Using a medium-fill simulation to evaluate the microbial contamination rate for USP medium-risk-level compounding.

PURPOSE The estimated microbial contamination rate for complex, multiple-step, medium-risk-level compounding was studied. METHODS The results of evaluations of the aseptic technique of pharmacists and technicians in compounding complex USP medium-risk-level sterile preparations were compiled to estimate the microbial contamination rate. The testing took place in 2002 and 2003 at a single institution and involved reconstitution of sterile dry growth medium and a series of complicated transfers of the medium from vials and ampuls to intravenous bags. The bags were incubated at 25-35 degrees C for 14 days and observed for microbial growth. RESULTS Of 539 evaluations, 28 (5.2%) resulted in preparations that yielded microbial growth. Pharmacists' compounding resulted in a slightly lower contamination rate (4.4%) than that of technicians (6.2%). Inadvertent touch contamination may have been the principal source of the contamination. CONCLUSION . A two-year series of 539 evaluations of the aseptic technique of pharmacists and technicians conducted with sterile growth medium and designed to simulate the compounding of USP medium-risk-level sterile preparations yielded an overall contamination rate of 5.2%.