Knowledge Base
Learn about infection control practices and considerations.
Sterile Gloves
How are gloves sterilised?
The most common method is using gamma irradiation, whereby products are exposed to gamma radiation which penetrates the packaging and kills all microorganisms. Gamma processing does not cause any significant rise in temperature or leave behind any chemical residue.
What is bioburden?
Bioburden is the total number of viable (live) microbes on a packaged item prior to sterilisation. This includes bacteria, yeasts and fungi.
What is a Sterilisation Assurance Level or SAL?
SAL is the expected probability of an item being non-sterile after exposure to a valid sterilisation process. The normal SAL for medical devices is 10-3 (one in a thousand) for less critical devices and 10-6 (one in a million) for more critical and invasive devices. Surgical gloves are sterilised at 10-6 SAL.
What does SAL 10ā»ā¶ mean?
A Sterility Assurance Level of 10-6 means that for every 1,000,000 items sterilised, there may be one that contains viable microorganism that have survived the sterilisation process. The SAL is a statistical probability that is used because it is impossible to prove that all viable microorganism have been killed during the sterilisation process. In practice the theoretical degree of processing to achieve the desired SAL is determined, and then routine processing is set at a higher level in order to achieve ‘overkill’.
How can I tell if gloves have been sterilised?
The packaging clearly shows they are sterile gloves. Each carton will have a red irradiation sticker, showing that the contents have been gamma sterilised. The irradiation sticker is yellow prior to sterilisation and changes colour to red during processing. A certificate of irradiation is available showing the lot number and carton number and confirming that the gloves have been sterilised.
What is dose setting?
Dose setting is the process undertaken to establish the level of radiation exposure (dose) required to destroy microorganisms (bioburden) on a product within a specified safety level (Sterilisation Assurance LevelāSAL). The process includes a determination of the number of organisms on the packaged, unsterilised product, followed by irradiation at a dose calculated to kill 90% of that number of microorganisms (sub-lethal dose). The sub-lethal dose takes into account the resistance of the microorganisms and the actual device.
What are endotoxins?
Endotoxins are potent inflammatory agents produced by the cell walls of gram-negative bacteria. They are capable of causing multiple local and systemic reactions including irritation, fever, tissue inflammation, diarrhoea, respiratory distress, and endotoxic shock. They are not destroyed by steam, ethylene oxide or irradiation sterilisation. Endotoxins are also adjuvants, a term applied to substances that can increase or magnify a Type I or Type IV sensitisation and/or allergic response. The presence of endotoxin with an allergen may speed up sensitisation or amplify a reaction.
What is a pyrogen?
A pyrogen is a fever producing substance. Endotoxins are pyrogens, although producing a fever is only one of the physiological consequences of endotoxin. Pyrogenicity, like the other consequences of endotoxin depends on the level and rate of introduction. Very low levels will not cause a fever. Higher levels increase the number and severity of potential adverse consequences.
Does sterilisation remove endotoxins?
No. The ethylene oxide, steam and radiation sterilisation processes used for gloves do not destroy endotoxins. These forms of sterilisation destroy microorganisms. Upon destruction, endotoxins, the pyrogenic lipopolysaccharides from the cell walls of dead gram negative bacteria, are released from the cell wall and remain capable of causing multiple local and systemic pathological conditions. It has been reported that sterilisation may actually increase endotoxin levels due to the break-up of the bacterial wall into multiple pieces.
Do surgical gloves have endotoxins?
Whether or not surgical gloves possess significant levels of endotoxin depends on the manufacture practices of each lot or batch. Some gloves have enough endotoxin for one pair to elicit a fever and initiate endotoxin related complications noted previously. Others have undetectable levels. Endotoxin activity is rate and dose related; the level is significant. Because the presence of endotoxin is dependent on manufacturing practices and raw materials, every lot of production must be carefully controlled and monitored.
Are endotoxins a concern in glove manufacturing?
Yes. Endotoxins are inflammatory agents produced by the cell walls of gram-negative bacteria. This type of bacteria readily grows in warm, moist or wet environments where basic nutrients are supplied such as in raw latex, stagnant leach tanks, untreated water and liquid powder mixtures (known as powder slurries). If bacterial growth is not controlled, the endotoxin level increases, potentially increasing endotoxin-associated responses in the glove user and/or patient. To control bacterial growth, manufacturers must maintain a clean, good manufacturing environment and may need to use small amounts of biocides at points during the manufacture of rubber latex and synthetic gloves to prevent microbial growth.
Are endotoxins found only on gloves?
No. Endotoxin may be present on medical equipment, infusion dialysis equipment, disinfection liquids, air cooler systems, water supplies, air filters, sterilised re-usable devices and generally in the hospital environment. Implants, medical devices utilised for invasive medical procedures and other medical instruments may be contaminated when in contact with sterile or clean medical fields contaminated with endotoxin.
