European Journal of N u c l e a r

Eur. J. Nucl. Med. 2, 105-107 (1977)


© by Springer-Verlag 1977

Microbial Contamination of Radionuclide Generators K. Sorensen, K. Kristensen, and P. Frandsen The Danish National Health Service, Isotope-Pharmacy and Pharmaceutical Laboratories, Bronshoj, Denmark

Abstract. Technetium-99m generators were grossly contaminated using 5 different strains of microorganisms. Elution of the generators showed that the number of microorganisms was reduced by a factor of 104-106 . There were no indications that the generators would support bacterial growth. It is concluded that it would be acceptable from a microbiologic point of view to omit autoclaving and membrane filtration of the final product provided that proper aseptic techniques are applied.

Material and Methods The generators used were first used for their normal purpose and then kept the time necessary for a sufficient decay of radioactivity. Before contamination with different strains of microorganisms the generators were disassembled and the aluminium oxide columns sterilized by autoclaving. The contaminated columns were eluted with portions of 10 ml of sterile 0.9% w/v NaC1 solution. The number of microorganisms per ml of the contamination suspensions after passing the columns and of the eluates were determined after incubation of suitable dilutions on solid agar substrate.

Experiments 1 and 2


Aseptic preparation of natrii pertechnetatis (99mTc) injectio from technetium-99m generators is a routine procedure at very many hospitals. The preparation is well suited for autoclaving or membrane filtration but radiation protection problems or lack of time may tend to prevent such measures being taken. It is therefore of great interest to investigate the possibilities of bacterial growth in such generator systems. No systematic work was found. Hamilton (1972) discusses the probability of bacterial contamination in generator eluates by measuring the environment of the generator system for bacterial contamination and finds it very low. Investigation by the Isotope-Pharmacy (Sorensen and Kristensen, unpublished), where sterility-tests were done on 60 samples taken from 19 hospital departments in three consecutive weeks on the last day of the use of technetium-99m generators, gave negative results in all tests. In the present study the bacterial counts of the eluates from massively contaminated technetium-99m generators were measured. For offprints contact." K. Sorensen, The Danish National Health Service, Frederikssundsvej 378, DK-2700 Bronshoj, Denmark

Technetium-99m generators from The Radiochemical Centre, Amersham were contaminated with a suspension of one of the below-mentioned microorganisms in sterile 0.9% w/v NaC1 solution (10 ml per generator). The following strains of microorganisms were used: Rhodotorula rubra, Staphylococcus epidermis, Bacillus subtilis, Escherichia coli, and Clostridium sporogenes. The number of microorganisms in the different contamination suspensions appears in Tables 1 and 2. In Experiment 1 the generators were eluted immediately 9 consecutive times. In Experiment 2 the generators were eluted after 1 and 2 weeks of standing at room temperature.

Experiment 3 Technetium-99m generators from 8 different manufacturers were contaminated with E. coli suspended in sterile 0.9% w/v NaC1 solution (10 ml per generator). The suspension contained 1.7 +0.2 x 107 microorganisms per ml. The generators were eluted immediately 3 times and again after 2 weeks of standing at room temperature.

Results and Discussion

After passing the generators the number of microorganisms of the contamination suspensions is reduced by a factor 104-106 (Tables 1, 2, and 3). In this respect there is no significant difference between the different


K. Sorensen et al. : Microbial Contamination of Radionuclide Generators

Table 1. The number of microorganisms per ml eluted from contaminated technetium-99m generators" by nine consecutive elutions (Experiment 1) Microorganisms

Contamination suspension

B. subtilis E. col± CI. sporogenes St. epidermis R. rubra a

Eluate number

Before passing generator

After 1 passing generator









1.2-+0.3x10 s t.l±0.2x106 1.3±0.4x105 1.5-+0.4x107 2.0±0.5x106

Microbial contamination of radionuclide generators.

European Journal of N u c l e a r Eur. J. Nucl. Med. 2, 105-107 (1977) Medicine © by Springer-Verlag 1977 Microbial Contamination of Radionuclide...
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