A composition or concentrate for cleaning medical or dental instruments comprising in combination a protease and a biostatically effective phenoxy alcohol such as phenoxyethanol selected such that at a working solution dilution of the combination, the phenoxy alcohol is at a concentration below the MIC of the selected phenoxy alcohol against Pseudomonas aeruginosa (ATCC 15442), and wherein the combination is nevertheless effective to reduce a 6 log concentration of Pseudomonas aeruginosa (ATCC 15442) by at least a 1 log concentration within 4 hours. The composition or concentrate may further include or more hydrolases and or boron or a boron compound. The composition may be used in methods for cleaning a soiled medical or dental instrument, for example in an ultrasonic bath.一種用於清潔醫療或牙科儀器之組成物或濃縮物，其包含一蛋白酶與一經選定具生物抑菌效力之苯氧醇(諸如苯氧乙醇)之組合，如此在該組合處於稀釋的使用溶液時，該苯氧醇之濃度低於該選定之苯氧醇對抗綠膿桿菌(ATCC 15442)之最小抑菌濃度(MIC)，以及其中該組合仍具有在4個小時內，將6對數濃度之綠膿桿菌(ATCC 15442)降低至少1對數濃度之效力。該組成物或濃縮物可進一步包括一或多種水解酶和/或硼或硼化合物。該組成物可應用於用於清潔受污染之醫療或牙科儀器之方法，例如於超音波浴中。
