Unit 5abx Flashcards
chemically modified antibiotics, and chemically synthesized chemotherapeutic agents which inhibit or kill microorganisms
what is antimicrobial
chemotherapeutic agents that either kill or inhibit the growth of microorganisms. naturally synthesized
what is antibiotic
drugs used to treat infections, cancers and other diseases and conditions
what is chemotherapeutic
define empirical treatment
assumed drug would work w/o actually testing to prove that it would
list modes of action of antimicrobials used for bacterial infection
- cell wall synthesis inhibition
- inhibition of protein synthesis at the ribosomal level
- inhibition of DNA, RNA
- folate pathway competitive inhibition
- active against cell membrane
list the characteristics of an ideal antimicrobial agent (“Magimycin”)
- bactericidal
- narrow-spectrum
- inexpensive
- non toxic, non irritating, non staining
- no sensitization
- high concentration of active form available in tissue
- taken orally but absorbed proximally
- no resistance
features of beta-lactams
beta-lactam ring, bind to PBP in cell wall. bactericidal against gram POS
penicillin features
beta-lactam. narrow spectrum (gram POS), cheap, effective. vulnerable to beta-lactamase
beta-lactam. extended spectrum some gram POS. vulnerable to beta-lactamase
ampicillin
beta-lactam.replace penicillin, inhibits beta-lactmase binding
oxacillin
beta lactam: cephems (cephalosporins)
cefazolin, ceftazidime, cefoxitin, ceftaroline
target binding site is d-ala d-ala in peptidoglycan
vancomycin
narrow gram POS. toxic use topically. interferes with sterol synthesis
bacitracin
modification of cephalosporins (cephems)
diff 2nd ring structure (6-membered dihydrothiazine) and 2 side chains
how do generations relate to spectrum and resistance to beta-lactamases
gram POS coverage is lost and gram NEG gained. resistance to b-lactamases increases w/generation
why is vancomycin effective against gram POS that have altered PBPs
no beta-lactam ring therefore not affected by b-lactamases and doesn’t bind to PBPs
drugs for above the diaphragm anerobic infections
Class: lincosamide such as clindamycin
drug for BELOW the diaphragm anerobic infections
metronidazole aka flagyl
class of drugs unsuitable for anerobic infections and why
aminoglyside b/c cellular uptake is aerobic
rationale for combo therapy amp and gentamicin
treat severe systemic infections, β-lactam
drug weakens cell wall allows greater uptake of the aminoglycoside
rationale for combo therapy trimethoprim and sulphamethoxazole TMP-SMX
less adverse effects than sulphas. useful in UTI and respiratory
specific drugs in MLS group- Macrolides
erythomycin, claithomycin, azithromycin, dirithromycin, c
specific drugs in the MLS group Lincosamides
clindamycin
specific drugs in the MLS group Streptogramin
Quinupristin - dalfopristin (Synercid)
why nitrofurantoin is useful for bladder infections but not kidney infections
high bactericidal levels are
achieved in urine but may be undetectable in other sites
why bacitracin and polymyxin B and E (colisitin) are used topically
nephrotoxic meaning interferes with sterol synthesis
why polymyxins: considered drugs of “last resort”
disrupt our phospholipid acts like detergent
why polymyxin E useful for ID as part of antibiogram
intrinsic resistance in the
Enterobacteriaceae family is rare and predictable as an identification aid
