host micro organism Flashcards
What is symbiosis in the host-microbe relationship?
A biological relationship where both organisms benefit.
What is commensalism in microbiology?
One organism benefits while the other is neither harmed nor helped.
What is parasitism in the host-microbe relationship?
A relationship where the microbe benefits at the expense of the host.
What is the difference between resident and transient microbial flora?
Resident flora colonizes for months or years, transient flora is temporary.
Give an example of a bacterial species found in the armpit and groin.
Aerobic diphtheroids.
Which bacteria are commonly found in the hair follicles and sebaceous glands?
Staphylococcus epidermidis and Propionibacterium.
What type of bacteria predominates in the gastrointestinal tract?
Anaerobes (90% of the microbial flora).
What is the role of microbial flora in host defense?
Activates the immune system and blocks pathogen colonization.
What is an opportunistic pathogen?
A microorganism that causes disease when the host is compromised.
What are two examples of true pathogens?
Bacillus anthracis and Yersinia pestis.
What is the definition of virulence?
The relative ability of a microorganism to cause disease.
What are two microbial virulence factors?
Fimbriae and capsules.
What is one way microbes resist phagocytosis?
By producing a polysaccharide capsule.
Name one bacterial species that produces leukocidins.
Staphylococcus species.
What is the function of adhesins?
They mediate microbial attachment to host tissues.
What is an example of an intracellular pathogen?
Chlamydia or Mycobacterium.
What is an exotoxin?
A toxin secreted by bacteria into the extracellular environment.
What is an endotoxin?
A lipid A component of the outer membrane of Gram-negative bacteria.
What is the main difference between exotoxins and endotoxins?
Exotoxins are proteins, endotoxins are lipid A components of Gram-negative bacteria.
What are two physical barriers in host defense?
Skin and mucous membranes.
Name one example of a cleansing mechanism in host defense.
Flushing of urine or tears.
What antimicrobial substance hydrolyzes bacterial cell walls?
Lysozyme.
What is opsonization?
The process of coating a bacterium with antibodies to enhance phagocytosis.
What is chemotaxis in immune response?
The migration of immune cells to an infection site.
