Block 2 - Host-Microbe Relationships Flashcards
Describe the term “symbiosis”.
the close associate and interaction of two dissimilar organisms living together
Those microorganisms which are normally and consistently found in or on the body in the absence of disease.
Describe “resident” flora and “transient” flora.
normal flora
resident: generally live in a specific place
transient: “non-pathogens” that are passing through the area
True or False:
Normal flora found in one area may cause an infection in another region of the body.
True
What is the term for each definition below?
Association between organisms in which one is benefitted and the other is neither benefitted nor harmed.
Both the microbe and host derive benefits from the relationship
Commensalism
Mutualism
What is the term for this definition?
Disease traits of the resident flora are demonstrated only when normal host-microbe relationship is altered.
What are some ways this can occur?
opportunism
a. Prolonged antibiotic therapy alters flora
b. Traumatic injury, surgery
c. Immunological compromise
d. Hormonal or chemical changes
What term(s) are described below?
Symbiotic relationship in which a microorganism lives in or on a host at the expense of the host.
- *A carrier of microbes from one host to another**
- (i.e: a. Insects and other animals b. Inanimate articles (fomite) e.g. personal items, eating utensils, tools, hospital instruments, food water, body discharges, bandages, etc)*
Parasitism
Vector
The growth and spread of a pathogen in or on a host resulting in injury to the host tissue.
Define the term “pathogen”.
Infectious Disease
A microbe capable of causing diease by invading tissues, providing toxins, or both
Virulence is the degree of what?
What are two things that effect virulence?
Describe each.
pathogenicity
Infectivity: how easily the microbe survives the normal host defenses and establishes infection
Severity: degree of the damage it causes the infection host
What are the four modes of transmission regarding pathogens?
Direct contact with the skin or mucous membranes of a diseased person (or carrier) with or without active penetration of the microbe through the skin or mucous membranes
Inhalation - droplets or particles in the air
Ingestion - of food and water (or other items we put into our mouths) that is contaminated with fecal material, insects, dead or live animals, soil, and other sources
Parenteral – direct contamination of blood, body fluids, or tissues by arthropod and other animal vectors and by nonsterile syringes and needles
What are the four “attachment and establishment factors” of the microbe?
Portal of Entry
Attachment
Quantity of microbe needed to establish infection
Quorum-sensing Regulators
What are the various chemicals that:
(1) restrain the disease-causing actions of the microbe until sufficient quantity of microbes are present
* then*,
(2) switch on the disease-causing actions all at once.
Quorum-sensing regulators
Within microbe attachment,
what is the features that the microbe may use to gain attachment to the host?
What type of “chemical” and “molecule” is used by the microbe to facilitate attachment?
Fimbrae: attach to specific receptor site on specific tissue
Surface chemicals: dissolve covering of cells and aid chemical attachment
Adhesive Matrix Molecules: produces biofilm thus providing “protection” for bacteria within harsh human environments
What are 4 examples of antiphagocytic factors of microbes?
Capsule: most notable - “slippery/slimey” nature assists bacteria from being completely engulfed by the phagocyte
Leukocidin: causes destruction of WBCs
“leuko = white / cidin = kill”
Coagulase: causes blood fibrin clot to form around the microbes (coagulase = enzyme that coagulates)
Survival of phagocytosis: resistance to killing within a phagocyte (e.g. mycobacteria, gonococcus, Listeria)
What are factors that promote the invasion and spread of a pathogen in/on the tissue?
“invasive” enzymes
