Beta lactams Flashcards
four classes of beta lactams
penicillins
cephalosporins
carbapenems
monobactams
MOA of beta lactams
inhibits cross-linkages in peptidoglycan –> leads to autolysis of bacteria
MRSA coverage
fifth generation cephalosporins
Penicillins
very short half lives (t1/2
Natural Penicilins
Pen G (IV) Pen V (PO) Spectrum: Good: Treponema pallidum, most streptococci (Strep pneumoniae) Moderate: enterococci Poor: everything else Very short half life Good for: syphilis, susceptible GNR infections (pharyngitis, endocarditis)
antistaphylococcal
agents: Nafcillin, oxacillin, dicloxacillin
Penicillinase resistant penicillins
Spectrum:
good: MSSA, streptococci
Poor: GNR’s, enterococci, anaerobes, MRSA
cleared through liver
Good for: MSSA (endocarditis)
aminopenicillins
agents: amoxicillin, ampicillin Spectrum: Good: streptococci, enterococci moderate: enteric GNR's, Haemophilus Poor: staphylococci, anaerobes, pseudomonas High incidence of diarrhea (PO) Amp (IV) Amox (PO) good for: susceptible GNR's, enterococci, streptococci, URI (streptococcal pharyngitis, otitis media)
Antipseudomonal pennicillins
agents: piperacillins, mizlocillin, carbenicillin, ticarcillin
Spectrum:
Good: pseudomonas aeruginosa, streptococci, enterococci
moderate: enteric GNR, Haemophilus
poor: staph, anaerobes
retains the Gram + activity of PCN (strep and enterococci)
Beta-lactamase inhibitor combinations
agents: ampicillin/sulbactam, amoxicillin/clavulanate (augmentin), piperacillin/tazobactam (zosyn), ticarcillin/clavulanate
good intrinsic GNR activity but susceptible to beta-lactamase, so they are paired with beta-lactamase inhibitors
beta-lactamase inhibitors
spectrum:
good: MSSA, streptococci, enterococci, many anaerobes, enteric GNRs, Pseudomonas aeruginosa (piperacillin/ticarcillin)
only amoxicillin/clav is oral
moderate: GNR’s with advanced beta-lactamases
poor: MRSA, EBSL producing GNR’s
Good for: empiric therapy of nosocomial infections (nosocomial pneumonia)
cephalosporins
can have cross reactivity with PCN allergies. Must get past reactions to any beta lactams patients have taken.
generally more resistant to beta-lactamases then PCN
First-Gen Cephalosporins
most commonly used in hospital, prophylaxis for surgery,
treats SSTI
Spectrum:
Good: MSSA, streptococci,
moderate: some enteric GNR’s
Poor: enterococci, anaerobes, MRSA, Pseudomonas
Good alternative for antistaphylococcal PCN’s
does not cross blood-brain barrier
Good for surgical prophylaxis
Second-Gen cephalosporins
Better gram - activity, somewhat weaker Gram + activity
more stable against Gram - beta-lactamase
particularly active against H.flu and N. gonorrhea
Spectrum:
good: H.flu, N. gonorrhea, GNR’s
moderate: streptococci, staphylococci, anaerobes
poor: enterococci, MRSA, pseudomonas
NMTT: prothrombin inhibition and anabuse type reaction
does not cross blood-brain barrier very well.
Good for: URI (CAP, gonorrhea, surgical prophylaxis
good intrinsic anaerobic activity, but resistance to them is increasing in B. fragilis
Third-Gen Cephalosporin
greater coverage of gram negative activity than first and second
good streptococcal activity, less staphylococcal activity
broad spectrum agents that have many uses
Spectrum:
good: streptococci, enteric GNR’s, pseudomonas
moderate: MSSA
Poor: enterococci, pseudomonas, anaerobes, MRSA
Problem with C.diff diarrhea
NMTT type reactions: prothrombin inhibition, anabuse type reactions
Good for: Lower respiratory tract infections, pyelonephritis, nosocomial infections, Lyme disease, meningitis, gonorrhea, SSTI, febrile neutropenia
Fourth-Gen Cephalosporin
broadest spectrum, with activity against both Gram - (pseudomonas) and Gram + organisms
Spectrum:
Good: pseudomonas, MSSA, streptococci, enteric GNR’s
moderate: acinetobacter
Poor: enetococci, anaerobes, MRSA
Emperic therapy for nosocomial infections
Good for: Febrile neutropenia, nosocomial pneumonia, postneurosurgical meningitis, other nosocomial infections
used for nosocomial infections, UTI and lower respiratory tract
Fifth-gen cephalosporin
only one active against MRSA (expresses PBP2a from mecA)
only one that actively binds with PBP2a
Spectrum
Good: MSSA, MRSA, enteric GNR’s
moderate: acinetobacter, Enterococcus faecalis
Poor: pseudomonas aerugonisa, enterococcus faecium, anaerobes
good for: SSTI, CAP
Carbapenems
agents: imipenem/cilastatin, meropenem, ertapenem, doripenem
spectrum:
Good: MSSA, Streptococci, anaerobes, enertic GNR’s, Pseudomonas, acinetobacter, ESBL-producing GNR’s
Moderate: enterococci,
poor: MRSA, Penicillin resistant streptococci
very broad spectrum agents
should not be used for empiric therapy for community acquired infections
Good for: mixed aerobic, anaerobic infections, infections caused by ESBL-producing organisms, intra-abdominal infections, nosocomial pneumonia, febrile neutropenia, other nosocomial infections
Monobactams
agent: aztreonam
has only one ring (4 membered beta lactam ring)
safe to administer in those who have beta lactam allergies
spectrum:
good: pseudomonas, most GNR’s
moderate: acinetobacter
poor: gram positive organisms, anaerobes
it is a gram negative drug
Good for: gram - infections, (pseudomonas)
