EXAM 3 Flashcards
what is the relationship between an infectious disease and a host
parasitism
Which of the following contribute to a pathogen’s invasiveness?
-F protein
-hyaluronidase
-endotoxins
-multiple portals of entry
hyaluronidase
The ability of some microbes, such as Trypanosoma or Giardia to alter their surface molecules and evade destruction by the host’s antibodies is called:
-antigenic variation
-virulence
-lysogenic conversion
-cytopathic effect
antigenic variation
______on the skin can prevent pathogens from establishing an infection through hair follicles.
However, those same pathogens may be able to get around that protection if they enter
the body through the_______
normal microbiota, parenteral
What is the LD50 of this pathogen?
10^7
Salmonella is able to enhance its________
by preventing fusion of the phagosome with the lysosome.
invasion
Which organism in the table most easily causes an infection?
Legionella pneumophila
What is an example of breaking the chain of infection by decreasing the number of susceptible hosts
Vaccination
Transmission of the corona virus by coughing and sneezing of an infected person in a closed
small space is what?
Direct transmission
A person carrying an infectious microorganism, may be infectious at:
-Incubation period
-Period of illness
-Period of convalescence
-All of the above
All of the above
What is an epitope?
Part of the antigen that binds the antibody
Which of the following cells would be safe from a natural killer (NK) cell’s cytotoxicity?
-a self-cell presenting with MHC I molecules
-a cancer cell
-a self-cell with a viral infection
-a self-cell without MHC I molecules
a self-cell presenting with MHC I molecules
Which of these is a purpose of fever? Choose the best answer.
-makes pathogenic microbe reproduction harder
-recruits phagocytes to the site of the infection
-prevents the physical entry of pathogens into the body
-responsible for perforin-mediated cytotoxicity
makes pathogenic microbe reproduction harder
What is the function of resident flora in immunity
take away habitat and nutrient availability from pathogens
Phagocytes bind to pathogen-associated molecular patterns (PAMPs) via:
pathogen-recognition receptors (PRRs)
How many antigens can bind IgM pentamers?
10
Antibody-dependent cell mediated toxicity (ADCC) is effective in removing what kind of
antigen?
large eukaryotic pathogens
Release of histamine by mast cells at the site of the wound causes
-Inux of phagocytotic cells to the wound area
-Edema (swelling)
-Redness
-All of the above
All of the above
What is the difference in the outcome between T-cell dependent and T-cell independent B
cell activation
T-cell dependent pathway creates memory cells that can fight the pathogen during
secondary infection
Pathogens that are super antigens create toxicity by
Creating excessive immune response, inflammation and fever
What is commensalism
-when an organism benefits from another without harming the other
EX:
-bacteria that lives on our skin doesnt affect us
-staphylococcus aureus
-skin microbiota
What is mutualism
-when two organisms benefit from each other
EX:
-E. coli benefits from living in our large intestines by getting nutrients. We benefit from E. coli because it helps us digest food
-escherichia coli
-gut micrbiota
What is parasitism
When an organism benefits from an organism while harming it
EX:
-streptococcus pyogenes (Strep throat) benefits from us but causes us to get sick etc.
What is symbiosis
two organisms living in the same environment
What is a pathogen
a microbe agent that cause disease
What is the difference between infectious and non-infectious disease
INFECTIOUS DISEASE: caused by direct effect from a pathogen (possible to pass from person to person)
EX: the flu, measles, strep throat, COVID
NON-INFECTIOUS DISEASE: caused by factors such as genetics, anatomical differences, radiation, or other environmental factors (not passed from person to person)
EX: cancer, diabetes, alzheimers
Whats the difference between communicable, non-communicable, and zootonic infectious diseases?
COMMUNICABLE: contagious disease that can spread from person to person (COVID)
NON-COMMUNICABLE: infectious disease that is not passed from person to person (LYME DISEASE)
ZOOTONIC DISEASE: pathogen transferred from animal to human (LYME DISEASE from ticks)
What kind of symbiosis is staphylococcus epidermidis?
mutualism because:
-promotes immune response to harmful microorganisms
-prevents growth of harmful microorganisms
-contributes to skin integrity
-host provides nutrients
What is microbiota
community of microorganisms living in our body
What is the difference between transient and resident microbiota?
TRANSIENT MICROBIOTA: present for days, weeks, months
RESIDENT MICROBIOTA: permanently colonize the host and do not cause disease under normal conditions
what is microbial antagonism
-competition for space and nutrients
-production of substances that are harmful to pathogens
-promote immune response to harmful microorganism
What is an example of opportunistic pathogen
1) a patient who has been taking antibiotics for a long time, is suffering from diarrhea caused by Clostridium difficile
2) Pseudomonas aeruginosa infections in a patient suffering from cystic fibrosis
A disease-causing microbe that is able to infect a healthy host is best categorized as:
-opportunistic pathogen
-primary pathogen
-normal microbiota
-transient microbiota
primary pathogen
What is pathogenicity and what are the 4 stages
the ability of a microbial agent to cause disease
1) exposure/contact (gain access to host tissue)
2) adhesion (attachment to the host cells)
3) invasion (penetrating tissue and cells)
4) infection (multiplication of the pathogen)
Eat, Apple, Ice cream, Inside
How does mycobacterium tuberculosis invade your cell
-macrophages in alveoli engulf bacteria but mycolic acid protects bacteria
-continue reproducing in the phagosome
-break open the phagosome and release in cytosol
-toxins from bacteria kill macrophages
-release the bacteria and infection of more cells
What is infection and what are the 3 kinds
a successful multiplication of the pathogen
1) local (confined to small part of body)
2) focal (spread of local infection to another location)
3) systemic (spread throughout the body)
EX: microorganisms that colonize teeth plaques, contribute to heart disease
What is virulence/virulence factors? What are the 6 factors?
VIRULENCE: the ability of a microorganisms to infect and cause damage to its host
VIRULENCE FACTORS: determine the extent and severity of disease
-capsules
-cell wall components
-adhesins
-exoenzymes
-toxins
-antigenic variation
What is infectious dose and lethal dose? what does ID50 and LD50 mean?
infectious and lethal dose are a method to quantify virulence of a pathogen
ID50: the amount of cells or virions required to infect 50% of hosts introduced to pathogen
LD50: the number of pathogenic cells, virions, or amount of toxins required to kill 50% of infected animals
how do microorganisms escape the immune response
-bacteria use a variety of virulence factors to evade phagocytosis by cells of the immune system
EX: many bacteria produce capsules, which are used in adhesion but also aid in immune evasion by preventing ingestion by phagocytes
What is antigenic variation
pathogens alter their surface antigens (and antibodies produced by host cells are rendered ineffective)
What is the difference between antigenic drift and shift?
ANTIGENIC DRIFT: a more GRADUAL change of antigens
ANTIGENIC SHIFT: a SUDDEN change of antigens prompted by a co-infection of two viruses with different antigens
Give an example of nosocomial factors
when someone uses/is exposed to antibiotics for a long period of time
What is the difference between signs, symptoms, and syndrome?
SIGNS: objective and measurable characteristics (body temp, heart rate, blood pressure, breathing rate)
SYMPTOMS: something felt or experience by patient but cant be clinically confirmed/ not measurable (nausea, loss of appetite, pain)
SYNDROME: a specific group of symptoms characteristic of a particular disease (Irritable bowel syndome)
What is morbidity/morbidity rate and what are the two aspects
MORBIDITY: number of cases of a disease
MORBIDITY RATE: number of people affected in relation to the total population in a given time period
TWO ASPECTS :
1) INCIDENCE: number or proportion of new cases during a specific time period (indicated speed of disease)
2) PREVALENCE: number or proportion of individuals with a particular illness in a given population during a specific time period
What is mortality/mortality rate
MORTALITY: number or deaths due to disease
MORTALITY RATE: number of deaths from a disease in relation to a population in a given time
What are the 4 patterns of incidence?
1) SPORADIC DISEASE (occurs occasionally in population)-typhoid fever
2) ENDEMIC DISEASE (constantly present in a population)- common cold
3) EPIDEMIC DISEASE (acquired by a larger number of hosts than expected in a given area in a short time) -influenza
4) PANDEMIC DISEASE (worldwide epidemic)-AIDS/COVID
What are the 5 different periods of disease in order
1) incubation period
2) prodromal period
3) period of illness
4) period of decline
5) period of convalescence
What is chain of infection and the 5 steps of it
-it explains how an infectious agent leaves it reservoir, moves to new host and causes infection to new host
-any action to break this chain can stop/reduce the spread of disease
1) reservoir
2) portal of exit (how it gets to another person)
3) mode of transmission
4) portal of entry
5) susceptible host
What is the difference between innate and adaptive immunity
What do leukocytes do and what are the two categories
they help with cellular defense
1) GRANULOCYTES (characterized by numerous granules visible in the cytoplasm)
2) ARGANULOCYTES (lack granules)
What is phagocytes and how do they recognize their targets?
-Phagocytes are cells whose main function is to find, ingest, and kill pathogens (WBC or WBC derivatives)
can recognize targets by
1) OPSONIZATION: process of tagging oh the pathogens so they can be recognized by phagocytes
2) PATHOGEN ASSOCIATED MOLECULAR PATTERNS (PAMPs): groups of molecules common on pathogenic microorganisms
What are phagocytotic cells
-release of toxic molecules that damage the microbes
-phagocytosis and removal of the microbes
-release of cytokines causing inflammation
-presenting antigens on the cell surface
What are natural killer cells and what are the two major mechanisms
-Identify infected cells without major histocompatibility class I molecules and induce programmed cell death of infected cells or cancerous cells
TWO MAJOR MECHANISMS
1) release of cytotoxins proteins and cytokines that trigger apoptosis in the target cell
2) perforin-creates pores in the membrane of the target cell
What are the signs of inflamation
-erythremia (redness)
-edema (swelling)
-heat
-pain
-fever (pyrogens)
What is an immunogen
an antigen that causes the body to produce specific antibodies
what is an antibody
molecules produced by the cells of the immune system that bind to immunogens and mark them for destruction and removal
What is the difference between MHC I and MHC II
MCH I: found on all nucleated self cells
MCH II: found on antigen presenting cells
What are antigen presenting cells
macrophages or dendritic cells
what is pseudomembrane
a layer of dead cells
EX: diphtheria
what is granuloma
defense mechanism of the immune cells that create walled-off lesions to prevent spread of infection
EX: tuberculosis
what are the defense mechanisms of the respiratory system
-mucociliary escaltor
-macrophages in the alveolar sacs
-nasal cavity contains mucus membrane with sticky and salty mucus with lysozymes
-traps bacteria and particles in nose hair
what are defense mechanisms in the digestive tract
-salivary gland produce saliva
-normal microbiota
-mucus membrane
-acidity of stomach
-peristalsis movement of materials through the gastrointestinal tract also helps to move transient pathogens out of the body
Which blood agar plate is alpha, beta, and gamma hemolysis?
left to right: beta, alpha, gamma
How is the mannitol agar plate (MSA) differential and selective
Differential
-contains mannitol
-fermentation of mannitol produces acids
-ph indicator turns yellow in acidic environment, no color change is basic
Selective
-high concentration of NaCl selects for members of the genus staphylococcus that are halotolerant
How is the eosin-methylene blue agar plate (EMB) selective and differential
Differential
-contains methylene blue that prevents growth of gram positive bacteria
Selective
-contains lactose/sucrose
-fermenters produce pink colonies
-high fermenter produces a green metallic colony
How is endo agar differential and selective
Selective
-only grows gram negative bacteria
-sodium sulfite and basic fuchsin make this medium selective by suppressing gram positive bacteria
Differential
-pink is positive for lactose fermenting
-colorless is negative for non-fermenting
