Anti Microbials (1) Flashcards by Meghan May

Overview of antimicrobial action

review chart

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What are the 3 Mechanism of Penicillins?

How do bacteria resisit it?

Bind penicillin-binding proteins (transpeptidases).
Block transpeptidase cross-linking of peptidoglycan in cell wall.
Activate autolytic enzymes.

Penicillinase in bacteria (a type of β-lactamase) cleaves β-lactam ring.

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Mostly used for gram-positive organisms (S. pneumoniae, S. pyogenes, Actinomyces). Also used for gram-negative cocci (mainly N. meningitidis) and spirochetes (namely T. pallidum).

Bactericidal for gram-positive cocci, gram-positive rods, gram-negative cocci, and spirochetes.

Penicillin

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What is the mechanism of teh drug we would tx pt with syphillus with?

Tx with Pen G

Bind penicillin-binding proteins (transpeptidases).
Block transpeptidase cross-linking of peptidoglycan in cell wall.

Activate autolytic enzymes.

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What toxic side effects are seen with Penicillin?

Hypersensitivity reactions,

hemolytic anemia.

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What is the Mechanism of aminopenicillins?

What drugs are aminopenicillins?

Which one has the best oral availability?

AMinoPenicillins are AMPed-up penicillin.: Same as penicillin. Wider spectrum; penicillinase sensitive. Also combine with clavulanic acid to protect against destruction by β-lactamase.

Amoxicillin, ampicillin are both aminopenicillins

AmOxicillin has greater Oral bioavailability than ampicillin.

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PNeumonic for Amoxicillin use:

ampicillin/amoxicillin HHELPSS kill enterococci.

H. influenza and H.pylori

E.coli

Listeria

Proteus

Salmonella

shigella

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What mechnism of resistance is seen with aminopenicillins?

What toxicity is assoicated with them?

Penicillinase in bacteria (a type of β-lactamase) cleaves β-lactam ring.

Hypersensitivity reactions; rash; pseudomembranous colitis.

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Same as penicillin. Narrow spectrum; penicillinase resistant because bulky R group blocks access of β-lactamase to β-lactam ring.

Dicloxacillin, nafcillin, oxacillin (penicillinase-resistant penicillins):

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What drug can we use to treat Staph Aureus (but not MRSA d/t altered penicillin binding proteins target sites)

What is it’s mechanism?

Use Nafcillin “ Use naf for staph’

penicillinase-resistant penicillins to treat Staph Aureus

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When using a penicillinase-resistant penicillin (specifically Nafcillin) what do we use it for and when side effects can we see?

Nafcillin for Staph Aureus

Sides: Hypersensitivity rxns and Interstitial nephritis

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Drug used to treate Pseudomonas spp. and gram-negative rods;

Piperacillin, ticarcillin (antipseudomonals)

use with β-lactamase inhibitors.

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When would you use Piperacillin or ticaracillin (antipseudomonals)

Duh, Pseudomonas

MOA:

Bind penicillin-binding proteins (transpeptidases).
Block transpeptidase cross-linking of peptidoglycan in cell wall.

Activate autolytic enzymes.

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What drugs are B-lactamase inhibitors and whenw would we use them?

Include Clavulanic Acid, Sulbactam, Tazobactam.

Often a_dded to penicillin a_ntibiotics to protect the antibiotic from destruction by β-lactamase (penicillinase).

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What is the general mechanism of Cephalosporins?

What bugs are NOT covered by cephalosporins?

β-lactam drugs that inhibit cell wall synthesis but are less susceptible to penicillinases. Bactericidal.

Organisms typically not covered by cephalosporins are LAME:

Listeria, Atypicals (Chlamydia, Mycoplasma), MRSA, and Enterococci.

Exception: ceftaroline covers MRSA.

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What drugs are the 1st gen Cephalosporins?

What is their use?

1st generation (cefazolin, cephalexin)—

Coverage: gram- positive cocci,

PEcK: Proteus mirabilis, E. coli, Klebsiella pneumoniae.

Cefazolin used prior to surgery to prevent S. aureus wound infections.

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What drug can we use to treat the “PEcK” or

Proteus miribalis, E.Coli, Klebsiella pneumonaie

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Use 1st gen cephalosporins

Cefazolin and Cephalexin

Drugs used to treat —gram-positive cocci, HEN PEcKS

Haemophilus influenzae, Enterobacter aerogenes, Neisseria spp., Proteus mirabilis, E. coli, Klebsiella pneumoniae, Serratia marcescens.

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2nd generation: cefoxitin, cefaclor, cefuroxime

What are my second gen Cephalosporins?

What bugs do they treat?

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Cefoxitin, Cefaclor,Cefuroxime

HEN PEcKS:

H. influenza, Enterobacter, Neisseria, Proteus, E.Coli, Klebsiella, Serratia

What does HEN PEcKS stand for?

What drugs treat these bugs?

What is their mechanism?

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H. Influenza, Enterobacter, Neisseria, Proteus, E. Coli, Klebsiella, Serratia

Second gen cephalosporins: Cefoxotin, Cefuroxime, Cefaclor

β-lactam drugs that inhibit cell wall synthesis but are less susceptible to penicillinases. Bactericida

What is the drug of choice to three Gonorrhea and meningitis?

What is it’s mechanism of action?

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Ceftriaxone: it’s a 3rd gen cephalosporin

What are my 3rd generation cephalosporins?

What is their coverage?

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= Ceftriaxone, Cefoxatime, Ceftazidime

Used for _serious gram negative infections r_esistant to other B-lactams

Ceftriaxone—meningitis, gonorrhea, disseminated Lyme disease.

Ceftazidime—Pseudomonas.

What drug can we use to treat a pseudomonas infection?

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Ceftazidine: 3rd gen cephalosporin

What is Cefipime and when would it be a beneficial drug?

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4th generation (cefepime)—gram-negative

organisms, with?activity against Pseudomonas

and gram-positive organisms.

What sensitivities do we need to worry about with cephalosporins?

**Hypersensitivity reactions**, autoimmune h**emolytic anemia**, disulfiram-like reaction, **vitamin K deficiency**. Exhibit cross-reactivity with penicillins.? **Incerease nephrotoxicity of aminoglycosides.**

What happens when we prescribe an aminoglycoside as well as a cephalosporin?

Increases chances for nephrotoxicity

What drug causes this side effect: Hypersensitivity reactions, autoimmune hemolytic anemia, disulfiram-like reaction, vitamin K deficiency. Exhibit cross-reactivity with penicillins.

Cephalosporins

\_\_\_\_\_\_\_\_is a broad-spectrum, β-lactamase– resistant carbapenem. Always administered w**ith cilastatin** (inhibitor of renal dehydropeptidase I) to decrease ?inactivation of drug in renal tubules.

Imipenem "With imipenem, “the kill is lastin’ with cilastatin.”

What is the side effect profile like for carbapenems?

GI distress, skin rash, and CNS toxicity (seizures) at high plasma levels.

Inhibits cell wall peptidoglycan formation by **binding D-ala D-ala portion of cell wall** precursors. **Bactericidal**. _Not susceptible to β-lactamases._

Vancomycin

When would we prescribe vancomycin?

Gram-positive bugs only—serious, multidrug-resistant organisms, including **MRSA, S. epidermidis, sensitive Enteroccocus species**, and **Clostridium difficile** (oral dose for pseudomembranous colitis).

What drug can we prescribe for the following diseases? Gram-positive bugs only—serious, multidrug-resistant organisms, including **MRSA, S. epidermidis, sensitive Enteroccocus species,** and **Clostridium difficile** (oral dose for pseudomembranous colitis).

Vancomycin

Well tolerated in general—but NOT trouble free. **Nephrotoxicity, Ototoxicity, Thrombophlebitis,** _diffuse flushing—red man syndrome_ (can largely prevent by pretreatment with antihistamines and slow infusion rate)

VAncomycin

How do bugs resist Vancomycin?

Occurs in bacteria via amino acid modification of D-ala D-ala to D-ala D-lac. “Pay back 2 D-alas (dollars) for vandalizing (vancomycin).”

What antimicrobials target the 30S of bacteria ribosome? are they bacteriocidal or static?

30S: Aminoglycosides = bacteriacidal Tetracyclines =bacteriostatic

What antimicrobials are will inhibit the 50S subunit?

Chloramphenicol and Clindamycin = bacteriostatic Erythromycin = macrolide and static Linezolid

What are teh aminioglycosides? What is the MOA? What toxicity do we worry about?

Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin Irreversible inhibition of initiation complex through binding of the 30S subunit Can cause misreading of mRNA Blocks translocation but NEEDS O2 for uptake thus no good for anaerobes. \*Toxicity: Nephrotoxicity, Neuromuscular blockade, Ototoxicity, Teratogenic

The combination of gentamicin with Furosomide would have what type of side effect?

aminoglycoside + loop = bad news! Serious **Ototoxicity**

When would we prescribe aminoglycosides to a pt?

**Severe gram-negative rod infections**. _Synergistic with β-lactam antibiotics._ **Neomycin** for _bowel surgery._

What is the mechanism of resistance of bugs against aminoglycosides?

Bacterial transferase enzyme**s inactivate the drug by acetylation, phosphorylation, or adenylation.**

Anti Microbials (1) Flashcards

(40 cards)