Antibiotics Flashcards
(29 cards)
Nafcillin
Class: (penicillin) beta lactam
Target: penicillin binding proteins (PBPs)
Mechanism: block transpeptidase cross linking of peptidoglycan in cell wall
Spectrum: narrow spectrum, anti-staph
resistant to B lactamase because of bulky R group
Gentamicin
Class: aminoglycoside
Target: binds to 30s subunit of bacterial ribosome
Mechanism: irreversible inhhibition of initiation of translation
Spectrum: bactericidal
- can cause mitochondria side effects
- can be synergistic with B-lactam abx
beta lactam agents
Penicillins:
- penicllin
- amoxicillin
Semi-synthetic penicillins (anti-staph)
- methicillin
- nafcillin
- oxacillin
Beta lactam/beta lactamase inhibitor combos
- amoxicillin/clavulanate
- piperacillin/tazobactum
Cefazolin
Class: (beta lactam) cephalosporin, 1st generation
Target: penicillin binding proteins (PBPs)
Mechanism: inhibit cell wall synthesis
Spectrum: bactericidal; 1st gen used for g+ cocci
-less susceptible to b-lactamase
(fluoro)quinolones action
- inhibit DNA-bound gyrase
- inhibit replication & transcription of bacterial DNA
- very selective for bacterial gyrase
Drugs that act on the central dogma (replication/transcription/translation) of biology of bacteria
examples of synthetic antimicrobials
sulfonamides
isoniazid
quinolones
linezolid
which classes of drugs have activity against pseudomonas aeruginosa?
-Beta-lactams (bind PBPs to inhibit cell wall synthesis)
-aminoglycosides (bind 30s subunit of ribosomes, inhibit translation)
-fluroquinolones (bind to & disrupt DNA gyrase, inhibit replication)
RIfamyins (Rifampin)
Class: antimycobacterial
Target: inhibit RPOb of RNA polymerase from binding, so that transcription of bacterial DNA is inhibited
Mechanism: inhibit DNA-dependent RNA polymerase, inhibiting transcription
Spectrum: effective for mycobacterium tuberculosis (acid fast bug)
Trimethoprim/sulfamethoxazole
Class: sulfonamide
Target: inhibit bacterial dihydrofolate reductase
Mechanism: interferes with folate synthesis
Spectrum: bacteriostatic
Metronidazole
Class: nitromidazole
Target: prodrug activated by bacterial enzyme
Mechanism: forms toic free radicals that damage DNA, inhibits DNA replication
Spectrum: bactericidal; only works on anaerobes
Penicillin
Class: (prototype) beta lactam
Target: penicillin binding protein
Mechanism: block transpeptidase cross linking of peptidoglycan in cell wall
Spectrum: gram positives
-is a structural analog of D-Ala-D-Ala
*bacteria (liek s. aureus) can produce a B-lactamase enzyme, which cleaves the B-lactam ring of penicillin, making the bacteria resistant
Vancomycin
Class: glycopeptide
Target: D-ala D-ala portion of cell wall (earlier step than PBPs)
Mechanism: inhibit cell wall synthesis
Spectrum: bactericidal; only used for gram + bugs
not susceptible to B-lactamase; first glycopeptide abx
-most effective therapy for MRSA infections
translation inhibiting abx (target: ribosomal protein synthesos_ are usually bactericidal or bacteristatic?
-static!
(other than amino glycosides)
-ex) tetracyclines, chloramphenicol, lincosamides, macrolides, streptogramins
Piperacillin/tazobactam
Class: beta lactam/ B-lactimase inhibitor
Target: penicillin binding proteins (PBPs) & beta lactamase
Mechanism: block transpeptidase cross linking of peptidoglycan in cell wall
Spectrum: extended spectrum
works by inhibiting the beta-lactamase & allowing the beta-lactam part to reach the PBP
Amoxicillin
Class: (penicillin) beta lactam
Target: penicillin binding proteins
Mechanism: block transpeptidase cross linking of peptidoglycan in cell wall
Spectrum: gram positives & gram negatives
Ceftriaxone
Class: (beta lactam) cephalosporin, 3rd generation
Target: penicillin binding proteins (PBPs)
Mechanism: inhibit cell wall synthesis
Spectrum: wider spectrum; used with gram negative infections too
Azithromycin
Class: macrolide
Target: bind to 50s subunit of ribosome
Mechanism: block translocation (step of translation)
Spectrum:
examples of natural antimicrobials
(produced during microbial chemical warfare in the environment)
**2/3 of all abx
penicillins
tetracyclines
chloramphenicol
vancomycin
rifamycin
aminoglycosides
macrolides
Isoniazid
Class: antimycobacterial
Target: targets mycolic acid
Mechanism: inhibits mycoside synthesis
Spectrum: effective for mycobacterium tuberculosis (acid fast bug)
Mechanisms of selectivity of translation inhibitors
- selective for prokaryotic ribosomes (70s)– compared to 80s eukoaryotic ribosomes
- selective accumulation (ex tetracycline inhibits eukaryotic ribosomes just as well as bacterial, but is selectively toxic for bacteria because animal cells don’t accumulate the drug)
- selective drug activation (prodrug– metronidazole)
Levofloxacin
Class: fluoroquinolone
Target: DNA- bound gyrase
Mechanism: inhibit DNA-bound gyrase (which inhibits bacterial DNA replication)
Spectrum: bactericidal, broad spectrum
-not to be taken with antacids
Methicillin
- semi-snthetic penicillin (B-lactam)
- mechanism: inhibits cell wall synthesis by binding to penicillin binding protein 2 (PBP2); designed to evade B-lactamse produced by s. aureus
**MRSA= methicillin resistnat staph. aureus: become resistant because they produce an altered PBP2 protein (PBP2a), so that methicillin can’t bind to inhibit cell wall synthesis
Augmentin
(Amoxicllin/clavulanate)
Class: beta lactam/ beta lactimase inhibitor
Target: penicillin binding proteins (PBPs) and B-lactamase
Mechanism: same as B lactam PLUS protects acainst B-lactamase that destroys B-lactam ring
Spectrum:
- anti-staphylcoccal med
- mechanism: B-lactam binds to PBP in cell wall, while B-lactamase inhibitor binds & inhibits B-lactamse, allowing the B-lactam abx to function
