Nanosphere reminds me of Cepheid ( CPHD), which is now a $2.6 billion market cap-company. Cepheid leveraged approval of a single MRSA infection test in 2007 to gain entry into hospitals and sell their entire array of diagnostic tests. I expect Nanosphere to follow the same path -- capitalize on the approval of the gram-positive test to grow sales of a larger menu of tests, several of which should be approved over the next 12-18 months. A test for the detection of C. difficile bacteria, a leading cause of serious diarrhea and a big problem for hospitals, should be approved fairly soon. So should a test to determine patients' suitability for use of the anti-clotting drug Plavix. Behind those tests are two huge possible approvals, each of which can be almost as big a commercial opportunity as the gram-positive infection test. Nanosphere is developing an enteric pathogens test that rapidly detects all stomach and intestinal bacteria. This would be a first-in-class test and is something hospitals clearly want. The company is also working on a rapid troponin detection diagnostic. Troponin is the protein that regulates muscle contraction and is used by doctors and hospitals to determine if a patient has suffered a heart attack. Current heart attack tests require hospitals to draw blood and test for biomarkers or send out the blood for lab tests. Nanosphere is hopeful that its troponin test will be more accurate than biomarkers and quicker than sending out blood for lab testing. I bought Nanosphere soon after the approval of the gram-positive test was announced on June 27. Even with the subsequent run-up in the stock price, Nanosphere's market cap is still well under $200 million. I believe the stock has a lot more upside, and again, I use Cepheid and its $2.4 billion market cap as a comp. For Nanosphere to reach a Cepheid-esque valuation, the company has to execute the gram-positive test launch successfully and then leverage it with more test approvals and launches. I'm fairly confident the company can accomplish these goals. Nanosphere is presenting at the UBS Global Life Sciences Conference on Weds. Sept. 19. Rosenblum is long Nanosphere shares.Subscribe to Dan Rosenblum's SharkBiotech.com newsletter. Follow Dan Rosenblum on Twitter.