Mycoplasma hyorhinis, cultivar α strains (1) do not grow on any of the standard media used for mycoplasma cultivation. These strains, which are found as contaminants in cell cultures, are detected by indirect methods.
A specialized medium has been described but it is not yet in wide use (2).
This practice should be used in conjunction with Practice E 1531.
All cell cultures to be examined for mycoplasma should undergo a minimum of two passages in antibiototic-free tissue culture medium before testing.