MICR 4423 MOCK EXAM QUESTIONS AND
CORRECT ANSWERS!!
· How do we define antibiotic resistance?
o The continued growth of bacterial cells in the presence of an ABX @ concentration that would
normally kill cells or stop growth
· What are the 4 main ways that bacterial cells can achieve antibiotic resistance? Give an
example of a mechanism for each way.
§ Block entry: porin
§ Pump out of cytoplasm: efflux
§ Modify or destroy: beta-lactamase or acetylase
§ Modify or mutate ABX target: modifications to 23srRNA that blocks MLS ABX
· What is innate resistance to antibiotics?
o The resistance of antibiotic producers
· What is one way that an antibiotic producer can protect itself from the antibiotics it
makes?
efflux pump
o Enzymes that inactivate ABX in cytoplasm
o Do last set of synthesis outside of celll
What is acquired resistance to antibiotics?
resistance of non-antibiotic-producers
· How can acquired resistance be acquired by cells?
o Spontaneous mutation where resistance takes over population because it provides an advantage
(vertical transmission)
o Horizontal gene transfer through competence (DNA uptake), conjugation (bacterial mating), or
phages/transduction of mobile genetic elements
, · What are some common means by which antibiotic resistance genes can be acquired by
cells?
(HGT) competence, conjugation, or phages
· What is the difference between genetic and non-genetic resistance?
o Genetic- Semi permanent. Resistant cells will continue to be antibiotic resistant even if you
passage them (grow them again and again on a new plate). Mediated by some change in the
DNA.
o Non-genetic- Typically temporary. Change the conditions and they are not resistant anymore.
What are two examples of non-genetic antibiotic resistance?
o Tolerance, persistence, biofilm
· How does resistance compare to tolerance and persistence?
o tolerance is genetic or nongenetic, persistence is impacted by genetics but not really inherited,
whereas resistance is typically genetically acquired
o Tolerance: ability of a whole population of bacteria to survive the transient ABX exposure
more effectively
§ Often induced. For example, exposure to a non-antibiotic compound (class example was an
anti-depressant) induces efflux pumps that help cells survive ABX exposure
o Persistence: a small subpopulation of nongrowing cells that can survive ABX exposure
§ Not typically induced
· What is meant by the resistome?
o All the ABX resistance out there
· What are the ESKAPE pathogens and why are they important?
o Enterococcus faceium, staphylococcus aureus, Klebsiella pneumonie, Acinetobacter
baumannii, pseudomonas aeruginosa, and Enterobacter species
o These bacteria are highly virulent and resistant to antibiotics
· What is the most common mechanism of resistance to β-lactam antibiotics?
CORRECT ANSWERS!!
· How do we define antibiotic resistance?
o The continued growth of bacterial cells in the presence of an ABX @ concentration that would
normally kill cells or stop growth
· What are the 4 main ways that bacterial cells can achieve antibiotic resistance? Give an
example of a mechanism for each way.
§ Block entry: porin
§ Pump out of cytoplasm: efflux
§ Modify or destroy: beta-lactamase or acetylase
§ Modify or mutate ABX target: modifications to 23srRNA that blocks MLS ABX
· What is innate resistance to antibiotics?
o The resistance of antibiotic producers
· What is one way that an antibiotic producer can protect itself from the antibiotics it
makes?
efflux pump
o Enzymes that inactivate ABX in cytoplasm
o Do last set of synthesis outside of celll
What is acquired resistance to antibiotics?
resistance of non-antibiotic-producers
· How can acquired resistance be acquired by cells?
o Spontaneous mutation where resistance takes over population because it provides an advantage
(vertical transmission)
o Horizontal gene transfer through competence (DNA uptake), conjugation (bacterial mating), or
phages/transduction of mobile genetic elements
, · What are some common means by which antibiotic resistance genes can be acquired by
cells?
(HGT) competence, conjugation, or phages
· What is the difference between genetic and non-genetic resistance?
o Genetic- Semi permanent. Resistant cells will continue to be antibiotic resistant even if you
passage them (grow them again and again on a new plate). Mediated by some change in the
DNA.
o Non-genetic- Typically temporary. Change the conditions and they are not resistant anymore.
What are two examples of non-genetic antibiotic resistance?
o Tolerance, persistence, biofilm
· How does resistance compare to tolerance and persistence?
o tolerance is genetic or nongenetic, persistence is impacted by genetics but not really inherited,
whereas resistance is typically genetically acquired
o Tolerance: ability of a whole population of bacteria to survive the transient ABX exposure
more effectively
§ Often induced. For example, exposure to a non-antibiotic compound (class example was an
anti-depressant) induces efflux pumps that help cells survive ABX exposure
o Persistence: a small subpopulation of nongrowing cells that can survive ABX exposure
§ Not typically induced
· What is meant by the resistome?
o All the ABX resistance out there
· What are the ESKAPE pathogens and why are they important?
o Enterococcus faceium, staphylococcus aureus, Klebsiella pneumonie, Acinetobacter
baumannii, pseudomonas aeruginosa, and Enterobacter species
o These bacteria are highly virulent and resistant to antibiotics
· What is the most common mechanism of resistance to β-lactam antibiotics?
