Cross-Contamination: The Particular Risk Posed by Beta-Lactam Antibiotics

Citing 21 CFR 211.42(c), the FDA criticised a drug manufacturer: "Your firm failed to perform operations within specifically defined areas of adequate size and to have separate or defined areas or such other control systems necessary to prevent contamination or mix-ups." What did the FDA object to?

This case concerned the manufacture of injectable drugs containing cephalosporins (beta-lactam antibiotics) and drugs that did not contain cephalosporins. Both were manufactured in the same premises. This is exactly what the FDA criticised: the absence of complete separation between cephalosporins and the other drugs, which created the risk of cephalosporin contamination of the non-cephalosporin products.

In fact, beta-lactam production and other production were separated into building sections that were physically separated and sealed, with dedicated air-handling systems. Nevertheless, since January 2025, cephalosporin monitoring had repeatedly detected cephalosporins in non-cephalosporin production. The FDA criticised this recurrence and had expected earlier detection through monitoring. It considered that:

• the monitoring was inadequate with regard to the number of samples and sampling locations
• the swab qualification was inadequate to detect low-level values
• samples had been assessed using solutions that were outside their stability period

The testing for product contamination was also criticised. In the FDA's view, it had not been taken into account that contamination is not evenly distributed. In addition, the company had inadvertently discarded monitoring samples before they could be analysed. Despite measures the company had committed to in order to improve matters, the FDA still required:

• A comprehensive assessment of the need for room modifications to separate cephalosporin and non-cephalosporin areas.
• An updated, comprehensive assessment of risk considerations for all beta-lactam contamination hazards in relation to processes, equipment and premises.
• A detailed plan with timelines for improving the risk assessments of contamination hazards.
• A comprehensive assessment of the documentation system in production and the laboratory for weaknesses. This also includes CAPAs regarding data integrity (ALCOA).
• A full investigation of the discarded samples, specifically regarding sampling location, date and quantity, and any additional testing where applicable.

Further deficiencies relating to aseptic processing and sterilisation, visual inspection and sterility testing, please also see "FDA Warning Letter to Baxter: Sterile Manufacturing Failures".

Conclusion: cross-contamination is a major concern for the FDA - particularly where beta-lactam antibiotics are concerned.

Please see the FDA website for the full Warning Letter.