Antibacterials - Cell Wall and Membrane Flashcards
What are common characteristics of cephalosporins?
Distribute throughout body well
Same Mechanism as penicllins
Most are IM/IV
Similar resistance to B-lactamases as Penicillin
What are the 1st generation cephalosporins best at treating?
Treat primarily gram positive - Strep and Staph
Cefazolin and Cephalexin
What are the therapeutic uses for Cefazolin and Cephalexin?
Uncomplicated Skin infections
Prophylaxis for surgery to prevent infection at incision site
What cephalosporin has best coverage of Strep/Staph (gram positives) with a longer half-life than most?
Cefazolin - IM and IV only
What 1st generation is primarily oral use with a short half life?
Cephalexin
What happens to the effectiveness to gram positives with increasing generations?
1st generation are best at gram positive including staph, but increasing generations have less gram positive effectiveness and more gram negative
What 2nd generation cephalosporin can penetrate the CSF and treat Haemophilus?
Cefuroxime
What 2nd generation Cephalosporin is good for anaerobes?
Cefoxitin
What makes 2nd generation Cephalosporin different from 1st generation?
They more gram negative coverage and less gram positive coverage and they can tolerate SOME B-lactamases.
What is the first line therapy against bacterial meningitis as empiric treatment?
Ceftriaxone
What is a unique attribute of Ceftriaxone?
Very long half-life compared to most B-lactams and is the ONLY treatment for Gonorrhea.
What are attributes of 3rd generation Cephalosporins?
They are most effective against B-lactamase positive - Gram Negative strains, less effective against gram positive strains.
What 3rd gen cephalosporin has extended effectiveness against pseudomonas?
Ceftazidime
What cephalosporin drug has extended effectiveness with B-lactamases?
Cefepime
What are common side effects of Cephalosporins?
Cross reactivity to penicillins, less chance in 3rd generation compared with 1st/2nd generation.
Also has risk of n/v/d and C.Diff development
What kind of bacteria contain extended-spectrum B-lactamases?
Gram Negative - mostly GI bacteria
–inactivate all penicillins and most cephalosporins–
What is the only treatment for bacteria with extended spectrum B-lactamases?
Carbapenems — Imipenem, broad spectrum
What is typically used for mixed infections and/or unknown infections?
Imipenem + Cilastatin, for extended half life
What are common side effects of Imipenem?
Cross allergies with penicillin and cephalosporins
Seizures, dizziness, confusion
n/v/d
What antibiotic does not have any cross reactivity with B-lactams and is only used for gram negative aerobic only?
Aztreonam - IM/IV only, resistant to many B-lactamases
Common side effects of Aztreonam?
Seizures, EKG changes, n/v/d - C.Diff
How does Vancomycin work?
Binds the peptide end of forming peptidoglycan preventing formation and cross linking.
What kind of organisms does Vancomycin target and when is it used?
Gram Positive. Only used for severe infections and mostly IV dosing. MRSA, Strep Pneumo, penicillin allergic individuals.
What are common side effects of Vancomycin?
Red Man Syndrome from histamine release
Nephrotoxicity/Ototoxicity
Phlebitis
What antibiotic has a unique mechanism of inhibiting enolpyruvyl transferase preventing cell wall production?
Fosfomycin
What is Fosfomycin used for in the United States?
Uncomplicated UTIs
E. Coli and Enterococcus
Off-Label – can be used for extended spectrum b-lactamase strains
–very expensive–
What is a topical only antibiotic that is effective for gram positive?
Bacitracin - inhibits recycling of molecules used to produce the cell wall
What topical drug targets the cell membrane in gram negative organisms?
Polymyxin B - Topical Use Only
–binds LPS on outer membrane–
What antibiotic is used against gram positives that targets the cell membrane depolarizing?
Daptomycin
What can Daptomycin treat and what area of the body is it ineffective for?
Complicated Skin infections including MRSA
–Not for Pneumonia–
What are beneficial qualities of Daptomycin?
No cross resistance with B-lactams or Cephalosporins
What is a unique side effect of Daptomycin?
Can cause elevated CPK levels and muscle pain/weakness
