Abstract
Laboratory containment systems are designed to remove potentially infectious aerosolized particles from the worker's environment. However, little evidence on the quantities of aerosol generated during common microbiological practices exists. This study's objective was to measure aerosol and splash contamination during the microbiology techniques of serial dilution and pipetting, undertaken by staff with a range of experience and training. High-titer suspensions of Bacillus atrophaeus were used, with sodium fluorescein added to the solutions to enable visualization of any splashes. Air samples were taken to measure the microbial aerosols produced during the study.
The results showed a range of air and surface contamination produced during the tests, with a high variance among participants. More experienced personnel on average produced significantly lower amounts of aerosol (6.9 cfu) when performing serial dilutions compared to inexperienced personnel (13.6 cfu), whereas no significant difference between the two groups was noted for the plating out procedure. This trend was followed when examining the splash results. The average contamination from aerosols and splashes was also significantly reduced for those trained at containment level 3 (CL3) compared to those who were not CL3 trained.
The study highlights that aerosol and splash contamination is produced by all users, even those highly trained and experienced, but that a correctly operating biological safety cabinet (BSC) will capture these aerosols. However, the contamination on the gloves and surfaces could potentially be spread within the laboratory and outside, indicating the need for effective personal protective equipment (PPE) and hygiene controls.