Antibacterial Agents II: Cell Wall Synthesis Inhibitors Flashcards
Name the 5 main β-lactam and cell wall synthesis inhibiting Abx.
- penicillins
- vancomycin
- cephalosporins
- carbapenems
- monobactams
What are the 3 stages of peptidoglycan synthesis?
- synth. of cell wall subunits in the cytosol
- linear polymerization of subunits at cell membrane
- cross-linking of peptidoglycan polymers at the cell wall
What inhibits stage 1 of peptidoglycan synthesis (synth. of cell wall subunits in the cytosol)?
fosfomycin, cycloserine
What inhibits stage 2 of peptidoglycan synthesis (linear polymerization of subunits at the cell membrane)?
bacitracin, vancomycin
What inhibits stage 3 of peptidoglycan synthesis (cross-linking of peptidoglycan polymers at the cell wall)?
penicillins, cephalosporins
Choose: Penicillins are BACTERICIDAL/BACTERIOSTATIC.
bactericidal
_____ is the generic term for enzymes that hydrolyze β-lactams, including penicillinases and cephalosporinases.
β-lactamase
β-lactamase is the generic term for enzymes that hydrolyze β-lactams, including ____ and _____.
penicillinases; cephalosporinases
β-lactamase is the generic term for enzymes that ____, including penicillinases and cephalosporinases.
hydrolyze β-lactams
How does MRSA occur?
alterations of penicillin binding proteins (PBPs) so they no longer bind
How are Penicillins absorbed, distributed, metabolized, and excreted?
A: good on empty stomach
D: throughout body- poorly into tissues- high conc in liver, kidney, skin
M: increased in kidney failure
E: kidney tubular secretion; breast milk
What is probenecid?
drug that blocks tubular secretion of penicillin to prolong it’s activity
Describe Penicillin G.
prototypical penicillin; powerful; inexpensive; hydrolyzed by acid and penicillinase enzyme
Describe Penicillin V.
acid-resistant; better absorbed than G; oral route ok; mild to moderate infections
Describe the penicillinase-resistant penicillins.
less potent than G; acid resistance and binding varies; eliminated by hepatic and renal routes; for gram + and gram - cocci; ex: methicillin, nafcillin, oxacillin, cloxacillin, dicloxacillin
Describe the extended spectrum penicillins.
increased hydrophobicity allows penetration thru porins; acid resistant but NOT penicillinase resistant; ex: ampicillin, amoxicillin
Describe the Anti-pseudomonal penicillins.
not resistant to penicillinase; effective against Pseudo. aeruginosa, enterococci, Bacteriodes fragilis; parenteral only; ex: ticarillin, piperacillin
What drug is not resistant to penicillinase; effective against Pseudo. aeruginosa, enterococci, Bacteriodes fragilis; parenteral only; ex: ticarillin, piperacillin?
the Anti-pseudomonal penicillins
What drug has increased hydrophobicity to allow penetration thru porins; acid resistant but NOT penicillinase resistant; ex: ampicillin, amoxicillin?
the extended spectrum penicillins
What drugs are less potent than G; acid resistance and binding varies; eliminated by hepatic and renal routes; for gram + and gram - cocci; ex: methicillin, nafcillin, oxacillin, cloxacillin, dicloxacillin?
the penicillinase-resistant penicillins
What drug is acid-resistant; better absorbed than G; oral route ok; for mild to moderate infections?
Penicillin V
What drug is the prototypical penicillin; powerful; inexpensive; hydrolyzed by acid and penicillinase enzyme?
Penicillin G
Name the 3 β-Lactamase Inhibitors.
- clavulanic acid
- sulbactam
- tazobactam
The ____ will extend the antibacterial spectrum of the accompanying penicillin ONLY if bacterial resistance is due to β-lactamase destruction AND the inhibitor is active against that particular β-lactamase.
β-lactamase inhibitor
The β-lactamase inhibitor will ____ of the accompanying _____ ONLY if bacterial resistance is due to β-lactamase destruction AND the inhibitor is active against that particular β-lactamase.
penicillin; extend the antibacterial spectrum
The β-lactamase inhibitor will extend the antibacterial spectrum of the accompanying penicillin ONLY if
_____ AND the inhibitor is active against that particular β-lactamase.
bacterial resistance is due to β-lactamase destruction
The β-lactamase inhibitor will extend the antibacterial spectrum of the accompanying penicillin ONLY if
bacterial resistance is due to β-lactamase destruction AND _____.
the inhibitor is active against that particular β-lactamase
Tx for Strep. pharyngitis, pneumoniae (CAP), sinusitis, otitis media, rheumatic fever, necrotizing fasciitis?
Pen G, Pen V, amoxicillin
Tx for Enterococci bacteremia, UTI?
Pen G, ampicillin + AG, ampicillin
Tx for Staph. aureus localized cutaneous infection, bacteremia, device-assoc. infections, pneumonia? (MSSA and MRSA)
MSSA: oxacillin
MRSA: NO penicillins
Tx for Neisseria gonorrhea?
Pen G (lots of resistance, tho)
Tx. for Neiserria meningititis meningitis?
Pen G
Tx for Moraxella catarrhalis otitis media, CAP?
amox/clav
Tx for Bacillis anthracis anthrax?
Pen G
Tx for Cornye. diphtheria?
Pen G
Tx for H. influenzae meningitis, otitis media, sinusitis, CAP?
ampicillin, amox/clav
Tx for E. coli UTIs, intra-abd infections, diarrhea, hemorrhagic colitis?
ampicillin, amox/clav
Tx for Klebsiella UTIs, intra-abd. infections?
ampicillin, amox/clav
Tx for H. pylori peptic ulcer disease?
ampicillin, amox/clav
Tx for Salmonella gastroenteritis, typhoid fever?
ampicillin, amox/clav
Tx for Pseudomonas aeruginosa opportunistic infections?
amox/clav, piper/tazo, ticar/clav
Tx for Clost. perfringens gas gangrene, food poisoning?
Pen G
Tx for Bacteriodes fragilis intra-abd. and brain abscesses?
Piper/tazo, ticar/clav
Tx for Treponema pallidum syphilis?
Pen G
Tx for Borrelia burgorferi Lyme disease (early)?
amoxicillin
____ are virtually non-toxic except for hypersensitivity reactions.
Penicillins
Penicillins are ____ except for hypersensitivity reactions.
virtually non-toxic
Penicillins are virtually non-toxic except for _____.
hypersensitivity reactions
How does penicillin become an antigen for hypersensitivity rxns?
functions as a hapten and combines with a protein
Most penicillin reactions are related to the _____, which creates cross-linking.
6-aminopenicillianic
___ of pts report a penicillin allergy but only ___ overall actually experience a rxn to exposure.
10%; 1-2%
What is a type 1 penicillin rxn?
IgE mediated antibodies; very rare but can be life-threatening; 30 min onset
What is a type 2 penicillin rxn?
cytotoxic Abs of IgG or IgM (complement dependent); rare; ex: hemolytic anemia
What is a type 3 penicillin rxn?
delayed allergic rxn; 72 hour onset; IgG or IgM immune complexes that activate complement and lodge in tissues
What is a type 4 penicillin rxn?
T cell mediated allergy; delayed onset; skin eruptions and thrombocytopenia
What is the most common penicillin reaction?
a maculopapular or morbilliform rash (mild and reversible)
How does vancomycin work?
it inhibits cell wall synthesis in stage 2 (linear polymerization)
How is vancomycin administered and excreted?
A: IV unless used for GI treatment
E: renal (t1/2: 6-10 days)
When should a vancomycin be used?
when less toxic agents are ineffective or not tolerated (ie penicillin allergy)
Tx for MRSA severe skin and soft tissue infection?
vancomycin
Tx for Staph and Strep meningitis, pneumonia, endocarditis, sepsis?
vancomycin
Tx for ampicillin-resistant Enterococci bacteremia, endocarditis?
vancomycin
Tx for C. diff pseudomembranous colitis?
metronidazole, oral vancomycin
What are the adverse rxns for vancomycin?
chills, fever, skin rash, ototoxicity (pretreat with acetaminophen and diphenhydramine)
Why do you pretreat vancomycin with acetaminophen and diphenhydramine?
b/c of the risk of ototoxicity
Because of ototoxicity, pretreat with _____ and _____ before giving vancomycin.
acetaminophen; diphenhydramine
What is Daptomycin?
a cyclic lipopeptide used to treat methicillin and vancomycin resistant staph and enterococci; restricted use
Where does Daptomycin act? What does it do?
at the bacterial membrane- causes loss of intracellular ions
Cephalosporins are a type of ____.
β-lactam antibiotics
How do cephalosporins work?
similar to penicillins but less susceptible to penicillinase and less cross-reactivity
How are cephalosporins absorbed, distributed, metabolized, and excreted?
A: orally or parenterally
D: penetrate well into most tissues and fluids, including the placenta; brain and CSF ONLY in 3rd gen
M/E: kidneys
How many cephalosporins generations are there?
5
What are the 1st generation cephalosporins?
Cefazolin, Cephalexin
What do the 1st gen cephalosporins work for?
gram + and - cocci, some gram - bacilli
_____ are more stable than penicillins to many beta-lactamases.
1st gen cephalosporins
Why is Cefazolin now the prototype drug?
low cost, low tox, good penetration, lengthened t1/2 (90 min)
Compared to Penicillin G, the _____ have greater activity against MRSA.
1st gen cephalosporins
Compared to ____, the 1st gen cephalosporins have greater activity against MRSA.
Penicillin G
Compared to Penicillin G, the 1st gen cephalosporins have greater activity against ____.
MRSA
Name a 2nd generation cephalosporin.
Cefuroxime
____ have greater activity against gram (-) bacteria and anaerobes, especially respiratory, but do not work against Pseudomonas.
2nd generation cephalosporins
2nd generation cephalosporins have greater activity against _____ and _____, especially _____, but do not work against Pseudomonas.
gram (-) bacteria, anaerobes; respiratory
2nd generation cephalosporins have greater activity against gram (-) bacteria and anaerobes, especially respiratory, but do not work against _____.
Pseudomonas
Name 3 3rd gen cephalosporins.
- Cefdinir
- Ceftriaxone
- Ceftazidime
Don’t give a _____ to a pt with a hx of penicillin allergy.
cephalosporin
Don’t give a cephalosporin to a pt with a hx of _____.
penicillin allergy
How is a 3rd gen cephalosporin different than 2nd gen?
expanded gram (-) bacilli coverage; also Enterobacter, Hemophilis, Neisseria and moderate antipseudomonal
How is a 4th gen cephalosporin different than 3rd gen?
more resistant to chromosomal and extended spectrum β-lactamases; good against pseudomonas and S. pneumoniae; some anaerobic
Name a 4th gen cephalosporin.
cefepime
Name a 5th gen cephalosporin.
Ceftaroline
What are the 5th gen cephalosporins similar to? How are they unique?
3rd gens; better gram (+) coverage including MRSA, S. pneumoniae, and E. faecalis; does NOT cover pseudomonas or anaerobes
Tx for MSSA, Strep surgical prophylaxis, skin infections?
cephalexin (po), cefazolin (IV)
Tx for Klebsiella pneumonia, UTIs?
cephalexin
Tx for E. coli, Proteus UTIs?
cephalexin
Tx for resistant E. coli, proteus, Klebsiella pneumonia, UTIs?
2nd gen cephalosporin
Tx for H. influenza meningitis, otitis media, sinusitis?
Cefuroxime (IV), Cefaclor (po)
Tx for M. catarrhalis otitis media, sinusitis?
Cefaclor (po)
Tx for Bacteriodes peritonitis, diverticulitis?
Cefoxitin
Tx for S. pneumoniae pneumonia, meningitis?
Cefotaxime, Ceftriaxone
Tx for N. gonorrhea?
ceftriaxone
Tx for Pseudo. aeruginosa UTIs, pneumonia?
Ceftazidime
What are the adverse rxns for the cephalosporins?
allergies/hypersensitivities, GI upset, superinfections, can intensify oral coagulants