Evolving pathogens Flashcards
antimicrobial agent
an agent that kills or slows the growth of microorganisms
antimicrobial resistance
the ability of microorganisms to survive exposure to an antimicrobial agent
what causes the variation and emergence of new alleles conferring resistance is due to
largely mutations
how to bacteria evolve
become resistant to antibiotics
wwhy are antibiotic resistant bacteria dangerous
they can multiply and pass on particular resistance to antibiotics, making them difficult to eradicate
how to viruses evolve
by mutating rapidly to change the shape of their antigen
why are evolved viruses dangerous
new vaccines must be constantly created to combat each strain
antibiotic
chemical that inhibits bacterial growth by interfering with its ability to build cell walls
bacterial conjugation
the process in which bacteria exchange genetic material by direct cell-cell contact
how does antibiotic resistance come about due to natural selection
antibiotics act as a selection pressure on bacteria, bacteria that are naturall resistant survive and pass on the avourable alleles onto the next generation or through bacterial conjugation
what is the main causes of antibiotic resistance
inappropraite use of antibiotics, patients prematurely stopping a course of antibiotics, widespread use of antibiotics
example of how inappropriate use of antibiotics can lead to antibiotic resistant bacteria
if doctors prescribe antibiotics to a viral infection, allowing normal bacteria to be exposed to the antibiotic as a selection pressure
how does patients prematurely stopping a course of antibiotics lead to antibiotic resitant bacteria
it leads to more bacteria having time to mutate and naturally develop resistance and it does not sufficiently eliminate all the pathogenic bacteria
how does widespread use of antibiotics lead to resistant bacteria
it leads to more bacteria being selected for antibiotic resistance
antigenic drift
small and gradual mutations in the genes encoding for for viral surface proteins
how does antigenic drift allow viruses to become resistant
as these changes are gradual, previous memory cells generated from the original virus can still be effective at combatting the virus, but as mutations increase a new subtype can form which may be too different from the originial
antigenic shift
sudden and significant mutations in the genes encoding for viral surface antigens
how does antigenic shift occur
when two or more different strains of a virus combine when co-invecting the same host uproducing a new viral subtype (called viral recombination)
what can viral recombination cause and why
can cause an epidemic or pandemic because natural immunity to the new strain is unlikely, making it highely infectious
epidemic
a dramtically increased occurence of a disease in a particular community at a particular time
pandemic
an epidemic that has spread across multiple countries and/or continents
