Cephalosporins, Carbapenems, and Monobactams Flashcards
List the organisms that 1st gen cephalosporins are effective against. Which is target?
Gram-pos: - MSSA (*target) - PCN-susc. Strep pneumo - Group streptococci - Viridians streptococci Grem-neg: (PEK) = - Proteus mirabilis - E. coli - Klebsiella pneumoniae
List the organisms that 2nd gen cephalosporins are effective against. *Which group is unique to this gen?
Gram-pos: (slightly less active than 1st gen) - MSSA (*target), PCN-susc. Strep pneumo, Group streptococci, Viridians streptococci. Gram-neg: (HENPEK) = - H. influenzae - Enterobacter spp. - Neisseria spp. - Proteus mirabilis - E. coli - Klebsiella pneumoniae (+ M. catarrhalis). Anaerobes: Bacteroides fragilis /group
List the organisms that 3rd gen cephalosporins are effective against. *Which is target?
Gram-neg (HENPECKSSS P) = - H. influenzae - Enterobacter spp. - Neisseria gonorrhoeae - Proteus mirabalis - E. coli - Citrobacter spp. - Klebsiella pneumoniae - Serretia marcescens - Salmonella spp. - Shigella spp.; *Pseudomonas aeruginosa (target) (still have gram-pos activity but less active than earlier gens)
Which 3rd gen. cephalosporin does NOT target pseudomonas, unlike the others? Which would you use instead?
Ceftriaxone - Ceftazidime
How does the activity of 4th gen cephalosporins change compared to 3rd gen?
Gram-pos: similar to ceftriaxone. Gram-neg: Similar to ceftriaxone but also adds: - Pseudomonas aeruginosa - Beta-lactamse-producing enterobacter spp.
List the categories/organisms that 5th gen cephalosporins are effective against. *Which is unique to this gen?
Resp pathogens - H. influenzae - strep. Pneumoniae - Moraxella - Staph aureus. Gram-pos + SSSI: - Strep pneumonia *MRSA*
*What important organisms are cephalosporins NOT active against? (6)
SMACLE - Stenotrophomonas maltophilia - MRSA (*except for the 5th gen) - Atypical bacteria (eg Legionella; cuz no cell wall) - C-diff - Listeria - Enterococcus spp.
All cephalosporins are eliminated via the ___________ except for ___________ and ___________ (how are each eliminated?)
- Kidney - Ceftriaxone (bile) - Cefoperazone (liver)
Which gens of cephalosporins are used for surgical prophylaxis?
1st and 2nd (2nd for more intense surgeries?)
What are some of the uses of ceftriaxone? (4 orgs)
- Uncomplicated gonorrhea (single IM dose) - CAP - PRSP - Viridans strep endocarditis
What’s the most important organisms that 4th gen cephalosporins cover (that ceftriaxone doesn’t)?
Pseudomonas
What are the major adverse effects of all gen cephalosporins? (2)
- Hypersensitivity 2. C-diff
- Are Carbapenems broad or narrow spectrum? - What major groups are they effective against? - What are their target organisms?
- Most broad-spectrum available - Many gram-pos and gram-neg aerobes, as well as gram-pos/neg anaerobes. - Targets: MSSA, bacteroides.
*What organisms are carbapenems NOT effective against? (7)
*NOT effective against: MRSA, PRSP, VRE, coag-neg staph, c-dif, atypical bacteria, S. maltophila
-______________, a carbapenem, undergoes hydrolysis by a dihydropeptidase enzyme in the ________________ to a toxic metabolite. - Therefore, it’s comarketed with _________, a DHP inhibitor (to prevents this)
- Imipenem - Renal brush border (hepatotoxic) - Cilastatin (not on test, but USMLE)
What major drug category do cephalosporins fall under? Carbapenems?
- Beta-lactams - Beta-lactams
What are carbapenem’s mech of action? - Baciocidal or static? - Time or conc-dependent?
Inhibitors of cell wall synthesis by binding to and inhibiting PBPs; primary target is PBP-2 - Bacteriocidal - Time-dependent
Name the major carbapenems. - Which 2 are the “best”?
DIME - Doripenem (best) - Imipenem (best) - Meropenem - Ertapenem
What are the mechs of resistance for cephalosporins? (which is most important?)
- Beta-lactamase enzymes (most important) - PBP alteration - Decreased membrane penetration
Beta-lactams are all cross-allergenic except for which one?
Aztreonam
Are cephalosporins bacteriocidal or bacteriostatic?
Bactericidal
Which subset of the cephalosporins are the only ones that have activity against anaerobes? - Which generation is it in?
Cephamycins - 2nd gen
*What gen. cephalosporin is used for the treatment of meningitis?
3rd gen
When treating meningitis w/3rd gen cephalosporins, if pseudomonas is suspected or present, what specific drug would you use?
Ceftazidime
What is the main thing that 5th gen cephalosporins are used for?
Drug-resistant organisms
Why were cephalosporins developed?
Beta lactams that are less susceptable to beta-lactamase enzymes.
Why were carbapenems developed?
- Extended spectrum of activity - Further beta-lactamase stability
What are the clinical uses of carbapenems?
- Empiric therapy for HA-infections - Polymicrobial infections - Infections due to β-lactamase-producing organisms (SPICE, SPACE, others)
*If pseudomonas is suspected, which carbapenem would you avoid?
*Avoid ertapenem if pseudomonas suspected
What are the main adverse effects of carbapenems?
- CNS (e.g. seizures) - GI - Hypersensitivity
Do carbapenems have hypersensitivity/cross-reactivity w/PCNs like cephalosporins do?
Yes
What category of drug is a monobactam? - How can it be administered?
Synthetic monocyclic beta-lactam - IV
Monobactams are beta-lactams. What specific part of the cell wall do they target? - What is the main class of organisms they target?
PBP-3 - of gram-negative aerobes
Recall: what class of organisms do monobactams inhibit? - What’s its main target?
Gram-neg aerobes * Pseduomonas
Recall: what is the class of drugs that aztreonam is a member of? Since aztreonam is the only beta-lactam that does have cross-allergencitiy, what clinical implications does this have?
- Monobactams - Can be used in PCN-allergic pts
What are the major adverse effects of monobactams?
N/D
What are the major adverse effects for 2nd gen cephalosporins, besides hypersensitivity and c-diff?
- Hypoprothrombinemia - Ethanol intolerance due to disulfiram-like rxn
Which gen’s of cephalosporins inhibit pseudomonas?
- 3rd (except ceftriaxone) - 4th
Which gen of cephalosporins are effective against anaerobes like bacteroides?
2nd gen only
