THE EFFICACY OF VARIOUS IRRIGATION SOLUTIONS IN REMOVING SLIME-PRODUCING STAPHYLOCOCCUS

To determine which type of irrigation solution and which method of irrigation most effectively removes slime-producing Staphylococcus from implant surfaces, we performed experimental washings of bacteria-coated stainless steel screws with various solutions delivered by bulb syringe or by jet lavage. The quantity of bacteria remaining on the screw surface was determined after irrigation with 1 L of saline, 1 L of antibiotic solutions, or 1 L of saline containing a liquid soap. Antibiotic solutions tested included bacitracin, neomycin, and polymyxin/neomycin. We found that the use of power irrigation increased the removal of bacteria by a factor of at least 100 over bulb syringe irrigation of the same volume, no matter which solution was used. This effect ranged from a 100-fold improvement for neomycin, to a 285-fold effect for the polymyxin solution. The addition of antibiotic drugs to the irrigation solution had no significant effect on bacterial removal, and none of the antibiotic solutions were statistically different from saline alone in the amount of bacteria removed from the screws. The addition of a liquid soap solution dramatically increased the amount of bacteria removed by irrigation, reducing the residual bacteria per screw from a colony count of 3.5 x 10(4) for polymyxin (the best of the antibiotic solutions), to 4.38 x 10(4). This difference was statistically significant as judged by Student's t test, with p = 0.01. We have concluded that the use of power irrigation improves the ability to clean this pathogenic bacteria from metallic surfaces, and that the addition of antibiotic drugs to the irrigation solution does not. The use of liquid soap in the irrigation solution does improve the efficacy of irrigation in removing slime-producing bacteria.