Lecture 8: Cephalosporins, Carbapenems, Monobactams Flashcards
Erdman's Section
How are the Cephalosporins strucutrally different than the Penicilins?
- They have 6-membered dihydrothiazine; helps with stability against B-lactamase
What is the Mechanism of Action for the Cephalosporins?
- Same as Penicillins
- Inhibits Cell Wall synthesis by binding to PBPs [Transpeptidase] leading to lysis
- Bactericidial
What are the ways that Cephalosporins have resistance?
Mechanisms?
- Productions of B-lactamases; they hydrolyze the amide bond breaking the ring
- Alterations in PBPs
- Altered Porins
What is the interesting scheme that Cephalosporins follow in terms of the Generations?
- 1st to 4th Gen: LOSE Gram (+) Activity and GAIN Gram (-) & B-lactamase activity
What are the First Generations Cephalosporins that are used?
- Cafazolin, Caphalexin
What is the spectrum of activity for the First Generation Cephalosporins?
- GOOD to Gram (+); Best in Cephalosporins [Group/Viridan Strep, PSSP, MSSA
- Gram (-): “PEK” –> P. Mirabilis, E. Coli, K. Pneumoniae
What are the Second Generation Cephalosporins that are used?
- Cefuroxime, Cefprozil, Cefoxitin [Cephamycin]
Less active to Gram (+) and More Active to Gram (-)
What is the spectrum of activity for the Second Generation Cephalosporins?
- Gram (+): Group/Viridan Strep, MSSA
- Gram (-): “HENPEK” –> H. Influenzae, Enterobacter sp., Neissera sp., P. Mirabilis, E. Coli, K. Pneumoniae
- Anaerobes: B. Fragilis [use Cefoxitin, Cefotetan, Cefmetazole]
What are the Third Generation Cephalosporins used?
- Cefraxone, Ceftazidime, Cefpodoxime
Less active in Gram (+) than 1st and 2nd gen & good aginat Gram (-)
What is the Spectrum of Activity for the Thrid Generation Cephalosproins?
- Gram (+): PRSP - Use Ceftriaxone & Cefotaxime
- Gram (-): “HENPECKSSS”–> H.Fluenzae, Enterobacter, Neisseria, P. Mirabilis, E. Coli, Citerbacter, K. Pneumoniae, S. Marcescen, Salmonella, Shigella
- Pseudomonas Aeruginosa [ONLY Ceftazidime & Cefoperazone
CEFTRIAXONE DONT COVER PSEUDO
What are the Fourth Generation Cephalosporins that are used?
- Cefepime
Poor Inducer of AmpC
What is the spectrum of activity for the Fourth Generation Cephalosporins?
- Gram (+): PRSP
- Gram (-): “HENPECKSSS” + Pseudomonas Aeruginosa
What is the Anti-MRSA Cephalosporin?
- Ceftaroline
What is the Spectrum of Activity for the Anti-MRSA Cephalosporin?
- Gram (+): Strep & Staph [PRSP] & MRSA [maybe like 4th line tho]
- Gram (-): “HENPECKSSS” with NO Pseudomonas Aeruginoas
What is Cefidercol and how does it work?
- Binds to Free Iron, with the help of porins, transport the antibiotic into the cell
What is the spectrum of activity of Cefiderocol?
- Gram (+): No real activity
- Gram (-): Enterobacterales, P. Aeruginoas, A. Baumannii, S. Maltophilia some MDR [ESBLs, AmpC, Carbapenemases
What is the spectrum of activity for Ceftolozane-Tazobactam?
- Gram (+): Strep
- Gram (-): “HENPECKSSS” + Pseudomonas Aeruginosa [Super active toward]
What is the spectrum of activity for Ceftazidime-Avibactam?
- Gram (+): Strep
- Gram (-): “HENPECKSSS” + Pseudomonas Aeruginosa [Super active toward]
What is an overall thing to keep in mind regarding the Spectrum of Activity for Cephalosporins/
- NOT ACTIVE toward MRSA [except Ceftaroline] Entercoccus sp., & Legionella Pneumophilia
What is the Pharmacodynamic Priniple for the Cephalosporins>
- Time-dependent; T>MIC
How are the Cephalosporins distributed in the Body?
- Into Tissues and Fluids; Pleural, Synovial, Bone, Bile, Placenta, Pericardial, Humor
Are Cephalosporins able to go into the CSF?
- NO with most 1st and 2nd Generations
- Parenteral Cefuroxime, 3rd & 4th Generations are able to go into CSF
How are the Cephalosporins Eliminiated from the Body?
- Kidneys via Glomerular filration and Tubular Secretion
- EXCEPT Ceftriaxone & Cefoperazone [Bile & Liver]
Are Cephalosporins removed from Hemodialysis?
- Most of them are EXCEPT Ceftriaxone
What is the Half Life for the Cephalosporins?
- ~2 hours
- EXCEPT Ceftriaxone ~8 hours [making it dosed once daily]
What are some of the Clinical Used for the First Generation Cephalosporins/
- MSSA, Group/Viridan Strep [Skin/Soft Tissue, Septic Arthritis, Osteomyelitis, Endocaraditis]
- Cefazolin is THE DOC for Surgical Proghylaxis
- Gram (-): PEK
- NOT for Meningitis [NOT into CSF]
What is the Clinical Uses of the Second Generation Cephalosporins?
- Oral agents good for; Pharyngitis, Tonsillitis, Sinusitis, Otits Media, Bronchitis, Pneumonia
- NOT recommended for Meningitis
- Cephamycins, Cefoitin, Cefotetan, Cefmetazole good in Bacteroids fragilis
What is the Clinical use of the Third Generations Cephalosporins?
- Gram (-) Bacterias [UTI, Bone/joint, Meningitis…]
- Pseudomonas Aeruginosa use Ceftazidme or Cefoperzone
- Ceftriaxime = Uncomplicated Gonorrhea
- Cefotaxime & Ceftiaxone = Gram (+); Group/Viridan Strep [Endocarditis] & PRSP [Meningitis]
What is the clinical use of Fourth Generation Cephalosporins?
- Pneumonia, Bacteremia, UTI, Skin, Soft Tissue…
- Antipseudomonal Activity
- NO to anaerbos so add Metronidazole
What is the Clinical use of the Anti-MRSA Cephalosporins?
- Skin and Soft tissue from MRSA
- NOT Pseudomonas Aeruginous
What is the Clinical Use of Cefiderocol?
- UTI [Pyelonephritis], HABP, VABP
- VERY $$$
What is the clinical use of Cephalosporin-B-Lactamase inhibitor combinations?
- UTI, IAI [with Metronidazole], HABP/VABP
What are some of the adverse effects of the Cephalosporins?
- Hypersensitivity [Rash, hives, itching…]
- Issues with 5-NMTT side chain
- GI [N, V, Pseudomembranous Colitis; Biliary Sludging
What is important to know about the cross-reactivity within Cephalosporins?
- Rate is ~1-5 % with 1st Generations being ~10% [except Cafazolin b/c of unique R1 group]
What is important to know about the 5-NMTT side chain within the Cephalosporins?
- Might cuase Hypoprothrombinemia or Disulfiram Reaction
- Found in Cefamandole, Cefotetan, cefmetazole, Cefoperazone, Moxalactam
What is the structural difference in the Carbapenems compared to the Cephalosporins?
- HAVE 5-member ring BUT theres a Sulfur group
What is the mechanism of action for the Carbapenems?
- Binds to PBPs that help with Cell Wall synthesis
- Bactericidal
Similar to the other B-lactams
What are the Mechanism of resistance for the Carbapenem?
- Alteration in Porins [effects Pseudomonoas Aeruginosa
- Hydrolysis by b-lactamase or Carbapenemase
- Alteration of PBP [NO MRSA or PRSP]
What is the spectrum of activity for the Carbapenems?
- VERY broad spectrum
What Gram (+) do the Carbapenems affect and which are the best for it?
- Imipenem & Doripenem
- Group/Viridan Strep, PSSP, E. Faecalis, MSSA [NEVER 1st line]
What Gram (-) do the Carbapenems affect and which are the best for it?
- Doripenem & Meropenem
- “HECK YES Ma’aM” or “HENPECKSSS”
- DOC for ESBL, AmpC,
- Acinetobacter sp., Pseudomonas Aeruginosa not good with Ertapenem
What Anaerobes are the Carbapenems good for?
- Gram (+): Peptostreptococcus, Clostridium
- Gram (-): ALL Bacteroides
What organisms are NOT active against Carbapenem?
- MRSA
- VRE
- C. Diff
- Stenotrophomonas Maltophilia
What is the pharmacodynamic prinicples of carbapenems?
- Time-dependent ; T>MIC
- They are Bactericidal; only Bacteriostatic for Enterococcus
What is important to know about the distribution of Carbapenems?
- In body tissue and fluids [saliva, sputum, humor, skin, soft tissue, bone, bile, endometrium…]
- CSF?? only Meropenem goes into the CSF
What is important to know about the Elimination of the Carbapenems?
- Kidney via Glomerular or Tubular
- Imipenem has DHP inactive it; so give with Cilastatin [protects from break down and helps with nephrotoxicity]
- ALL Carbapenems NEED DOSAGE ADJUSTMENTS
What is important to know about the half life of the Carbapenems?
- Imipenem, Meropenem, Doripenem = 1 hour
- Ertapenem = 4 hours
What are the clinical uses of the Carbapenems?
- Polymicrobial or Nosocomial Infections
- Ertapenem =/= Pseudomonas Aeruginosa
- Gram (-) that make ESBLs, AmpC [DOC]
What are the Adverse Effects of the Carbapenems?
- Hypersensitivity [Rash, hives, itching…]
- GI: N, V, D, C. Diff
- CNS - DIRECT TOXIC EFFECT [Insomina, agitation, confusion, dizziness, Seizures (from previous seizures or high doses)]
What is the main sturctual feature of a monbactam?
- Just a square brother
What is the mechanism of action for the Monobactams?
- Inhibits cell wall synthesis by inhibiting PBPs BUT…
- Bind to PBP-3 helping be active to Gram (-)
What is the Monobatacm that is used?
- Aztreonam
What is the spectrum of activity for the Monobactams/
- ONLY good for Gram (-)
- HENPECKSSS + Pseudomonas Aeruginosa [60% of strains]
What is important to know about the Pharmacodynamic principles of Aztronam?
- T>MIC
- Distrubtion: Body Tissues and Fluids; DOES go into CSF
- Elimination: Kidneys & removed via Hemodialysis
What is the Clinical use of Aztreonam?
- Gram (-) infections [EVEN Pseudomonas Aeruginosa]
- For those that have a Penicillin allergy
little to no Cross-reactivity