An adapter (10) utilized to interconnect a fluid container (88) and an administration feeding set (90) having a hollow retractable spike (52) and a sliding shaft seal (18) for maintaining a fluid-tight seal around spike (52). The sliding shaft seal (18) includes a conduit (77) which sealingly engages around the retractable spike (52) in fluid tight engagement when adapter (10) is biased by a spring (19) between an engaged position and a disengaged position.