NURS 5334 ANTIBIOTICS | UPDATED Questions with 100% Verified
Answers
Question:
What is the mechanism of action of penicillins in bacterial
cell wall synthesis?
Answer:
Penicillins interfere with the final stage of bacterial cell wall
synthesis called transpeptidation. They bind to
penicillin-binding proteins (PBPs), which catalyze cross-
linking of the peptidoglycan cell wall. This binding weakens
the cell wall, leading to bacterial cell death. Penicillins are
bactericidal and work in a time-dependent manner
Question:
Define the term 'Minimal Inhibitory Concentration (MIC)'.
Answer:
MIC is the lowest concentration of an antimicrobial drug that
prevents visible growth of a microbe after 24 hours of
incubation. It is a quantitative measure of in vitro
susceptibility and is commonly used by clinical labs to guide
therapy
Question:
Why is continuous infusion dosing preferred for beta-lactams
like cephalosporins in certain infections?
Answer:
Beta-lactams exhibit time-dependent killing, meaning their
efficacy depends on the duration that drug levels remain
above the MIC. Continuous infusion maintains drug
concentrations above the MIC for a longer period, enhancing
bacterial killing and clinical outcomes compared to
intermittent dosing
,Question:
What factors affect the penetration of antibiotics into the
cerebrospinal fluid (CSF)?
Answer:
Key factors include lipid solubility (more lipid-soluble drugs
penetrate better), molecular weight (lower molecular weight
drugs penetrate better), protein binding (high protein binding
restricts penetration), and susceptibility to transporters or
efflux pumps. The blood-brain barrier integrity and
inflammation of the meninges also influence penetration
Question:
Explain the difference between bacteriostatic and bactericidal
antibiotics
Answer:
Bacteriostatic antibiotics inhibit bacterial growth and
replication at achievable drug concentrations but do not
necessarily kill bacteria outright. Bactericidal antibiotics kill
bacteria, reducing viable colony counts by ·99% within 18-24
hours. A drug can be bacteriostatic for one organism and
bactericidal for another
Question:
What is the primary cause of resistance to penicillins in many
bacteria?
Answer:
The primary cause is the production of beta-lactamase
enzymes (penicillinases) that hydrolyze the beta-lactam ring,
rendering penicillins inactive. This enzymatic inactivation is
the major mechanism of resistance.
Question:
, How do beta-lactamase inhibitors enhance the efficacy of
beta-lactam antibiotics?
Answer:
Beta-lactamase inhibitors like clavulanic acid, sulbactam, and
tazobactam bind to and inactivate beta-lactamase enzymes,
protecting the beta-lactam antibiotic from degradation, thus
restoring or enhancing its antimicrobial activity against
beta-lactamase producing bacteria
Question:
Why are cephalosporins generally ineffective against Listeria,
Clostridium difficile, and Enterococcus?
Answer:
These organisms have intrinsic resistance mechanisms or lack
the target penicillin-binding proteins that cephalosporins act
upon, making cephalosporins ineffective regardless of
generation.
Question:
What distinguishes first-generation from second-generation
cephalosporins in terms of antibacterial spectrum?
Answer:
First-generation cephalosporins primarily cover gram-positive
bacteria, including methicillin-sensitive Staphylococcus
aureus, with modest gram-negative coverage.
Second-generation cephalosporins have increased activity
against gram-negative bacteria but somewhat reduced
gram-positive coverage
Question:
Describe the spectrum and clinical use of carbapenems
Answers
Question:
What is the mechanism of action of penicillins in bacterial
cell wall synthesis?
Answer:
Penicillins interfere with the final stage of bacterial cell wall
synthesis called transpeptidation. They bind to
penicillin-binding proteins (PBPs), which catalyze cross-
linking of the peptidoglycan cell wall. This binding weakens
the cell wall, leading to bacterial cell death. Penicillins are
bactericidal and work in a time-dependent manner
Question:
Define the term 'Minimal Inhibitory Concentration (MIC)'.
Answer:
MIC is the lowest concentration of an antimicrobial drug that
prevents visible growth of a microbe after 24 hours of
incubation. It is a quantitative measure of in vitro
susceptibility and is commonly used by clinical labs to guide
therapy
Question:
Why is continuous infusion dosing preferred for beta-lactams
like cephalosporins in certain infections?
Answer:
Beta-lactams exhibit time-dependent killing, meaning their
efficacy depends on the duration that drug levels remain
above the MIC. Continuous infusion maintains drug
concentrations above the MIC for a longer period, enhancing
bacterial killing and clinical outcomes compared to
intermittent dosing
,Question:
What factors affect the penetration of antibiotics into the
cerebrospinal fluid (CSF)?
Answer:
Key factors include lipid solubility (more lipid-soluble drugs
penetrate better), molecular weight (lower molecular weight
drugs penetrate better), protein binding (high protein binding
restricts penetration), and susceptibility to transporters or
efflux pumps. The blood-brain barrier integrity and
inflammation of the meninges also influence penetration
Question:
Explain the difference between bacteriostatic and bactericidal
antibiotics
Answer:
Bacteriostatic antibiotics inhibit bacterial growth and
replication at achievable drug concentrations but do not
necessarily kill bacteria outright. Bactericidal antibiotics kill
bacteria, reducing viable colony counts by ·99% within 18-24
hours. A drug can be bacteriostatic for one organism and
bactericidal for another
Question:
What is the primary cause of resistance to penicillins in many
bacteria?
Answer:
The primary cause is the production of beta-lactamase
enzymes (penicillinases) that hydrolyze the beta-lactam ring,
rendering penicillins inactive. This enzymatic inactivation is
the major mechanism of resistance.
Question:
, How do beta-lactamase inhibitors enhance the efficacy of
beta-lactam antibiotics?
Answer:
Beta-lactamase inhibitors like clavulanic acid, sulbactam, and
tazobactam bind to and inactivate beta-lactamase enzymes,
protecting the beta-lactam antibiotic from degradation, thus
restoring or enhancing its antimicrobial activity against
beta-lactamase producing bacteria
Question:
Why are cephalosporins generally ineffective against Listeria,
Clostridium difficile, and Enterococcus?
Answer:
These organisms have intrinsic resistance mechanisms or lack
the target penicillin-binding proteins that cephalosporins act
upon, making cephalosporins ineffective regardless of
generation.
Question:
What distinguishes first-generation from second-generation
cephalosporins in terms of antibacterial spectrum?
Answer:
First-generation cephalosporins primarily cover gram-positive
bacteria, including methicillin-sensitive Staphylococcus
aureus, with modest gram-negative coverage.
Second-generation cephalosporins have increased activity
against gram-negative bacteria but somewhat reduced
gram-positive coverage
Question:
Describe the spectrum and clinical use of carbapenems
