Consequences of accidents on hygienic status of microbiological laboratories

During the routine operation of any microbiology andmolecular biology laboratory accidents with the releaseof genetically modified micro organisms cannot beexcluded. Common laboratory guidelines request thecontaminated area being confined and disinfected(GenTSV), and the disinfection has to be done withparticularly licensed agents (BiostoffVO). The control ofthe effectiveness of the treatment is requested, thekinetics and spatial distribution of the germs released,however, are virtually unknown.The study presented here, was designed to record thespread and distribution of indicator bacteria after acontrolled release as a simulation of the worst casescenario. Beside the spread of the released bacteria theeffectiveness of cleaning and disinfection procedureswas recorded. In this study the indicator bacteria Arthrobacter agilis and E.coli were released andsamples collected using contact slides, sedimentationplates and an RCS collector system at ten differentlocations within the laboratory between -2 to +6 hoursafter the release of the bacteria.After six hours the indicator gram positive germs wererecovered from almost all points in the laboratory, evenfrom already cleaned and disinfected areas. The effectof the disinfection procedures was only for a short time,and the areas were re-contaminated aftersedimentation of germ containing aerosols. The gramnegative bacteria, in contrast, were only recoveredaround the location of the release.Based upon our experiments the followingrecommendation can be given:1.) In case of an accident, a contamination of alllaboratories adjacent to the one where theaccident occurred2.) The air condition should be switched off, toaccelerate the sedimentation of the aerosols