Antibiotics (rest of beta lactams Flashcards
What is the similar structure between cephalosporins
- 7-aminocephalosporonic acid
What is the difference between cephalosporins and cephamycin’s (cefoxitin)
- An O where the S is
What is the MOA of cephalosporins
- Same as penicillins, bactericidal
How does resistance for cephalosporins occur
- Lack of PBP or altered PBP with reduced affinity
- Beta lactamase production
- Resistant to beta- lactamase produced by staph aureas and common gnb
- Efflux
- Inability of drug to penetrate
What are the adverse effects of cephalosporins
- Considered safe drugs
- Hypersensitivity
- Allergic
- Skin rash
- Diarrhea
- Fever, granulocytopenia, hemolytic anemia
- Biliary pseudolithiasis (ceftriaxone)
Why can ceftriaxone cause biliary pseudolithiasis
- Ceftriaxone eliminated by the billiard system so a long half life
- Only have to give once a day
What is biliary pseudolithiasis
- Mimics gallstones
What are the first generation cephalosporins
a) Oral:
- Cephalexin
- Cefadroxil
b) IV/IM
Cefazolin
What are first generation cephalosporins active against
- Active against gpc (gram positive cocci)
- Some gram negative bacilli (gnb) E.coli, proteus and klebsiella
- Not active against enterococci or MRSA
Are first generation cephalosporins the DOC for any infections
- No except cefazolin is for surgical prophylaxis
Do first generation cephalosporins penetrate the CNS
No
What are the second generation cephalosporins
a) Oral
- Cefuroxime axetil
- Cefprozil (cefaclor)
b) IV/ IM
- Cefuroxime
c) Cephamycin: cefoxitin
What are second generation cephalosporins active against
- Same activity as first generation but greater coverage of gnb (not pseudomonas aeruginosa)
- Active against gpc (gram positive cocci)
- Some gram negative bacilli (gnb) E.coli, proteus and klebsiella
What are cephamycin’s used for
- Used in mixed aerobic/ anaerobic infections (good in gut, diabetic gout infections as there Is both aerobic and anaerobic)
- Better anaerobic function
What are the third generation cephalosporins
a) Cefotaxime, ceftriaxone
- IV/IM
- Don’t cover Ps. Aeruginosa
b) Ceftazidime
- IV/IM
- Reserved for Ps. Aeruginosa (still has a lot of gp effectiveness)
c) Cefixime
- Oral agent
Third generation cephalosporins activity
- Enhanced activity against gnb
- Decreased activity against gpc except Strep pneumoniae
Can third generation cephalosporins penetrate the CNS
Yes
What are the fourth generation cephalosporins
- Cefepime
- Reserved for hospital cause such broad spectrum
What are the fourth generations activity
- Fourth gen cephalosporins
- Enhanced activity enterobacter and citrobacter
- Active against Ps. Aeruginosa
What are the fifth generation cephalosporins and what are they active against
- Ceftaroline and ceftobiprole
- Activity against MRSA, ampicillin sensitive E. faecalis and penicillin resistant S. pneumoniae
Carbapenems
Structurally related to beta lactams
What are the carbapenems
- Imipenem-cilastatin, meropenem, ertapenem (very broad spectrum agents)
What is imipenem combined with
- Cilastatin (a renal di-petidase inhibitor)
What is the activity of carbapenems (imipenem and meropenem)
Gram positive, gram negative including pseudomonas and anaerobic organisms
What makes ertapenem different then the other carbapenems
- Long half life (once daily)
- Poor activity against enterococcus sp and P. aeruginosa
monobactams
- mono cyclic beta lactam ring
- Resistant to beta lactamases
- Aztreonam (not available in canada)
- Active against gnb including Ps. aeruginosa
- Not active against ESBL or AmpC producers
