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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?

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.


Distinguish between empiric and directed antibiotic therapy.

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.


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

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.


What are Nafcillin and Cefazolin first-line treatments for?

What drugs are not indicated for this?

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

Quinolones are not indicated for MSSA.


What are some general adverse effects of antibiotic use?

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

Increased costs, blah blah wah wah


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

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

If they are, use Aztreonam.


What can quality as "misuse" of an antibiotic?

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)


What is an antibiotic stewardship?

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


What factors should be considered when selecting an antibiotic?

The identity of the infection and spectrum of coverage


Formulation, bioavailability, achievable concentrations

Allergy, toxicity

Adherence/convenience and cost.

Other patient comorbidities and drug interactions


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


Inpatient (non-ICU)

Inpatient (ICU)

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...


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?


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


How are pseudomonal pneumonias treated?


Aspiration pneumonia?

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

MRSA: Vancomycin or Linezolid

Aspiration: Clindamycin (for oral anaerobes)


Recall the four classes of beta-lactams.

What role do clavulanate and sulbactam serve?

Penicillins, Cephalosporins, Carbapenems, Monobactams.

Beta-lactam inhibitors, given in conjunction.


What beta-lactams are appropriate to treat pneumococcus?

What else is pneumococcus known as?

Cefotaxime, Ceftriaxone.

Streptococcus Pneumoniae.


What is the mechanism of action of macrolides?

Which are in common use today?

What is their spectrum of action?

Bind the 50S subunit to prevent transpeptidation.

Clarithromycin & Azithromycin (erythro for surgical ileus?)

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


What is the mechanism of action of Fluoroquinolones?

Which are indicated for pneumococcus?

Which are indicated for pseudomonas?

Bacterial topoisomerase inhibition.

Moxifloxacin, Levofloxacin

Ciprofloxacin, Levofloxacin


What is the mechanism of action of Tetracyclines?

Which are currently in use?

What is their spectrum of action?

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"


What drugs are indicated for resistant G+ pneumonia?

Try to remember their side effects.

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

Linezolid (bone marrow suppression & neuropathy)

NOT Daptomycin! (bound by surfactant)


What is the standard treatment regimen for CAP?

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

(Coag+ Staph or Pseudomonas? Longer duration)


What are the risk factors for multidrug resistance infection?

Hospitalization >5 days

Acute care >2 days

Nursing homes / Long-term care facilities

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

Infected family member.


What is the empiric therapy for hospital acquired pneumonia?

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)


What organisms are seen in pneumonia of the immunocompromised?

(eg HIV, post-transplant)

HIV: Strep pneumoniae >> PCJ, MAC, Histoplasma

Post-transplant: CMV, RSV, Aspergillus, Mucormycosis


What respiratory infections are seen in the following scenarios:

Bird exposure

Rabbit exposure

Farm workers

Travel to SW United states

Bird: Chlamydophila psittaci (psittacosis), avian flu

Rabbits: Francisella tularensis (tularemia)

Farm: Coxiella burnetti (Q fever; a rickettsial)



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

Pseudomonas, Staph Aureus, MAC, Aspergillus


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

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.


What are some of the atypical bugs seen in pneumonia?

Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila.


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

How should these be treated?

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!

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