MCB4271 EXAM 2 QUESTIONS AND ANSWERS
What does it mean for a microbe to be resistant to antibiotics? - Answer -Non-
achievable concentration to kill microbe -> toxic to humans, bacteria are deemed
resistant
What contributes to clinical resistance? - Answer -Multiple factors such as type of
bacteria, infection site, antibiotic pharmocokinetics, and the immune response affecting
clinical outcomes of antibiotic treatment
Antibiotic resistance is a term that is relative to...? - Answer -Antibiotic concentration
that can kill bacteria in a Petri dish
What is minimum inhibitory concentration (MIC)? - Answer -a minimum concentration of
an antibiotic required to completely inhibit bacterial growth
The infection is susceptible to treatment if...? - Answer -The antibiotic MIC falls within a
concentration that is non-toxic to humans
The infection manifests clinical resistance when...? - Answer -The MIC of a specific
antibiotic is toxic to humans and the infection can no longer be treated with that
antibiotic.
What are the three connected microbial ecosystems? - Answer -Environmental, non-
clinical, and clinical
What ecosystem has the lowest resistance gene selection and why? - Answer -
Environmental because every singel antibiotic resistant gene is present in that
environment but it is simply not selected for.
What ecosystem encapsulates use of antibiotics in food animals and increasing
concentrations of antibiotics in the environment? - Answer -Non-clinical ecosystem
Which ecosystem has the highest selective pressure? - Answer -Clinical ecosystem
because relative concentration of antibiotics is high.
What did Edward Abraham and Ernst Chain do? - Answer -Identified an enzyme from
bacteria that is able to destroy penicillin, was the first official indication of a bacterial
mechanism of action responsible for antibiotic resistance
Anti-antibiotics are natural defense mechanisms for whom? - Answer -Humans do not
develop antibiotic resistance, bacteria naturally develop counter-attack mechanisms
against other microbes that are trying to kill them.
,What are the two major types of resistance? - Answer -Intrinsic and Acquired
What is intrinsic resistance and give an example. - Answer -Naturally occurring
resistance to antibiotics. The outer membrane of gram-negative bacteria makes them
more resistant to more antibiotics than gram-positive bacteria.
Bacteria that naturally produce antibiotics have an _______ ability to defend
themselves. - Answer -intrinsic
What is acquired resistance and give an example. - Answer -Genetic mutations.
Acquisition of mobile elements carrying antibiotic resistant genes.
What is the type of resistance that poses the highest risk? - Answer -Intrinsic resistance
What came first antibiotics or efflux pumps? - Answer -Efflux pumps
What are the three major mechanisms of antibiotic resistance? - Answer -Directly
targeting antibiotic, targeting antibiotic availability, and target modification.
What is a way to directly target the antibiotic? - Answer -Antibiotic inactivation
What are the ways to target antibiotic availability? - Answer -Antibiotic efflux, reduced
permeability, or resistance by absence (deletion of a gene).
What are the ways to modify the target of the antibiotic? - Answer -Antibiotic target
modification, replacement, or protection.
What is the WHO antibiotic classificatio system C1 and C2? - Answer -Criterion 1: the
antimicrobial class is the sole, or one of limited available therapies, to treat serious
bacterial infections in people.
Criterion 2: The antimicrobial class is used to treat infections in people cause by either
bacteria that may be transmitted to humans from nonhuman sources or bacteria that
may acquire resistance genes from nonhuman sources.
What antibiotics are considered critically important? - Answer -Antimicrobial classes
which meet both C1 and C2 are termed critically important for human medicine.
What are the prioritization criteria for WHO? - Answer -P1 = high absolute number of
people, or high proportion of use in patients with serious infections in healthcare
settings affected by bacterial diseases for which the antimicrobial class is the sole or
one of few alternatives to treat serious infections in humans.
P2 = High frequency of use of the antimicrobial class for any indication in human
medicine, or else high proportion of use in patients with serious infections in heakthcare
settings, since use may favor selection of resistance in both settings.
P3 = The antimicrobial class is used to treat infections in people for which there is
evidence of transmission of resistant bacteria (non-typhoidal Salmonella and
, Campylobacter spp.) or resistance genes (high for E. coli and Enterococcus spp.) from
non-human sources
What are the highest and high priority? - Answer -Highest priority = three out of three
prioritization criteria
High priority = two out of three prioritization criteria
Which antimicrobial classes are deemed critically important antimicrobials due to
meeting C1, C2, P1, P2, and P3. - Answer -Cephalosporins (3rfd, 4th, and 5th
generation), glycopeptides, macrolides and ketolides, polymyxins, and quinolones.
What is antibiotic inactivation? - Answer -Enzymatic modification of antibiotic to confer
drug resistance
What are the three ways that antibiotics can be inactivated? - Answer -Enzymatic
degradation, enzymatic modification of antibiotic, and antibiotic inactivation by
sequesteration.
What are 2 examples of enzymatic degradation? - Answer -Hydrolysis and
Linearization
What are 5 examples of enzymatic modification of an antibiotic? - Answer -
Nucleotidylation, phosphorylation, glycosylation, acylation, and hydroxylation.
Summarize the Abraham and Chain experiment. - Answer -Took the extract from B. coli
and incubated the extract with penicillin antibiotic and it inactivated penicillin. Concluded
that it must have been an enzyme that is responsible for deactivating the penicillin
antibiotic.
Why did Abraham and Chain think that it was an enzyme that deactivated penicillin/ -
Answer -Because it got inactivated by heat or by papain (a protease that digests
enzymes)
Who was actually able to extract penicillinase from clinical isolates of penicillin resistant
bacterial strains? - Answer -William Kirby
How do beta-lactamases work? - Answer -Enzymes that hydrolyze the beta-lactam ring
releasing CO2 and rendering the antibiotic ineffective at killing bacteria.
Currently, there are over ______ beta-lactamases identified. - Answer -1,000
What protects the beta-lactam ring from beta-lactamases? - Answer -Bulky side
groups, R-group gets bulkier and bulkier with each generation of penicillins and
cephalosporins.
What does it mean for a microbe to be resistant to antibiotics? - Answer -Non-
achievable concentration to kill microbe -> toxic to humans, bacteria are deemed
resistant
What contributes to clinical resistance? - Answer -Multiple factors such as type of
bacteria, infection site, antibiotic pharmocokinetics, and the immune response affecting
clinical outcomes of antibiotic treatment
Antibiotic resistance is a term that is relative to...? - Answer -Antibiotic concentration
that can kill bacteria in a Petri dish
What is minimum inhibitory concentration (MIC)? - Answer -a minimum concentration of
an antibiotic required to completely inhibit bacterial growth
The infection is susceptible to treatment if...? - Answer -The antibiotic MIC falls within a
concentration that is non-toxic to humans
The infection manifests clinical resistance when...? - Answer -The MIC of a specific
antibiotic is toxic to humans and the infection can no longer be treated with that
antibiotic.
What are the three connected microbial ecosystems? - Answer -Environmental, non-
clinical, and clinical
What ecosystem has the lowest resistance gene selection and why? - Answer -
Environmental because every singel antibiotic resistant gene is present in that
environment but it is simply not selected for.
What ecosystem encapsulates use of antibiotics in food animals and increasing
concentrations of antibiotics in the environment? - Answer -Non-clinical ecosystem
Which ecosystem has the highest selective pressure? - Answer -Clinical ecosystem
because relative concentration of antibiotics is high.
What did Edward Abraham and Ernst Chain do? - Answer -Identified an enzyme from
bacteria that is able to destroy penicillin, was the first official indication of a bacterial
mechanism of action responsible for antibiotic resistance
Anti-antibiotics are natural defense mechanisms for whom? - Answer -Humans do not
develop antibiotic resistance, bacteria naturally develop counter-attack mechanisms
against other microbes that are trying to kill them.
,What are the two major types of resistance? - Answer -Intrinsic and Acquired
What is intrinsic resistance and give an example. - Answer -Naturally occurring
resistance to antibiotics. The outer membrane of gram-negative bacteria makes them
more resistant to more antibiotics than gram-positive bacteria.
Bacteria that naturally produce antibiotics have an _______ ability to defend
themselves. - Answer -intrinsic
What is acquired resistance and give an example. - Answer -Genetic mutations.
Acquisition of mobile elements carrying antibiotic resistant genes.
What is the type of resistance that poses the highest risk? - Answer -Intrinsic resistance
What came first antibiotics or efflux pumps? - Answer -Efflux pumps
What are the three major mechanisms of antibiotic resistance? - Answer -Directly
targeting antibiotic, targeting antibiotic availability, and target modification.
What is a way to directly target the antibiotic? - Answer -Antibiotic inactivation
What are the ways to target antibiotic availability? - Answer -Antibiotic efflux, reduced
permeability, or resistance by absence (deletion of a gene).
What are the ways to modify the target of the antibiotic? - Answer -Antibiotic target
modification, replacement, or protection.
What is the WHO antibiotic classificatio system C1 and C2? - Answer -Criterion 1: the
antimicrobial class is the sole, or one of limited available therapies, to treat serious
bacterial infections in people.
Criterion 2: The antimicrobial class is used to treat infections in people cause by either
bacteria that may be transmitted to humans from nonhuman sources or bacteria that
may acquire resistance genes from nonhuman sources.
What antibiotics are considered critically important? - Answer -Antimicrobial classes
which meet both C1 and C2 are termed critically important for human medicine.
What are the prioritization criteria for WHO? - Answer -P1 = high absolute number of
people, or high proportion of use in patients with serious infections in healthcare
settings affected by bacterial diseases for which the antimicrobial class is the sole or
one of few alternatives to treat serious infections in humans.
P2 = High frequency of use of the antimicrobial class for any indication in human
medicine, or else high proportion of use in patients with serious infections in heakthcare
settings, since use may favor selection of resistance in both settings.
P3 = The antimicrobial class is used to treat infections in people for which there is
evidence of transmission of resistant bacteria (non-typhoidal Salmonella and
, Campylobacter spp.) or resistance genes (high for E. coli and Enterococcus spp.) from
non-human sources
What are the highest and high priority? - Answer -Highest priority = three out of three
prioritization criteria
High priority = two out of three prioritization criteria
Which antimicrobial classes are deemed critically important antimicrobials due to
meeting C1, C2, P1, P2, and P3. - Answer -Cephalosporins (3rfd, 4th, and 5th
generation), glycopeptides, macrolides and ketolides, polymyxins, and quinolones.
What is antibiotic inactivation? - Answer -Enzymatic modification of antibiotic to confer
drug resistance
What are the three ways that antibiotics can be inactivated? - Answer -Enzymatic
degradation, enzymatic modification of antibiotic, and antibiotic inactivation by
sequesteration.
What are 2 examples of enzymatic degradation? - Answer -Hydrolysis and
Linearization
What are 5 examples of enzymatic modification of an antibiotic? - Answer -
Nucleotidylation, phosphorylation, glycosylation, acylation, and hydroxylation.
Summarize the Abraham and Chain experiment. - Answer -Took the extract from B. coli
and incubated the extract with penicillin antibiotic and it inactivated penicillin. Concluded
that it must have been an enzyme that is responsible for deactivating the penicillin
antibiotic.
Why did Abraham and Chain think that it was an enzyme that deactivated penicillin/ -
Answer -Because it got inactivated by heat or by papain (a protease that digests
enzymes)
Who was actually able to extract penicillinase from clinical isolates of penicillin resistant
bacterial strains? - Answer -William Kirby
How do beta-lactamases work? - Answer -Enzymes that hydrolyze the beta-lactam ring
releasing CO2 and rendering the antibiotic ineffective at killing bacteria.
Currently, there are over ______ beta-lactamases identified. - Answer -1,000
What protects the beta-lactam ring from beta-lactamases? - Answer -Bulky side
groups, R-group gets bulkier and bulkier with each generation of penicillins and
cephalosporins.
