Bacterial colonization of functionalized polyurethanes

A protocol was developed for studying the growth of bacteria upon polyureth anes subsequent to the establishment of an adherent bacterial population. A n inocula of approximately 10(5) cfu S. aureus were spread on functionalize d polyurethanes which included Pellethane, sulfonated Pellethane, phosphona ted Pellethane, quaternized amine polyurethanes, and a zwitterionic phospho nated polyurethane. After 24 h incubation, Pellethane, sulfonated Pellethan e, and phosphonated Pellethane showed bacterial growth by at least a factor of 10. In contrast, the zwitterionic phosphonated polyurethane showed a fa ctor of 10 decrease in bacteria after 24 h and the quaternized amine polyur ethanes reduced the bacteria to only a few hundred after only 1 h. When tre ated with bovine serum albumin, Pellethane, sulfonated Pellethane, and phos phonated Pellethane again showed bacterial growth by as much as a factor of 10 over 24 h. The quaternized amine polyurethanes and the zwitterionic pho sphonated polyurethane still exhibited bactericidal abilities even when coa ted with bovine serum albumin, with the zwitterionic material reducing bact eria by more than a factor of 10 over 24 h and the quaternized amine polyur ethane reducing the bacteria to only a few hundred after only 1 h. A zone o f inhibition study suggested that the bactericidal activity of the zwitteri onic phosphonated polyurethane was due to the leaching of cadmium ions. A q uaternized amine polyurethane which contained chloride instead of iodide as the counterion to the amine moiety was less bactericidal than the iodide-c ontaining polymer when treated with albumin. Thus, bacteria were able to co lonize Pellethane, phosphonated sulfonated Pellethane, and phosphonated Pel lethane, but the iodide-containing quaternized amine polyurethane and the z witterionic polyurethane prevented colonization. (C) 1999 Elsevier Science Ltd. All rights reserved.