Anti-bacterial therapy Flashcards
what is a bactericidal?
eradicates the bacteria
- dependent on concentration
- critical to use the appropriate dose
- preferred for meningitis and UTI (immune system is not able to resolve these cases on their own)
what is a bacteriostatic?
inhibits bacterial replication and allows host to eradicate it
-dependent on time
what are common causative agents of UTI?
E. coli (90%), other gram neg bacilli (may be MDR), staph. saprophyticus,group B strep
what info should you get when treating for UTI?
prior UTIs
prior antimicrobials
exposure to or symptoms of STDs
what are the empiric treatments for UTIs?
TMP-SMX (3 dys-bacteriostatic)
Fluoroquinolone (3 dys)
Less preferred bc they take longer
Nitrofurantoin (7 dys)
Amox/Clav (7 dys)
what are common causative agents of cellulitis?
S. aureus
group A strep
group B strep
what info should you get when treating for cellulitis?
prior infections
MRSA risk profile
human/animal bite
comorbidities
what are the empiric treatments for cellulitis?
dicloxacillin (MRSA gap) TMP-SMX (GAS gap) Clindamycin (MRSA gap) doxycycline (less MRSA experience) linezolid (cost, side effect profile) fluoroquinolone and rifampin (less exp, drug interactions, resistance)
what info should you getn when treating URI?
prior episodes/treatment recent travel sick contacts animal exposures TB risk/HIV risk Occupation
what would you use to treat URI?
most are viral bacterial pathogen likelihood increases with more severe symptoms -beta-lactam (penicillin/cephalosporin) -macrolid -lincomycin
what would you use to treat LRI?
empirical recommendations are more evidence based
- Health pts
- –doxycycline
- –macrolide (not if high local resistance)
- co morbidities/recent antibiotic use
- –“respiratory” fluoroquinolone
- –Amox/clav combination
what separates penicillin and cephalosporins?
penicillin is 5 member ring whereas the other is 6 member ring
what is the MOA of penicillin?
bactericidal-need the right concentration
inhibits bacterial cell wall synthesis
what do you use penicillin for?
Staph (coagulase-negative)
strep pyrogenes
other gram positives (enterococcus)
what would you use for uncomplicated otitis media?
amoxicillin
what would you use for pre-partum GBS prophylaxis?
ampicillin
what would you use for S bacterial endocarditis prophylaxis?
Penicillin V
what would you use for H. pylori treatment?
amoxicillin
when would you use anti-staph penicillin?
coagulase-negative staph
MSSA
beta-lactamase producing strep
***bacterial endocarditis
what are the broadened spectrum penicillin?
amox/clavulanate (augmentin)
ampicillin/sulbactam (unasyn)
piperacillin/tazobactam (zosyn)
what are the extended spectrum penicillins?
ticarcillin mezlocillin azlocillin piperacillin (only one that is mostly used today) ***only given in the hospital
why are cephalosporins better than penicillin?
more dosage options
better bio availability
what is the MOA of cephalosporins?
bactericidal
inhibit bacterial dihydropeptidase
what are the 1st generation cephs?
cefazolin
cephalexin
cefadroxil
what are the 2nd gen cephs?
cefoxitin
cefuroxime
what are the 3rd gen cephs?
ceftriaxone
cefpodoxime
what are teh 4th gen cephs?
cefipime
ceftaroline (pseuod)
which ceph will cover MRSA in vitro?
ceftaroline
what do 1st gen cephs work against?
non-beta lactamase producing gram positive, no anaerobes
-same coverage as penicillin but better bio availability
what do 2nd gen cephs work against?
non-BL producing organism, more gram N, less gram P, more anaerobes
-indicated in clean-contaminated surgical procedures
what do 3rd gen cephs work against?
more resistance to BL producing organisms
more gram P, more gram N, no anaerobes
what indications does ceftriaxone have?
OM with effusion
CAP
meningitis (accumulates well in the brain)
NOT recommended for surgical prophylaxis
what do 4th gen cephs work against?
similar to 3rd gen, but have better resistance to BL producing organisms, no anaerobes
***mostly used to limit serious infections in the inpt setting
what are the MOA of fluoroquinolones?
bactericidal
inhibits bacterial DNA synthesis
what are indications for fluor?
good against staph, NOT strep, good against gram negative (non BL producing), NOT anaerobes
which fluor are good agents against strep?
levofloxicin
moxifloxacin
which fluor is a good agent against anaerobes?
moxifloxacin
what should you use for uncomplicated uTI?
cipro
what are benefits of fluors?
broad spectrum
once a day
all orally available
why would you not use fluor for meningitis?
it does not penetrate BBB
which antibiotic requires renal adjustment?
fluoro
penicillin
cephs
would you use fluor for URI?
no, not evidence based
which are the macrolides?
erythromycin
azithromycin
clarithromycin
what is the MOA of macrolides?
bacteriostatic
inhibits bacterial protein synthesis which prevents replication
what do macrolides work against?
gram P organisms (strep, listeria, clostridium), good atypical coverage **mycoplasma, legionella, chlamydia), NOT staph, NOT gram N, NOT anaerobic
what are clinical indications of macrolides?
mono outpatient therapy for CAP, combo inpatient therapy w/ ceftriaxone for CAP
atypical pneumonia
GU infections cause by chlamydia
some URI
which antibiotics are the worst for GI flora?
macrolides
what are the tetracycline agents?
tetracycline
doxycycline
minocycline
tigecycline (glycylcycline)
what is the MOA of tetras?
bacteriostatic
inhibits bacterial protein synthesis
what are drawbacks of tetras?
rapid development of resistance and toxicities
what are clinical indications of tetras?
rickettsial infections (Lymes, RMSF)
prophylaxis, intra-abdominal, gyn infections (Dox)
2a infections caused by acne (Mino)
serious infections by susceptible bacteria -hail mary (Tige)
who is contraindicated for tetras?
children (staining of bone and teeth), expecting mothers
what is the agent for lincomycin?
clindomycin
what is the MOA of lincomycin?
bacteriostatic
inhibits protein synthesis
what are the clinical uses of lincomycin?
gram P infections by some strains of strep and staph (alt to beta lactam) anaerobic infections (gut, pelvis)
what are clinical side effects of lincomycin?
severe enterocolitis (1-2% pseudomembranous colitis) sig resistance among gram P
what are agents of sulfonamides?
sulfamethoxazole
trimethoprim
TMP-SMX (bactrim)
sulfaisoxazole (gantrisin)
what is the MOA of sulfonamides?
bacteriostatic
inhibits bacterial folic acid synthesis
what are the clinical indications for sulfonamides?
peds URI
PCP pneumonia treatment
topical bacterial infections for burns (silvadine)
ocular infections
what are drawbacks for using sulfonamides?
rash/exfoliation
folic acid deficiency
allergy
what are agents of nitrofurantoin?
macrodantin
macrobid
what are clinical indications of nitrofurantoin?
alt for uncomplicated UTI caused by gram N (E. coli, Klebsiella, Proteus)
who is contraindicated for nitrofurantoin?
CrCl of less than 50
- have to be secreted from kidneys into the blood
- won’t be absorbed w/o good kidney function
what are clinical indications of metronidazole?
excellent against bacteroids, clostridium, helicobacter, trichomonas,**drug of first choice for c. diff
what are clinical indications of rifampin?
bactericidal
TP and
meningitis caused by gram P (pneumococcus) b/c of CNS penetration
good mycobacterial in combination with other agents (isoniazid, ethambutol)
what are drawbacks of using rifampin?
hepatotoxic
numerous drug interactions
lost of resistance has limited uses
what is the MOA of aminoglycosides?
bacteriostatic
inhibits protein synthesis
what are drawbacks of using aminoglycosides?
have to adjust to renal function
ototoxic with long term use
what is the MOA of vancomycin?
bactericide
must be given IV (large molecule)
what are clinical indications of vanc?
- **effective against MRSA but resistance is rising
* ***used to treat c. diff if metronidazole isn’t working
what are drawbacks of using vanc?
renal and ototoxic
what is linezolid used for?
MRSA,!! VRE!!!
what is a drawback of using linezolid?
food-drug interactions effects metabolism of serotonin and catecholamines
what is daptomycin used for?
bactericidal
**MRSA (skin/soft tissue), **MSSA, anti staph, maybe against VRE
IV only
***inpatient use against serious gram P infections
