The long road to fast and accurate resistance detection

I’d like to say that molecular diagnostics will soon provide nearly instantaneous detection of antimicrobial resistance in clinical samples, allowing for rapid targeting of appropriate therapy. I’d like to say that, but I can’t. Even MRSA, a bug with a relatively simple resistance mechanism (simple relative to, say, MDR Acinetobacter), is proving to be a tough nut to crack. Remember this post of mine, about Cepheid’s recall of their Xpert SA/MRSA blood culture assay? Well, another “valued customer” notice went out last week, informing users that this product requires “additional test optimization” and “clinical re-validation”—so it will be unavailable until at least the end of 2012. Labs and hospitals that have come to rely on this test to improve their antimicrobial management of S. aureus bacteremia will now have to find another approach.

I’m posting not to knock Cepheid, but to make the point that bringing new rapid diagnostic methods to a clinical microbiology laboratory environment, and applying them to clinical care in unforgiving situations (e.g. would you like to have your MRSA bacteremia treated with nafcillin for the first 2-3 days?) is difficult! The makers of agar plates will be keeping their day jobs for a while….