Devices and methods are provided for sealing a catheter insertion site to maintain sterility. In one aspect of the invention, mounting handle/dressing assemblies and kits are disclosed for creating a sterile sealed environment around a catheter insertion site. For example, the dressings of the present invention can be pre-disposed around a mounting handle and connector. The connector is joined to the proximal end of the catheter and then the dressing can be slid along the mounting handle until it surrounds the insertion site. Once the dressing is adhesively applied to the skin and locked into place by an annular fitting between the dressing and the connector, the handle can be removed and discarded, leaving only the dressing, and catheter connector in place. The catheter connector preferably has a needle-free connector port at its proximal end for connection to IV lines or other infusion devices.