Thermo Fisher Scientific agreed to sell its microbiology business to Astorg for about $1.075 billion, consisting of cash and a $50 million seller note. The unit provides antimicrobial susceptibility testing and culture media solutions used in clinical, pharmaceutical, and food safety workflows. Thermo Fisher said the transaction is part of continued portfolio management within specialty diagnostics, with closing expected in 2026. For Astorg, the acquisition expands a private equity platform in diagnostics and laboratory services tied to antimicrobial stewardship. The deal matters for lab supply chains and product roadmaps because susceptibility testing remains a key infrastructure layer for clinical microbiology—areas where vendor continuity and regulatory processes drive switching timelines.