2 - (Most Exam Q's) Host-Microbe Relationships Flashcards
Types of Host-Microbe Relationships
Symbiosis - define Normal Flora - define Commensalism Mutualism Opportunism Parasitism Vector
- Symbiosis – the close association and interaction of two dissimilar organisms living together.
- Normal flora – those microorganisms which are normally and consistently found in or on the body in the absence of disease.
the close association and interaction of two dissimilar organisms living together.
Symbiosis
those microorganisms which are normally and consistently found in or on the body in the
absence of disease.
Normal flora
a. Resident vs. transient flora
b. Nature and variety of microbes are often distinctive for different regions of the body
c. Normal flora of one area may cause infection in another region of the body
Types of Host-Microbe Relationships
Types of Host-Microbe Relationships
Symbiosis Normal Flora (microbiota) Commensalism Mutualism Opportunism Parasitism Vector
– association between organisms in which one is benefitted and the other is neither benefitted nor harmed.
Commensalism
– both the microbe and host derive benefits from the relationship
Mutualism
– disease traits of the resident flora are demonstrated only when normal host-microbe relationship is altered.
Opportunism
a. Prolonged antibiotic therapy alters flora
b. Traumatic injury, surgery
c. Immunological compromise
d. Hormonal or chemical changes
– symbiotic relationship in which a microorganism lives in or on a host at the expense of the host.
Parasitism
– a carrier of microbes from one host
to another
Vector
a. Insects and other animals
b. Inanimate articles (fomite) e.g. personal items, eating utensils, tools, hospital instruments, food water, body discharges, bandages, etc.
– the growth and spread of a pathogen in or on a host resulting in injury to the host tissue
Infectious disease
Infectious disease
a. Pathogen –
a microbe capable of causing disease by invading tissues, producing toxins, or both
Infectious disease
b. Virulence –
(1) Infectivity – how easily the microbe survives the normal host defenses and ESTABLISHES infection
(2) Severity of the damage it causes the infected host
the degree of pathogenicity
b. Virulence –
(1) ______ – how easily the microbe survives the normal host defenses and ESTABLISHES infection
(2) _____ of the damage it causes the infected host
Infectivity
Severity
Modes of Transmission
Direct Contact
Inhalation
Ingestion
Parenteral
Modes of Transmission
- Inhalation -
droplets or particles in the air (aerosolized could be on tiny water droplet, dust particle, etc)
Modes of Transmission
- 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
Modes of Transmission
- Parenteral –
direct contamination of blood, body fluids, or tissues by arthropod and other animal vectors and by nonsterile syringes and needles (mosquitos etc)
Microbial Virulence Factors
What enables the ESTABLISHMENT of infection?
Name all four factors
Attachment ; Establishment Factors
- Portal of Entry
- Attachment
- Quantity
- Quorum-sensing Regulators
– The organism must enter the correct portion of the body (e.g. ingestion vs. inhalation vs wound)
Choosing correct portal allows for what two things?
a. Portal of Entry
(1) Overcome local defenses
(2) Find right/best environment for growth/survival
– The attachment of the microbe to tissue is required in order to establish a site of infection
Three methods of attachment?
Attachment
(1) Fimbrae – attach to specific receptor sites on specific tissue
(2) Surface chemicals – dissolve covering of cells and aid chemical attachment
(3) Adhesive Matrix Molecules – produce biofilms thus providing “protection” for bacteria within harsh human environments.
three methods of attachment for microbes?
Fimbrae
Surface Chemicals
Adhesive Matrix Molecules
– a certain minimum number of organisms are required to establish infection – presumably needed to overcome host defenses
Quantity
– 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. (TYPICALLY DONE VIA OPERON THAT REGULATES THE BACTERIA AND SWITCHES WHEN THE BACTERIA HAS MULTIPLIED ENOUGH AND IN A POSITION FOR AN ATTACK; AND MAJOR SYMPTOMS COME ON FAST!)
Quorum-sensing Regulators
