In Activation of B. Subtilis Spores and E. Coli Endotoxin by Ethylene Oxide

Abstract

Exposure of Bacillus subtilis spores to ethylene oxide (EO) showed correlation between the killing rate and the EO concentration, when the temperature was kept at 55 degrees C and the relative humidity at 100%. The co-efficient of dilution was calculated to be 0.9. The effect of EO on Escherichia coli endotoxin was investigated by the chromogenic Limulus Amebocyte Lysate (LAL) test. A solution of endotoxin was dried on glass tubes and exposed to 450 or 900 mg EO/l during 1-46 h under the same conditions as the spore inactivation. The LAL activity of the endotoxin was reduced to about 30%. The EO-treated endotoxin was tested in the rabbit pyrogen test. The summed temperature increase for three rabbits was 0.9 degrees C, while the same assay using untreated test pieces showed an increment of 3.7 degrees C. Administration of the same quantity of EO-treated and untreated endotoxin to the rabbits, as adjusted by the LAL-test, produced the same temperature increment. The addition of polymyxin B (PB) to an endotoxin solution reduced the LAL activity by 75%. Had the endotoxin been exposed to EO, thereby reducing the LAL activity by 70%, addition of PB further reduced the activity by 99%. The reaction of EO on the endotoxin reduced the LAL activity as well as the pyrogenic response and increased the affinity to PB.

Evaluation of sterilisation methods for bio-ink components: gelatin, gelatin methacryloyl, hyaluronic acid and hyaluronic acid methacryloyl

“…The mechanism of sterilisation is alkylation of sulfhydryl, amino, carboxyl, and hydroxyl groups, which damages proteins and nucleic acids [39]. Inactivation of bacterial endotoxin by EtO has also been reported [40].…”

Depyrogenation by the Flowing Afterglow of a Reduced‐Pressure N2–O2 Discharge (Gaseous Plasma Treatment)

“…However, the spores in unpackaged deposits present membrane damage whereas, within the pouch, there is no such severe membrane breach, but in both cases there is sufficient lethal damage by UV radiation to the DNA to inactivate the spores. 10 In the present case, the level of damage to the membrane in the form of chemical erosion is observed to follow strictly the UV fluence (dose) (see Figure 27 of Moisan et al [26] ), but probably (this is an assumption) requiring the contribution of the singlet oxygen molecules O 2 ( 1 D g ), eventually with O atoms: this is called photosensitized oxidation of type II.…”

“…The energy thus released can contribute to the achievement of chemical reactions, for instance erosion of a given material. 10 In fact, the level of UV damage to the spore DNA is most probably the same within and without the pouch, but the process of determining the viability of the spore implies its rehydration, whereby a breach in the membrane (resulting from its significant erosion, as is the case when the deposit is exposed unpackaged) terminates the spore germination process process ( [26] , Section 5.4.3). This thus prevents one from advocating that inactivation of unpackaged spores is actually due to DNA damage.…”

“…Autoclaves, which rely on moist heat (121–135 °C), cannot fulfil this high temperature requirement and, besides, most MDs partially or entirely made from polymers would not withstand such elevated heat treatment. Depyrogenation can be achieved by chemical exposure to ethylene oxide (EtO) and H 2 O 2 . A drawback of these chemical processes is that they require some venting period before use (up to 24 h for EtO) because toxic residues are generated that impregnate the medical devices.…”