The test is the fourth assay on the firm's Revogene system and it detects five common genetic causes of drug resistance.
Cincinnati, Ohio-based Meridian will acquire Quebec City-based GenePOC for $120 million, and hopes to quickly convert customers to a PCR-based instrument.
Overall, the share prices for 18 of the index's 27 companies fell month over month. Exact Sciences was the only firm whose share price improved in the double digits.
The firm will acquire GenePOC for $50 million with potential for milestone payments of an addition $70 million by Meridian's fiscal 2023.
Canaccord said Meridian Bioscience's preannounced second quarter top-line miss and expected ongoing weakness in its MDx business were among the reasons for the downgrade.
The company said it has faced competitive pressures in its diagnostics business, partially offset by organizational streamlining efforts it initiated last year.
Many diagnostic firms saw gains in their stock prices last month as Invitae and NantHealth also saw healthy increases.
The 360Dx Index was up 12 percent last month as shares of Accelerate Diagnostics, Veracyte, and Exact Sciences each improved more than 40 percent month over month.
The firm lowered topline and non-GAAP earnings per share guidance for fiscal 2019.
OraSure CEO Stephen Tang discussed the firm's plans for international expansion, while Meridian CEO Jack Kenny said the firm needs to develop a new MDx platform.