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98 Cards in this Set
- Front
- Back
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Define Minimal Inhibitory Concentration (MIC)
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Concentration of antimicrobial that inhibits growth
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Define Minimum Bacterocidal Concentration (MBC)
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Concentration of antibiotic needed to kill
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To be effective an antimicrobial needs to be above the ___ for how long?
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Above the MIC for 50% of the dosing interval
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If MIC is above the breakpoint-
If MIC is below Breakpoint- |
Resistant
Susceptible |
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Name the B-lactams
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Penicillin
cephalosporins carbapenems monobactam |
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Name the MLS group
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Macrolide
Lincosamide Streptogramins |
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As a group the Beta Lactams and Vancomycin work at the level of
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Cell Wall Synthesis
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B lactams are bacteriocidal or bacteriostatic?
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Bacteriocidal
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In terms of pharmacodynamics and kinetics, with B lactams what do you need to ensure?
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needs to be above MIC for 50% of dosing interval
in other words they have time dependent pharmacodynamics |
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Whats the role of penicillin binding protein in the bacteria?
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it is a transpeptidase that makes the pentaglycine bridge
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B lactams act on what to inhibit...
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Act on PBP to inhibit cross linking of peptidoglycan
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3 ways bacteria become resistant to beta lactams
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secrete B lactamase, Alter PBPs, decrease drug permeability
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Which bacteria secrete B lactamase?
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lots of anaerobes, staph aureus, haemophilus, gonorrhea
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Bacteria alter PBPs?
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Staph aureus, MRSA, strep pneumo
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Bacteria that has decreased permeability to escape B lactams?
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Psuedomonas
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What does a beta lactamase target?
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Targets the amide bond of a beta lactam to destroy the ring
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Why is Beta Lactamse more of a problem with Gram negative?
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In G+ it diffuses away because only 1 cell wall
For G+, the B lactamase gets concentrated between membranes |
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Clavulanic acid, Sulfbactam, and tazobactam are examples of
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B lactamase inhibitors, they bind to B lactamase better than B lactam, give in conjunction w B lactam drug
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Drugs in the Penicillin Class called aminopenicillins
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Ampicillin (IV)
Amoxicillin (PO) |
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Antistaphylococal drugs in the penicillin class
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Methicillin
Oxicillin Nafcillin Dicloxacilin |
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Extended Spectrum Drugs in the Penicillin Class
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ticarcillin, Piperacillin
these work well against gram -, especially psudomonal infection |
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Penicillin most used for-
Resistance an issue with- |
Group A and B Strep
Enterococci Spirochetes Resistance: psudomonas, Strep Viridans, enterococci |
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Benzathine is used for
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treating Syphilus, its a depot prep with LONG half life
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What is the mechanism of resistance for anti-staph penicillins?
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PBP alterations
how you get methicillin resistant Staph Aureus (its resistant to all B lactams) |
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Aminopenicillin extends the spectrum of PCN to include activity against
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Gram Negative Rods like Haemophilus and H pylori
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Outpatient bacterial sinusisits, otitis media, and peptic ulcer disease is usually treated with
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Amoxicillin
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Agumentin contains____ is useful for
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clavulinate + aminopenicillin
has good activity Haemophilus, MSSA, anaerobes head/neck/ear drug |
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Fight pseudomonas with this penicillin class
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Antipseudomonal, ticaracillin and pipercillin, they are IV only
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B Lactam Allergies go over 4 classes
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Type 1- Immediate hypersensitivity/ anaphylaxis
Type 2- Drug as hapten, hemolytic anemia Type 3- Arthus/ serum sickness Type 4- Delayed T cell mediated/ fever rash |
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How do cephalosporins work and what differs from similar drugs in class?
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They bind PBP
are more stable to B lactamase than penicillin and aminopenicillin |
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Outpatient bacterial sinusisits, otitis media, and peptic ulcer disease is usually treated with
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Amoxicillin
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Agumentin contains____ is useful for
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clavulinate + aminopenicillin
has good activity Haemophilus, MSSA, anaerobes head/neck/ear drug |
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Fight pseudomonas with this penicillin class
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Antipseudomonal, ticaracillin and pipercillin, they are IV only
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B Lactam Allergies go over 4 classes
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Type 1- Immediate hypersensitivity/ anaphylaxis
Type 2- Drug as hapten, hemolytic anemia Type 3- Arthus/ serum sickness Type 4- Delayed T cell mediated/ fever rash |
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How do cephalosporins work and what differs from similar drugs in class?
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They bind PBP
are more stable to B lactamase than penicillin and aminopenicillin |
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Cephalosporins 3rd generation are known for
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being good at CNS penetration
and as a class have high therapeutic/toxicity ratio (safe) |
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1st generation Cephalosporins
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Cefazolin (IV)
Cephalothin (IV and PO) |
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2nd generation Cephalosporin
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Cefoxitin (IV)
Cefuroxime (IV and PO) |
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3rd Generation Cephalosporin
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Broad spectrum- Ceftriaxone
Antipseudomonal- Ceftazidime |
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4th generation Cephalosporin
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Cefepime
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Use 1st generation cephalosporins for
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Gram + infections like Strep or Staph (wont work on MRSA)
surgical prophylaxis |
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Use 2nd generation Cephalosporins for
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Some Gram negatives, H influenza, enterobacteraciae, some intra abdominal infections
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Ceftriaxone is used for
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Gram positive infections, S aureus, Strep, pneumococcosu
good for meningitis too bc crosses into CSF |
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Ceftazime works for
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psuedomonas infections
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cefapime used a lot for
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hospital acquired infections like pneumonia
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Aztreonam is ___ and used for ___
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a Monobactam (penicillin class)
ONLY has activity against G- aerobes like psuedomonas |
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If patient is allergic to penicillin what's a B lactam drug that is ok to use
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Axtreonam (monobactam) it has little cross allergy
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If you have a known Gram Negative Rod infection which penicillin drug will you use?
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Azteronam (monobactam)
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This drug binds PBP and has the broadest spectrum G+ and G- activity
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Carbapenem
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dug of choice for 3rd generation cephalosporin resistant klebsiella, enterobacter infections
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carbapenem
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Carbapenems will not work on
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Listeria, MRSA, enterococci
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major form of resistance to carbapenems?
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decreased permeability of Gram negative outer membrane by loss of porins
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Describe class and action vancomycin
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its a glycopeptide
interferes w cell wall synthesis by binding d-alanine of peptide precursor Does not work through PBP |
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Staph is bacteriocidial against ___, but doesnt work as well for ___
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Is bacteriocidal for MRSA
1st generation cephalosporins and anti-staph B lactams work better than vanc for normal staph |
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Vancomycin works best on
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Gram + organisms including MRSA
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How do bacteria gain resistance to Vancomycin?
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Change in cell wall amino acid Dala- D ala to D ala-Dlactate
problem with enterococci |
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How do you give Vancomycin?
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for most infections give it by IV, if give it by GI it will stay in colon (useful for C diff infection)
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Macrolides work by___
bacteriocidal or bacteriostatic? |
inhibiting protein synthesis they binding 50S ribosome
bacteriostatic |
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Pharmacodynamics for Macrolides
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time above MIC like B lactams
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How do bacteria gain resistance to macrolides
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ribosomal methylation, drug efflux
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what class is erythromycin?
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In the MLS class, it's a macrolide
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Erythromycin is used for
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Gram + strep/staph infections, Diphtheria, B. pertussis, campylobacter, mycoplasma, legionella
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What is similar but tolerated on GI than erythromycin?
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Clarithromycin/Azithromycin
also covers H.influenza, M. catarrhalis |
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Macrolides are good for
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upper/lower RT infection, atypical coverage, myco, H.pylori, chlamydia trachomatis
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Streptogramin class and action
what's it used for? |
in the MLS category, acts on the ribosome
role in gram + infections MRSA won't work great on enterococcus |
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Amioglycosides action, bacteriocidal or bacteriostatic?
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Bind 30S ribosome, bacteriocidal
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Pharmcokinetics/dynamics of Aminoglycosides
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concentration dependent, higher the Cmax the better it works (B lac and Macrolides are time dependent)
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Gentamycin, Streptomycin, Amikacin are examples of what drug class?
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Aminoglycoside
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Aminoglycosides work against___ do not work against ___
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Gram Negative aerobes, no activity against anaerobes
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Good example of synergy in antibiotic therapy for G+ infections
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Aminoglycoside + penicillin or vanco
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How are bacteria resistant to aminoglycoside?
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enzymatic inactivation sulfonation/acetylation/phosphorylation
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Type of infections aminoglycosides are useful for
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Unusual ones- plague/tularemia/brucellosis
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Possible problems with taking aminoglycosides
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it can get toxic, nephrotoxicity, ototoxicity
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Class and action of clindamycin?
Bacteriocidal or static? |
In the MLS group (its the L) binds to ribosomes
bacteriostatic |
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Resistance to Clindamycin?
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ribosomal methylation (like other MLS)
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Clindamycin good for what kind of infection?
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Gram Positive cocci
Staph/Strep Anaerobes above diaphragm |
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How does Tetracycline work?
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inhibits protein synthesis by binding 30S ribosome
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resistance to tetracycline?
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by ribosomal methylation or drug efflux
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Tetracycline used for
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G+, some G- (not psuedomonas), some anaerobes, Atypicals Mycoplasma, Chlamydia, Rickettsia
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How do Cotrimoxazole agents work (trimethoprim/sulametaxole)
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Block 2 steps in biosynthesis of nucleic acid; PABA--folic acid and folic acid to folinic acid
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Resistance to Trimethoprim
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increased production of dihydrofolate reductase
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Most use for Trimethoprim
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broad spectrum NOT pseudomonas
MRSA especially CA acquired |
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Metronidazole- bacteriostatic or cidal
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bacteriocidal
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Uses of Metronidazole
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Anaerobic infections below diaphragm, protazoal infections
Bacterial vaginosis C diff infection |
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How do Fluoroquinolones work?
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Inhibiting DNA gyrase and topoisomerase
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Resistance to Fluoroquinolones through____
Fluros are bacteriostatic or cidal? |
DNA gyrase/topo mutations or drug efflux
bacteriocidal |
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Pharmakodynamics for fluoroquinolones
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AUC/MIC
becomes very bioavailable orally |
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Levofloxacin, moxifloxacin, ciprofloxacin are examples of
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fluroroquinolones
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Flouroquinolones are good for treating
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Gram negatives
cipro is good at psudomonas moxi and levo for strep and some MRSA All the atypicals |
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Fluroquinolones indicated for
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UTIs, GI infections, STDs
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How does Rifampin work?
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Inhibits DNA dependent RNA polymerase
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Resistance to rifampin
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occurs rapidly bc RNA Pol mutates NEVER USE ALONE
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Rifampin good for treating
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G+s staph and strep, some G- including TB
it's good at getting into biofilms |
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How do lipopeptides work and what's an example
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Doptomycin
Ca dependent increase permeability to K channel |
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Daptomycin works on
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gram positives MRSA and vanco resistant enterococcus
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Oxazolidine is called ___ and it works by
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Linezolids
inhibiting protein synthesis at translation |
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Use linezolid for
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G+ MRSA infections (its oral which is rare)
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Polymyxins are
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old antibiotics brough back that intercalate with LPS in gram negative membrane
they get pretty toxic |
