1-4 part B Flashcards
what are the 4 groups of antibiotics that use disruption of bacterial cell wall as a mechanism of action?
B-lactams
glycopeptides
polypeptides
others
how is disruption of bacterial cell wall done?
(peptidoglycan unique to bacteria and most pathogens contain it)
antibiotic disrupts construction of peptidoglycan and exposes plasma membrane
4 types of B-lactams
penicillins
cephalosporins
carbapenems and monobactams
(and B-lactamase inhibitors)
2 types of glycopeptides
vancomycin and teichoplanin
2 types of polypeptides
bacitracin and polymixins
peptidoglycans are created in the cytoplasm of bacteria cells and involves the use of ____as a carrier.
this repeated unit is then transported across the membrane by ____.
this is repeated unit is attached to a growing peptidoglycan chain.
peptidoglycan cross-links are formed by _______.
- UDP (uridine diphosphate)
- lipid (bactoprenol)
- transpeptidation
this is the exchange of one peptide bone for another.
(commonly done in gram negative bacteria)
transpeptidation
what antibiotics inhibit transpeptidation
B-lactam antibiotics
these are not antibiotics but are enzymes that help B-lactam antibiotics by preventing their degradation by b-lactamases
b-lactamase inhibitors
(clavulanic acid, sulbactam, and tazobactam)
(Augmentin!!! = clavulanic acid + amoxicillin)
this antibiotic binds terminal D-ala–D-ala and sterically inhibits addition of peptidoglycan subunits to the cell wall.
it also binds to existing peptidoglycan chains to inhibit the transpeptidation reaction that crosslinks the chains.
(type of glycopeptide)
vancomycin
this antibiotic has been important for antibiotic resistant staphylococcal and enterococcal infections
vancomycin
this antibiotics prevent recycling of lipid carrier
bacitracins (polypeptide)
this antibiotic binds phospholipids and disrupts outer and inner membranes of gram negative bacteria (topical because of more general mode of action=toxic)
polymixins (polypeptide)
-second line of treatment for Mycobacterium tuberculosis)
-crosses blood brain barrier and is NMDA receptor agonist (causes neurological side effects)
cycloserine
(other antibiotic deals with cell wall)
these antibiotics inhibits Mycobacteria by affecting synthesis of mycolic acid (abundant wax in cell wall)
isoniazid and ethionamide (other antibiotics deals with cell wall)
this antibiotic inhibits Mycobacteria by affecting attachment!! of mycolic acid in the cell wall
ethambutol (other antibiotics deals with cell wall)
what are the classes of 2. inhibition of protein synthesis antibiotics:
1.
2.
3.
4.
5.
- oxazolidinones
- Tetracyclines
- aminoglycosides
- chloramphenicol and Lincosamides
- macrolides
this class of antibiotic that affects the inhibition of protein synthesis by binding (23S rRNA) and prevents formation of 70s initiation complex
oxazolidinones
this class of antibiotic that affects the inhibition of protein synthesis by binding (16s rRNA) of 30S subunit and prevent binding of aa-tRNA to A site
tetracyclines
this class of antibiotic that affects inhibition of protein synthesis by binding to 30s subunit and distort A site, causing translation misreading, which inhibits protein synthesis
aminoglycosides
this class of antibiotics that affects inhibition of protein synthesis binds to 50s subunit and inhibit peptidyltransferase activity
chloramphenicol and lincosamides
this class of antibiotics that affects inhibition of protein synthesis binds (23s rRNA) in the 50s subunit and block the translocation reaction. Also prevent formation of the 50s subunit
macrolides
- inhibition of protein synthesis
A. linezolid=
B. streptomycin, amikacin, gentamycin, tobramycin=
C. erythromycin, azithromycin, clarithromycin=
A. is a oxazolidinones
B. aminoglycosides
C. macrolides
with the basic mechanism of antibiotic action, this way alters DNA replication and RNA transcription
- inhibition of nucleic acid synthesis
(has enzymes that detangle these ring molecules after they are created by DNA synthesis)
this class of antibiotics that inhibits nucleic acid synthesis, interferes with type II topoisomerases and stabilizes DNA double strand breaks
(aka inhibits enzyme that does the untangling=kills cell)
quinolones (ciprofloxacin and other -floxacins)
this class of antibiotics that inhibits nucleic acid synthesis bids to RNA polymerase and prevents the initiation of transcription
Rifampin and Rifabutin
this class of antibiotics that inhibits nucleic acid synthesis is a prodrug with no inherent antimicrobrial activity that produces DNA-damaging radicals under anaerobic conditions via enzymes functioning in anaerobes and microaerophiles
(gut)
metronidazole
this mechanism of antibiotic action prevents precursors to folic acid
(humans cant make folic acid; get it from diet)
- antimetabolites
sulfonamides, trimethoprim, dapsone, and p-aminosalicyclic acid
- antimetabolites
how do bacteria resist antibiotics?
1
2
3
4
- impermeable barrier
- target modification
- antibiotic modifications
- efflux pump mechanism
this is a common mech of resistance to antibacterial agents.
hydrolysis of B-lactam ring by B-lactamase
penicillins, cephalosporins
this is a common mech of resistance to antibacterial agents.
change in penicillin-binding protein
methicillin
this is a common mech of resistance to antibacterial agents.
efflux pump pushes drug out of cell
tetracyclines
this is a common mech of resistance to antibacterial agents.
mutations in 23S rRNA
oxazolidinones
this is a common mech of resistance to antibacterial agents.
mutations in genes encoding DNA gyrase and topoisonmerase IV
quinolones
this is a common mech of resistance to antibacterial agents.
change in binding site in the peptidoglycan target
(D-ala–D-ala changed to D-ala–D-lac)
vancomycin
what are the 5 genetic elements involved in resistance gene dissemination
plasmids
transducing bacteriophage
bacterial chromosomal genes
transposons
integrons
this genetic element involved in resistance gene dissemination has some that can promote their own transfer by conjugation
plasmids
this genetic element involved in resistance gene dissemination can package non-phage DNA (=transfer by transduction)
transducing bacteriophage
this genetic element involved in resistance gene dissemination has mutations and transfer by transformation (out into the environment)
bacterial chromosomal gene
this genetic element involved in resistance gene dissemination hop into other genetic elements (can amplify)
transposons
this genetic element involved in resistance gene dissemination are large segments of DNA containing complete sets of genes are are found on plasmids, transposons, and bacterical chromosomes
integrons
development and spread of drug-resistant pathogens caused by drug treatment, which destroys drug sensitive strains
superinfection
in a superinfection, the killing of the normal flora removes the inhibitory effect of the normal flora (which produces nutrients/antibacterial substances). this allows for what to happen then
allows for uninhibited growth of potentially pathogenic bacteria and fungi
(superinfection common organisms: MDR, candida!!!, MRSA, Clostridium difficule)
how to prevent emergence of drug resistance:
give drug in high concens, give 2 or more drugs at same time, use drugs only when necessary
