Which of the following is an example of nanoparticle probe technology for Gram-positive blood cultures?

• A. Nanosphere Verigene Blood Culture Gram-Positive (BC-GP) Assay
• B. FISH
• C. Accelerate PhenoTest
• D. Nanosphere Verigene Blood Culture Gram-Negative (BC-GN) Assay

Answer: (A)

Nanoparticle probe technology uses probes labeled with nanoparticles, typically gold, to generate a detectable signal when a specific DNA target is present. The Gram-Positive Verigene Blood Culture assay from Nanosphere fits this approach: it screens positive blood culture specimens with organism-specific probes and uses gold-nanoparticle–labeled reporters on a microarray to produce a rapid, readable signal for identifying Gram-positive bacteria and certain resistance genes. This makes it a direct example of nanoparticle probe technology for Gram-positive blood cultures. The Gram-Negative Verigene assay uses a similar nanoparticle-based approach but targets Gram-negative organisms, which is why the Gram-positive version is the one described in the question. Other options differ in method: FISH relies on fluorescent probes, not nanoparticles, and Accelerate PhenoTest is a phenotypic, imaging-based platform rather than a nanoparticle probe system.