Federal inspectors knew about problems at a major baby formula plant in Michigan months before a recent recall, it was revealed on Monday.

The Food and Drug Administration (FDA) confirmed to Politico that it was aware in November that the potentially deadly Cronobacter bacteria had been detected in the Zeeland plant where Reckitt makes its Enfamil ProSobee Simply Plant-Based Infant Formula.

Inspectors “made note” of the positive test during a “limited inspection” of the Reckitt plant where the bacteria was first detected in September, the FDA said. The contaminated batch was initially destroyed.