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Antibiotics
AB
Question | Answer |
---|---|
Fosfomycin | inhibits binding of PEP to GlcNAc --> no production of MurNAc (analog of PEP) |
D-cycloserine | inhibits production of pentapeptide by blocking action of D-Ala racemase & ligase (analog of D-Ala) |
Vancomycin | inhibits transglycosylation (flipping out and joining of adjacant GlcNAc-MurNAc) --> binds to D-Ala-D-Ala = inc in osmotic lysis |
Bacitracin | inability to recycle GCL-P, therefore, unable to bind to cytoplasmic membrance to begin formation of peptidoglycan |
Penicillin/Cephalosporin | form stable structure with transpeptidase so cross-linking CAN'T take place |
Linezolid | Bind to the 23S of the 50S subunit --> instable 70S; cidal = streptococci & static = staph & enterococci |
Aminoglycosides | Bind to & interfer with proteins of the 30S; bactericidal; broad spectrum; nephro-/ototoxicity |
Streptomycin | AMINOGLYCOSIDE; 1) produce kink @ A-site = misreading and incorrect codon inserted, 2) production of faulty outer membrane proteins = leaky membrane, 3) inability of polysomal production = 70S instability = fall apart |
Spectinomycin | forms instable 70S complex (not misreading); bacteriostatic; GONORRHEA treatment (when beta-lactamase producing species) |
Tetracyclines | bind to 30S & inhibit binding of aa-tRNA @ A-site; bacteriostatic; broad spectrum; RESISTANCE: mutation in OmpF (no uptake) |
Chloramphenicol | binds to 50S & alters tRNA structure (no ability to add aa-tRNA to A-site); bacteriostatic; broad spectrum; RESISTANCE: acetyltransferases that acetylate the hydroxyl group |
Lincomycin/Clindamycin | binds to 50S & alters tRNA structure = no ability to add aa-tRNA to A-site); bacteriostatic; narrow spectrum (G+ bacteria, clind = anaerobic G- or bacteroides); RESISTANCE: methylation of 23S rRNA |
Macrolides | erythromycin derived (w/ lactone ring); block movement along mRNA; bacteriostatic; medium spectrum (Mycoplasma, Legionella, Chlamydia, Camplylogacter); RESISTANCE: methylation of 23s rRNA or hydrolysis of lactone ring by esterase |
Ketolides (Telithromycin) | binding w/in exit tunnel of 50S rRNA = no ability to fully produce nascent polypeptide; static or cidal |
Streptogramins | Dalfopristin (bind 50S --> prevent elongation); Quinupristin (premature release of peptide chains); Synercid (both); static (either alone) or cidal (synercid) |
Sulfonamides | inhibits folic acid synthesis via dihydropteroate synthetase (no dihydropteroic acid); analog of PABA; bacteriostatic; broad spectrum (NOT M. tuberculosis); CAN'T synthesize thymidine/uridine |
Trimethoprim | inhibits dihydrofolate reductase = NO BH4; analong of BH2; bacteriostatic; broad spectrum |
PAS | inhibits folic acid synthesis via dihydropteroate synthetase (no dihydropteroic acid); effective on M. tuberculosis |
Rifampin/Rifabutin | binds to beta-subunit of RNA pol (no unwinding); bacteriocidal; narrow spectrum (strep/staph, neisseria, mycobacteria); NO TRANSCRIPTION |
Quinolones | bind to DNA gyrase --> unable to unwind DNA; bactericidal; narrow (nalidoxic acid = no Pseudomonas) or broad (rest); treatment of UTIs |
Metronidazole | disrupts DNA/inhibits replication/DNA breaks; administered as a prodrug & metabolized by oxidoreducatses (H. pylori/E. histolytica/Giardia); Bactericidal; narrow spectrum |
Polymyxins (Colistin) | hydrophobic tail (insert into membrane) & hydrophilic head (binds to PE/LPS to disrupt membrane); bactericidal; narrow spectrum (pseudomonas) |
Amphotericin B (& nystatin) | hydrophobic face (bind to ergosterol) & hydrophilic face (forms pore for leakage of H2O/electrolytes); lead to NVD, NEPHROTOXIC, ANEMIA |
Azoles | inhibit ergosterol synthesis (via 14-alpha-demethylase) |
Allylamines | inhibit ergosterol synthesis (via squalene epoxidase) |
Echinocandins | block cell wall synthesis (via 1,3-beta glucan synthase) |
Flucocytosine | replace uracil w/ 5-flurouracil in fungal RNA; interfere w/ DNA synthesis via inhibition of thymidylate synthetase |