Beta Lactams Flashcards
What 4 families of antibiotics are classified as Beta Lactams and what is their mechanism of action?
Penicillin, Cephalosporin, Carbapenem, Monobactam
MOA: bind PBPs (penicillin-binding proteins) and prevent crosslinking of bacterial cell wall
Bactericidal
What are 4 common side-effects of Beta Lactams use?
- hypersensitivities (anaphylaxis)
- myelosuppression
- rashes
- GI symptoms (nausea, vomiting, C. diff)
Why are beta lactams poor candidates for deep-seated or serious infections?
Which antibiotic in this group has the most bioavailability?
poor bioavailability and low serum concentrations
Amoxicillin has best bioavailability
What 4 organisms do beta lactams not have coverage against?
- MRSA (except Ceftaroline)
- atypical intracellular organisms: Legionella, Mycoplasma, Chlamydia
What kind of killing do beta lactams have?
TIME-dependent killing
- efficacy depends on amount of time concentration is above the MIC
What is the only beta lactam antibiotic that has coverage against MRSA?
Ceftaroline
Among patients with penicillin allergy, what percentage of them can tolerate treatment with penicillins?
85-90%
- either never truly allergic or resolution of remote prior allergy
What are the oral and IV forms of penicillin?
Oral = Penicillin V
IV = Penicillin G
What 5 organisms does Penicillin typically have coverage against?
- Streptococcus (MAJORITY; Group A universally sensitive)
- Staphylococcus (minority - most resistant)
- Enterococcus (some)
- Oral anaerobes (most)
- Syphilis (universally sensitive)
What are the oral and IV forms of aminopenicillin?
Oral = Amoxicillin
IV = Ampicillin
What organisms do aminopenicillins typically cover?
What 3 Gram - organisms do aminopenicillins NOT cover?
some Gram + (strep, enterococcus, listeria) but NOT MSSA
- limited Gram - coverage (no Klebsiella, Moraxella, SPICE-A)
What antibiotics are preferred for enterococcal infections if susceptible?
AMINOPENICILLINS
- add aminoglycosides for synergy with enterococcal endocarditis
What are the 4 common anti-staphylococcal penicillins? Which one is PO?
What are these antibiotics the first-line treatment for?
IV = Methicillin, Nafcillin, Oxacillin
Oral = Dicloxacillin
- first-line treatment for MSSA
When is Dicloxacillin a better choice then its IV counterparts?
for non-severe MSSA cellulitis
- all other MSSA infections (bacteremia, osteomyelitis, sepsis) should be treated with IV antibiotics
Which IV penicillin is better tolerated: Nafcillin or Oxacillin?
Nafcillin
- less rash and hepatitis occurance
What are the two main anti-pseudomonas penicillins?
Piperacillin and Ticarcillin
- typically given with beta-lactamase inhibitors for broader coverage
What 4 organisms do beta lactamase inhibitors help provide additional coverage against?
- MSSA
- H. influenza
- Moraxella
- virtually all anaerobes
What are the 4 most common configurations of Penicillin/Beta-Lactamase inhibitors?
How are they administered: IV or Oral?
- Amoxicillin/Clavulanate - PO
- Ampicillin/Sulbactam - IV
- Piperacillin/Tazobactam - IV
- Ticarcillin/Clavulanate - IV
What are the brand names for the 4 common Penicillin/Beta-Lactamase inhibitors?
- Augmentin - Amox/Clav
- Unasyn - Amp/Sulbactam
- Zosyn - Pip/Tazo
- Timentin - Ticar/Clav
What two organisms does Augmentin NOT have coverage over?
Pseudomonas and SPICE-A organisms
What additional organism does Unasyn cover for that Augmentin does not?
Acinetobacter
- no activity against other SPICE organisms or pseudomonas
What coverage does Zosyn have that Augmentin and Unasyn do not?
Covers pseudomonas AND SPICE-A organisms
What 5 groups of organisms does Zosyn NOT cover?
- MRSA
- VRE (vancomycin-resistant enterococcus)
- coag-negative Staphylococcus
- Atypicals (Legionella, Mycoplasma, Chlamydia)
- ESBLs (extended-spectrum beta lactamase)
What is the only cephalosporin that covers enterococcus?
Ceftaroline (5th Generation)
- no other cephalosporins cover enterococcus
What are the only 2 cephalosporins that cover Pseudomonas infections?
Ceftazidime (3rd Generation)
Cefepime (4th Generation)
What are the only 2 cephalosporins with good anaerobe coverage?
Cefoxitin (2nd Generation)
Cefotetan (2nd Generation)
What are the two most commonly used 1st Generation cephalosporin?
Which is oral and IV?
Oral = Cephalexin
IV = Cefazolin
What are the brand names for Cefazolin and Cephalexin?
Cefazolin = ANCEF, Kefzol
Cephalexin = KEFLEX
What 5 organisms do 1st Generation cephalosporins (Cefazolin/Cephalexin) cover?
- MSSA
- Streptococcus
- Proteus
- Klebsiella
- E. coli
Gram + more than Gram -
- typically used for non-purulent cellulitis
Which 1st Generation cephalosporin is used for surgery prophylaxis and which is used for PCN-allergic patients?
Cefazolin for both
What is the most common 2nd Generation cephalosporin and how is it typically administered?
Cefuroxime (both oral and IV)
What coverage does Cefuroxime have and what additional organisms is it good against vs 1st Generation?
Gram + > Gram - (better Gram - coverage than 1st Generation)
- covers: H. influenza, Enterobacter, Neisseria
What are 4 common uses for Cefuroxime?
- respiratory infections (upper and lower)
- gonorrhea
- UTIs
- Lyme Dz (doxycycline alternate)
What are the two “Cefomycins” of the 2nd Generation cephalosporins?
Cefoxitin
Cefotetan
- covers anaerobes and Gram - organisms, but no Pseudomonas or Gram +
What are the 3 most common 3rd Generation cephalosporins?
Which are IV vs oral administation?
Ceftriaxone (Rocephin) - IV
Cefotaxime - IV
Cefpodoxime - PO
What coverage do 3rd Generation cephalosporins have?
What 2 organisms does this class NOT cover?
Good Gram +, excellent Gram - (E.coli, Proteus, Klebsiella, H.flu, Neisseria, SPACE-A)
- does NOT cover Pseudomonas or anaerobes
What two hepatic conditions can Ceftriaxone cause?
Biliary sludging and cholecystitis
What makes Ceftazidime different from other 3rd Generation cephalosporins?
ONLY Gram - coverage, including Pseudomonas
- virtually no Gram + or anaerobe coverage
What is the common 4th Generation cephalosporin and what coverage does it have?
Cefepime - IV
- broad Gram + (MSSA, strep) and Gram - (pseudomonas) but WEAK anaerobe coverage
- empiric neutropenic fever (better than Ceftazidime)
What is the common 5th Generation cephalosporin and what coverage does it have?
What are its only two FDA indications?
Ceftaroline - IV
- covers MRSA, VISA, VRSA, Strep; similar Gram - coverage as Ceftriaxone (no pseudomonas, ESBL)
FDA: complicated SSTI and community-acquired PNA
What are 4 common Carbapenems and what is their coverage?
Imipenem, Ertapenem, Meropenem, Doripenem - IV
- BROADEST SPECTRUM Abx (Gram +, Gram -, pseudomonas, ESBL, anaerobes)
What 3 organisms does Ertapenem not cover that other carbapenems do cover?
does not cover Pseudomonas, Acinetobacter, and Enterococci
What coverage does the monobactam Aztreonam have?
Aerobic Gram - organisms
What is the difference in coverage between these 3 broad-spectrum antibiotics:
Carbapenems, Zosyn, Cefepime
Carbapenem (broadest coverage) > Zosyn (no ESBL) > Cefepime (weak anaerobe/no enterococcus)
