AGACNP Barkley Review -Antibiotics | Complete Questions & Verified Answers | Adult-Gerontology Acute Care NP
Abx selective toxicity & mechanism of antibiotic action Abx unique MOA that makes them selectively toxic to bacteria
- ability to disrupt bacterial cell wall or inhibit cell wall synthesis
- lethal or nonlethal inhibition of bacterial protein synthesis
- inhibition of bacterial nucleic acid synthesis
- antimetabolites
DNA or RNA synthesis inhibitors fluoroquinolones, rifampin
T/F: any antibiotic may promote resistance, but broad True
spectrum agents are the most likely to cause it
Mechanisms of antibiotic resistance 1) production of drug-metabolizing enzymes
2) decreased drug uptake
3) change in drug receptor w/ decreased binding of abx
4) synthesis of compounds that antagonize the antibiotic
Ways organisms become resistant to antibiotics 1) spontaneous mutation - occurs only to one drug
2) conjugation
- mostly in GN bacteria, occur b/w normal flora & pathogens
-R-factor w/c is extra-chromosomal DNA encoding for resistance that is
passed from one bacteria to the next
- responsible for multiple-drug resistant bugs
CDC's campaign to prevent antimicrobial resistance Infection Prevention
- vaccinate
- remove catheters
Diagnose & Tx infections effectively
- target the pathogen
- contact the experts
Use ABX wisely
- practice antimicrobial control
- use local data
- tx infection, NOT contamination or colonization
- know when to say "NO" to Vanco
- stop ABX when infection has cleared or unlikely a bacterial infection
Prevent transmission
- isolate the pathogen
- break the chain of contagion
Who should receive ABX prophylaxis? 1) Select surgical patients - cardiac, peripheral vascular, orthopedics, GI, GYN
(hysterectomy)
2) severely neutropenic
3) pt at risk for bacterial endocarditis
4) pts w/ recurrent UTIs, severe rheumatic endocarditis
,AGACNP Barkley Review -Antibiotics | Complete Questions & Verified Answers | Adult-Gerontology Acute Care NP
Indications for ABX combinations 1) initial therapy for severe infection - until organism is ID'd
2) mixed infections - common in GI, pelvic, brain abscesses
3) prevent emergence of resistance - TB, HIV, certain parasites
4) to decrease toxicity
5) to promote synergistic effect - PCN + gentamicin, TMP-SMZ*
ABX combination disadvantages 1) increased risk of adverse effects like allergy or toxicity
2) risk of suprainfection (ex. C. diff & yeast infection*
3) risk for drug resistance
4) increase cost
Cell wall synthesis inhibitors PCN, cephalosporins, carbapenems, aztreonam, vancomycin, fosfomycin,
teicoplanin
Penicillins - inhibit transpeptidases necessary for cell wall synthesis & activate autolysis
w/c cleave bonds in the cell wall.
- *target the PCN binding proteins (PBP) - PBP1 & PBP3 (crucial targets)
- resistance is d/t inability of drug to reach PBPs or enzymatic inactivation of
the drug
- PCN resistant drugs produce beta-lactamase which cuts into the beta-lactam
ring of the drug which inactivates the ABX so the ABX is no longer become
anti-infective.
•Allergic reactions (1-5%); Anaphylaxis (.004-.015%)
•Cross reaction - 3-7% PCN to Ceph
•Prolonged high dose = granulocytopenia, interstitial nephritis
Bacterial cell wall Gram positive vs Gram negative
Gram negative has an outer membrane and gram positive does not w/c
prevents PCN from reaching PBPs (target molecules)
PCN: Narrow-spectrum PCNase sensitive PCN G, PCN V K
useful for Strep, Neisseria, many anaerobes, & spirochetes
PCN: Narrow-spectrum PCNase resistant Nafcillin, Oxacillin, Cloxacillin, Dicloxacillin
- useful for Staph aureus
, AGACNP Barkley Review -Antibiotics | Complete Questions & Verified Answers | Adult-Gerontology Acute Care NP
PCN: Broad-spectrum Ampicillin, Amoxicillin, Bicampicillin
- useful for H. flu, E. coli, P. mirabilis, N. gonorrheae, enterococci
susceptible to beta-lactamase
PCN: Extended-spectrum - Piperacillin, Carbenicillin, Ticarcillin, Mezlocillin
useful for H. flu, E. coli, P. mirabilis, N. gonorrheae, enterococci
PLUS
pseudomonas, enterobacter, proteus, B. fragilis, & Klebsi
susceptible to beta-lactamase
PCN side effects & toxicities 1) Pain at IM injection site - bec PCN is thick/viscious
2) reactions to procaine & potassium - from the injection, not PCN itself
3) rare neurotoxicity
4) ALLERGY - can occur immediate (2-30 mins), accelerated (1-72h); late (days
to weeks)
anaphylactic reactions occur w/ PCNs more than any other drugs
*Incidence is 0.02% but mortality is 10%
Allergy is exposure dependent, NOT dose dependent.
What to do if pt has PCN allergy? AVOID PCNs ENTIRELY
mild allergy - can give cephalosporin
severe allergy or anaphylaxis - avoid PCN & cephalosporin (5-10% cross-
sensitivity)
Alternatives to PCN
- Vanco & erythromycin
Life-threatening + NO abx alternatives, give PCN according to
desensitization schedule
PCN Combined with a Beta-Lactamase Inhibitor -cillin/bactam
-cillin/clavulanate
limited toxicity; great for Pseudomonas
Ampicillin + sulbactam (Unasyn)
Amox + clav (Augmentin)
Ticarcillin + clav (Timentin)
Piperacillin + tazobactam (Zosyn)
Abx selective toxicity & mechanism of antibiotic action Abx unique MOA that makes them selectively toxic to bacteria
- ability to disrupt bacterial cell wall or inhibit cell wall synthesis
- lethal or nonlethal inhibition of bacterial protein synthesis
- inhibition of bacterial nucleic acid synthesis
- antimetabolites
DNA or RNA synthesis inhibitors fluoroquinolones, rifampin
T/F: any antibiotic may promote resistance, but broad True
spectrum agents are the most likely to cause it
Mechanisms of antibiotic resistance 1) production of drug-metabolizing enzymes
2) decreased drug uptake
3) change in drug receptor w/ decreased binding of abx
4) synthesis of compounds that antagonize the antibiotic
Ways organisms become resistant to antibiotics 1) spontaneous mutation - occurs only to one drug
2) conjugation
- mostly in GN bacteria, occur b/w normal flora & pathogens
-R-factor w/c is extra-chromosomal DNA encoding for resistance that is
passed from one bacteria to the next
- responsible for multiple-drug resistant bugs
CDC's campaign to prevent antimicrobial resistance Infection Prevention
- vaccinate
- remove catheters
Diagnose & Tx infections effectively
- target the pathogen
- contact the experts
Use ABX wisely
- practice antimicrobial control
- use local data
- tx infection, NOT contamination or colonization
- know when to say "NO" to Vanco
- stop ABX when infection has cleared or unlikely a bacterial infection
Prevent transmission
- isolate the pathogen
- break the chain of contagion
Who should receive ABX prophylaxis? 1) Select surgical patients - cardiac, peripheral vascular, orthopedics, GI, GYN
(hysterectomy)
2) severely neutropenic
3) pt at risk for bacterial endocarditis
4) pts w/ recurrent UTIs, severe rheumatic endocarditis
,AGACNP Barkley Review -Antibiotics | Complete Questions & Verified Answers | Adult-Gerontology Acute Care NP
Indications for ABX combinations 1) initial therapy for severe infection - until organism is ID'd
2) mixed infections - common in GI, pelvic, brain abscesses
3) prevent emergence of resistance - TB, HIV, certain parasites
4) to decrease toxicity
5) to promote synergistic effect - PCN + gentamicin, TMP-SMZ*
ABX combination disadvantages 1) increased risk of adverse effects like allergy or toxicity
2) risk of suprainfection (ex. C. diff & yeast infection*
3) risk for drug resistance
4) increase cost
Cell wall synthesis inhibitors PCN, cephalosporins, carbapenems, aztreonam, vancomycin, fosfomycin,
teicoplanin
Penicillins - inhibit transpeptidases necessary for cell wall synthesis & activate autolysis
w/c cleave bonds in the cell wall.
- *target the PCN binding proteins (PBP) - PBP1 & PBP3 (crucial targets)
- resistance is d/t inability of drug to reach PBPs or enzymatic inactivation of
the drug
- PCN resistant drugs produce beta-lactamase which cuts into the beta-lactam
ring of the drug which inactivates the ABX so the ABX is no longer become
anti-infective.
•Allergic reactions (1-5%); Anaphylaxis (.004-.015%)
•Cross reaction - 3-7% PCN to Ceph
•Prolonged high dose = granulocytopenia, interstitial nephritis
Bacterial cell wall Gram positive vs Gram negative
Gram negative has an outer membrane and gram positive does not w/c
prevents PCN from reaching PBPs (target molecules)
PCN: Narrow-spectrum PCNase sensitive PCN G, PCN V K
useful for Strep, Neisseria, many anaerobes, & spirochetes
PCN: Narrow-spectrum PCNase resistant Nafcillin, Oxacillin, Cloxacillin, Dicloxacillin
- useful for Staph aureus
, AGACNP Barkley Review -Antibiotics | Complete Questions & Verified Answers | Adult-Gerontology Acute Care NP
PCN: Broad-spectrum Ampicillin, Amoxicillin, Bicampicillin
- useful for H. flu, E. coli, P. mirabilis, N. gonorrheae, enterococci
susceptible to beta-lactamase
PCN: Extended-spectrum - Piperacillin, Carbenicillin, Ticarcillin, Mezlocillin
useful for H. flu, E. coli, P. mirabilis, N. gonorrheae, enterococci
PLUS
pseudomonas, enterobacter, proteus, B. fragilis, & Klebsi
susceptible to beta-lactamase
PCN side effects & toxicities 1) Pain at IM injection site - bec PCN is thick/viscious
2) reactions to procaine & potassium - from the injection, not PCN itself
3) rare neurotoxicity
4) ALLERGY - can occur immediate (2-30 mins), accelerated (1-72h); late (days
to weeks)
anaphylactic reactions occur w/ PCNs more than any other drugs
*Incidence is 0.02% but mortality is 10%
Allergy is exposure dependent, NOT dose dependent.
What to do if pt has PCN allergy? AVOID PCNs ENTIRELY
mild allergy - can give cephalosporin
severe allergy or anaphylaxis - avoid PCN & cephalosporin (5-10% cross-
sensitivity)
Alternatives to PCN
- Vanco & erythromycin
Life-threatening + NO abx alternatives, give PCN according to
desensitization schedule
PCN Combined with a Beta-Lactamase Inhibitor -cillin/bactam
-cillin/clavulanate
limited toxicity; great for Pseudomonas
Ampicillin + sulbactam (Unasyn)
Amox + clav (Augmentin)
Ticarcillin + clav (Timentin)
Piperacillin + tazobactam (Zosyn)
