Antibacterial Resistance Flashcards
Bacterial population can rapidly _____ themselves to gain resistance to antibiotics, _______ resistant traits, and ______ them to other bacteria
Bacterial population can rapidly modify themselves to gain resistance to antibiotics, propagate resistant traits, and transfer them to other bacteria
define antibacterial resistance
ability of bacterium to survive and multiply in presence of an antibiotic
define innate (intrinsic) resistance
innate ability of a bacterial species to resist the activity of an antibiotic through its inherent structural or functional characteristics
define acquired (extrinsic) resistance
organism obtains the ability to resist the activity of an antibiotic to which it was previously susceptible
why is antibacterial resistance a problem?
drug resistance is reversing the progress of antibiotic development
new antibiotic development has rapidly slowed down
How many deaths a year are from antibiotic-resistance infections?
23,000 deaths
Where are many of the bacteria that cause antibiotic resistant infections found?
in livestock
Are antibiotics used only for therapeutic reasons in animals?
used for therapeutic and non-therapeutic
How is antibacterial resistant spread?
- antibiotic use selects for drug-resistant organisms
- resistance not induced by antibiotic itself but by environment created by antibiotics
- resistant strains can spread far and wide
How do bacteria disrupt or prevent the action of the antibiotic?
-preventing antibiotic from reaching its target
-modifying or bypassing antibiotic target
What are the way bacteria prevent the antibiotic from reaching its target?
-reduce ability of antibiotic to enter the cell
-expel the antibiotic out of the cell via efflux pumps
-antibiotic inactivation by modification or degradation
how do bacteria reduce the ability of antibiotic to enter the cell?
altering porins in the cell wall
how do bacteria expel the antibiotic out of the cell via efflux pumps?
-membrane proteins export or pump out antibiotics
-decreases antibiotic concentration inside the cell
how do bacteria inactivate antibiotics through modification or degredation?
enzymes degrade or modify the antibiotic so it is no longer effective
What enzyme do most bacteria possess to degrade antibiotics? which antibiotics is degreaded?
B-lactamases
B-lactam antibiotics
what does B-lactamase inhibitors do?
-structural analog of B-lactams
-extend activity of B-lactam antibiotic
-inhibit activity of B-lactamase
which of the following will bind first to the B-lactamase - B-lactam antibiotic or B-lactamase inhibitors?
B-lactamase inhibitor - has a higher affinity
How do bacteria modify the antimicrobial target?
bacteria have acquired mutations or modified structures that are no longer recognized by antibiotic
How do bacteria bypass the antibiotic target?
bacteria acquired a “new” enzyme that allows bypass of a metabolic pathway that the bacteria could be blocking
Can we prevent antibacterial resistance from developing?
no but we can slow it down by using antibiotics wisley
Why can’t we stop antibiotic resistance from developing
bacteria naturally develop resistance - it is their constant survival mechanism since they are always competing with other bacteria
what are some principles for using antibiotics wisley?
-prescribe antibiotics only for bacterial infections
-educate clients on the proper use of antibiotics
-determine the most appropriate antibiotic for the infection
How can giving an antibiotic for a viral infection negatively affect the body?
affect/kill normal flora > decrease in normal flora > inc susceptibility to other pathogens
Why is it important to give antibiotics to animals as directed and not only give 1/2 of the course?
stopping halfway through leaves a population that has been under antibiotic pressure and the fittest will the survive and they will proliferate > create antibiotic resistance population
How can you determine the most appropriate antibiotic for infection?
isolate the bacterial pathogen and performing antibiotic susceptibility testing (AST)
what are the 3 antibiotic susceptibility tests we are focusing on in this course?
disk diffusion
broth dilution (MIC)
E-tests
How are disk diffusions done?
- make lawn bacterial culture (evenly inoculated)
- place filter disks containing antibiotic
- incubate
- measure ZOI
where is the highest concentration of antibiotic with a disk diffusion test?
around the disk, decreases as drug diffuses away
what is zone of inhibition?
diameter around bacterial clearance from disk
Is a disk diffusion test quantitative or qualitative?
qualitative
Which antibiotic would you use?
Erythromycin
Is a broth dilution test quantitative or qualitative?
quantitative
How are broth dilution test read?
lowest concentration of antibiotic that inhibits bacteria growth is the MIC (minimum inhibitory concentration)
What is the tube that is circled in red in a broth dilution test?
minimum inhibitory concentration
what test is this?
broth dilution in a microtiter plate
what is MBC?
minimum bactericidal concentration
What is an E-test?
ease of Kirby-bauer test with ability to determine MIC value
what is the MIC?
0.25 ug/ml
How is the MIC value determined in a E-test?
where the elliptical zone of inhibition crosses the E-test
How are the plastic strips for E-test filled with antibiotic? (same conc. throughout, gradually inc, gradually dec?)
plastic test strips impregnated with gradually decreasing conc. of antibiotic
