Antimicrobial Therapy Flashcards
What does bacteriostatic mean?
antimicrobial drug that requires host defense mechanism to get rid of bug. Use in healthy people
What does bactericidal mean?
Antimicrobial that eradicates bug without use of host defense
What is minimum inhibitory concentration?
lowest concentration of antimicrobial drug that can inhibit growth of organism on a defined medium. This will vary from person to person
What patient factors affect MIC to kill bug
Pregnancy and lactation, immune system, age, disease
What drugs are avoided in pregnancy?
tetracycline - causes tooth dysplasia and inhibits bone growth
with what type of drugs is a compromised immune system problematic?
bacteriostatic drugs
What differs typically in young and old patients compared to older children and adults?
rental, hepatic and CV function differs
Which drugs block cell wall synthesis by inhibition of peptidoglycan cross-linking
penicillin, methicillin, ampicillin, piperacillin, cephalosporins, azteronam, imipenem
Which drugs block peptidoglycan synthesis of cell wall?
Bacitracin, vancomycin
Which drugs block nucleotide synthesis (metabolism)?
sulfonamides, trimethoprim
Which drugs block DNA topoisomerases, nucleic acid function or synthesis
Fluoroquinolones and rifampin
Which drugs inhibit cell membrane function?
isoniazide, amphotericin B
Which drugs block protein synthesis at 50S ribosomal subunit?
Chloramphenicol, macrolides, clindamycin, streptogramins, linezolid
Which drugs block protein synthesis at 30 S ribosomal subunit
Aminoglycosides, tetracyclines
What is the mechanism of penicillin?
- binds PCPs (penicillin-binding proteins)
- Blocks transpeptidase cross-linking of peptidoglycan
- Activates autolytic enzymes
What is the clinical use of penicillin?
Used for gram positive organisms mostly: S. pneumoniae, S. pyogenes, Actinomyces and syphilis. Bactericidal for gram + cocci & rods, gram-negative cocci, spirochetes.
What has penicillin resistance?
Beta Lactamases - cleave Beta lactam ring
What are the penicillinase-resistant penicillins and what are they used to treat?
Methicillin, Nafcillin, dicloxacillin. Use Naf for Staph. (not MRSA)
How do ampillicin/amoxicillin differ from penicillin?
Wider spectrum, but still penicillinase sensitive. Combine with clavulanic acid to protect against beta lactamase. AmOxicillin = greater Oral bioavailability than ampicillin.
What are aminopenicillins (amox/amp) used to treat?
HELPSS kill enterococci
Haemophilus influenza, E. coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, Shigella, Enterococci.
What are Ticarcillin, carbenicillin, and piperacillin used for?
anti-pseudomonals. TCP - takes care of pseudomonas (and gram - rods).
Penicillinase sensitive, use with clauvulanic acid.
What are the beta lactamase inhibitors?
CAST: Clauvulanic Acid Sulfbactam Tazobactam - often added to penicillin antibiotics to evade destruction
What are the beta lactam drugs that inhibit cell wall synthesis and are less susceptible to penicillinases
Cephalosporins
Which organisms are not covered by cephalosporins?
LAME! Listeria Atypicals (Chlamydia, Mycoplasma) MRSA Enterococci
What are the clinical use of first generation cephalosporins and what are the names of these drugs?
Drugs: cefazolin, cephalexin PEcK P - proteus mirabilis E. coli Klebsiella
What do the 2nd generation cephalosporins treat and what are the drug names?
Drugs: cefoxitin, cefaclor, cefuroxime HEN PEcKS H- H.influenza E - enterobacter aerogenes N - neisseria P =- proteus mirabilis E. coli K - Kleibsiella S - serratia
What are the third generation cephalosporins and what are they used to treat?
Drugs: ceftriaxone - used for meningitis and gonorrhea
cefotaxime,
ceftazidime - used for pseudomonas
Treat serious gram negative infections resistant to other beta lactams
What are the 4th generation cephalosporins and what are they used for?
Drugs: cefepime. Increased activity against pseudomonas and gram positive organisms.