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Please place the steps in the correct order to assess your knowledge of Koch's postulates.
the microorganism must be present in every case of the disease, but not in healthy hosts
the microorganism must be grown in pure culture from diseased hosts
the same disease must be produced when a pure culture of the microorganism is introduced into susceptible hosts
the same micro organism must be recovered from the experimentally infected host
Please place the four steps of Koch's postulates in the correct order as they would normally be applied.
Find evidence that a particular microbe is present in every case of a particular disease.
Isolate the suspected microbe from an infected host and cultivate it in pure culture in the laboratory.
Inoculate a susceptible healthy subject with the pure culture of the potential pathogen and observe the resulting disease.
Reisolate the disease agent from the test subject which now shows signs of disease.
Which of the following are limitations of Koch's postulates?
The suspected pathogen cannot be cultured in the laboratory.
The suspected pathogen cannot be cultured in the laboratory.
The disease is polymicrobial, caused by more than one pathogen.
Acute illnesses
incubation period- illness- convalescence
Chronic illness
incubation period- illness (long lasting)
Latent illness
incubation period- illness- convalescence-latency - recurrence
In this relationship, one organism benefits and the other remains unharmed.
commensalism
In this relationship, one organism benefits while the other is harmed.
parasitism
In this relationship, both organisms benefit.
mutualism
Identify all the beneficial characteristics of normal microbiota from the choices below
Cover binding sites that otherwise could be used for attachment by pathogens.
Consume nutrients that otherwise could be used by pathogens.
Produce compounds that could either be toxic for pathogens and/or useful for us.
People considered obese have a different normal flora in the gastrointestinal tract compared to people who are considered lean.
True
Which molecule is responsible for displaying fragments of proteins made within the cell and would therefore be useful in detecting a virally infected cell?
MHC
This fungus grows on grains and nuts and produces aflatoxin. Ingestion of this toxin can damage the liver and increases the risk of liver cancer. Fungal spores and other products can cause hypersensitivities in some people.
Aspergillus flavus
The fungus causes disease in immunocompromised hosts, such as AIDS patients. It generally infects the mucous membranes, causing thrush (an infection of the throat and mouth) or vulvovaginitis.
Candida Albicans
Consider the figure of a lichen. In this symbiotic relationship, the photosynthetic alga provides the fungus with organic nutrients. The fungus provides the alga with water and protection. Which of the normal microbiota relationships described below is most similar to this association?
Mutualism - intestinal bacteria providing host with vitamins E and K.
Which of the following statements about normal microbiota is FALSE?
The variety of species within the normal microbiota phyla in the intestinal tract remains constant throughout a person's life.
Place the statements about the progression of a disease into the correct order, from start to finish.
Incubation period - time between entry of a microbe into a host and the start of signs and symptoms.
Prodromal period - period of early, vague symptoms such as malaise.
Illness phase - infected person experiences signs and symptoms of the disease.
Convalescence phase - period during which signs and symptoms disappear and the person recovers.
Which of the following statements indicates the significance of Koch's work?
His postulates are used to show that specific microorganisms can cause specific diseases.
signs
Fever Swelling Rash Pus Formation
Symptom
Pain Nausea Headache Malaise
A patient is suffering from a severe case of influenza, caused by influenza virus. He takes analgesics (painkillers) and also a fever-reducing medication, and after a few days begins to feel better. However, just as he thinks he will be able to return to school, the patient suddenly worsens, developing chest pain, and a productive cough (coughing up sputum). When he notices that his sputum contains blood, he goes to the doctor who diagnoses pneumonia, caused by the bacterium Streptococcus pneumoniae. In this scenario, the influenza virus is ______ while the S. pneumoniae is _______.
a primary pathogen; a secondary pathogen
This term refers to a microbe establishing itself and multiplying on a body surface
colonization
This term refers to a microbe that causes disease in otherwise healthy individuals.
primary pathogen
This term refers to a microbe that causes disease only when the body is already compromised in some way.
opportunistic pathogen
This term refers to the degree of pathogenicity (disease causing ability) of a microbe.
virulence
Type 1 hypersensitivity
Includes anaphylaxis-a systemic fatal reaction with airway obstruction and respiratory collapse
Type II hypersensitivity
Involves complement-assisted lysis of cells coated with antibodies as seen in transfusion reactions
Type III hypersensitivity
Immune complexes form and become lodged in blood vessel walls
Type IV hypersensitivity
T cell-mediated delayed hypersensitivity reactions including contact dermatitis and graft rejection reactions
Hemolytic disease of the newborn
Fetal RBC leakage sensitizes the mother to make anti-Rh antibodies.
Anti-Rh antibodies that are IgG can cross the placenta and induce complement-mediated lysis of fetal RBCs.
Hemolytic disease is a type II hypersensitivity reaction.
Secondary or acquired immunodeficiencies can be caused by infections, cancer, immunosuppressive agents, or pregnancy.
True
Hemolytic disease of the newborn (erythroblastosis fetalis) is rare in the United States today because
treatment with RhoGAM medication prevents Rh-positive blood cells from stimulating a primary immune response in Rh-negative women.
Place each of the following types of transplants in order based on their likelihood of inducing rejection reactions (least likely to most likely).
Autografts (from a different area on the patient's own body)
Isografts (from an identical sibling)
Xenografts (from another species)
Allografts (from a different individual of the same species)
Autoimmunity occurs when a person's immune system fails to differentiate between "self" and "non-self" antigens.
True
Type 1 diabetes mellitus
T cells destroy pancreatic islet (beta) cells
Myasthenia gravis
Autoantibodies prevent muscle contraction.
Graves' disease
Autoantibodies cause overstimulation of thyroid.
Rheumatoid arthritis
Lymphocytes destroy joint tissues.
Systemic lupus erythematosus (SLE, lupus)
Autoantibodies form immune complexes in small blood vessels.
Consider the figure of a step in the sequence of type I hypersensitivity reactions. If the allergen shown were to attach at position A,
the mast cell would not degranulate, because no IgE cross-linking would occur.
In people with HIV, cell-mediated immunity is affected but humoral immunity is not.
False
Primary immunodeficiency characteristics
Examples of these disorders include SCID and CGD
These disorders are rare and may be life- threatening
These disorders result from a genetic defect
