General Antibiotic Considerations + Allergies Flashcards
(23 cards)
Identify tertiary references that are appropriate for clinical infectious diseases questions
IDSA (disease/pathogen/vanco dosing guidelines)
Johns Hopkins (some recommendations are opinions)
Sanford Guide (spectrum of activity table)
UpToDate/Lexicomp (DO NOT USE for complicated dosing)
Mandell’s (for extreme nerding lol)
Don’t forget antibiogram
Others: package inserts, CredibleMeds, review articles, FDA, CDC, CDC Yellow Book, Pediatrics Red Book
Identify bacteria that have the highest risk of clinically relevant inducible AmpC expression
(HECK YES!)
Hafnia alvei
Enterobacter cloaca
Citrobacter freundii
Klebsiella aerogenes
Yersinia enterocolitica*
Recall examples of antibiotics that may have efficacy in vitro but should likely not be used for those infections in vivo
- Aminoglycoside monotherapy NOT appropriate for non-UTI Pseudomonas infections.
- Daptomycin should not be used for lung infections (pulmonary surfactant interference).
- Fluoroquinolones are not routinely recommended for MRSA infections (resistance).
- Third-gen cephalosporins should not be used for Enterobacter or Citrobacter (resistance).
How to defeat Pseudomonas?
Pseudomonas always lives 4 a challenge!
piperacillin-tazobactam
aminoglycosides (no monotherapy)
levofloxacin
4C’s: carbapenems (not ertapenem), cefepime, ceftazidime, ciprofloxacin
aztreonam
Oral MRSA options
Skin doesn’t like carrying MRSA.
sulfamethoxazole-trimpethoprim
doxycyline
linezolid
clindamycin
minocycline
How to treat Gram negative anaerobes (ie. Bacteroides fragilis)?
Colons Be Like: My Anaerobes Might Go 2 Crazy!
carbapenems
beta-lactamase inhibitors
metronidazole
moxifloxacin
G2C: second-generation cephalosporins (cephamycins)
How to treat atypical bacterial infections?
FLOCK of MICE on BICYCLES
levoFLOXacin
moxiFLOXacin
macrolides:
azithroMYCin
clarithroMYCin
tetracyclines:
doxyCYCLine
Recognize clinically relevant adverse effects and drug-drug interactions
1. Binding w/ divalent cations (fluoroquinolones, tetracyclines)
**2. Warfarin **
metronidazole, sulfamethoxazole-trimethoprim, fluconazole, voriconazole -> incr. [warfarin]
rifampin (inducer) -> decr. [warfarin]
3. QtC prolongation (fluoroquinolones, macrolides, voriconazole, antiarrythmics, antipsychotics)
4. Enzyme induction & inhibition
(rifamycins: CYP3A4, CYP2C9/19 inducers)
5. Pharmacodynamic interactions
aminoglycosides + amphotericin/cyclosporin/radiocontrast/NSAID/foscarnet = nephrotoxicity
vancomycin + piperacillin-tazobactam = nephrotoxicity
aminoglycosides + loop diuretics = ototoxicity
Identify antimicrobials that should not be taken by pregnant and/or breastfeeding women
Tetracyclines not recommended for pregnant women.
In children, doxycycline can be used safely for 21 days or less.
Conduct a medication history for a patient with an antimicrobial allergy that collects the
information necessary for allergy assessment
Important points:
* Did rxn occur w/ 1st dose or after other doses?
* Symptoms? (if skin rxn, hives= bumpy/itchy within 24 hours)
* Rxn within 5-10 years?
* Did they need treatment?
* Have you taken the med since?
Distinguish antimicrobial allergy from antimicrobial side effect
Allergy: immune rxn (Type I-IV hypersensitivity)
Side effect: predictable rxn (aminoglycoside nephrotoxicity)
Classify allergic reactions as one of the four Gell and Coombs subtypes of hypersensitivity
antibody-mediated:
**Type I ** (immediate, but after first dose for antibodies)
IgE => anaphylaxis, angioedema, urticaria, hypotension, bronchospasm
Type II (delayed)
IgM and/or IgG => cytotoxic
not antibody-mediated:
Type III (delayed)
IgM and/or IgG => immune complexes => activates complement
Type IV (delayed)
Most common with antibiotics, especially sulfa drugs
T-cell => skin rxns (SCARs, maculopapular)
Which antibiotic classes are concentration dependent?
=> higher doses given less frequently
Cmax/MIC aminoglycosides, fluoroquinolones, daptomycin
AUC:MIC
fluoroquinolones, vancomycin, daptomycin, azithromycin, linezolid
Which antibiotic classes are time dependent?
=> lower doses given frequently OR extended infusion
T>MIC
beta-lactams, linezolid, trimethoprim-sulfamethoxazole, macrolides, tetracyclines
Which antibiotics most commonly cause skin reactions?
Amoxicillin, trimethoprim-sulfamethoxazole, ampicillin, cephalosporins
What is penicillin skin testing and when is it not appropriate?
=> determine if rxn is Type I (IgE-mediated immediate hypersensitivity) in pts w/ hx of rxn
X SCARs
X non-IgE mediated rxns
X severe immunosuppression
X anaphylaxis within 5 years
What do you do if a patient is truly IgE allergic, but beta-lactam is first line?
Drug desensitization
Series of diluted injections, incr. drug strength over time
Sulfa allergies
=> commonly rechallenge
skin rxns
common: maculopapular rash
rare: SJS, TEN, thrombocytopenia
Cross-reactivity b/w sulfa abx/non-abx sulfa drugs is UNLIKELY.
What is the most common skin manifestation of antibiotic allergy?
maculopapular rash (AKA -exanthema/eruption, morbilliform rash) via *Type IV *
=> on trunk and symmetrical
=> happens after several days
(In kids, viral infection=> maculopapular rash. May be mistaken for beta-lactam allergy.)
For every antimicrobial, consider:
Never ever let charming clinicians push drugs.
Narrowest spectrum
Evidence-based
Least side effects
Convenient for outpatients
Cheapest
Pregnancy contraindications
Drug-drug interactions
Which antibiotics are most likely to cause QtC prolongation?
Fluoroquinolones and macrolides
prolongated QtC => Torsades de Pointes (TDP, life-threatening arrhythmia)
Which medications do NOT need to be renally adjusted?
linezolid
moxifloxacin
ceftriaxone, oxacillin/nafcillin tetracyclines
azithromycin/erythromycin
metronidazole
fosfomycin
Which medications need hepatic dose adjustments?
Clindamycin
Tigecycline
Metronidazole
Voriconazole
Caspofungin
Rifampin
