Antibiotics Flashcards
definition: bactericidal
lethal to bacterial
definition: bacteriostatic
slows bacterial growth
(allows for host defenses to eliminate bacteria)
definition: broad spectrum antibiotic
active against a wide variety of bacteria
definition: narrow spectrum antibiotic
active only against a few species of microorganisms
How does antibiotic resistance develop?
Spontaneous (RANDOM) mutation occurs that prevents bacteria from being killed by antibiotic.
Remainder of bacteria are killed by antibiotic, resistant organism remains and replicates freely (unless killed by host)
definition: superinfection
new infection that appears during course of treatment for primary infection
What we do that can result in development of resistant bacteria
- use antibiotics unnecessarily
- use broad spectrum instead of narrow spectrum antibiotics
- too long of an antibiotic course
- stopping the full course too early
Prior to starting antibiotics, what should be done first?
obtain cultures
List drugs/drug classes that disrupt bacterial cell walls
penicillins
cephalosporins
vancomycin
lipoglycoproteins
daptomycin
are drugs that disrupt bacterial cell walls bacteriostatic or bactericidal?
bactericidal
mechanism of action of drugs that disrupt bacterial cell walls
allow for H2O influx into bacteria –> cell bursts & dies
What is the significance of a drug containing a beta lactam ring?
Some bacterial strains can develop beta lactamase enzymes that break open the beta lactam ring = inactive antibiotic
Mechanism of action of penicillins
bind penicillin binding proteins (PBPs) on bacterial cell = weakening of bacterial cell wall
How can resistance develop to penicillins?
beta lactamase
alteration of PBP expression (drug cant bind)
List some penicillins.
PCN G, PCN V
nafcillin
oxacillin
ampicillin
amoxicillin
piperacillin
Route of administration of PCN G
IV or IM
adverse effects PCN G
allergy reactions
injection site reactions
Which drug results in the most anapylaxis
PCN
Treatment of PCN induced anaphylaxis
supportive care: cardiopulmonary support
epinephrine
If your patient is allergic to PCN G, which other drugs may be of concern
Other PCNs
cephalosporins (maybe!)
What is a beta lactamase inhibitor
drug that inhibits the enzyme that inactivates PCN
Name some beta lactamase inhibitors (never available to be given alone though!)
subactam
clavulanate
tazobactam
List three drugs that are PCNs combined with beta lactamase inhibitors
unasyn
augmentin
zosyn
Do PCNs have a beta lactam ring
yes
Do cephalosporins have a beta lactam ring
yes
mechanism of action of cephalosporins
bind PBPs and disrupt cell wall synthesis
Two trends in cephalosporins as the generations go from 1–>5 are:
- increased ability to reach the CSF
- increased resistance to beta lactamases
Excretion of cephalosporins
unchanged by kidneys (lower the dose in ESRD or CKD)
Name some commonly used cephalosporins
ceftriaxone
cefazolin
cefepime
cephalexin
List the carbapenems
imipenem
meropenem
ertapenem
Do carbapenems contain a beta lactam ring?
yes
Mechanism of action of carbapenems
same as PCN
(bind PBPs, disrupt cell wall = lysis)
resistant to beta lactamase
What is MRSA
staph infection that is resistant to all beta lactam antibiotics
(this bacterial strain produces a PBP that has a low affinity for antibiotics)
Drug of choice for MRSA
vancomycin
Does vancomycin contain a beta lactam ring
no
Mechanism of action of vancomycin
inhibit cell wall synthesis by binding & inhibiting precursors to cell wall
(NOT PBP binding)
elimination of vancomycin
unchanged by kidneys (decreased dose in ESRD/CKD)
Adverse effects of vancomycin
renal failure
ototoxicity (rare)
rapid infusion can = histamine release
red man syndrome
(histamine release
–> flushing/rash/itching
–> tachycardia/hypotension/angioedema)
Max rate of infusion of vancomycin
1g/hr
What is red man syndrome
allergic reaction to vancomycin
- flushing
- hypotension & tachycardia
- N/V
- itching
- angioedema
- rash: face, neck, upper torso
Treatment of red man syndrome
supportive
antihistamines
mechanism of action of daptomycin
insert self in bacterial cell membrane & allow for K+ efflux
proteins can’t be manufactured & cell death occurs
adverse effects of daptomycin
+/- muscle injury
List drugs that affect bacterial protein synthesis
tetracyclines
macrolides
clindamycin
linezolid
aminoglycosides
Are drugs that affect bacterial protein synthesis bactericidal or bacteriostatic?
bacteriostatic
List some tetracyclines
tetracycline
doxycycline
mechanism of action of tetracyclines
prevent addition of further amino acids (inhibit bacterial protein synthesis)
Adverse effects of tetracyclines
GI irritation
teeth discoloration
hepatotoxicity
renal toxicity
photosensitivity
Who to avoid tetracyclines in?
Pregnancy >4m
Peds <8yrs
List some macrolides
erythromycin
azithromycin
clarithromycin
mechanism of action of macrolides
block addition of new amino acids (prevents synthesis of bacterial proteins)
adverse effects of macrolides
epigastric pain, N/V, diarrhea
can prolong QT interval in high [ ]
mechanism of action of clindamycin
prevents addition of amino acids on bacterial proteins
mechanism of action of linezolid
prevents addition of amino acids on bacterial proteins
adverse effects of linezolid
reversible myleosuppression (monitor CBC)
rarely neuropathy with prolonged therapy
List some aminoglycosides
gentamicin
tobramycin
amikacin
Mechanism of action of aminoglycosides
inhibit bacterial protein synthesis + aid in production of abnormal (inactive) proteins
route of administration of aminoglycosides
at the site of infection (cannot be absorbed from GI tract)
PO if GI infection
IV if systemic infection
topical if skin infection
goal peak & trough of aminoglycosides
peak = high enough to kill bacteria
trough = low (avoid toxicity)
adverse effects of aminoglycosides
irreversible ototoxicity (tinnitus/HA –> hearing loss)
nephrotoxicity (usually reversible)
**monitor trough levels for prevention of both
List two drugs/classes that disrupt bacterial DNA function
fluoroquinolones
metronidazole
Are drugs that disrupt bacterial DNA function bactericidal or bacteriostatic
bactericidal
List some fluoroquinolones
ciprofloxacin
ofloxacin
moxifloxacin
levofloxacin
adverse effects of fluoroquinolones
GI effects
CNS effects (rare)
phototoxicity
tendon rupture
Risks for tendon rupture w/ fluoroquinolones
age >60
on glucocorticoids
transplant history
mechanism of action of metronidazole
breaks helical DNA structure –> cell death
Mechanism of action of sulfonamides
compete with PABA (para-aminobenzoic acid) to decrease DNA/RNA/protein synthesis
adverse effects of sulfonamides
hypersensitivity reactions (can be severe)
hematologic effects (decrease in all blood levels)
kernicterus
renal damage
In which patient ages should sulfonamides be avoided
<2m old or >32 weeks gestation
**due to deposition of bilirubin in brain resulting in various neuro deficits and death
what is bactrim
TMP/SMZ
trimethoprim/sulfamethoxazole
adverse effects of trimethoprim
itching, rash, GI effects
rare hematologic suppression
What is bactrim primarily used for?
UTIs
