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Appl Environ Microbiol. 1968 August; 16(8): 1156-1162
Copyright © 1968 American Society for Microbiology. All Rights Reserved.

Microbial Contamination on Disposable Hypodermic Syringes Prior to Sterilization by Ionizing Radiation¹

Welsh School of Pharmacy, University of Wales Institute of Science and Technology, Cardiff, Wales
Radiobiology Laboratory, Churchill Hospital, Oxford, England

ABSTRACT

A large number of syringes were taken from the production lines of three independent manufacturers; the numbers and types of microorganisms contaminating these randomly sampled syringes were assessed in the laboratories maintained by each of these manufacturers for routine sterility testing, according to a standard protocol devised by the Research Committee of the UK Panel on Gamma and Electron Irradiation, which coordinated the investigation and analyzed the results. Items produced by a manufacturer were assessed for microbiological contamination both in their own laboratories and in the laboratories of the other manufacturers. The level of "false-positive" results was determined independently for each laboratory by the testing of "known sterile" items which had been subjected to the radiation-sterilization process. Both the percentage of syringes initially sterile and the average number of organisms per contaminated syringe differed among the three manufacturers. When corrected for interlaboratory differences, the number of syringes initially sterile ranged from 16 to 48%, and the mean number of organisms per contaminated syringe was 20 to 70. Of 964 syringes tested by all three laboratories, only one contained over 1,000 aerobic organisms (1,133). The most common organisms found were coagulase-negative, gram-positive cocci. Two manufacturers assessed contamination by anaerobic organisms; of 610 syringes, 1 contained 4,275 organisms and 3 more had 100 to 1,000 organisms, but 488 (80%) were uncontaminated by anaerobes. The results are discussed in the context of the choice of radiation dose necessary for the sterilization of medical products manufactured under controlled hygienic conditions.

¹ A publication of the Research Committee of the UK Panel of Gamma and Electron Irradiation. Members of the Committee are as follows: A. M. Cook (Chairman), R. J. Berry (Technical Secretary), R. W. H. Cook, C. G. Crawford, J. F. B. Dealler, J. O. Dawson, R. S. M. Frohnsdorff, G. E. Gale, J. C. Kelsey, F. J. Ley, P. J. Lindop, and K. Tattersall. The manufacturers paricipating in this study (who are all Full Members of the UK Panel on Gamma and Electron Irradiation) were Gillette Surgical Ltd., Reading, Berks.; Johnson and Johnson (Great Britain) Ltd., Slough, Bucks.; and Smith and Nephew Research Ltd., Harlow, Essex.