Antibiotics

Tamar Barlam

Infectious Disease

Director, Antimicrobial Stewardship

Why is antibiotic choice important?

Safe, broad-spectrum antibiotics are readily available

One can easily cover most common infections with excellent therapeutic results

So what’s the big deal?

A Changing Landscape forNumbers of Approved Antibacterial Agents

Bars represent number of new antimicrobial agents approved by the FDA during the period listed.

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1983-87 1988-92 1993-97 1998-02 2003-05 2008

Infectious Diseases Society of America. Bad Bugs, No Drugs. July 2004; Spellberg B et al. Clin Infect Dis. 2004;38:1279-1286;New antimicrobial agents. Antimicrob Agents Chemother. 2006;50:1912

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Between 1962 and 2000, no major classes of antibiotics were introduced

Fischbach MA and Walsh CT Science 2009

Antibiotic Resistance

Antimicrobial-resistant infections can cause worse patient outcomes, longer hospital stays, and higher mortality rates than similar infections with antibiotic-susceptible bacteria.

Total costs related to AR infections are estimated as high as $30 billion.

Inappropriate antibiotic use is believed to be the major contributor to the development and spread of AR bacteria. Studies have demonstrated approximately 30 to 50% of

antibiotic treatments are inappropriate.

Resistant StrainsRare

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Resistant Strains Dominant

Antimicrobial Exposure

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Selection for antimicrobial-resistant Strains

Campaign to Prevent Antimicrobial Resistance in Healthcare Settings

Choosing an Antibiotic

What is wrong with the patient? Is it an infection? Is it bacterial? How sick is the patient? Host factors that might influence likely

pathogens: social history, age, residence, comorbid conditions

Host factors that might influence drug choice: allergy, pregnancy, renal/liver function

Attributes of the drug

What is its spectrum? Gram positive or gram negative? Aerobic or anaerobic or both?

Does it reach adequate levels at site of infection?

Bacteriostatic or bacteriocidal? Endocarditis Meningitis Osteomyelitis

How are they different?

Cefazolin Ceftriaxone Cefepime Ampicillin-sulbactam Ertapenem Levofloxacin Ciprofloxacin

Ceftriaxone Cefepime Piperacillin-tazobactam Piperacillin-tazobactam Meropenem Ciprofloxacin Cefepime

Case #1

54 yo female with poorly controlled diabetes comes to the ED with a buttock abscess with surrounding erythema. The abscess was I&D’d and material sent for culture.

Case #1

Patient was placed on clindamycin and discharged home.

Case #1

Case #1 Inducible macrolide resistance.

Encoded by plasmid-borne gene erm.

Constitutive – all test resistant Inducible – clindamycin can

test susceptible

Bacteria Isolated from Culture of Abscess Material, Deep Tissue Specimens, or Blood.

Jenkins T C et al. Clin Infect Dis. 2010;51:895-903

© 2010 by the Infectious Diseases Society of America

Case #2

23 yo healthy male with tibial fracture after MVA. ORIF performed and patient was discharged after an uneventful hospital course. Pain persisted and after six weeks, there was complete non-union. One month later, a small pustule formed and drained purulent material. Patient was seen by ortho and taken back to OR.

What is the patient’s diagnosis? Treatment?

Case #2

Case #2

What if these were the culture results?

Case #3

47 yo active IVDU, HCV positive, presents with severe left arm pain and swelling. The patient had injected heroin into the veins of that arm 1 day prior.

On the morning of admission, he had severe bilateral pleuritic chest pain

Case #3

Rest of exam: T103 Other VSS II/VI SEM at LSB, decreased breath sounds

R>L base, rales bilaterally No HSM

WBC 18,000 w/ 26% B; H/H 13/40, plts 300K other labs wnl

Case #3

Case #3

Describe what the patient likely has. What would you do next? Antibiotics?

Case #3

Case #3

Antibiotic? Duration?

Case #3

What if patient if this was his isolate: