Multiple cultures becoming contaminated simultaneously or in sequence. Contamination spreading despite apparently good technique. Cross-contamination between neighboring cultures.
Common Causes
1Creating bubbles in medium during pipetting
2Splash-back from waste beaker contaminating work area
3Operator talking, coughing, or sneezing over open cultures
4Not using plugged pipettes when transferring medium
5Drawing liquid into pipette plug creating contaminated aerosols
6Room air drafts, eddies, and turbulence in culture area
7Excessive traffic and extraneous activity near culture work
Solutions
1Avoid creating bubbles in medium or pipette during all manipulations
2Use plugged pipettes (cotton-plugged at top) especially when transferring medium
3Never draw liquid into pipette plug; change filter immediately if plug becomes wet
4Discard waste into beaker with funnel or use vacuum aspiration
5Avoid working when sick with a cold, or wear a mask
6Face away from work when talking is necessary
7Use automatic pipette aids and change filters regularly
8Dedicate appropriate space for tissue culture, reduce traffic and extraneous activity
9Allow 20 minutes after airflow initiation before opening containers in biosafety cabinet