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Chapter 81. Osteomyelitis

Student Questions

Case pertaining to questions 1–6:

An 82-year-old woman with no known allergies was admitted to the hospital to receive surgical and medical management for suspected osteomyelitis of the tibia. During surgical debridement, a bone biopsy was obtained for culture and histopathology. The microbiology laboratory reported Staphylococcus aureus, susceptible to vancomycin, linezolid, daptomycin, trimethoprim-sulfamethoxazole but resistant to penicillin, oxacillin, ciprofloxacin, erythromycin, and clindamycin.

Select an appropriate intravenous antimicrobial regimen for this patient.

A. Linezolid

B. Nafcillin

C. Trimethoprim-sulfamethoxazole

D. Vancomycin

Answer: D

Option A: Incorrect. Linezolid can be used for osteomyelitis, but given the common treatment duration is not optimal due to adverse effects.

Option B: Incorrect. The organism cultured is resistant to oxacillin and should be considered resistant to nafcillin as well.

Option C: Incorrect. Even though it is susceptible, use of trimethoprim-sulfamethoxazole is usually used as an oral option and is not considered to be an appropriate initial therapy in most cases.

Option D: Correct. Vancomycin is widely considered the first-line therapy for MRSA infections including osteomyelitis.

Which laboratory parameter(s) should be monitored weekly in this patient receiving intravenous antibiotic therapy?

A. Liver function tests

B. BUN/SCr

C. Eosinophils

D. B and C

Answer: B

Option A: Incorrect. Liver function tests are not considered to be routinely needed in patients receiving intravenous antimicrobial therapy. This is also dependent on the antimicrobial regimen selected.

Option B: Correct. BUN/SCr should be routinely be monitored in most regimens which include an agent with renal clearance.

Option C: Incorrect. Eosinophils are not routinely monitored in patients receiving intravenous antibiotics.

Option D: Incorrect. Eosinophils are not frequently monitored unless the possibility of allergy arises.

Response to therapy can be evaluated by the following laboratory test(s):

A. CPK

B. CRP

C. ESR

D. B and C

Answer: D

Option A: Incorrect. CPK is monitored with daptomycin therapy, but is not associated with response to therapy.

Option B: Incorrect. CRP is an inflammatory marker which can be followed to assess response to therapy ...

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