Why is mycoplasma contamination such a problem, and how do you detect it?

Why

Because the infection is invisible, it can run for months while quietly changing every result. Drexler and Uphoff and the review by Nikfarjam and Farzaneh list effects including inhibited proliferation, increased apoptosis, chromosomal aberrations, altered gene expression and reduced transfection efficiency. Mycoplasmas consume arginine and other nutrients and release nucleases that degrade cellular nucleic acids.

Reported incidence in surveys has often been in the range of 15 to 35 percent of cultures, with much higher figures in some settings. Routine PCR against conserved 16S ribosomal sequences is the usual test, fast and sensitive, with primers broad enough to catch Acholeplasma but narrow enough to avoid amplifying ordinary bacteria. A fluorescent DNA stain shows extranuclear specks, and an indicator cell line raises its sensitivity.

Culture on specialized broth remains the reference method but takes weeks. Prevention matters more than treatment. The same review points out that routine antibiotic use hides sloppy technique and is itself a major cause of contamination, so many labs culture without antibiotics.

Quarantine incoming lines, test them before they join the main incubator, and discard rather than treat whenever stocks allow.