Antibiotics Flashcards by Kelli True

definition: bactericidal

lethal to bacterial

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definition: bacteriostatic

slows bacterial growth

(allows for host defenses to eliminate bacteria)

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definition: broad spectrum antibiotic

active against a wide variety of bacteria

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definition: narrow spectrum antibiotic

active only against a few species of microorganisms

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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)

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definition: superinfection

new infection that appears during course of treatment for primary infection

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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

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Prior to starting antibiotics, what should be done first?

obtain cultures

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List drugs/drug classes that disrupt bacterial cell walls

penicillins
cephalosporins
vancomycin
lipoglycoproteins
daptomycin

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are drugs that disrupt bacterial cell walls bacteriostatic or bactericidal?

bactericidal

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mechanism of action of drugs that disrupt bacterial cell walls

allow for H2O influx into bacteria –> cell bursts & dies

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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

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Mechanism of action of penicillins

bind penicillin binding proteins (PBPs) on bacterial cell = weakening of bacterial cell wall

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How can resistance develop to penicillins?

beta lactamase
alteration of PBP expression (drug cant bind)

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List some penicillins.

PCN G, PCN V
nafcillin
oxacillin
ampicillin
amoxicillin
piperacillin

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Route of administration of PCN G

IV or IM

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adverse effects PCN G

allergy reactions
injection site reactions

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Which drug results in the most anapylaxis

PCN

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Treatment of PCN induced anaphylaxis

supportive care: cardiopulmonary support
epinephrine

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If your patient is allergic to PCN G, which other drugs may be of concern

Other PCNs
cephalosporins (maybe!)

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What is a beta lactamase inhibitor

drug that inhibits the enzyme that inactivates PCN

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Name some beta lactamase inhibitors (never available to be given alone though!)

subactam
clavulanate
tazobactam

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List three drugs that are PCNs combined with beta lactamase inhibitors

unasyn
augmentin
zosyn

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Do PCNs have a beta lactam ring

yes

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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:

1. increased ability to reach the CSF 2. 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

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