Abx in children Flashcards
what host factors should be taken into account when picking abx for kids
age, pregnancy, immune status
site of infection
renal/hepatic fxn
what are the elements of pharmacokinetics?
drughost
ADME absorption distribution metabolism excretion
what abx have 100% oral bioavailability
clinda
flagyll
fluoroguinolones
what abx distributions completely to the tissues (has NO blood level)
azithro
what are the elements of pharmacodynamics
effects
time course of activity
toxicity
what is the MIC
minimum inhibitory concentration
minimum amount of an abx necessary to inhibit the growth of an organism
what is the MBC
minimum bactericidal concentration
the minimum amount of an abx necessary to kill 99% of an organism
what is the attainable drug level
concentration of the drug in tissues (blood, uring, CSF) which will result when it is administered according to a standard dose
what does it mean to say an organism is susceptible to an abx
organism will be inhibited or killed by the average attainable drug level in the body
MIC
what does it mean to say an organism is resistant to an abx
organism will not be killed by average attainable drug level in the body
MIC>attainable drug level
what are the major parameters of efficacy of abx
time/MIC
peak/MIC
24 hour AUC/MIC
in what drugs do we look at peak/MIC
animoglycosides
daptomycin
in what drugs do we look at AUC/MIC (area under concentration and time curve for the abx)
fluoroquinoloes
macrolides
tetracycline
vancomycin
in what drugs do we look at time > MIC
beta lactams
what are the mechanisms by which drugs achieve resistance to abx
- diminished intracellular drug concentration–> either by increased efflux or by decreased membrane permability
- drug inactivation–> usually by enzymes possessed by organism
- target modification
- target bypass
which drugs are affected by increased efflux resistance
tetracyclin (tetA)
quinolones (norA)
which drugs are affected by decreased membrane permeability resistance
beta lactams (ompF, oprD)
quinoloes (ompF)
aminoglycosides (decreased energy)
which drugs are affected by drug inactivation resistance
beta lactams (lactamase)
aminoglycosides (modifying enzyme)
ampC–cephalosporinase in Klebsiella
which drugs are affected by target modification resistance
quinolones (gyrase)
rifampin (DNApol)
beta lactams (PBP)
macrolides (rRNA methylation)
streptomycin (rDNA genes)
macrolides (methylation)
which drugs are affected by target bypass resistance
glycopeptides
bactrim
trimethoprim resistance
what is induction verus selection with regard to resistance
- selection is a problem on a population level over time–> statistically 1/1x10e6 is resistant to a drug
- induction is a problem for the individual during therapy–> AmpC cephalosporinase–> ESSCAPPPEM
what are the ESSCAPPPEM organisms and why do we care
care because have AmpC cephalosporinace activity
enterobacter
stenostrophomonas
serratia
cirtobacter
acinetobacter
pseudomonas
providencia
proteus
morganella
what are the two reasons/theories behind dual therapy of abx
either synergistic or combination
synergistic–> two drugs have an effect greater than the sum of their treatments–> increases rate and killing for example
–> i.e amp/gent for enterococcus
combination–> invovles using drugs with different MOAs to decrease the chance of resistance to break through
what are the cell wall synthesis inhibitor abxs
- beta lactams–> penicillins, cephalosporins, carbapenems
(beta lactamase inhibs in organisms can mess with these) - glycopeptides–>vanco
what are the protein synthesis inhibitor abxs
- aminoglycosides–> gentamicin, tobramycin, amikacin, streptomycin
- macrolides–> erythromycin, clarithromycin, azithromycin
- other–> clinda, linezolid, tetracyclines (doxy)
what are the RNA or DNA synthesis inhibitor abxs
- RNA transcription inhibitor –> rifampin
- DNA synthesis inhibitors–> fluoroquinolones (cipro and levofloxacin)
- nucleotide synthesis inhibitors–> TMP-SXT
how does metronidazole work
toxic free radical production
what are bacteriostatic abxs
inhibit bacterial cell growth
need INTACT IMMUNE SYSTEM to fight infection
what are bacteriocidal abxs
kill bacteria directly
do not rely on immune system of patient
(therefore okay in immunocompromised)
empiric therapy for septicemia in younger than 6 weeks
amp + (gent or cefotaxime) + acyclovir
empiric therapy for septicemia in older than 6 weeks
cefotaxime + (cloxacillin or vanco)
empiric therapy for meningitis in less than 6 weeks
amp + (gent or cefotaxime) + acyclovir
empiric therapy for meningitis in older than 6 weeks
cefotaxime + vanco with or without acyclovir with or without steroids
empiric therapy for strep pharyngitis/tosillitis
penicillin V or amoxicillin or penicillin G
empiric therapy for acute otitis media
amoxicillin or amox clav
empiric therapy for mastoiditis
cefotaxime + (cloxacillin or vanco) with or without metronidazole
empiric therapy for sinusitis
amox clav or (treat as mastoiditis if IV therapy needed)
empiric therapy for cervical lymphadenitis
cephalexin or clinda or (cefazolin plus or minus vanco)
empiric therapy for preseptal cellulitis
cephalexin or clinda or (cefazolin with or without vanco)
empiric therapy for orbital cellulitis
cefotaxime + (cloxacillin or vanco) plus or minus metro
empiric therapy for dental abscess
amox clav or (penicillin G + metro)
empiric therapy for pneumonia older than 3 months mild
amoxicillin and/or clarithromycin
empiric therapy for older than 3 months severe
cefotaxime + (clox or vanco) plus or minus clarithro plus or minus oseltamivir
empiric therapy for hospital acquired pna
(cefotaxime or pip-tazo) + (clox or vanco) plus or minus genta
empiric therapy for UTI mild
amox clav or cefixime
empiric therapy for UTI severe
(cefotaxime with or without gent) or pip tazo
empiric therapy for secondary peritonitis
pip tazo or (amp + gent + metro)
empiric therapy for mild cellulitis
cephalexin with or without TMP-SXT
empiric therapy for severe cellulitis
(clox or vanco) with or without clinda
empiric therapy for dog/cat/human bites
mile–> amox clav
severe–> pip tazo
empiric therapy for nec fasc/bacterial myositis
penicillin + clinda with or without vanco
empiric therapy for bone and/or joint infection
cefazolin with or without vanco
what is the number one indication for abx use in kids
otitis media
80% of kids have 1 or more episodes (30% have three or more)
milder disease often resolves spontaneously
how is otitis media usually treated
empirically
amox clav or high dose amoxicillin
what does amoxicillin (with or without clav) cover?
respiratory tract flora (s pneumo, h influenzae, m catarrhalis)
- -> high dose overcomes pneumococcus insensitivity
- -> clav inhibits beta lactamases in haemophilus and moraxella
side effect of clavulanic acid
diarrhea
what bugs are most commonly causes of sepsis/meningitis in kids
respiratory colonizers
pneumococcus, menongococci, Hib, GAS
what abx offers good CSF penetration
cefotaxime
what do the first generation cephalosporins cover
more gram + than gran -
what do the third generation cephalosporins cover
gram - more than gram +
what do the fourth generation cephalosporins cover
extended spectrum
beta lactamase stable
what is first line for pertussis
azithro
what does clinda cover
anaerobic coverage –> but bacteriostatic
covers some strains of MRSA
what are the common coliforms
ecoli
klebsiella
enterobacter
how do you treat “bowel spills” (i.e ruptured appendix)
requires multidrug empiric coverage
ampicillin + cefotaxime + metro
ampicillin + genta + metro
pip tazo
is gentamicin avail orally
no only IV
what are the side effects of gentamicin
nephrotoxic
ototoxic (vestibular and cochlear)
–monitor renal function, potassium, audiometry
what does gentamicin cover
gram negativ orgs
what does metronidazole cover
excellent anaerobic coverage
side effects of metronidazole
metallic taste
peripheral neuropathy
disulfiram reaction
when do you use TMP SMX
skin and soft tissue infection
empiric option for UTI
**caution in those with G6PD
most common organisms causing neonatal sepsis
coliforms
GBS
listeria
top 10 pediatric abx
amox/amoxclav cloxacillin (IV) vanco cefotaxime (IV) azithro gentamicin (IV) metronidazole clinda penicillin V TMP SMX
cephalexin