antimicrobials Flashcards
antimicrobial drugs
1) target microorganisms
- bacterial, fungals, virals, parasitic
combating covid-19
1) prophylaxis
2) treatment
- dexamethasone
- anti-viral drugs
histor of antimicrobials
1) paul ehrlich
- arsenic compounds that killed microbes
2) alexander fleming
- penicillin from penicillium notatum
3) gerhard domagk
- sulfanimide
4) selman waksman
- gave definition of antibiotics
antibiotics
1) substances that are produces naturally by microorganisms that kill other microorganisms
2) ANTIBACTERIAL!!! current definition
naturally occuring
1) produced by microorganisms like bacteria and fungi
semisynthetic
1) chemically altered antibiotics
2) pharmicologically more active
synthetic
1) completely synthesized in a laboratory
penicillin
1) beta lactam with side chain
amoxicillin
1) semisynthetic
2) same beta lactam but different side chain
selective toxicity
1) target bacterial cell without damaging human cell
- target a uniquely bacterial molecule
2) target a molecule that is synthesized in bacterium but can be obtained elsewhere in humans
3) bacterial ribosomes
4) bacterial enzymes
three aspects of bacteria targeted by antibiotics
1) bacterial cell envelope
2) biosynthetic processes within bacteria
3) bacterial metabolism
antibiotic classification
1) cell wall synthesis inhibitors
2) protein synthesis inhibitors
3) metabolic pathways inhibitor
4) nucleic acid synthesis inhibitor
cell wall synthesis
1) beta-lactam antibiotics
- penicillins
- cephalosporins
- carbapenems
- monobactams
2) vancomycin (glycopeptide) and bacitracin
beta-lactam anitbiotics
1)beta-lactam core structure
- antimicrobial
2) side chains
- pharmacokinetic properties
- spectrum of activity
3)impair last stage of cell wall synthesis by interfering with penicillin binding proteins
4) directly bind to PBP
peptidoglycan
1) peptide chains of NAGA and MAMA
2) last stage is transpeptidase binding protein for cross linking
vancomycin
1) binds to alanine on side chain of newly synthesized peptide chain
2) blocking alanine bridge formation
3) * PBP-binding site (penicillin binding protein binding site)
bacterial ribosome
1) 70s = 30s and 50s
2) ours are 80s = 40s and 60s
inhibition of metabolic pathways
1) folic acid
- vitamin required to make nucleotides and AAs
2) we can get it from food but bacteria synthesize it from PABA
3) sulfonamide binds to the enzyme that converts PABA to folic acid
quinolones
1) inhibit topoisomerase that regular SNA super coiling
metronidazole
1) the reduced nitro group can hinder DNA replication, transcription, and repair, resulting in cell death
rifampin
1) inhibit RNA synthesis
antibiotic spectrum
1) range of bacteria that an antibiotic inhibits or kills
2) narrow spectrum vs broad spectrum
3) broad may cause secondary or superinfections by transient pathogens or normal microbiotia
antimicrobial potency
1) diffusion susceptibility
2) MIC
- minimum concentration of an antibiotic that inhibits the entire growth of bacterial strain
3) MBC
- minimum concentration required to kill the strain
zones of inhibition
1) size of the zone is proportional to the potency
bacteriostatic
1) inhibit growth
bactericidal
1) kill bacteria
antimicrobial potency
1) determination of the MIC and mbC by dilution test
2) standard amount of bacterium with graded doses of antibiotic
toxicit
1) cause of adverse reactions
2) prescribing drugs to pergnant women need considerations
4) toxic to kidneys, liver, or nerves
-ex. aminoglycosides => ototoxicity
- tetracycline hepatic and renal toxicity
non-toxic
1) blakc hair tongue
2) tetracycline causes teeth and bone discoloration
hypersensitivity
1) anaphylactic shock
disruption of normal microbiota
1) may result in secondary infections
2) overgrowth
- oral candidiasis, hairy tongue
3) of greatest concern to hospitalized parients
intrinsic resistance
1) porins limit entry of large antibiotics
acquired resistance
1) mutation within the same species or acquisition of R plasmids via horizontal gene transfer
enzymatic inactivation of drug
1) beta-lactamase
2) scientists made clavulanate to amoxicillin to inhibit this enzyme
altered uptake and efflux
1) efflux pump and decreased accumulation
misuse of antibiotics
1) emergence of resistant strains
2) before prescribing antibiotics to your patient
3) collect patient sample
empiric therapy
1) prior to identification of the organisms
2) ideally, the treatment has been selected after the organisms has been identified and drug susceptibility established
- exception is critical ill patient
- broad spectrum therapy
prescribed for
1) prophylaxis
2) specific / definitive therapy
2) empirical / presumptive therapy
