Micro - Antimicrobials Part 1 Flashcards
How do imipenem, aztreonam, and cephalosporins work?
They block cell wall synthesis by inhibiting cross-linking of peptidoglycans
How do bacitracin and vancomycin work?
They block peptidoglycan synthesis
What antibiotic works by disrupting bacterial/fungal cell membranes?
Polymyxins
Sulfonamides and trimethoprim work by blocking the synthesis of what molecules?
Nucleotides
How do fluoroquinolones exhibit their antibacterial effects?
DNA topoisomerase inhibition
Rifampin blocks the synthesis of what bacterial molecule?
mRNAs
Chloramphenicol works by what mechanism?
It binds to the 50S ribosomal subunit and blocks the synthesis of protein
Lincosamides work by what mechanism?
They bind to the 50S ribosomal subunit and block the synthesis of protein
Streptogramins work by what mechanism?
They bind to the 50S ribosomal subunit and block the synthesis of protein
Linezolid works by what mechanism?
It binds to the 50S ribosomal subunit and blocks the synthesis of protein
Macrolides work by what mechanism?
They bind to the 50S ribosomal subunit and block the synthesis of protein
Tetracyclines work by what mechanism?
They bind to the 30S ribosomal subunit and block the synthesis of protein
Aminoglycosides work by what mechanism?
They bind to the 30S ribosomal subunit and block the synthesis of protein
Name six antibiotics that are bacteriostatic.
Erythromycin, Clindamycin, Sulfamethoxazole, Trimethoprim, Tetracyclines, and Chloramphenicol (remember: were ECSTaTiC about bacteriostatics)
Name six antibiotics that are bactericidal.
Vancomycin, Fluoroquinolones, Penicillin, Aminoglocysides, Cephalosporins, and Metronidazole (remember: Very Finely Proficient At Cell Murder)
Penicillin _____ is administered intravenously; penicillin _____ is administered orally.
G; V
Penicillin is the prototype for which class of antibiotics?
β-Lactams
Penicillin blocks _____ to inhibit cross-linking and activates _____ enzymes as well.
Transpeptidase; autolytic
Which types of bacteria are killed by penicillin?
Gram-positive cocci and rods, gram-negative cocci and spirochetes; bacteria with penicillinase are resistant
What are the two major toxicities associated with penicillin treatment?
Hypersensitivity reactions and hemolytic anemia
Methicillin, nafcillin, and dicloxacillin have the same mechanism of action as what class of antibiotics?
Penicillins
What differentiates methicillin, nafcillin, and dicloxacillin from penicillin?
Methicillin, nafcillin, and dicloxacillin are resistant to penicillinase and are effective against bacteria like Staphylococcus aureus
Methicillin, nafcillin, and dicloxacillin are resistant to penicillinase as a result of what difference in their structure?
A bulkier R group
Methicillin, nafcillin, and dicloxacillin are narrow-spectrum antibiotics that are used clinically for the treatment of what conditions?
Staphylococcus aureus infections, except methicillin-resistant Staphylococcus aureus
(remember: naffor staph)
Why are nafcillin and dicloxacillin ineffective against methicillin-resistant Staphylococcus aureus?
Because of altered penicillin-binding protein target sites
What are the two major toxicities associated with methicillin treatment?
Hypersensitivity reactions and interstitial nephritis
Which drug can be administered with ampicillin to make it more effective against penicillinase-producing organisms?
Clavulanic acid, an inhibitor of penicillinase
Which has greater oral availability: amoxicillin or ampicillin?
AmOxicillin has better Oral availability
Which drugs have a wider spectrum of effectiveness: ampicillin/amoxicillin or penicillin?
Ampicillin and amoxicillin have a broader spectrum of effectiveness (remember: AMPicillin is Amped up penicillin)
What are the three major toxicities caused by ampicillin and amoxicillin?
Hypersensitivity reactions, rash, and pseudomembranous colitis
In addition to some gram-positive bacteria, which gram-negative rods are susceptible to ampicillin and amoxicillin?
H. influenzae, E. coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, enterococci (remember: ampicillin/amoxicillin HELPS kill enterocicci)
True or False? Ticarcillin, carbenicillin, and piperacillin are resistant to penicillinase.
False; but they can be used with clavulanic acid to give them resistance to penicillinase
Which bacteria are ticarcillin, carbenicillin, and piperacillin active against?
Gram-negative rods, including Pseudomonas(remember: Ticarcillin, Carbenicillin, and Piperacillin Takes Care of Pseudomonas)
What is a common toxicity of ticarcillin, carbenicillin, and piperacillin?
Hypersensitivity reactions
Cephalosporins belong to what class of drugs?
β-Lactams
Are cephalosporins more or less susceptible to penicillinase than other -lactams?
Less susceptible
Name two examples of first-generation cephalosporins.
Cefazolin and cephalexin
First-generation cephalosporins cover which organisms?
Gram-positive cocci, Proteus mirabilis, Escherichia coli, and Klebsiella pneumoniae. (remember: PEcK)
Name three examples of second-generation cephalosporins.
Cefoxitin, cefaclor, and cefuroxime
Second-generation cephalosporins cover which organisms?
Gram-positive cocci, Haemophilus influenzae, Enterobacter aerogenes, Neisseria, Proteus mirabilis, Escherichia coli, Klebsiella pneumoniae, and Serratia marcescens(remember: HEN PEcKS)
Name three examples of third-generation cephalosporins.
Ceftriaxone, cefotaxime, and ceftazidime
Third-generation cephalosporins cover which organisms?
Serious gram-negative infections that are resistant to other -lactams
Why are third-generation cephalosporins a good choice for treatment of meningitis?
Because they penetrate the blood-brain barrier
Which third-generation cephalosporin is used for Pseudomonascoverage?
Ceftazidime
Which cephalosporin is often used to treat gonorrhea?
Ceftriaxone
Name one example of a fourth-generation cephalosporin.
Cefepime
Fourth-generation cephalosporins are different from third-generation cephalosporins in that the fourth-generation drugs have increased activity against which organisms?
Pseudomonasand gram-positive organisms
True or False? Unlike penicillin, hypersensitivity reactions are not a major toxicity of cephalosporins.
False; hypersenstivity reactions are a potential toxocity of all cephalosporins