The present disclosure relates to a medical diagnostic system. In various embodiments, the system includes a housing, a first receptacle in the housing for receiving a reagent container, a second receptacle in the housing for receiving a working fluid and waste container, where the second receptacle is larger than the first receptacle, two reagent access needles positioned and fixed within the first receptacle with each of the two reagent access needles being substantially horizontal to horizontally access the reagent container, and a working fluid access needle and a waste access needle positioned and fixed within the second receptacle with the working fluid access needle and the waste access needle being substantially horizontal to horizontally access the working fluid and waste container.