Monday, April 30, 2012

Pharmacology I

A 90 year old man with HTN, HL, a-fib, COPD, kidney stones, BPH, GERD, osteoarthritis, h/o GI bleed, gout, and dementia is admitted from the nursing facility where he lives to the hospital because of shortness of breath and cough. CXR shows a lobar pneumonia. Sputum induction grows MRSA. He gets severe red man syndrome with vancomycin so he is started on the drug shown above by the resident. This cyclic lipopeptide depolarizes the bacterial cell membrane and is approved for skin and soft tissue infections as well as bacteremia with MRSA. The resident remembers to write for weekly CKs and to check for peripheral neuropathy and myopathy.

Challenge: However, this patient won't get better. Why? What's the mechanism?

Image is in the public domain.


Reflex Hammer said...

I had to look this one up: "Pulmonary surfactant antagonizes daptomycin, and it should not be used to treat pneumonia."

That was an awesome question!

jbwpac said...

Daptomycin- won't kill MRSA

Craig Chen said...

it's dapto! Reflex hammer, you're right - it is neutralized by surfactant. In other types of infection, it is a reasonable drug for MRSA
Pharmacology I

The drug shown is daptomycin. Daptomycin is inactived by pulmonary surfactant; thus, it is not useful in treatment of MRSA pneumonia.

Sources: UpToDate; Wikipedia.