Microbiology: Exam 3

Define and give an example of a symptom.

It is what is felt by a patient as the result of a disease/body function response; an example would be pain

Define what a syndrome is.

It is determined by both the signs and the symptoms and often confirmed through a lab test

Define and give an example of a communicable disease.

It is spread from one hot to another; examples include influenza and chicken pox

Define and give an example of a noncommunicable disease.

It is not spread from one to another; an example would be tetanus

Define descriptive epidemiology.

It is the collection and analysis of data

Define analytical epidemiology

It is the analysis of a specific disease and determines the probable cause.

Define experimental epidemiology

It is a study that includes a hypothesis and controlled experiments/clinical trial

What important advancement did John Snow achieve and what category of epidemiology does his work fall under?

He mapped the occurence of cholera in London and this was an example of ...

What important advancement did Ignaz Semmelweis achieve and what category of epidemiology does his work fall under?

He tested that improved sterilization of doctor's hands prior to exams would reduce the death rate afterword and this was an example of ...

What important advancement did Florence Nightingale achieve and what category of epidemiology does his work fall under?

He noticed that individuals with a lower incidence of typhus were treated in hospitals with better sanitation

Define prevalence and what it entails.

It is the number of new and existing cases at a particular time and it tells us how long a disease can persist in a population

Define incidence and what it entails.

It is the number of new cases of a disease during a particular time and it tells us about the spread of the disease

What is the difference between mortality and morbidity?

Mortality is the number of deaths per population whereas morbidity is the incidence per population.

Define and give an example of an endemic.

It is a disease that is constantly present at a low population; the common cold is an example

Define and give an example of an epidemic.

It is a disease that infects an unusually high number of individuals in a population; an example would be influenza

Define a pandemic.

It is a type of epidemic and it is usually worldwide

Are human host-to-human host epidemic cases reported over a long or short period of time?

Longer period of time

Define and give an example of common-source epidemics.

It originates from a contaminated common source such as food or water where many people become sick at the same time; an example would be cholera

Define latent disease.

It is a disease where the causative agent is inactive for a time but then activates and produces symptoms

Describe the relationship between the pathogen and the host in chronic disease and give an example.

The pathogen will only take what it needs, inflicts minimal harm to the host, and is likely to reoccur for long periods of time; some examples would be tuberculosis and mononucleosis

What is a focal infection?

It is a systemic infection that began as a local infection

What is sepsis?

It is the spread of microbes from a site of infection

What is septicemia?

It is blood poisoning/the growth of bacteria in the blood

What are the six steps of disease progression in order?

Infection, incubation, prodromal period, acute period, decline period, and convalescent period.

What is an HAI?

It is a healthcare-associated infection that is acquired while receiving treatment in a healthcare facility; also known as nosocomial infection

How many patients are affected by HAI's and how many die?

About 1 in 25 hospital patients are affected; 2 million per year are infected, and there are over 70,000 deaths

Which microorganisms that are involved in HAI's are the most resistant to antibiotics?

Staphylococcus aureus and Escherichia coli

Define a reservoir.

It is a habitat of an infectious agent where the agent CAN survive but may not be located there

What is a carrier?

It is a living organism with a reproducing pathogen inside them and being shed into the environment

What are examples of a direct person to person transmission diseases?

Rhinovirus, influenza, STD's and they are transmitted through touching, kissing, etc.

Define and give examples of droplet transmission.

When microbes spread from respiratory droplets over short distances (think puff daddy); examples include rhinovirus and influenza

What are fomites?

These are inanimate contaminated objects; dishes, eating, toys, toothbrushes, etc.

Define airborne transmission.

When infectious agents begin in respiratory droplets but they are dispersed via dust

Define and give an example of a vector.

It is a living organism that transfers a pathogen; examples include arthropods (fleas) and vertebrates (rodents)

Define mechanical transmission and give an example.

This is an example of passive transport and an example would be an arthropod carrying a pathogen on its feet and touching some food and when a human eats the food they get sick.

Define biological transmission and give an example.

This is an example of active transport and an example would be an arthropod biting a person while sucking their blood picking up some pathogen and passing it to another host when it bites them.

Define pathogenicity.

It is the potential ability to cause disease in a host

Define virulence.

It is the ability of a pathogen to infect or damage a host

What is ID50?

It is the number of microbes/viruses required to produce an infection in
50% of healthy humans

What does a low ID50 entail?

The easier it is for an infection to
occur.

Which type of bacteria make endospores?

Gram-positive bacteria.

Define adhesion/adherence.

It is the process of pathogens attaching to
host cells at the portal of entry

Where are adhesins/ligands typically located?

They are found on a pathogen's glycocalyx which is the polysaccharide layer on the outside of the cell wall; can also be on the pili or fimbriae

What is a way a pathogen can protect itself from phagocytosis that involves forming a layer?

The pathogen is able to release glycocalyx to form a capsule around the cell wall in order to increase survival

Which diseases' pathogens are able to form a capsule?

Pneumonia, anthrax, and the plague

Which enzyme is involved in phagocytosis and how does it work?

The lysozyme is able to break down the peptidoglycan layer and it is found in the lysosome.

How can a pathogen use clots to protect itself?

Bacteria will produce coagulase which converts fibrinogen into fibrin to make a clot and when they are done they will release kinase to digest the fibrin clots.

Which pathogen uses coagulases?

Staphylococcus

Which pathogen will release from a clot by using kinases?

Streptococcus

What can microbes do to avoid being inactivated by an antibody?

They are able to alter their surface antigens thus making antibodies unable to bind.

How can bacteria directly affect the human host once they enter the host cell?

It uses the host cell nutrients, excreting waste products, and quickly growing in size resulting in cell rupture.

What are siderophores?

They are microbial proteins secreted into the environment that bind iron more tightly than host cells

Why are siderophores bad for the host cell?

Iron will bind to the siderophore receptors which means the host cell is unable to uptake it; iron is required for most pathogenic bacteria

Which type of bacteria create exotoxins?

Gram-positive and gram-negative bacteria

Which type of bacteria create endotoxins?

Gram-negative bacteria

Where are endotoxins found?

In the lipopolysaccharide layer of a gram-negative cell

Define LD50.

It is the number of toxins required to kill 50% of healthy humans.

What does a lower LD50 entail?

The lower the number, the higher the potency of the toxin

What are toxoids?

They are inactivated exotoxins used in vaccines

What are antitoxins?

They are antibodies against specific exotoxins

Give an example of an A-B toxin inhibit the host cell's protein synthesis.

Diphtheria toxins

Give an example of an A-B toxin that damages the host DNA which cause mutations and lead to cancer.

Genotoxins

What is the mechanism of botulism?

The neurotoxin prevents transmission of nerve impulses; flaccid paralysis results

What is the mechanism of tetanus?

The neurotoxin blocks nerve impulses to the muscle relaxation pathway; results in uncontrollable muscle contractions

What is the mechanism of anthrax?

Two A components enter the cell via the same B. The A proteins cause shock and reduce the immune response.

Which type of bacteria has an O-antigen which comes in contact with the environment?

Gram negative.

What are the advantages of having an O-antigen?

It varies among bacterial strains which ensures bacteria are unique.

What are the disadvantages of having an O-antigen?

It becomes a target for the human immune response and it is a location for viral attachment.

What is lipid A capable of doing?

It can release endotoxins which negatively affect humans.

What is Lipid A?

It is a portion of the lipopolysaccharide that secretes toxins when the cell wall lyses or during binary fission.

How does the body develop a fever?

When endotoxins are released the macrophage is able to produce cytokines which travel to the hypothalamus.

Define innate immunity.

Defenses that a human obtains from birth.

Define adaptive immunity.

Responses to a specific causative agent (after innate immunity has been breeched)

In terms of the immune system, what is the first line of defense?

They are physical factors like skin and mucous membranes and chemical factors such as perspiration, lysozymes, earwax, saliva, and gastric juice.

In terms of the immune system, what is the second line of defense?

Natural killer cells, phagocytes, inflammation, and fever.

How does innate immunity work?

When toll-like receptors found on the macrophage/dendritic cells attach to the pathogen-associated molecular patterns

What happens when TLRs come in contact with PAMPs?

Cytokines are released.

What is the epidermis made of?

It is made of tightly packed epithelial cells containing keratin.

What is the dermis and what does it do?

It is the inner portion made of connective tissue and it provides support and aid in tissue repair.

In terms of skin, what is a way to inhibit microbial growth?

Shedding the top layer of the skin/dryness of the skin

How many skin cells does the human shed everyday?

40-50 thousand skin cells

What is the mucous membrane made of?

It consists of an epithelial layer and underlying connective tissue

What is ciliary escalator and what does it do?

They are mucous coated hairs and microbes trapped in mucus are transported away from the lungs

How do lysozymes lyse cells?

By breaking down the peptidoglycan in the cell walls

What type of pH level inhibits microbial growth and give four examples of what substances have these pHs?

A lower pH stops the growth; gastric juice, vaginal secretions, ear wax, and urine.

What does a high white blood cell count tell us?

There may be a bacterial infection, autoimmune disease, or side effects of medicine.

What does a low white blood cell count tell us?

There may be a viral infection, pneumonia, autoimmune disease, or cancer

What is important of granulocytes?

They contain large granules that can be viewed with a light microscope after staining.

What is important of agranulocytes?

The granules are not visible with a light microscope after staining.

What is a neutrophil?

It is a granulocyte that kills and digests pathogens (phagocyte)

What is an eosinophil?

It is a granulocyte that produces toxic proteins that target parasites (phagocyte)

What is a basophil?

It is a granulocyte that communicates with other cells when pathogens are in the blood by releasing histamines.

What is a monocyte?

It is an agranulocyte that breaks down bacteria and matures into a macrophage

What is a dendritic cell?

It is an agranulocyte that is phagocytic and is found in mucous membranes.

What is a lymphocyte?

It is an agranulocyte that is involved in adaptive immunity/creates antibodies.

Define chemotaxis.

It is the first step of phagocytosis where chemical signals attract phagocytes to the microbes.

What are the three stages of inflammation?

Vasodilation, phagocytosis, and tissue repair.

What is the difference between acute and chronic inflammation?

Symptoms will develop rapidly and last a short time for acute whereas for chronic the symptoms develop slower and last longer.

What is the purpose of vasodilation?

It increases permeability in the blood vessels therefore the host defensive substances can now pass from the blood into the blood vessels of the affected area.

What is margination?

When phagocytes stick to blood vessels in response to cytokines at the site of inflammation