Essentials Host-Microorganism Interactions Flashcards
(54 cards)
HUMAN AND MICROBE INTERACTIONS:
acquiring a microorganism from another human serving as the reservoir
Direct transmission
HUMAN AND MICROBE INTERACTIONS:
can occur when microorganisms from one individual contaminate a vehicle of transmission, such as water (e.g., cholera), that is then ingested by another person.
Indirect Transmission
animals, insects, other humans
Vectors
water, food, air, medical devices, various other inanimate objects
Vehicles
HUMAN AND MICROBE INTERACTIONS:
Hospital-acquired, health care-associated, or long-term care-associated infections historically are referred to as
Nosocomial infections
ANIMALS AS MICROBIAL RESERVOIRS:
WHEN A HUMAN INFECTION RESULTS FROM SUCH AN ENCOUNTER
ZOONOTIC INFECTION
SKIN SERVES AS A PHYSICAL AND CHEMICAL BARRIER TO MICROORGANISMS:
microorganisms that inhabit many surfaces of the human body
*Colonizers *Normal flora
*Normal microbiota, *Human microbiome
SKIN SERVES AS A PHYSICAL AND CHEMICAL BARRIER TO MICROORGANISMS:
they are able to survive, but do not multiply, on the surface and are frequently shed with the host cells.
Transient colonizers
SKIN SERVES AS A PHYSICAL AND CHEMICAL BARRIER TO MICROORGANISMS:
not only survive but also thrive and multiply; their presence is more persistent.
Resident microbiota
PATHOGENS, AND THE CHARACTERISTICS THAT ENABLE THEM TO CAUSE DISEASE
VIRULENCE FACTORS
THE ORGANISM’S ABILITY TO CAUSE DISEASE
PATHOGENICITY
THE MEASURE OR DEGREE OF PATHOGENICITY OF AN ORGANISM
VIRULENCE
THE ORGANISM IS VERY LIKELY TO CAUSE DISEASE
HIGH PATHOGENICITY
THE ORGANISM IS MUCH LESS LIKELY TO CAUSE INFECTION
LOW PATHOGENICITY
ORGANISMS THAT CAUSE INFECTION WHEN ONE OR MORE OF THE HOST’S DEFENSE MECHANISMS ARE DISRUPTED OR MALFUNCTION
OPPORTUNISTIC PATHOGENS
ORGANISMS THAT CAUSE INFECTION WHEN ONE OR MORE OF THE HOST’S DEFENSE MECHANISMS ARE DISRUPTED OR MALFUNCTION AND THE INFECTIONS THEY CAUSE IS CALLED
OPPORTUNISTIC INFECTIONS
Microbial Virulence Factors
- Attachment
- Invasion
- Survival against inflammation
- Survival against the immune system
- Microbial toxins
- Biofilm formation
MICROBIAL VIRULENCE FACTORS:
ONCE SURFACE ATTACHMENT HAS BEEN SECURED, MICROBIAL INVASION INTO SUBSURFACE TISSUES AND ORGANS (I.E., INFECTION) IS ACCOMPLISHED BY DISRUPTION OF THE SKIN AND MUCOSAL SURFACES BY SEVERAL MECHANISMS OR BY THE DIRECT ACTION OF AN ORGANISM’S VIRULENCE FACTORS
INVASION
MICROBIAL VIRULENCE FACTORS:
AVOID PHAGOCYTOSIS BY PRODUCING A LARGE CAPSULE THAT INHIBITS THE PHAGOCYTIC PROCESS
SURVIVAL AGAINST INFLAMMATION
MICROBIAL VIRULENCE FACTORS:
TOXINS ARE BIOCHEMICALLY ACTIVE SUBSTANCES RELEASED BY MICROORGANISMS THAT HAVE A PARTICULAR EFFECT ON HOST CELLS
MICROBIAL TOXINS
MICROBIAL VIRULENCE FACTORS:
MICROORGANISMS TYPICALLY EXIST AS A GROUP OR COMMUNITY OF ORGANISMS CAPABLE OF ADHERING TO
BIOFILM FORMATION
Bacterial Toxins:
*General toxin common to almost all gram-negative bacteria
*Composed of the lipopolysaccharide portion of cell envelope
*Released when a gram-negative bacterial cell is destroyed
Endotoxins
Bacterial Toxins:
*Most commonly associated with gram-positive bacteria
*Produced and released by living bacteria; do not require
bacterial death for release
*Specific toxins target specific host cells; the type of toxin varies with the bacterial species
*Some kill host cells and help spread bacteria in tissues (e.g., enzymes that destroy key biochemical tissue components or specifically destroy host cell membrane)
*Some destroy or interfere with specific intracellular activities (e.g., interruption of protein synthesis, interruption of internal cell signals, or interruption of the neuromuscular system)
Exotoxins
OUTCOME OF INFECTIOUS DISEASES:
INFECTIOUS PROCESSES THAT DEVELOP QUICKLY
ACUTE INFECTIONS
