A simple and easy in vitro model to test the efficacy of IV lines' needleless connectors against contamination

BACKGROUND: Hub colonization after manipulation is responsible for 29% to 60% of catheter-related bloodstream infections (C-RBSI). Prevention can be achieved by the use of hub connectors, but its efficacy is generally based on instillation of high concentrations of microorganisms, which do not reflect the real contamination in daily practice. Our purpose was to create an in vitro model lasting long enough to be used for the comparison of the efficacy between various connectors against contamination simulating the real daily handling. METHODS: The model consisted of 40 blood culture bottles with an inserted cannula with a needle-free closed connector. Twice a day, each line was manipulated while instilling 1 mL of two different fluids (saline and propofol). We manipulated the bottles as follows: ten bottles with clean gloves and disinfecting connectors with alcohol (controls), ten bottles with hands (no gloves), ten bottles with gloves impregnated with a 0.5 McFarland (MF) solution of Staphylococcus aureus (SA), and ten bottles with gloves impregnated with a 0.05 MF solution of SA. The bottles were incubated in a BACTEC System at 37°C under continuous agitation up to 10 days. When a bottle turned positive, 100 μL of the fluid was cultured and incubated followed by microorganism identification using standard procedures. RESULTS: Overall, all bottles in the control group were negative at the end of the incubation time. In the three contamination experiments, almost all (38/40) bottles were positive during the incubation time. We only found differences regarding the median time to positivity (interquartile range (IQR)) between saline and propofol in the manipulation with SA 0.05 MF: 240 h (154.82 to 360.00) vs. 66 h (58.01 to 69.11), p = 0.008. CONCLUSIONS: A daily connector handling with 0.05 McFarland S. aureus solution while instilling saline proved to be a useful model lasting long enough to be used for the comparison of the efficacy of different types of closed needleless connectors against contamination. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40635-014-0027-9) contains supplementary material, which is available to authorized users.