Chapter 10 Flashcards
Dysbiosis
microbiota disruption
What could be said about Normal Microbiota and Opportunistic Pathogens
Though some microbes can be normal microbiota for on species, it could be a harmful pathogen for another
Pathogenicity
ability of a microbe to cause disease
Virulence
The degree or extent of disease that a pathogen causes
Virulence: Low v High
low are easy to treat, high is difficult to treat
Virulence factors
ways pathogens overcome our defenses
What does it take for a pathogen to persist
Must endure over time
Must find a balance b/n breaking down defenses and living within a host
How are agents that kill a host quick like?
Cause high-mortality outbreaks
Are short in duration
Are geographically isolated
What happens when pathogen is grown in a culture?
Agent becomes attenuated, weakened, could be used as a vaccine
Infectious dose-50
Number of cells or virions needed to establish an infection in 50% of exposed hosts
Low v High ID-50
High: takes a lot more organisms to start infection
Low: only takes a few organisms to start an infection
Lethal dose-50
amount of toxin needed to kill 50% of affected hosts that aren’t treated
High v Low LD-50
High: Takes a lot of toxin to kill host
Low: Takes little toxin to kill host
Toxins
molecules that generate a range of adverse host effects such as tissue damage and suppressed immune response
Toxigenic
Microbes that make toxins
Toxemia
toxins in the bloodstream
Classes of toxins
Endotoxin
Exotoxin
Endotoxin
Specific to gram “-“ bacteria, due to outer membrane having LPS, released into blood stream when bacteria dies
Exotoxin
Toxic, soluble proteins that can affect a wide range of cells and can be gram “+” or “-“
Exotoxin types
Neurotoxins – affect the nervous system
Enterotoxins – target the GI tract
Hepatotoxins – affect the liver
Nephrotoxins – damage the kidneys
Type 1 Exotoxins
Membrane-acting extracellular toxins that bind to target via receptors on the surface
Type 2 Exotoxins
Membrane-damaging toxins that disrupt the host cell plasma membrane causing lysis
Type 3 Exotoxins
Intracellular toxins that bind to a receptor and enter the cell
What are the 5 steps to infection?
Enter the host
Adhere to host tissues
Invade tissues and obtain nutrients
Replicate while warding off immune defenses
Transmit to a new host
Portal of entry
any site that a pathogen uses to enter the host
Adhesins
virulence factors used to stick to host cells in a specific or nonspecific manner
Invasins
Allow pathogens to invade host tissues
Cytopathic effects
Cytocidal: kills cells
Noncytocidal: non-lethal warfare on cells
Latency
ability to exist with stealth inside host
Antigenic masking
When in host, pathogen conceals antigenic features, by coating itself with host molecules
Antigenic masking: Mimicry
Emulating host molecules, capsules resembling host carbohydrates
Antigenic masking: Variation
Continuously altering its surface molecules, thus preventing immune response
How do cells avoid phagocytosis
Bursting from of phagosome
Blocking fusion of phagosome with lysosome
Neutralize enzymes of phagocytes
Use chemical warfare against phagocytes
Portal of Exit
like portal of entry, but for leaving. Isn’t usually the same as entry portal, but can be
Symptoms when a pathogen transmits to others
Itchiness
Sneezing
Coughing
Diarrhea
Biosafety levels
Dictates the behavior of the job, since healthcare workers in come in contact with pathogens on a near daily basis. However, not all pathogens have the same level of harm
BSL criteria
Level infectivity
Mortality rates/extent of disease
Mode of transmission
Availability of preventions or treatments
BSL 1-4
1.Rarely cause disease in healthy people
2.Infectious agents associated with human infection; not airborne
3. Serious or lethal human diseases, Many have airborne transmission
4. Dangerous and “exotic” pathogens, Tend to be lethal in humans
Standard/universal precautions
Limiting bloodborne pathogens
All patients are treated like they are that
Handling precautions
Transmission precaustion
1-contact disease transmission: Minimize transmission of infectious agents spread by fomites and healthcare workers
2-droplet disease transmission: Procedural mask when in the patient’s room
Limit patient transport
3-airborne disease transmission: Airborne infection isolation room (AIIR)
Specialized pressure systems
