Beta Lactam Antibiotics & Cell Wall Synthesis Inhibitors Flashcards by Sarah Zoretic

List the natural penicillins

Penicillin G - IV, IM

2. Penicillin V - PO

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List the anti-staphylococcal penicillins

Methicillin - *discontinue for clinical use
Oxacillin - PO
Dicloxacillin - PO
Nafcillin - IV, PO

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List the extended spectrum (amino-) penicillins and associated beta lactamase inhibitors

Ampicillin + sulbactam - IV

2. Amoxicillin + clavulanic acid - PO

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List the anti-pseudomonal penicillins and associated beta lactamase inhibitors

Ticarcillin + clavulanic acid - IV

2. Pipericillin + tazobactam - IV

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What are the clinical indications for use of natural penicillins (penicillin G, V)

Gram(+) cocci:

Strep pneumoniae* - pneumococcal pneumonia
Strep pyogenes - pharyngitis, Scarlet Fever
Strep viridans group - endocarditis

= resistance significant

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Why were anti-staphylococcal penicillins created?

(Widespread penicillin G/V resistance due to bacterial production of beta lactamase prompted need to discover other penicillins that were less susceptible to degradation by beta lactamases (aka poor substrates for beta lactamases) and could cover strains of staph aureus, and gram(+) streptococci that produce beta lactamase

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Why do anti-staphylococcal penicillins have excellent activity against staph aureus?

(= methicillin, nafcillin, oxacillin, dicloxacillin)
chemical appendages make these penicillins poor substrates for beta lactamase –> excellent activity against staph aureus

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What gram (+) diseases do the extended spectrum amino-penicillins cover?

= ampicillin, amoxicillin
RESPIRATORY INFECTIONS - CAP, sinusitis, bronchitis, pharyngitis
- Amoxicillin is active against penicillin sensitive S.pneumonia and often used for pharyngitis in children because of “Taste”

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What gram(-) diseases do the extended spectrum amino-penicillins cover?

= ampicillin, amoxicillin
Bronchitis in COPD
*Respiratory infections

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Extended spectrum amino-penicillins are used against what gram(+) cocci and gram(-) organisms?

Gram(+) cocci:
1. Strep. pneumoniae*
2. Strep pyogenes*
3. Strep viridans group
4. Enterococci 
Gram(-): 
1. H. influenza*

*= Respiratory infections

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Anti-pseudomonal pencillins are used when?

= ticarcillin, piperacillin, (ureidopenicillin?)
Used when situation favors development of pseudomonas aeruginosa infections
- p. aeruginosa = opportunistic pathogen that can cause serious infections that are difficult to treat
**for EMPIRICAL therapy of serious infection, e.g. PNA, when suspected organisms are gram(-) and if pseudomonas aeruginosa is a concern

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What populations are at risk for pseudomonas aeruginosa infections?

Burn patients
Cystic fibrosis patients
Injection drug users
Immunosuppressed patients

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What are some examples of when you would use an anti-pseudomonal penicillin?

Severe PNA in a hospitalized patient with structural lung disease (COPD)
Neutropenic fever - sepsis
Aspiration PNA in a hospitalized patient or stroke victim

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List the 1st generation cephalosporins

Cefazolin, cephalexin, cephradrine

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List the generation, route and distinctions for: cefazolin

1st generation
Parenteral, IV, IM
Penetrates well into BONE

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List the generation, route and distinctions for: cephalexin

1st generation
PO
2x daily for pharyngitis

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List the generation, route and distinctions for: cephradrine

1st generation
parenteral and oral
–

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What is the spectrum of activity for 1st generation cephalosporins?

Gram(+) cocci, streptococci and staph aureus. NOT ACTIVE AGAINST: MRSA, MRSE, enterococci

MRSE = methicillin-resistant staph epidermis

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What are the clinical uses for 1st generation cephalosporins?

Surgical prophylaxis if skin flora are likely pathogens; soft tissue and skin infections due to S. aureus, S. pyogenes

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List the 2nd generation cephalosporins

Cefoxitin
cefotetan
cefaclor
cefuroxime axetil

List the generation, route, and distinctions for: cefoxiitn

2nd generation
IV, IM
Active vs anaerobes, e.g B. fragilis
(Same as cefotetan)

List the generation, route, and distinctions for: cefotetan

2nd generation
IV, IM
Active vs anaerobes, e.g. B fragilis
(Same as cefoxitin)

List the generation, route, and distinctions for: cefaclor

2nd generation
PO
Serum-sickness (skin and joint adverse reactions) in pediatrics

List the generation, route, and distinctions for: cefuroxime axetil

2nd generation
PO
poor substrate for beta-lactamase

What is the spectrum of activity for 2nd generation cephalosporins?

- less active than 1st generation agents vs gram(+) organisms - enhanced activity vs gram(-) = E.coli, Klebsiella, H.influenza, Moraxella catarrhalis, Proteus spp.

What are the clinical uses for 2nd generation cephalosporins?

When facultative gram(-) bacteria and anaerobes are likely pathogens e.g. intra-abdominal and gynecological sepsis, surgical prophylaxis for intra-abdominal and colorectal surgery

List the 3rd generation cephalosporins

1. Ceftriaxone 2. Cefotaxime 3. Cetazidime 4. Cefaperazone ALL PARENTERAL!!!!

What is the generation and distinctions for: ceftriaxone

``` 3rd generation = parenteral Long t(1/2) ~8 hours, 1x daily Penetrates CSF and bone Active vs NEISSERIA GONORRHEA BILIARY CLEARANCE ```

What is the generation and distinctions for: cefotaxime

3rd generation = parenteral | ENTERS CSF, USEFUL FOR MENINGITIS due to H.influenza, S.pneumonia, N.meningitidis

What is the generation and distinctions for: cetazidime

3rd generation = parenteral | Active vs PSEUDOMONAS AERUGINOSA

What is the generation and distinctions for: cefaperazone

Disulfiram like alcohol intolerance | Active vs pseudomonas aeruginosa

What is the spectrum of activity for 3rd generation cephalosporins?

Comparable to 1st generation vs S.aureus, S. pneumonia, S. pyogenes And ENHANCED ACIVITY vs gram(-) rods, enteric organisms

List the 4th generation cephalosporin

Cefepime

List the generation, route, and distinctions for: cefepime

4th generation IV, IM - Activity > or = to cefotaxime vs gram(-) bacteria, H. influenza, N. gonorrhea, N. meningitidis - Excellent penetration into CSF - Activity similar to ceftazidime vs pseudomonas aeruginosa

What is the spectrum of activity of 4th generation cephalosporins?

Exerts gram(+) activity comparable to 1st generation cephalosporins, combined with extended gram(-) activity of 3rd generation agents. Insensitive to many beta lactamases

What is the name of the monobactam

Aztreonam

What is the activity spectrum of the monobactam aztreonam?

Gram(-) RODS - e.g. Klebsiella, Pseudomonas, Serratia | NOT ACTIVE vs gram(+) spp or anaerobes

What are the distinctions associated with the monobactam aztreonam?

- Binds to PBP 3 of gram(-) rods - Substitute for extended spectrum penicillin or gen 3,4 cephalosporins if these are contraindicated because of hypersensitivity - Safe alternate for aminoglycosides in elderly or in patients with renal impairment - Synergistic with ahminoglycosides - Parenteral IV, IM - NOT USED ALONE in empirical therapy because of its "narrow" spectrum of activity

What are the names of the 3 carbapenems?

1. Imipenem/cilastatin 2. Meropenem 3. Ertapenem

How is imipenem/cilastatin administered?

IV, IM

List the names of the 5 drugs that are used to manage penicillin hypersensitivity or MRSA

1. Vancomycin 2. Erythromycin 3. Clindamycin 4. Tigecycline 5. Linezolid

When do you use vancomycin?

1. Penicillin hypersensitivity 2. Narrow spectrum: gram(+) cocci including: A. MRSA - methicillin resistant staph aureus B. PRSP - penicillin resistant strep pneumo

When do you use erythromycin?

1. Pencillin hypersensitivity 2. Narrow spectrum: gram(+) cocci and beta lactamase secreting staph aureus BUT NOT: - MRSA - PRSP (pencillin-resistant strep pneumo)

What do you use with penicillin to decrease toxin synthesis in life threatening streptococcal toxic shock & necrotizing fasciitis?

Clindamycin

When do you use tigecycline?

Broad spectrum including: - MRSA - VRE = vancomycin resistant enterococcus

When do you use linezolid?

``` VRSA = vancomycin resistant staph aureus VRE = vancomycin resistant enterococcus ```

Describe cell wall biosynthesis in gram(+) bacteria (strep, staph, enterococci)

Cell wall synthesis involves cross-linking a unique dipeptide D-ala-D-ala to a string of glycine (1) Subunit assembly (2) Peptidoglycan elongation (transglycosylase) (3) Peptidoglycan cross-linking (transpeptidase PBPs) PBP = penicillin binding protein

What is the MOA of penicillins and related beta lactam antibiotics? (other penicillins, carbapenems, monolactams, cephalosporins)

Beta-lactams (e.g. penicillins) resemble D-ala-D-ala they inhibit cross-linking enzyme(s)/transpeptidase(s) --> inhibit transpeptidase(s) and related PBPs IRREVERSIBLY (peptidoglycan cross-linking step)

How is nafcilin cleared? And what is its associated toxicity?

Clearance --> hepatic, biliary | Toxicity: hypersensitivity (like all the others) + increased p450 induction