Problems in one of Nabriva’s subcontracting plants have stalled the FDA’s review of the company’s proposed IV antibiotic Contepo.

The FDA sent a complete response letter to Nabriva saying that “manufacturing deficiencies” in the European plant meant the agency couldn’t approve Contepo (fosfomycin) just yet, Nabriva CEO Ted Schroeder said in a conference call on Wednesday. “We expect that this will be a solvable set of issues,” he said.

Schroeder said the company is exploring back-up supply chains for Contepo and it will request a meeting with regulators and the drug subcontractor as soon as possible.

Contepo is one of three drugs in Nabriva’s pipeline. Another antibiotic, lefamulin, is due for a PDUFA response for pneumonia in August. It has undergone a Phase II trial for skin infections and is currently in a Phase I trial for pediatric patients.