Week 7 Flashcards
What class of antibiotics are responsible for causing discoloration and hypoplasia of teeth and bone?
tetracyclines
What class of antibiotics are responsible for preventing binding of tRNA to the mRNA by binding to the 30S subunit?
tetracyclines
This type of antibiotic is slowly degraded into nephrotoxic compounds in the container, so they shouldn’t be given to patients if over 6 months old.
tetracyclines
Which antibiotic was developed to combat resistant to tetracyclines?
Glycylcycline (Tigecycline)
Which class of antibiotics bind to the 30S ribosome subunit and distort its structure causing misreading of the mRNA?
aminoglycosides
What are some major side effects of aminoglycosides?
Ototoxicity (may be irreversible), nephrotoxicity, neuromuscular paralysis
Which class of antibiotics bind to the 50S subunit of ribosome and inhibits translocation steps of protein synthesis?
Macrolides
Which class of antibiotics is known for its drug-drug interactions with inhibition of CYP3A4 (grape juice)?
Macrolides
Which class of antibiotics is similar to macrolides, but its MOA is inhibiting RNA synthesis by RNA polymerases?
Macrocyclics (Fidaxomicin)
Which class of antibiotics is similar to macrolides and binds to 50S ribosome subunit and inhibits protein synthesis by blocking the polypeptide exit tunnel?
Lincosamides (clindamycin)
Which class of antibiotics bind to the bacterial 23S ribosomal RNA of the 50S subunit which inhibits the formation of the 70S initiation complex and translation of bacterial proteins?
Oxazolidinones (linezolid, tedizolid)
Which class of antibiotics inhibits both A & B subtypes of monoamine oxidase?
Oxazolidinones (linezolid, tedizolid)
Which class of antibiotics disrupts elongation and typically used in combination?
Streptogramins (dalfopristin/quinupristin)
Which class of antibiotics attacks the 50S ribosomal subunit and inhibits protein synthesis at the peptidyl transferase reaction?
Chloramphenicol
Which form of penicillin is orally administered and more stable in acidic conditions?
Penicillin V
Penicillin V is the oral form of penicillin and is more stable in acidic conditions. It is typically used for minor infections due to its poor bioavailability, narrow spectrum, and requirement of multiple daily dosing.
Which antibiotic is the standard therapy for primary, secondary, or early latent syphilis?
Penicillin G
A single dose of benzathine penicillin G is the standard therapy for primary, secondary, or early latent syphilis caused by the spirochete Treponema pallidum, providing low but persistent serum levels of penicillin.
What is the most common mechanism of antibiotic resistance in penicillin?
The most common mechanism of antibiotic resistance in penicillin is the production of beta-lactamases by bacteria, such as Staphylococcus aureus. These enzymes degrade the beta-lactam ring of penicillin, rendering them ineffective.
Which molecular structure makes the antibiotics nafcillin, oxacillin, methicillin, and dicloxacillin resistant to cleavage by bacterial beta-lactamases?
bulky R group
What are the antistaphylococcal penicillins?
Oxacillin, Nafcillin, Dicloxacillin (Methicillin)
Why are anti-staphylococcal penicillins not effective against MRSA?
Methicillin-resistant Staphylococcus aureus (MRSA) produces altered penicillin binding proteins that have a low affinity for binding beta-lactam antibiotics. This renders anti-staphylococcal penicillins ineffective.
For which bacterial infections is empiric treatment with nafcillin, oxacillin, or dicloxacillin most appropriate?
skin and soft tissue infections
Which of the following best describes the mechanism of action shared by the tazobactam and sulbactam?
Tazobactam and sulbactam inhibit bacterial β-lactamases. These drugs protect penicillin antibiotics from destruction by β-lactamases, enabling penicillin-based therapy for bacteria such as methicillin-sensitive Staph aureus.
When compared to other penicillins, piperacillin and ticarcillin have important additional indications due to activity against which of the following bacteria?
Pseudomonas species
Pseudomonas is a gram-negative aerobic bacteria that can cause a wide variety of serious infections, including pneumonia, urinary tract infection, and otitis externa. Piperacillin and ticarcillin are extended-spectrum penicillins, which unlike other penicillins, can be used to treat Pseudomonas infections.
What is the difference between the pharmacokinetic properties of the amino-penicillins amoxicillin and ampicillin?
The amino-penicillins, amoxicillin and ampicillin, have similar spectrums of activity, but amoxicillin has better oral bioavailability; a mnemonic is that aMOxacillin is administered by MOuth, and AMPicillin comes in AMPules. Amoxicillin is often given orally for common pediatric illness, including infections of the ear, sinuses, or throat. On the other hand, ampicillin is administered intravenously for more serious infections that require anaerobic coverage such as aspiration pneumonia.
Which of the following best describes the mechanism by which Enterococcus may become resistant to ampicillin?
Ampicillin-resistant strains of Enterococcus produce β-lactamase, which cleaves the β-lactam ring and prevents β-lactam antibiotics from blocking bacterial transpeptidase peptidoglycan cross-linking. Resistant Enterococcus infections may be treated with ampicillin plus sulbactam or with vancomycin.
What is a distinguishing feature of cephalosporin antibiotics in comparison to the penicillin antibiotic ampicillin?
They are resistant to penicillinase, but vulnerable to other beta-lactamases
Like ampicillin, cephalosporins are β-lactam antibiotics that bind penicillin binding protein (transpeptidase), preventing it from cross-linking peptidoglycan in the bacterial cell wall. However, while ampicillin is susceptible to β-lactamase (penicillinase), β-lactamases are ineffective against cephalosporins.
Aztreonam is most effective in treating infections caused by which of following pathogens?
gram negative aerobics
What is the primary treatment for Listeria monocytogenes?
Ampicillin
Vancomycin is an important antibiotic used to treat gram _____ bacterial infections.
positive
Vancomycin is often used as empiric treatment when methicillin-resistant Staphylococcus aureus (MRSA) is suspected. Vancomycin is not effective against gram negative organisms.
What is the mechanism of action of vancomycin?
Vancomycin is a glycopeptide antibiotic which obstruct the synthesis of bacterial cell walls. Vancomycin binds to the cell wall precursors D-alanine-D-alanine. By binding to these oligopeptides, vancomycin inhibits the synthesis of peptidoglycan necessary to make up the cell wall.
What is the difference between lipoglycopeptides and glycopeptide antibiotics?
lipoglycopeptides are more potent
Imipenem is administered as a broad spectrum antibiotic but it is easily degraded by the kidneys. What is administered alongside to prevent this?
Cilastatin
The lowest concentration of drug required to inhibit the growth of an organism.
Minimum inhibitory concentration
Why do you need to use a loading dose?
for rapid onset and establishment above MIC levels
This refers to the phenomenon where bacterial growth remains suppressed even after the concentration of an antibiotic has fallen below the minimum inhibitory concentration (MIC).
post-antibiotic effect
Acrosomal rxn
Fertilin and integrin are two molecular determinants involved in which process?
The fusion of sperm head and secondary oocyte membranes. It is also responsible for blocking polyspermy.