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An ongoing dialogue on HIV/AIDS, infectious diseases,
January 30th, 2014
Unanswerable Questions in Infectious Diseases: Persistent MRSA Bacteremia
Older person, many medical problems. Probably is on hemodialysis, with the vascular surgeons having some difficulty with access. There’s diabetes, of course, and cardiovascular disease, and oh yeah, a mechanical aortic valve that’s around 10 years old. Some toes are missing from prior surgical treatment of osteomyelitis.
Now? Fever and mental status changes have brought him/her to the hospital, and 100% of the umpteen blood cultures done since admission are positive for MRSA. They remain positive even though the MIC to vancomycin is 1.0 and the trough concentration of the drug is 18.
Since starting on vancomycin, the patient has improved somewhat, but continues to have fevers and, yes, positive blood cultures. Lots of them — it’s been days. Vancomycin MIC is checked again, and it remains unchanged. Maybe even it’s 0.5 this time. An exhaustive search for a removable focus of infection has yielded nothing — no abscess, no valvular vegetations/root abscess, no spinal osteomyelitis, clots. A cardiac surgeon has been consulted, and passes on the opportunity to replace the valve, thank you very much. The dialysis AV fistula is functioning, for now, but is not red or draining.
So the question is this:
With persistent MRSA bacteremia despite “appropriate” vancomycin therapy, should the antibiotics be changed?
Lots of options out there. Linezolid. Daptomycin. Ceftaroline (off label, of course). Combination therapy, with the idea that more should be better, naturally. You could add gentamicin (really?), or rifampin (biofilms!), or do a vancomycin/beta-lactam combination.
Let’s hear from you — vote on these options (as I said, there are lots of them this time), then comment away.