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Despite of progress in medicine, iatrogenic infections are important problem in all countries. One of the contamination ways can be universally used disposable syringes.

We want to pay attention to possible mechanism of contamination connected with construction and injection practices of commonly used types of disposable syringes: contact of plunger with sterile surface of barrel. Two (or more) strokes of the plunger can transport a contaminant from the external compartment into the sterile compartment.