Bacterial contamination plastic container

Containers made flxm fibrous materials such as paper, cardboard and sacking, are generally heavily contaminated (especially with moulds and bacterial spores) and should not be taken into clean or aseptic areas where fibres or microorganisms shed flxm them could contaminate the product. Ingredients which must be brought into clean areas must first be transferred to suitable metal or plastic containers. 

To cut down the risk of fungal and bacterial contamination, the Petri dishes should be contained in a plastic box. Clean the box and lid internally and externally with 70% alcohol before use (see Note 5). 

For adherent cell cultures, the following protocol for HeLa cells may serve as an example. Cervical adenocarcinoma (HeLa) cells (purchased from the American Tissue and Cell Culture Corp. ATCC Manhasset, VA, USA), cell line CCL-2, were seeded in 75 cm sterile plastic cell culture flasks (Fisher Scientific) at a concentration of approximately 2 X 10 cells cm l Typically, the growth medium consisted of 20ml Dulbecco s Modified Eagle s Medium (DMEM ATCC), supplemented with 10% fetal bovine serum (FBS ATCC). To prevent bacterial contamination, 2.5ggmT of amphotericin B (ATCC) and lOOIUmT penicillin/streptomycin (ATCC) was added to the medium. The cells were incubated at 37 °C in an atmosphere containing 5% COj. 

Further contamination is then inevitable on standing. Tests condncted with a large plastic container filled with tap water showed an initial bacterial connt of 18/ml, which, after only a week, had risen to 45,000/ml. Thus, the equipment commonly nsed to store and dispense fresh water in mobile environments leaves mnch to be desired, unless it is subject to additional treatment. This may range from the simple nse of purifying chemicals added to the water, or flltration or a complete water treatment system. Of these, filtration is by far the most attractive of the low cost methods. 

Earlier reports indicated that bacterial and fungal contamination were less likely in plastic bags, because they require no air venting. However, recent observations have shown that solutions in plastic containers are as liable to contamination as are solutions in glass bottles (8), probably because of the frequent presence of small holes in the plastic layers. Bags should be squeezed before use, to detect such microscopic leaks. 

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