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Microbial contamination on disposable hypodermic syringes prior to sterilization by ionizing radiation
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.
Insights
Microbiological contamination in syringes varied significantly between manufacturers. Most syringes had low levels of contamination, primarily gram-positive cocci, impacting radiation sterilization dose selection.
Area of Science:
- Microbiology
- Sterilization Science
- Medical Device Manufacturing
Background:
- Syringe manufacturing involves rigorous sterility testing to ensure product safety.
- Radiation sterilization is a common method for medical devices, requiring accurate contamination data for effective dose determination.
Purpose of the Study:
- To assess and compare microbiological contamination levels in syringes from three independent manufacturers.
- To evaluate inter-laboratory variability in sterility testing and determine false-positive rates.
- To inform the selection of appropriate radiation doses for sterilizing medical products.
Main Methods:
- Random sampling of syringes from three manufacturers' production lines.
- Microbiological assessment of contamination in each manufacturer's own laboratory and others'.
- Determination of false-positive rates using radiation-sterilized, known sterile items.
Main Results:
- Significant differences in initial sterility percentages (16-48%) and mean organism counts (20-70) were observed among manufacturers.
- Most syringes (964 tested) showed low aerobic contamination; only one exceeded 1,000 organisms.
- Coagulase-negative, gram-positive cocci were the most prevalent contaminants; anaerobic contamination was low (80% uncontaminated).
Conclusions:
- Manufacturer-specific contamination levels necessitate tailored approaches to radiation sterilization.
- Inter-laboratory variations in sterility testing highlight the need for standardized protocols.
- Accurate microbial load data is crucial for optimizing radiation sterilization efficacy and safety.