Intro to Antibiotics I Flashcards
overprescription of antimicrobials
facilitate resistance
prophylactic therapy
prevent infection or prevent dangerous disease in those already infected
ex/ HIV infection to prevent opportunistic or post-exposure prophylaxis in those in contact with meningococcal meningitis
preemptive therapy
provide early, targeted therapy in high risk pts asymptomatic but who are infected
ex/ CMV tx if CMV + after solid organ transplant
empiric therapy
infecting organism not known, antibiotics streamlined based on susceptibility and duration
ex/ staph aureus bacteremia treated empirically with vancomycin
post-treatment suppressive therapy
cover patient with antimicrobial therapy at lower dose when infection has not been completely eradicated and immunological or anatomical defect still resent which lead to original infection
ex/ ortho implant that has become infected
gold standard for ID of bacteria
gram stain
minimum inhibitor concentration
lower concentration of drug that inhibits growth
dilution test
serially diluted antibiotics tested with organism
MIC determined
disk diffusion
antibiotic on disk
-measure size of clear zone
determine susceptible or resistant
NO MIC
optical diffusion
test strip with varying antibiotic concentrations on agar
determine MIC
narrow spectrum
single or limited group of microorganisms
extended spectrum
gram positive and significant number of gram negatives
broad-spectrum
wide variety of bacterial species
-gram positive and negatives
bacteriostatic
arrest growth and replication of bacteria
protein synthesis inhibitors
bacteriocidal
kill bacteria
concentration dependent
extent of killing increases with concentration
aminoglycoside
fluoroquinolones
time dependent
serum concentration above minimum kills bacteria
beta-lactam
vancomycin
tetramycin
concentration dependent
ticarillin
time dependent
resistance mechanisms
reduced entry into pathogen
enhanced export
enzymes that destroy antibiotic
proteins transform prodrugs
alteration of target proteins
alternate pathways to those inhibited by antibiotics
penicillins
thiazolidine ring connected to beta lactam ring
-attached to side chain
mechanism of penicillins
inhibit transpeptidation rxn - last step in peptidoglycan synthesis
beta-lactams are analogs of D-Ala-D-Ala
-bind PBPs - stops cross-linking of the D-Ala
covalent binding
-cell autolysis
bacterial resistance to beta-lactams
beta-lactamases
-drug destruction and inactivation
natural PCNs
PCN G and V
gram positive cocci
streptococcus pneumoniae
pregnant with syphilis
PCN V
no alternative - if allergic need to be desensitized
anti-staphylococcal PCN
PCNase resistant
-staph aureus and staph epidermidis
not MRSA
oxacillin, dicloxacillin, nafcillin
aminopenicillins
extended spectrum
often given with beta-lactamase inhibitor
extends beyond gram + and -
haem influenza, E. coli, proteus, listeria
ampicillin, amoxicillin
upper resp tract infection with s. pyogenes, s. pneumoniae, h. influenza
ampicillin (and sulbactam)
or amoxicillin ( and clavulinic acid)
anti-pseudomonal PCNs
pseudomonas, enterobacter, proteus
piperacillin - extends to klebsiella and anaerobes
piperacillin and ticarillin
hospital acquired pneumonia
anti-pseudomonal PCNs
ticarcillin or piperacillin
cephalosporins MOA
beta-lactam
-same as PCNs
cephalosporins
classified in generations
no cephalosprin
active against MRSA, listeria, enterococci
first gen cephalosporin
gram positive
moderate gram neg
orally active anaerobes
cefazolin, cephalexin
surgical prophylaxis
first gen cephalosporins
cefazolin
cefalexin
second gen cephalosporin
increased gram negative activity
cefoxitin, cefuroxime
bacteriodes fragilis
cefoxitin
third gen cephalosporin
less active gram positive and more active enterobacter
ceftriaxone
ceftazidime
DOC for serious gram negative infections
klebsiella, proteus, providencia, serratia, haemophilus
third gen cephalosporin
gonorrhea and severe lymes
ceftriaxone
covers pseudomonas
ceftazidime
fourth gen cephalosporins
serious infection in hospitalized pts
cefepime - active against pseudomonas
empirical tx for hospital infections
cefepime
4th gen cephalosporin
cross reactive with PCN
1% risk in cephalosporin use
intolerance to alcohol
cephalosporin adverse effect
disulram like rxn due to MTT group of cefotetan
