ICWS Flashcards
Name the 4 Penicillin groups
- Natural Penicillins
- Penicillinase Resistant Penicillins
- Extended spectrum penicillins
- Antipseudomonal penicillins
Name the Natural Penicillins
Pen G (IV, IM)
Pen V (oral)
Benzathine pen. (IM)
Procaine pen. G (IM)
Name the Penicillinase Resistant Penicillins
Nafcillin (IV/IM)
Dicoloxacillin (oral)
Oxacillin (IV/IM, oral)
Methicillin (testing only)
Name the extended spectrum penicillins
Ampicllin (oral)
Amoxicillin (oral)
Name the antipseudomonal penicillins
Piperacillin (IV/IM)
Ticarcillin (IV/IM)
What are the general rules regarding ICWS?
- All ICWS (lyse cells)
- All have B-lactam rings
- All are bacterioCIDAL
What is the spectrum of the penicillins?
Progress from very G+++ w/ some G- to very G— w/ some G+
- Extended spectrum: More extended G- coverage (more broad spectrum)
- Antipsuedomonals are the only ones with coverage for psuedomonas
What is the MOA for penicillins?
Target penicillin binding proteins (PBPs) which form the trans-pep and trans-glyco bonds
What is the MOR for penicillins?
Penicillinase: Inactivates abx by hydrolyzing B-lactam ring
*Excludes penicillinase resistant class
Why do Penicillinase Resistant Penicillins not work against MRSA?
- MRSA has nothing to do with B-lactamase
- MRSA produces an alternate PBP which decreases the binding affinty of B-Lactam abx to PBPs
What is the only B-Lactam that can be used against MRSA?
Ceftaroline
Which penicillin is metabolized by the liver?
Penicillinase Resistant (Hepatic metabolism w/ kidney excretion)
What is the purpose of the B-Lactamase inhibitors
When used in conjunction w/ the antipsuedomonal penicillins or extended spectrum penicillins, they help to extend the spectrum of the abx to include many organisms that are resistant due to B-lactamase production
Name the 3 B-Lactamase inhibitors
Clavulnaic acid, Sulbactam, and Tazobactam
+extended spectrum/antipsuedomonal
Toxicities of Penicillins
- Allergy (all forms)
- Electrolyte imbalances
- GI distubrances
- Superinfections
- Relatively safe though
While very similar, what is the advantage cephelosporins have over penicillins?
7-methyl group increases their resistance to B-lactamase
Name the 1st gen. cephalosporins
1st gen: Narrow spectrum
- Cephazolin IV/IM
- Cephalexin (Keflex) ORAL
Name the 2nd gen. cephalosporins
2nd gen: Intermediate spectrum
- Cefaclor ORAL
- Cefuroxime IV/IM
- Cefprozil ORALe
Name the 3rd gen cephalosporins
3rd gen: Broad spectrum (but remember, this does not mean the most broad of all abx)
- Cetrioxone IV/IM
- Cefotaxime IV/IM
- Ceftazidime IV/IM
- Cefixime ORAL
Name the 4th gen cephalosporins
4th gen:
-Cefepime IV (100% bioavailability)
Name the 5th gen cephalosporins
“Unnamed”
-Cetaroline fosamil IV
Which class has the broadest spectrum coverage of all B-lactams?
4th gen cephalosporins (Cefepime)
MOA for cephalosporins
Bind to PBP’s to interfere with bacterial cell wall synthesis (same as penicillins)
What is the spectrum of the 1st gen cephalosporins
Good G+ Moderate G- Increased B-lactamase resistance No antipseduomonal (similar to natural penicillins)
What is the spectrum of the 2nd gen cephalosporins
Lower G+ activity
Somewhat increased G- activity
Increased B-lactamase resistance
No antipseduomonal
What is the spectrum of the 3rd gen cephalosporins
Less active against G+
Much more active against Enterobacteriaceae
What is the spectrum of the 4th gen cephalosporins
More resistant to some B-lactamases (compared to 3rd gen)
Antipsuedomonal!
Better G+ coverage
Very good broad spectrum coverage
Penicillinase Resistant penicllins are the DOC for:
MSSA
Extended spectrum penicillins are the DOC for:
Lysteria
H. pylori
Antipseudomonal penicillins are the DOC for:
P. aeruginosa and acinetobacter
Ceftazolin is the DOC for:
Surgical prophylaxis
When would be an appropriate time to use 4th gen cephalosporins?
Important for serious infections (pseudomonas, enterobacteriaciae, etc.)
What is the spectrum of the 5th gen cephalosporins
- Effective against MRSA and VRSA! Binds to mutated PBP (PBP2A) with very good affinity (unlike the other B-lactams)
- Also good for CABP (complicated skin infections)
- No antipseudomonal activity
What are the contraindications for 3rd gen. cephalosporins?
Neonates (bilirubin displacement)
What are the toxicities of the cephalosporins?
- Fairly safe
- Superinfection
- Disulfiram-like rxn after alcohol consumption
- Allergy (10% cross sensitivity w/ penicillins)
- Dose dependent renal tubular necrosis (synergistic nephrotoxicty w/ amingoglycosides!) so avoid in pts with poor renal function
- Diarrhea
What is the MOR for the cephalosporins?
Same as penicillins
Name the Monobactams (1)
Aztreonam IV/IM/ inhalation
What is the spectrum of Aztreonam (Monobactam class)
Aerobic G-
What is an appropriate use of Aztreonam?
Good alternative for G- rxns in penicillin allergic pts
Is there cross sensitivity with Aztreonam and other B-Lactam abx?
No! Good alternative for people with pen. allergies
What is the toxicity of Aztreonam?
Very minimal
- Phlebitis
- Skin rash
- Abnormal liver function
Name the Carbapenems (3)
- Imipenem + Cilastin IV
- Meropenem IV
- Ertapenem IV/IM
CarbaPENEMS end in PENEM
What is the spectrum of the Carbapenems
- Mixed aerobic/anaerobic infections
- One of the best classes for broad spectrum coverage (empirical therapy!)
- Indicated for organisms resistant to other antimicrobials
What is the purpose of cilastin being paired with Imipenem?
- Imipenem is rapidly inactivated by renal tubule dihydropeptidases
- Cilastin is a dihydropeptidase inhibitor
Which bacteria rapidly develops resistance against imipenem and meropenem?
Pseudomonas (recommend giving in combo w/ aminoglycoside)
Which carbapenem should you never use for a psuedomonas infection?
Ertapenem (not effective enough)
What is a major toxicity concern for imipenem?
Imipenem can cause SEIZURES at high levels! Use cautiously in pts with: -Brain lesions -Head trauma -Hx of CNS disorders such as seizures
**Meropenem less likely to cause seizures
Name the 3 drugs that are ICWS but are NOT B-Lactams
Vancomycin
Fosfomycin
Bacitracin
What is the MOA for Vancomycin?
Prevents elongation of the polypeptide chain by binding to terminal D-Ala-D-Ala (= no tethering)
Imipenem/cilastin and Meropenem are the DOC for:
Serratia
Enterobacter
What is the MOR to Vancomycin?
Modification of the D-ala-D-ala binding site, inhibiting Vanco from binding
(Vancomycin-resistant enterococci - VRE)
What is the spectrum coverage of Vanco?
G+ only
Vancomycin is the DOC for:
MRSA
C. diff*
Staph superinfection
HOWEVER, due to emergence of Vanco-resistant enterocci (VRE), Vanco is the drug of last resort (*exception is C. Diff)
When would you give Vanco via an IV? When would you give Vanco orally?
IV- systemic infections
Oral- GI infections caused by c. diff and staph
What are the adverse affects of Vanco?
- Ototoxicity
- Nephrotoxicity
- “Red man” syndrome: flushing from histamine release
What is the MOA for Fosfomycin?
f by preventing NAG to NAM reduction
What is the spectrum coverage of Fosfomycin?
G+ and G-
What is the use of fosfomycin?
Uncomplicated lower UTIs in women (but not necessarily drug first choice)
Fosfomycin plus what other drugs cause a synergistic rxns? (3)
B-lactam
Aminoglycosides
Fluorquinolones
What is the spectrum of Bacitracin?
Mainly G+ bacteria
What is the MOA of Bacitracin?
Interferes with the final dephosphorylation step in the phospholipid transmembrane carrier cycle
What is Bacitracin commonly use in combo with?
Neomycin and Polymyxins (think Neosporin)
What is the most common use of Bacitracin
Superficial skin and eye infections following minor injuries
