Mycoplasma infections are very, very bad news; these special prokaryotes can rapidly spread through your cell culture and inhibit cell proliferation, induce apoptosis, cytokines and radicals, and otherwise transform your cells. Worst of all, since contamination is not easy to spot, you may not realize your culture is contaminated until it’s too late.
The 100 types of Mycoplasma are the smallest known self-replicating microorganisms, and are estimated to contaminate between 5 and 35% of cell cultures. They can hurt people, too: one strain, Mycoplasma pneumoniae, causes about 20% of pneumonias.
So, how can you rescue your cell culture from the Mycoplasma threat?
- Destroy your contaminated cultures and start over. This is the traditional method, and while very effective, it’s also very expensive. Moreover, there’s no guarantee your next culture won’t also be contaminated.
- Treat with trypsin, S-bromouracil or antisera. However, these methods don’t reliably rid a sample of enough Mycoplasma to continue working. They have also showed inconsistent results, or no results whatsoever!
- Antibiotics can eradicate Mycoplasma, but it’s often helpful to know which strains of Mycoplasma are in your samples, and resistance can be a persistent problem.
One new method for treating with antibiotics involves using a cocktail of several antibiotic types. One group from Argentina (Coronato and colleagues) reported a successful series of treatments: first, incubation with Tylosine for 12 days, followed by incubation for 10 days with Minocycline. While the whole process took 22 days (at least), Mycoplasmas were eradicated, no recurrence of infection was seen, and the treatments did not affect cell growth. Two years later, German researchers found that treatment with fluoroquinolone Mycoplasma removal agents for one week showed 64% eradication; two weeks of ciprofloxacin (cipro) showed 77% eradication; and a BM (Boehringer Mannheim)-cyclin (which contains pleuromutilin and tetracycline derivatives) showed 84% eradication. These cocktail methods, while not perfect, seem to offer the best results (about 75% recovery) in eliminating Mycoplasma.
Certainly a lot cheaper (and less frustrating) than throwing your cells away.
How do you handle Mycoplasma contamination?
Chung, T.S. et al. (2005). Detection of Mycoplasma infection in cultured cells on the basis of molecular profiling of host responses. Genomics and Informatics, 3(3) 63-67.
Coronato, S., et al. (1994). A simple method to eliminate mycoplasma from cell cultures. J. Virol. Methods. 46(1):85-94.
Fleckenstein, E., and Drexler, H. (1996). Elimination of Mycoplasma contamination in cell cultures. Biochemica, 1:48-51.