Exam 1 - Smith - Antimicrobials I Flashcards by Brennan Stringam

Name some antimicrobials that affect the cell wall synthesis in bacteria.

Beta lactams

Penicillins
Cephalosporins
Carbapenems
Monobactams

Vancomycin

Bacitracin

How well did you know this?

Not at all

Perfectly

All beta-lactam drugs are known for 3 things. Name them.

Require actively proliferating microorganisms

Are INACTIVE against organisms devoid of peptidoglycans
-Viruses, mycobacteria, and fungi

Are Type II Time-Dependent - Most effective is dosed to achieve serum concentrations for at least 50% of dosing interval

How well did you know this?

Not at all

Perfectly

To be effective, beta-lactams must first do what?

Evade bacterial defenses

Penetrate outer cell layers

Protect beta-lactam ring structure

**Bind to transpeptidase enzymes (AKA Penicillin-binding protein (PBP)

How well did you know this?

Not at all

Perfectly

What is transpeptidase?

Penicillin binding protein

How well did you know this?

Not at all

Perfectly

If a penicillin binds transpeptidase, what happens?

Bacterial cell wall is unable to form, and the bacteria is killed (autolyse)

How well did you know this?

Not at all

Perfectly

What are 2 natural penicillins?

Penicillin G - this is the only naturally occurring penicillin

Penicillin V (Penicillin VK)

Great against Gram (+), except S aureus, and are very susceptible to bacterial beta-lactamases

How well did you know this?

Not at all

Perfectly

What are 2 aminopenicillins (extended spectrum penicillins)?

Ampicillin

Amoxicillin

Can effect Gram (-)’s
Still susceptible to beta-lactamases

**These drugs are often paired with beta-lactamase inhibitors

How well did you know this?

Not at all

Perfectly

What are 4 penicillinase-resistant penicillins? (Anti-staphylococcal penicillins)

Methicillin

Nafcillin

Oxacillin

Dicloxacicillin

**Relatively resistant to beta-lactamases

USE NAF FOR STAPH - First line treatment of choice for staphylococcal endocarditis

How well did you know this?

Not at all

Perfectly

What are the 3 anti-pseudonomal penicillins to know?

Aztreonam

Piperacillin

Ticarcillin

*Ticarcillin and then piperacillin have the broadest spectrums of activity

How well did you know this?

Not at all

Perfectly

What drug has 5 generations and what is that based on?

Cephalosporins

Based on their activity profile

How well did you know this?

Not at all

Perfectly

What is imipenem?

Broadest antibacterial available - It is a CARBAPENEM

How well did you know this?

Not at all

Perfectly

What is the only true naturally occurring penicillin?

Penicillin G

How well did you know this?

Not at all

Perfectly

Pen G. Tell me about it

NATURAL

Narrow spec - good against G(+)
*Rapidly hydrolysis by penicillinase enzymes (beta-lactamase enzymes)
Administered IV or IM (intramuscularly) - Poor Oral bioavailability - stomach acids destroy the drug

How well did you know this?

Not at all

Perfectly

Pen V. Tell me about it

Acid-stable - so can be taken orally

Similar to Pen G, but less effective

How well did you know this?

Not at all

Perfectly

What is benzathine penicillin?

Drug of choice when prolonged, low conc req’d

Treatment for syphilis

How well did you know this?

Not at all

Perfectly

Aminopenicillins are what?

Extended spec penicillins

Better Gram (-) coverage than either Pen G or Pen V
Extends to sensitive strains of G(-) bacteria (H. Influenzae) and enterics
Still sensitive to beta-lactamases
Used for Listeria, prophylaxis of infective endocarditis, and UTIs

How well did you know this?

Not at all

Perfectly

What is usually administered with a beta-lactamase inhibitor?

Aminopenicillins

How well did you know this?

Not at all

Perfectly

What are the 2 main aminopenicillins?

Ampicillin

Amoxicillin

*Amoxicillin has higher oral absorption, longer half-life, and less likely to cause adverse GI effects than ampicillin

How well did you know this?

Not at all

Perfectly

Amoxicillin does what to renal tubular excretion of methotrexate?

Causes prolonged high serum levels of methotrexate

How well did you know this?

Not at all

Perfectly

What is the drug-of-choice for standard prophylactic prevention of bacterial endocarditis when appropriate?

Amoxicillin

*An alternative, in case of allergy is: **Cephalexin - 1st generation cephalosporin

**IF a beta-lactam allergy: Use clindamycin, azithromycin (Z-Pak), or clarithromycin

How well did you know this?

Not at all

Perfectly

Ampicillin. Tell me about it.

Amoxicillin is much better to use b/c the side effects and requirements are lessened

How well did you know this?

Not at all

Perfectly

What is the drug of choice in patients unable to take oral penicillins?

Ampicillin (parenterally)

Ampicillin causes diarrhea - pseudomembranous colitis (C diff overgrowth), rashes, hypersensitivity rxns
Oral contraceptives are not as effective if ampicillin is taken, and it slows renal excretion

How well did you know this?

Not at all

Perfectly

How does probenecid increase serum levels of most beta-lactam antibacterials?

Uric acid reducer

Inhibits organic anion transporters
Probenecid does not interact with nafcillin, oxacillin, and dicloxacillin since they are Lipophilic and undergo biliary excretion, not renal

How well did you know this?

Not at all

Perfectly

What is the mnemonic to know?

USE NAF FOR STAPH

*Use nafcillin for S aureus infections

What are 4 drugs to know that are penicillinase-resistant penicillins?

Methicillin (discontinued in US) Nafcillin Oxacillin Dicloxacillin -These are the drugs of choice against S aureus and s epidermidis that are not MRSA

What is the drug of choice for serious S aureus infections?

Nafcillin

What should you know about oxacillin and dicloxacillin?

Activity and beta-lactamase resistance similar to methicillin, but ACID STABLE, so orally active, and reduced risk of interstitial nephritis

Name 3 anti-pseudo Oral penicillins.

Carboxypenicllins Ureidopenicillins Monobactams -Used for serious bacteremia, pneumonias, burn victims, UTIs

What are 2 carboxypenicillins to know?

Indanyl carbenicillin Ticarcillin -This is more active than indanyl carbenicllin, and is an injectable agent against G(-) bacteria, esp P aeruginosa

What is the broadest spec of the antipseudomonal penicillins?

Piperacillin

What is a great drudge to use for pts with IgE-mediated penicillin allegory?

Aztreonam (IV) Can cause c diff overgrowth

What are common side effects of penicillins?

Hypersensitivity -10% of people are allergic to penicillins and these people are usually cross sensitive to all other beta-lactams, including cephalopsporins Local effects Lethargy, confusion Superinfection risk

What is pseudomembranous colitis induced diarrhea?

Aminopenicillins (ampicillin), piperacillin, cephalosporins, and aztreonam

Cephalosporins have how many generations and based on what?

5 By antimicrobial activity - Resistant to many older beta-lactamases - Renally excreted - Pts with history of anaphylaxis CANNOT take this**

_____________ have a cross allergy with penicillins of only ~5%.

Cephalosporins **Pts with a history of anaphylaxis cannot take cephalosporins

1st generation cephalosporins - what drugs and what do they do?

Cephalexin Cefazolin -Active against G(+), some G(-) - Not good against enterococci, MRSA, and S epidermidis

2nd generation cephalosporins - what drugs and what do they do?

Cefaclor Cefuroxime Cefoxitin -Increased activity against G(-) that’s 1st gen, but less active than the 3rd gen

3rd generation cephalosporins - what drugs and what do they do?

Cefdinir Cefotaxime Ceftaxidime Ceftriaxone -Less active than 1st gen against G(+) cocci, but much more active against G(-)’s like enterobacteriaceae

4th generation cephalosporin - what drug and what does it do used for?

Cefepime -Good activity against G (+) and G (-); even more beta-lactamase resistance

5th generation cephalosporin - what drug and what does it do?

Ceftaroline -Good activity against MRSA, G (+) and G (-)

Cephalosporins generations 1-3- as generations increase, so does what two things?

Gram (-) activity and beta-lactamase resistance Also, spectrum gets broader

What is special about 4th and 5th generation cephalosporins?

Good with both Grams and good resistance to beta-lactamases *5th gen is good against MRSA **B/c 2,3,4,5 generations are more broad spec, superinfection is a risk

________ is used for prophylaxis prior to surgery, and its most active against S aureus and strep.

Cefazolin

What is cefaclor used to treat?

Oral sinusitis and otitis media caused by H influenzae

What is Cefoxitin used for?

Kill anaerobes and extended beta-lactamase resistance

What is Cefuroxime used for?

Can cross the blood brain barrier to reach CNS

What has the broadest spectrum of all the cephalosporins and are extremely effective against G(-) organisms?

3rd generation cephalosporins -Useful for G(-) bacteremias **-Can cross the BBB**

What 3rd gen cephalosporin is active against Pseudomonas aeruginosa?

Ceftazidime

What is the highest selling cephalosporin?

Cefdinir

What are the 1st line treatment options for strep throat?

Penicillin Amoxicillin

What is Cefepime?

4th generation - Used for Strep and methicillin-susceptible staph and P aeruginosa - Poor anaerobic coverage

What is Ceftaroline?

5th gen cephalosporin - Active against MRSA * Used for community-acquired (CA) pneumonia and complicated skin infections

Go thru Cephalosporins: 1st Gen 2nd Gen 3rd Gen 4th Gen 5th Gen

1st - Cephalexin, Cefazolin 2nd - Cefaclor, Cefuroxime, Cefoxitin 3rd - Cefdinir, Cefotaxime, Ceftazidime, Ceftriaxone 4th - Cefepime 5th - Ceftaroline

Tell me about Carbapenems.

Imipenem (Primaxin namebrand) BROADEST SPECTRUM COVERAGE AVAILABLE TO MAN (IV or IM) Used for multi-drug resistant organisms

What two bugs are resistant to Carbapenems?

MRSA Mycoplasma

T/F - Carbapenems are very stable in the presence of beta-lactamases, including penicillinase and cephalosporinase that are resistant to most beta-lactam antibiotics.

TRUE

What is an adverse effect of carbapenem use?

Renal clearance is critical - Renal insufficiencies will cause seizures

What is Imipenem coadministered with?

Cilistatin - This protects the imipenem from being degraded by the renal enzyme dehydropeptidase 1 - Meropenem and ertapenem are not inactivated by the renal enzyme and don’t require cilistatin

What are the protectors that are sometimes coadministered with antibiotics?

Usually beta-lactamase inhibitors or help protect the drug from being degraded too quickly