Spread and control of mycoplasmal infection of cell cultures

Summary Environmental sampling was performed during trypsinization and passage of 3T-6 cell cultures that contained a mean of 4.3×10⁷ colony forming units (CFU) per ml supernatant ofA. laidlawii. The lip of the culture flask and the outside of the used pipet were always heavily contaminated. The outside of the culture flask (3/7), the work surface (8/12) and the outside of a pan of disinfectant (4/5) were regularly contaminated with mycoplasmas. Airborne mycoplasmas were detected eight of 32 times (25%) by settling plates; simultaneous forced-air samplers by two different methods were always negative. The technician’s hands were contaminated two of 15 samples. When hands were contaminated, more contamination was detected in the environment. Droplets ofA. laidlawii andM. orale inoculated onto work surfaces survived drying for a minimum of 3 days, even in laminar airflow cabinets. Twenty-five of 31 (80.6%) cell culture technicians carriedM. salivarium in their throats; only two carriedM. orale. It is concluded that mycoplasma-infected cultures are the most common source of further infection. Recommendations for prevention and control of mycoplasmal infection are listed. These studies were supported in part by Contract No. 1-GM-2112 from the National Institute of General Medical Sciences, Contract No. 1-CB-23868 from the National Cancer Institute, General Research Support Grant 5-S01-RRO5582 from Research Resources, National Institutes of Health, and by a Grant-in-Aid from the State of New Jersey.