Aim: Manufacturers’ instructions recommend changing the infusion line together with the infusion bottle after each administration. We investigated if the complete infusion line may be microbiologically contaminated after short-time antibiotic and rinse-solution application.

Method: Immediately after the change of an infusion administration set after 72 hours the remaining antibiotic solution was inactivated with yolk and cultured on blood agar for 48 hours at 36°C to detect possible contaminants.

Results: Among 87 investigated samples no microbial growth was detected. One sample which hadn’t any contact to antibiotics yielded 1 colony forming unit (cfu) of coagulase-negative staphylococci.

These results suggest that in case of consecutive antibiotic-short- and rinse-infusions the infusion line may be in place up to 72 hours without contamination. This, however, may be only the case for infusion sets, which are in contact with antibiotics. If no antibiotic is administered, the infusion bottle and the infusion line must be renewed together for every change. To clarify this question into more detail, a larger consecutive study is required.

Conclusion: I.v. administration sets without any contact to antibiotics must be changed together with their infusion bottle after administration. In case of consecutive antibiotic-short- and rinse-infusions our pilot study suggests using the i.v. administration sets for up to 72 hours without renewing it at every infusion-set exchange.