Factors influencing microbiological assay of cell-culture mycoplasma.

A total of 6432 cell cultures was assayed for mycoplasmas over a 6-year period by aerobic and anaerobic incubation of agar and broth media. Mycoplasmas were detected in 375 cultures (5.8%). M. orale and A. laidlawii accounted for 61.3% of the isolates. Anaerobic incubation detected 98.1% of the isolates; aeorbic incubation detected 45.8%. Of factors studied to determine their effect on mycoplasma assay, only two, anaerobic incubation and presence of mycoplasmacidal/static antibiotics, were significant. In separate studies, 86 of 2656 cell cultures (3.2%) were infected with strains of M. hyorhinis that did not grow on cell-free media. Recommendations are given for microbiological assay of cell-culture mycoplasmas.