Microbial Factors Contributing To Phatogenesis And Virulence Flashcards
Mechanism by which the disease is caused.
Pathogenesis
Ability of a microbe to produce disease in susceptible individual l.
Pathogenicity
Two types of pathogens.
True/frank pathogen
Oppurtunistic pathogen
This type of pathogen can be recognized to cause disease in healthy immunocompetent individual.
True pathogens
Common bacterial species of true pathogen.
Yersinia pestis
Bacillus anthracis
Due to invasive medical procedures against diseases, patients become more____.
A. Susceptible to infection
B. Less susceptible in infection
C. Normal flora is seen increasing in causing infection to immunocompromised individuals
D. All of the above.
A and C
Examples of opportunistic pathogens.
Haemophilus influenzae
Staphylococcus epidermidis
An opportunistic pathogen that is life threatening in human.
Haemophilus influenzae
An oppurtunistic pathogen that can infect in patient with prosthetic devices
Staphylococcus epidermidis
An infection that occurs as the result of medical treatment or procedures.
Iatrogenic infection
T or F
Indwelling urinary catheters develop what?
Urinary tract infection
T or F
Patients with immunosuppresisve drugs after transplant are resistant in infections.
False- they are susceptible
Is the relative ability of microorganisms to cause disease or the degree of pathogenicity.
Virulence
T or F
Organisms that can establish low infective dose are more virulent than organisms that require high no. of infection.
True
T or F
Shigella causd disease with relatively low infective dose.
True (100 organisms)
These are mechanisms that allow bacteria to persist in host amd cause disease.
Microbial virulence factors
These allow the pathogen to evade or overcome host defenses.
Virulence factors
Examples of virulence factors.
- inhibiting phagocytosis
- adhesion to host cells/tissue
- enhacing intracellular survival after phagocytosis
- damage tissue through production of toxins and extracellular enzymes
T or F
Capsules and toxins are common virulence factors of bacteria.
True
Which is not true about the defined virulence factor of a bacteria?
A. Diptheria and Cholera toxins
B. Capsule of streptococcus pneumoniae
C. Fimbriae of N. gonorrhoeae
D. Pili of Staphylococcus epidermidis
D
Examples of phagocytic cells.
Macrophages
Polymorphonuclear cells
What is the extremely important event in the life of invading pathogen and survival rate is to _____.
Avoid phagocytosis
Common mechanism for evading phagocytosis.
Polysaccharide capsules
Species of bacteria that are highly virulent through polysaccharide capsule.
S. pneumoniae
H. influenzae
T or F
Capsule can be made by polysaccharide, protein, or combination.
Truee
How does the capsule protect the pathogen from the immune response of host?
They mask the cell surface structure that can be recognized by the receptors of phagocytes.
What is the concept of lipid A in escaping phagocytosis?
- it interferes with the binding of the host antibodies.
- Antibodies bind to antigen through Fab/antigen-binfing portion
- Protein A binds to Fc portion of IgG that prevents opsonization (markings).
Streptococci produce___ that lyses RBCs. Staphylococci produce ____ that is toxic in WBCs
Hemolysins
Leukocidins
Staphylococcus release ____ that cause lysosomal discharge in cytoplasm.
Leukocidins
Staphylococci leukocidins, called
Panton Valentine
Lethal to WBCs and contributes to invasiveness of bacteria.
Panton Valentine
This cause the host to less able direct the polymorphynuclear neutrophils (PMNs) and macrophages going to the site of infections.
Chemotaxis
T or F
Some diseases cause by exotoxins (botulism, staphylococcal) adhesion to cells/tissue is important.
False
Cell surface structures that mediate atrachement are called?
Adhesins
What is the main adhesins in bacteria,
Fibriae (pili) and surface polysaccharide
Which is/are not true about fibriae in adhesion of the bacteria to the host?
A. They can be resistanced to the host
B. Increased the organisms’ colonizing ability
C. Phagocytosis is less likely to occur
D. Replicates the bacterial cells
D
Example of bacteria that uses fimbriae that adheres to the small intestine in which they release toxins to cause diarrhea.
Eschericia coli
This bacteria uses fibriae to infecth epithelia cells of the genitourinary tract.
Gonococci (N. gonorrhoeae(
How bacteria survive in intracellular activities in phagocytosis?
- From being resistanced to the effect of lysosomal content
- escaping from phagosome
Secretory antibodies produced ____ to protect against infection.
Lactoferrin
Lysozyme
It competes with bacteria for free iron.
Lactoferrin
This genera of bacteria uses lactoferrin as a source of iron.
Meningocci
T or F
Non -pathogenic Neisseria spp. can be inhibited by the lactoferrin.
True
This enzymes degrades IgA found at mucusal surface.
Immunoglobulin (IgA) proetease
Pathogens that have immunoglobulin protease
H. influenzae, N. gonorrhoeae, N. meningitidis
T or F
Some pathogens circumvent host antibodies by shifting key cell surface antigens.
True
Example of pathogens that can shift key cell surface antigen.
Influenza virus
Borrelia spp.
These species are easily engulfed by macrophages, but they can survive and multiply intracellularly.
Chlamydia
Mycobacterium
Brucella
Listeria
Pathogens exhibit an ability to penetrate and grows on tissue.
Invasion
T or F
Gonococcus organism is invasice they can infect the fallopian tube.
True
T or F
Salmonella spp. is invasive.
False- dissemination
Pathogen spread infection to distant sites are called?
Dissemination
Example of dissemination pathogen.
Corynebacterium diptheriae
T or F
Organisms that survive phagocytosis may be disseminated rapidly and the organisms are not invasive.
True
Example of highly invasive species of bacteria.
Clostridium perfringens
Disease from infection only noticeably only in tissue cause by ____.
Exotoxins and endotoxins
These are poisonous subs. Produced by organisms that can disrupt metabolism and cause harm.
Toxins
This type of toxins is produced by both gram + and - bacteiria.
Exotoxins
Exotoxins can mediate the direct spread of microorganisms through ____.
Matrix of connective tissues.
How does the bacteria spread in the matrix of connective tissue?
The bacteria produce substances like proteases and hyaluronidase that liquify the hyaluronic acid of the tissue.
T or F
Endotoxin is exclusive only in gram positive bacteria.
False (gram -)
T or F
Endotoxin has enzyme activity.
False
What is the constituent of Endotoxins?
Lipopolysaccharide
T or F
Endotoxin can be destroyed by heating
False
Two subunits of exotoxins
Nontoxic
Toxic (bind toxin to the host cells)
Toxin gene is encoded by phages, plasmids, transposons.
True
Example of exotoxins bacteria.
A. Clostridium difficile
B. Diphtheria
C. Botulinum
D. Salmonella
A,B,C
This exotoxin bacteria inhibits protein synthesis and affects the heart, nerve tissue, liver.
Diptheria toxins
It is a neurotoxin that blocks nerve impulse transmission and can cause flaccid paralysis especially in infant.
Botulinum toxin
They produce exfoliatin that can cause rash and massive skin peeling.
Streptococcus pyogenes
S. aureus
Endotoxins composed of LPS on the ___ of gram negative bacteria.
Outer membrane
3 regions of LPS In gram negstive.
Antigenic O-specific polysaccharide
Core polysaccharide
Inner lipid A
Which is not the effect of LPS in the body?
A. Changes in bp, clotting
B. Change in body temp., metabolism
C. Damage Body Immunity
D. Change in pH of blood and urine
D.
The toxic activity of endotoxin is found in ___.
Inner lipid A
Endotoxins stimulate the fever in the center of ___.
Hypothalamus
Increase in body temp:
Severe hypotension:
- 1 hour
- 30 mins
Effect of endotoxin that may be lethal.
Septic or endotoxic shock
T or F
Endotoxin can cause coagulation in blood.
True
It occurs within a minute after exposure to endotoxin. Sequention of Neutrophils in the lungs mostly.
Sever neutropenia
This follows neutropenia because neutrophils are released in bone marrow.
Leukocytosis
