Three different methods were used for detecting and isolating microorganisms with high radiation resistance from the microbial contamination on infusion sets prior to sterilization. By all three methods, microorganisms with a radiation resistance high enough to be a critical factor in a sterilization process (D-6 value greater-than-or-equal-to 30 kGy) were found with a frequency of approximately two colony forming units (cfu) per 100 product items, even though the product items in two of the series of analyses were irradiated with doses of 3-6 kGy. The frequency of occurrence of isolates with D-6 values greater-than-or-equal-to 30 kGy was 0.45 per 1000 cfu of the total aerobic count. Eight different isolates of microorganisms had D-6 values greater-than-or-equal-to 40 kGy when irradiated in dried laboratory preparation. All but one of these were classified according to morphologic criteria as Deinococcus, and all but one had nonlinear dose-response relationships in semilogarithmic presentation.
|Publication status||Published - 1991|