces coagulase (blood clotting) ans other enterotoxins. Antibiotic resistance is a big concern. Most are penicillin resistant. MRSA also becoming more common.

What are opportunist microbes?

Opportunists are in the border between normal and pathogenic. They are species that cause disease when given opportunities during stresses. For example, for example, stomach ulcers occur when stress allows a bacteria to grow.

Why would one want to use PCR amplification of DNA?

PCR amplification of DNA amplifies a small amount of DNA into a very large amount. Large amounts of DNA can be used for performing experiments and DNA sequencing

What are some ways that parasites vary?

Parasites very widely in their ability to enter host, multiply, and damage tissues.

Pathogens that are present in many people but do not always cause symptoms in all individuals are termed A. opportunistic. B. recurring. C. latent. D. convalescent.

Pathogens that are present in many people but do not always cause symptoms in all individuals are termed A. opportunistic.

T/F: Polymerase inhibitors have a poor therapeutic index because they are ineffective at killing bacteria.

Polymerase inhibitors have a poor therapeutic index because they are ineffective at killing bacteria. False - they are good at killing bacteria, but also often toxic to humans.

Poor sleep quality has been shown to A. directly cause increased susceptibility to developing symptoms when exposed to the common cold. B. be associated with increased susceptibility to developing symptoms when exposed to the common cold. C. alter virulence factors in the virus that cases the common cold. D. increase a person's risk of being exposed to the virus that causes the common cold.

Poor sleep quality has been shown to B. be associated with increased susceptibility to developing symptoms when exposed to the common cold.

T/F: Possessing a gene that codes for an enzyme that can metabolize an antibiotic is the only way for a bacterium to become resistant to that antibiotic.

Possessing a gene that codes for an enzyme that can metabolize an antibiotic is the only way for a bacterium to become resistant to that antibiotic. False, the bacterium could not possess the target enzyme that the drug disrupts.

What is the job of a resident macrophage?

Resident macrophages fight off pathogens and reside in most tissues. They screen for infection locally. At one point they were white blood cells that made their way to the tissues they reside in.

What is a sequelae?

Tissues never recover after a pathogen has gone

M tiberculosis (what does their growth resemble, where is the primary infection, who is affected, transmission)

Some species appear to grow like mold at times Primary infection is in the macrophages of the lungs. Sales first or ingested by macrophages in alveoli but survive and multiply. Results in formation of a tubercle by fibroblasts to isolate the infection. Common problem worldwide. More than 2 billion people currently infected, but only about 5% develop symptoms. Transmitted through small mucus droplets during cough/sneeze.

What makes some strains of bacteria harmful and others not?

Subtle genetic variants can make it so that some strains of the same species can I have small differences that are hard to detect. Their virulences can differ.

Summarize the evidence suggesting that exposure to microbes may be a good thing from a health standpoint.

Summarize the evidence suggesting that exposure to microbes may be a good thing from a health standpoint. Some epidemiological evidence suggests that children raised in less cleanly environments are less likely to develop autoimmune disorders and allergies. This was done by determine rates of those diseases in children raised in urban environments vs. those raised in farming communities. The evidence is entirely based on association and no real experiment was done, so the evidence is not conclusive.

Temperature is a good method for sterilizing tools, waste, experimental reagents, etc... What are the limitations of temperature sterilization?

Temperature is a good method for sterilizing tools, waste, experimental reagents, etc... What are the limitations of temperature sterilization? Heat sterilization is very effective because it dentures protein so well. The obvious problem is that many things (including humans) are also damaged by heat, so it is only a viable method for metal, glass, and trash/waste.

C. Tetani (other name

Tetanus Tightness toxin prevents inhibition of skeletal muscle, leads to spastic paralysis Vaccine is affective but needs a booster every 10 years Natural immunity is rare because if you survive the infection

T/F: Tetnospasmin causes muscle spasms by directly increasing calcium levels inside muscle tissue.

Tetnospasmin causes muscle spasms by directly increasing calcium levels inside muscle tissue. False - it blocks inhibitory neurotransmitters in the spinal cord.

The ability of a microbe to infect a person and cause disease is termed its A. virulence. B. latency. C. therapeutic index. D. viability. E. none of the above.

The ability of a microbe to infect a person and cause disease is termed its A. virulence.

Listeria monocytogenes (what does it cause, who does it affect, who does it especially effect, how is it transmitted, resistence)

The causative agent leading to listeriosis. One of the leading causes of death from foodborne illness especially among the very young and the old. Also a significant risk during pregnancy, potentially causing uterine infections in spontaneous abortion Can cause widespread infection leading to septicemia meningitis and pneumonia. Most commonly transmitted through unpasteurized dairy and undercooked meat. Avoids phagocytosis through a very lens factor that is activated at acidic pH to escape lysosomes/Phagosomes

T/F: The composition of food in diet is the best predictor of which bacterial species will be present in the digestive tract.

The composition of food in diet is the best predictor of which bacterial species will be present in the digestive tract. True

The composition of human gut bacterial populations has been shown to be influenced by which of the following factors? A. the use of broad spectrum antibiotics. B. gender. C. age. D. diet. E. more than one of the above.

The composition of human gut bacterial populations has been shown to be influenced by which of the following factors? E. more than one of the above. A. the use of broad spectrum antibiotics. C. age. D. diet.

What are the first and second steps in microscopy?

The first step is to identify shape in gram status. The second step is culturing (this takes time).

What is the first step in identifying virulence factors?

The first step is to use a Gram stain. Gram stains are cheap. The second step is selective and differential Media. In other words it answers the question what surfaces does it grow on.

What is the goal of mass spectrometry (MS)?

The goal is to identify specific set of molecules (usually proteins) from an unknown sample that give a specific signature.

What is the goal of molecular cytology/anti-body labeling? How do they do it?

The goal is to observe the location of a protein in or on a cell. This process uses antibodies against the proteins that are linked to a fluorescent marker. This can be an effective way to identify the presence of specific virulence factors.

What is an obligate aerobe?

The microbe cannot grow without oxygen

What is the goal of selective media and differential media?

The use of selective media and differential media is done with the goal of culturing the microbe on a series of media and eliminate possibilities until a single species can be assumed with some degree of confidence.

What are the pros and cons of using selective and differential media when trying to identify virulence Factors?

These tests are cheap and easy, but not affective for identifying specific strains.

What are the pros and cons of using a Gram stain?

They are cheap and easy but are slow.

Why aren't the newer methods of culturing used more frequently?

They are more expensive

How does PCR Amplification of DNA work?

They individually label for nuclear tides that they run on a gel. They apply an electrical charge. The smaller molecules run fast towards the bottom of the gel. The large molecules run slowly. On a graph, waves represent the gelling results and give a DNA sequence.

Describe the process that takes place during mass spectrometry.

They take A bacterial culture and put it into a device. A laser is used to ionized a sample or another words vaporize it. The smashed pieces flying to the vacuumed tube. There is a magnet that polls in negative pieces to one side and positive pieces to another side of the magnet. The heavier molecules don't get as far. Lighter ones go the furthest. There is a detection sensor at the bottom.

What is staphylococci?

This is a major category of pathogens that includes S. Epidermidis and S aureus

What is m:z?

This is the notation for the ratio of mass to charge that every individual molecule has. This ratio doesn't tell you much alone unless it is compared to other mass to charge ratios for other bacteria in a database. It is almost 100% accurate.

T/F: The more bacteria/viruses one is exposed to, the more likely one will become infected or ill.

True.

T/F parasites do not attack the whole body but rather one specific thing.

True. Because of the coded proteins, the parasites don't attack the whole body but rather one specific thing. They are specialized. For example, E. coli affects the G.I. and urinary tract. Hepatitis affect the liver.

S. Typhi (what is it where can you get it)

Typhoid fever spread through contaminated water supply

What is molecular cytology?

Using antibodies and other stains to identify specific proteins on material services. Effective for detecting specific virulence factors that are already suspected.

Very early (and sometimes non-specific) symptoms of an infection begin during which phase of an infection? A. Incubation B. Prodromal C. Invasive D. Convalescent

Very early (and sometimes non-specific) symptoms of an infection begin during which phase of an infection? B. Prodromal

Define the term virulence.

Virulence is the degree of how harmful and pathogenic a parasite is. It is the measure of how bad the parasite is.

T/F: Viruses are more likely to be latent than bacteria because they replicate more slowly.

Viruses are more likely to be latent than bacteria because they replicate more slowly. False. They are more likely to be latent because they easily become dormant due to they lack of metabolism.

What does the term "broad spectrum" mean in the context of antibiotics? In what situations should broad vs narrow spectrum antibiotics be selected for treatment?

What does the term "broad spectrum" mean in the context of antibiotics? In what situations should broad vs narrow spectrum antibiotics be selected for treatment? Broad spectrum antibiotics are those that target a wide variety of bacteria, whereas narrow spectrum are more selective in which species are affected. If the specific pathogen has been identified and an effective narrow-spectrum antibiotic is available, it is the best option. If the pathogen is unknown, it is being used as a precaution, or a narrow spectrum option is not available.

What is a selection pressure? Be able to give examples.

What is a selection pressure? Be able to give examples. A selection pressure is any environmental conditions that makes survival and/or reproduction difficult for a species. This pressure is what makes variable survival possible. Examples can be any environmental change - temperature, pH, salinity, etc... Medicines (antibiotics mainly) are also potent selection pressures for microbes that cause disease

What is a virulence factor, and what kinds of molecules are they?

What is a virulence factor, and what kinds of molecules are they? Virulence factors are any characteristic or structure of a microbe that contributes to its virulence (pathogenicity). Because genetic material (DNA) is all that one cell can pass on to future generations, and the only thing that DNA codes for is protein, nearly all virulence factors are proteins. This makes them especially good at causing damage in host tissues, since they also mostly comprise protein.

Which of the following categories of antimicrobials interfere with protein synthesis? A. tetracyclines B. aminoglycosides C. ß-lactam antibiotics D. Sulfonamides E. more than one of the above.

Which of the following categories of antimicrobials interfere with protein synthesis? E. more than one of the above. A. tetracyclines B. aminoglycosides

Which of the following infections produces intense, involuntary muscle spasms? A. Botulism. B. Tetanus. C. MRSA D. Plague. E. none of the above.

Which of the following infections produces intense, involuntary muscle spasms? B. Tetanus.

Why is naming a specific bacterial pathogen difficult, and why is being precise with naming important?

Why is naming a specific bacterial pathogen difficult, and why is being precise with naming important? Naming a bacterial species is easy, but there are many different subtle genetic variants (serotypes and strains) within any given species. Coming up with a new name for every genetic variant is difficult, and keeping track of all of them even more difficult. However, doing this is important because those subtle genetic variations from one strain to another may lead to very large differences in virulence. This is why being precise with naming matters - you need to be sure that you know exactly what pathogen you are fighting.

You saw in lab the individual antibiotics worked well for some bacteria, but poorly in other species. Explain why this general pattern occurs.

You saw in lab the individual antibiotics worked well for some bacteria, but poorly in other species. Explain why this general pattern occurs. Antibiotics are highly specific. Usually this involves blocking a specific enzyme/reaction. If a particular bacterium does not have the enzyme being targeted, the drug will have minimal effect.

Where does an ectoparasite live? Where does an Endoparasite live?

ectoparasites live on the body and an Endoparasite lives in organs and tissues