The Importance Of Removing Antibiotics And Antifungals From Media Used In Cell Culture.

Three common additives to cell culture media are the beta-lactam family of antibiotics (penicillin), aminoglycosides family of antibiotics (streptomycin), and the antifungal family polyene macrolides (amphotericin B). Penicillin, streptomycin, andamphotericin B are often added to culture media to prevent unwanted contamination in the culture. However, overuse of antibiotics and antifungals can mask serious problems including mycoplasma contamination, increased resistance to contaminants, and decreasing the in vitro in vivo correlation. At times antibiotics and antifungals are a critical addition to cell culture media (primary cells and cultures under selection), but should be removed from media when not absolutely necessary.

Another serious issue with the overuse of antibiotics and antifungals is with the reproducibility of data. The overuse of antibiotics and antifungals can result in a lower proliferation rate of cells, alteration or complete reduction of specific protein synthesis, and general cytotoxicity of the culture.  These factors will result in variations in data generated from lab to lab.  Keeping antibiotics and antifungals in culture media is often rationalized by scientists as another layer of protection from unwanted microbes.  However, antibiotics and antifungals in culture media can be a crutch and encourage the cutting of corners in aseptic technique.

Simple steps in the appropriate direction for healthy cultures without antibiotics or antifungals include vigilant aseptic technique inculding working in biosafety hoods, appropriate personal protection, sterilizing all instrumentation used, and spraying hands with 70% often.  All cultures should be procured from reputable sources (national cell banks) that use stringent quality control practices to ensure sterility of the line upon receiving. Finally, screening for mycoplasma should be performed periodically including prior to banking cells, executing larger studies, and upon receiving cells from a new source/ vendor.

-Nick Hibbard, Director, Laboratory Operations, IONTOX.