Abstract
Different technologies for sterilisation of heat-sensitive biomedical materials have been studied to solve problems related to the use of ethylene oxide. These methods include low temperature steam with 2% formaldehyde (LTSF) as a sterilising agent. We used LTSF sterilisation to sterilise polyurethane vascular access catheters with lumina ranging from 1.98 - 2.64 mm in diameter after contamination with one of the following test strains: Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis, Bacillus stearothermophilus, Escherichia coli, Candida albicans.
Method: Germ suspensions were prepared for each strain in concentrations sufficient to ensure over 106 cfu per catheter. Sixteen catheters per strain were contaminated, two of which were left as positive controls (not sterilised); the remaining 14 were subjected to LTSF sterilisation. Of these, 7 were prewashed with enzymatic detergents. At the end of the sterilisation cycle the biomedical devices were washed with Muller-Hinton (MH) broth, followed by seeding onto blood agar, incubation at the optimal temperature for each germ, and counting of colonies of test organisms after 24, 48, 72 and 96 hours and 5, 7 and 10 days. In each cycle test devices in compliance with DIN 58.948, section 14 were used. Biological indicators consisted of paper strips impregnated with sheep blood and an inoculum of Bacillus stearothermophylus ATCC 7953 containing 1.9 3 106 cfu. Control strips were incubated and observed for a period of 10 days.
Results: The operating parameters of the sterilisation cycles were correct, as were the changes in chemical indicators. All of the control strips presented microbial growth after 24 hours. No microbial growth was recorded in the MH broths recovered from the sterilised catheters and on the blood agar plates. Enterococcus faecalis was seen to grow in one catheter that was processed without prewashing by day 10 of incubation, still obtaining a reduction in cfu of more than 6 log.
Conclusion: Low temperature steam (60ºC) with 2% formaldehyde was found to be biologically effective as sterilisation method in 6F, 7F and 8F polyurethane vascular access catheters.

Keywords: sterilisation, low temperature, formaldehyde, catheter

Abstract
The Bowie & Dick test is the test carried out daily as a routine measure in the sterilisation departments of hospitals in order to test the functional and performance capabilities of sterilisers. However, the Bowie & Dick indicator systems available on the market are apparently not equally suited to this purpose. This drawback persists despite new pertinent standards and guidelines. Hence the question as to which indicator system does the responsible user on site avail of can (or indeed must) arise. This paper describes a test which is intended to facilitate decision-making for the user on site and can be easily conducted using one's own steriliser.

Keywords: Bowie & Dick test, standard, test procedure