Apr26 M1-Antimicrobial antibiotics Flashcards
aminoglycosides coverage (3) + do they cross the BBB
-gram negative only. (including pseudomonas) EXCEPT Salmonella spp and Neisseria spp -TB and TB mycobacteria for some -giardia (protozoa) for paromomycin *DON'T CROSS THE BBB*
other activities of aminoglycosides (2)
- some have TB and non TB-mycobacteria activity
- paromomycin = anti-parasitic activity against giardia lamblia
paromomycin is what and does what
- aminoglycosides Abx
- anti-parasitic activity against giardia lamblia
good and bad situations to use aminoglycosides
good for: UTIs and complicated infections
bad for: bacteremia (too slow acting)
aminoglycoside nephrotoxicity: why and charact
- high trough (accumulated) levels, tubule toxicity
- reversible
- more toxic if with other nephrotoxic drugs
important irreversible SE of aminoglycosides and how to prevent it
hearing loss. prevent by stopping the Abx when have tinnitus (ringing in the ear), tinnitus is reversible
aminoglycosides how to determine the next dose given
measure the trough rate and adjust the next dose
other side effect of aminoglycosides than nephrotoxicity and vestibular, cochlear toxicity
muscular blockade. avoid them in pts with neuromuscular diseases:
- botulism
- DMD (Duschenne)
- myasthenia gravis
- etc
how to make sure tinnitus (and hearing loss) and nephrotoxicity are avoided while using aminoglycosides
monitor for a therapeutic drug level
how to recognize aminoglycosides by their name
end with cin (gentamicin, amikacin) or mycin (tobramycin, streptomycin, paromomycin) (but azythromycin and clarithromycin are macrolides, ketolides)
how to recognize fluoroquinolones by name
end with floxacin (gatifloxacin, grepafloxacin)
most important fluoroquinolones
- Ciprofloxacin (po or IV) = Cipro
- Levofloxacin (po or IV) = Levaquin
- Moxifloxacin po (Avelox)
2 fluoroquinolones considered to be the respiratory ones
- Levofloxacin (Levaquin)
- Moxifloxacin (Avelox)
fluoroquinolones how many generations and what they cover
- are BROAD SPECTRUM
FQs activity against S pneumoniae
gen 2,3,4 increasing. 4 is best
FQs activity against MSSA (and which one specifically)
moxifloxacin (gen 4) ONLY
moxifloxacin good and bad situations to use it
good for: community acquired pneumonia
bad for: UTIs
are broad spectrum so associated with c.diff
FQs enteric gram negative rods coverage
gen 2,3,4 are good. gen 1 is weak
FQs pseudomonas spp coverage
gen2,3,4 decreasing. gen 2 is the best
FQs atypical bacteria coverage
gen2,3,4 are good.
FQs anaerobes coverage
gen4 only
FQs: which cover enterococcus faecalis
gen4 only
fluoroquinolones: how much more bioavailability if give IV instead of po + preferred mode of administration
bioavailability is same for po and IV.
so give orally if possible
sulfonamides coverage
- broad spectrum (all bacteria requiring endogenous folic acid synthesis. bc sulfonamides block that)
- anti-parasitic coverage (toxoplasma)
- covers pneumocystis jeroveci
sulfonamides exceptions: bacteria that are not covered
- GAS (can’t give sulfonamides for skin infection)
- enterococcus spp
do FQs cross the BB
no
sulfonamides: how much more bioavailability if give IV instead of po + preferred mode of administration
bioavailability is same for po and IV.
so give orally if possible
sulfonamides: do they cross the BBB?
no (can’t treat meningitis with Septra)
sulfonamides: one common one
trimethoprim-sulfametoxazole (Septra) (TMP-SMX)
best Abx for toxoplasma and pneumocystis jeroveci (can see jeroveci more in HIV)
sulfonamides (Septra)
tetracyclines Abx spectrum
- gram negative ENTERIC RODS
- anaerobes
- atypical bacteria
tigecycline Abx spectrum
- gram negative ENTERIC RODS (includes tetracycline resistant + multiresistant enterobacteriaceae)
- gram posities (MRSA, VRE, penicillin-R strep pneumoniae)
- anaerobes
- atypicals
cyclines (tetra and tige): how much more bioavailability if give IV instead of po + preferred mode of administration
bioavailability is same for po and IV.
so give orally if possible
how clindamycin (in the lincosamides category) works and type of activity (conc or time dependent)
- inhibits protein synthesis
- time dependent bacteriostatic activity
how resistance to clindamycin develops
similar to resistance to macrolides
- modification of target site (target mutation)
- efflux pump (pump)
clindamycin coverage
gram positives and anaerobes
clindamycin: how much more bioavailability if give IV or IM instead of po + preferred mode of administration
bioavailability is same for po and IV or IM.
so give orally if possible
cyclines (tetra and tige): is it used for meningitis (does it cross the BBB)
no
clindamycin does it cross the BBB
no
main adverse reactions with clindamycin
- moderate diarrhea, possibly (bc kills gut anaerobes)
- C.diff association (pseudomembranous colitis)
metronidazole coverage
- anaerobes (gram+ and gram-)
- C.diff
- parasites (giardia lamblia, entamoeba histolytica)
metronidazole: how much more bioavailability if give IV or IM instead of po + preferred mode of administration
bioavailability is same for po and IV.
so give orally if possible
important limit to using rifamycins
- induce RAPID resistance if used on their own
- always use with other Abx to buffer the resistance
when can you use rifamycins alone
- as prophylaxis for meningitis from N meningitidis and H influenzae (if someone was in contact, saliva)
- to people known to be carriers (prophylaxis, reduce risk for others): will have yellow secretions, orange urine and tears
when would you use rifamycins (rifampin or rifabutin)
- TB and non-TB mycobacteria tx
- post exposure prophylaxis for meningitis from N meningitidis or H influenzae
pharmaco key point with rifamycins
MAJOR drug interactions
-rifampin and rifabutin both metabolized by CYP-450 enzymes in liver
adverse reactions of all rifamycins
- mainly GI (nausea, increase in liver enzymes)
- skin rashes
adverse reactions related to rifampin
orange-red colouration of body fluids (urine, tears). stains contact lenses
reversible
rifabutin specific adverse reactions
- bronze discolouration of skin
- violet-red colouration of urine
specific things to follow in patient using rifamycins
- monitor liver enzymes
- avoid alcohol and drugs to avoid liver toxicity
nitrofurantoin when to use
- ONLY for 1. non-complicated cystitis TREATMENT and 2. UTI PROPHYLAXIS
- you only achieve therapeutic concentrations in the urine
specific conditions where you would give an Abx like nitrofurantoin for UTI prophylaxis
- babies with vesicoureteral reflux with urine splashing up ureters and kidneys (risk UTI)
- honeymoon cystitis (used to UTIs after intercourse)
Abx designed specifically for multiresistant gram positive cocci (MRSA, VRE, VISA, VRSA)
- oxazolidinones (Linezolid)
- streptogramins (Quinipristin, Dalfopristin) (Synercid)
- daptomycin
- Ceftaroline (5th generation ceph) (this one only for MRSA)
Abx designed specifically for multiresistant gram negative rods
- carbapenems
- carbapenem + beta-lactamase inhibitors
- tigecycline
oxazolidinones (Linezolid): how much more bioavailability if give IV or IM instead of po + preferred mode of administration
bioavailability is same for po and IV.
so give orally if possible
do oxazolidinones penetrate the BBB
yes. are very good for meningitis
(important) adverse reactions with prolonged use of oxazolidinones (Linezolid)
- thrombocytopenia (if >2 weeks of tx, is reversible)
- inhibition of monoamine oxidase (get serotonin syndrome).
(important) how to avoid serotonin syndrome with use of oxazolidinones (Linezolid)
- avoid SSRIs
- avoid or limit tyramine containing foods (cheeses, smoked and processed meats)
