Prudent Use of Antibiotics - Graham Flashcards

1
Q

About how many antibiotics prescriptions are unnecessary?

Why does this happen, given that 97% of physicians know overuse contributes to antibiotic resistance?

What conditions should Abx not be prescribed for?

A

Perhaps 50%.

Usually either patients expecting or insisting on receiving them, or physicians trying to cover their asses.

NEVER for common cold. Not for undifferentiated fever.

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2
Q

Distinguish between empiric and directed antibiotic therapy.

A

Empiric: When the identity of the infection has not been conclusively identified, treat the “most likely culprits”. Broad spectrum use of multiple drugs (more adverse effects, costs)

Directed: Following identification. Narrow spectrum, needingly only 1-2 drugs.

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3
Q

Why is MIC not an adequate justification for choice of antibiotic?

A

MIC varies from organism to organism for a given drug, and are susceptible to many other factors (combinatorial effects, pharmacogenomics). They don’t exist in a vacuum.

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4
Q

What are Nafcillin and Cefazolin first-line treatments for?

What drugs are not indicated for this?

A

Nafcillin (oxacillin) and Cefazolin are first-choices for invasive MSSA infection.

Quinolones are not indicated for MSSA.

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5
Q

What are some general adverse effects of antibiotic use?

A

Antibiotic resistance, allergy/hypersensitivity, C. Diff enterocolitis, various side effects.

Increased costs, blah blah wah wah

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6
Q

What do you do if a patient with a basic G+ infection says he or she is allergic to penicillins?

A

Grill them, because they’re probably not actually allergic.

If they are, use Aztreonam.

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7
Q

What can quality as “misuse” of an antibiotic?

A

Given when they are not needed,

Continued when they are no longer necessary,

Given at the wrong dose,

Given for the wrong infection (incl Broad spectrum for known infection)

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8
Q

What is an antibiotic stewardship?

A

A system of people, informatics and policy which promotes optimal selection and dosing of antibiotics. Meant to improve outcomes while minimizing adverse effects.

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9
Q

What factors should be considered when selecting an antibiotic?

A

The identity of the infection and spectrum of coverage

Resistances

Formulation, bioavailability, achievable concentrations

Allergy, toxicity

Adherence/convenience and cost.

Other patient comorbidities and drug interactions

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10
Q

What are the most common causes (top 4) of community-acquired pneumonia in the following settings:

Outpatient

Inpatient (non-ICU)

Inpatient (ICU)

A

Outpatient: Strep pneumoniae, mycoplasma pneumoniae, haemophilus influenzae, chlamydophila pneumoniae

Inpatient (non-ICU): Strep pneu., Mycoplasma pneu., Chlamydophila pneu., Haemophilus influenza; same as outpatient

Inpatient (ICU): Strep pneu., Staph aureus, Legionella, Gram-negatives…

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11
Q

What is the basic course of treatment for outpatient CAP?

Inpatient CAP?

What if the patient is in ICU?

What if a PCN allergy is present?

A

Macrolide or Doxycycline. FQ or beta-lactam + macrolide if co-morbidities present.

Beta-lactam + macrolide.

ICU? Add a Fluoroquinolone.

PCN allergy? Replace beta-lactam + macrolide with Aztreonam

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12
Q

How are pseudomonal pneumonias treated?

MRSA?

Aspiration pneumonia?

A

Pseudomonas: Beta-lactams like Pip+Tazo, Cefepime, Meropenem, PLUS a fluoroquinolone (Cipro, Levo).

MRSA: Vancomycin or Linezolid

Aspiration: Clindamycin (for oral anaerobes)

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13
Q

Recall the four classes of beta-lactams.

What role do clavulanate and sulbactam serve?

A

Penicillins, Cephalosporins, Carbapenems, Monobactams.

Beta-lactam inhibitors, given in conjunction.

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14
Q

What beta-lactams are appropriate to treat pneumococcus?

What else is pneumococcus known as?

A

Cefotaxime, Ceftriaxone.

Streptococcus Pneumoniae.

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15
Q

What is the mechanism of action of macrolides?

Which are in common use today?

What is their spectrum of action?

A

Bind the 50S subunit to prevent transpeptidation.

Clarithromycin & Azithromycin (erythro for surgical ileus?)

Broad: G+, G-, and atypical pneumonias.

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16
Q

What is the mechanism of action of Fluoroquinolones?

Which are indicated for pneumococcus?

Which are indicated for pseudomonas?

A

Bacterial topoisomerase inhibition.

Moxifloxacin, Levofloxacin

Ciprofloxacin, Levofloxacin

17
Q

What is the mechanism of action of Tetracyclines?

Which are currently in use?

What is their spectrum of action?

A

Bind the 30S subunit to prevent aminoacyl-tRNAs from binding.

Doxycycline & minocycline (higher efficacy)

“G+ and G- bacteria found in the respiratory tract. Also cover atypical organisms”

18
Q

What drugs are indicated for resistant G+ pneumonia?

Try to remember their side effects.

A

Vancomycin (IV only; ototox/nephrotox/thrombophlebitis/REDMAN)

Linezolid (bone marrow suppression & neuropathy)

NOT Daptomycin! (bound by surfactant)

19
Q

What is the standard treatment regimen for CAP?

A

Treat for 5-7 days. Upon cessation, patient should be afebrile, not needing O2, and clinically stable.

(Coag+ Staph or Pseudomonas? Longer duration)

20
Q

What are the risk factors for multidrug resistance infection?

A

Hospitalization >5 days

Acute care >2 days

Nursing homes / Long-term care facilities

Recent IV Abx, chemo, wound care, or dialysis.

Infected family member.

21
Q

What is the empiric therapy for hospital acquired pneumonia?

A

If risk-factor negative: Ceftriaxone OR Amp+Sulbactam OR Ertapenem OR Fluoroquinolone

If risk-factor positive: Anti-pseudomonal beta-lactam PLUS Anti-pseudomonal FQ/AMG (plus Vanco/Linezolid)

22
Q

What organisms are seen in pneumonia of the immunocompromised?

(eg HIV, post-transplant)

A

HIV: Strep pneumoniae >> PCJ, MAC, Histoplasma

Post-transplant: CMV, RSV, Aspergillus, Mucormycosis

23
Q

What respiratory infections are seen in the following scenarios:

Bird exposure

Rabbit exposure

Farm workers

Travel to SW United states

A

Bird: Chlamydophila psittaci (psittacosis), avian flu

Rabbits: Francisella tularensis (tularemia)

Farm: Coxiella burnetti (Q fever; a rickettsial)

SW: Coccidioides, HANTA VIRUS OH SHIT SON

24
Q

Patients with COPD, CF, bronchiectasis are prone to infection by what organisms?

A

Pseudomonas, Staph Aureus, MAC, Aspergillus

25
Q

How can you quickly gauge whether a patient with a respiratory infection needs admittance to the hospital?

A

CURB-65 score: Confusion, BUN > 18, RR > 30, BP > 190/60, Age > 65

Score of 0-1 is low risk, can send home

Score of 2 suggests observation (inpatient)

Score of 3-5 is severe, admit and maybe turf to ICU.

26
Q

What are some of the atypical bugs seen in pneumonia?

A

Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila.

27
Q

What are some specific risk factors for penicillin-resistanct strep pneumoniae?

How should these be treated?

A

Age > 65yrs, Beta-lactam therapy, Alcoholism and other medical morbidities, Exposure to day-care

High dose Pen G / Ampicillin, Cefotaxime / Ceftriaxone, maybe Vancomycin / Rifampin, fluoroquinolones (non-meningeal)

Too much info!