Clostridium difficile


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	Clostridium difficile
	Clostridium difficile (C. diff) is an anaerobic (i.e. it cannot tolerate oxygen), spore-forming rod-shaped bacterium found in the human gastrointestinal tract. It is closely related to Clostridium botulinum, which causes botulism and produces 'Botox' toxin, Clostridium tetani, which causes tetanus, and Clostridium perfringens, which causes gas gangrene. C. diff was first isolated in the 1930s and its medical importance as a cause of antibiotic-associated diarrhoea and colitis was first recognised about thirty years ago. C. diff is found in the digestive tracts of about 5% of healthy adults and 20-40% of hospital patients. It causes disease when it germinates from its spore form in the colon and then produces toxins. The most dangerous toxin, known as Ribotype 027, is thought to have originated in Canada and has since spread to the USA, UK and Europe. Paradoxically, treatment with antibiotics makes C. diff Associated Disease (CDAD) more likely as such treatment will often kill the 'good' bacteria living in the gut as well as the 'bad'. This gives C. diff spores the opportunity to rapidly grow and produce dangerous toxins as they have little competition from other organisms that would normally limit their ability to colonise the gut wall. C. diff is attracting much media attention and public concern. This is hardly surprising as the latest available government figures show C. diff –related deaths as quadrupling between 1999 and 2005. The same statistics for C. diff show about double the mortality rate compared with MRSA. Reporting of incidences of C. diff in the over-65s is now mandatory. The Health Protection Agency’s 'Surveillance of Healthcare Associated Infections Report 2007' claims that over 55,000 cases were reported last year. Alleged deficiencies in the reporting regime may mean that the true number could to be far higher. Apart from its greater incidence of infection, there is a key difference between most common HAIs and C. diff. MRSA and C. diff are both bacteria, but when you kill MRSA (which many Chemex products do very effectively), it’s dead. When you try to kill C. diff it forms microscopic spores rather like a plant producing seeds. These spores can survive in all sorts of environments and are very difficult to kill. That means you can kill the organism quite easily - it cannot tolerate oxygen, for example - but its defence mechanism is that it forms a spore which waits for the ideal conditions to start growing again. The spores are what make C. diff so difficult to eradicate. This distinction has also led to the perception that while MRSA is spread mainly through poor hand hygiene, C. diff is spread more through dirty wards and equipment. This is only partially true as poor hand hygiene is still a significant contributory factor; the lack of hand washing facilities was noted as a factor in the 2007 Stoke Mandeville outbreak for example. Both MRSA and C. diff can be spread hand-to-hand but C. diff spores can survive on inanimate surfaces for far longer. Also, alcohol rubs kill MRSA but the usual advice is that the only effective way to get rid of C. diff spores is to wash them away with lots and lots of soap and water. This doesn’t kill them however, it flushes them away. There is much conflicting advice on effective treatments against C. diff spores. 1) “Alcohol Kills C. diff Spores” Wrong. Alcohol rubs can be effective against many pathogens (such as MRSA, for example) but are ineffective against spores. Yet many protocols still recommend alcohol-based hand disinfection to fight C. diff as an adjunct to washing with soap and water. *2) “Soap and Water Kills C. diff* Spores” Also wrong. It has been shown that the mechanical action of hand washing with soap and water can help remove spores but does not kill them. It merely helps you wash them away. However, the current best advice for removing the spores is lots of soap and water. 3) “Normal Cleaning Chemicals Kill C. diff Spores”** Traditional hospital cleaning agents based on quaternary ammonium compounds have a very limited effect on C. diff spores. In fact, quat-based cleaning agents have been shown to substantially increase the sporulation capacity of C. diff, especially when used at sub-optimal concentrations. *4) “Chlorine Bleach Kills C. diff* Spores”** Studies have shown that even 10% (strong) bleach is largely ineffective against C. diff spores even after ten minutes’ exposure. It is also well known that the efficiency of chlorine-based disinfectants such as bleach rapidly reduces on contact with soils. Also, organic soiling can combine with chlorine-based bleaching agents to form extremely toxic trihalomethanes. Trihalomethanes have some fairly unendearing properties: they are used as refrigerants and solvents, are carcinogenic and serious environmental pollutants as well. Chloroform, for example is a trihalomethane and can be formed when chlorine or hypochlorite react with organic substances such as urine, sweat or skin particles. Chloroform can also decompose to phosgene gas – used to devastating effect in WW1 – under the influence of ultraviolet light. In addition, mixing a chlorine-releasing compound such as bleach with anything containing ammonia can easily lead to the formation of chloramine gas which is also highly carcinogenic. These are among the reasons why chlorine bleach should never be used on urine spills, for example. However, switching from cleaning with detergent to cleaning with bleach has been cited as a factor in reducing the incidence of C. diff associated disease. However, the study that cites this also notes that such results were not reproduced in all wards studied and other, conflicting evidence suggests that such changes in cleaning protocols have no effect. *5) “Hydrogen Peroxide with Chlorine Based Disinfectants Kills C. diff* Spores” Until Chemex AntiBak*, the use of ‘mutually compatible’ disinfectants with hydrogen peroxide was one of the more effective disinfection protocols. When used properly, this combination can be better at killing C. diff* spores than bleach or disinfectant alone but is still not completely effective, plus this would generally be part of a ‘deep clean’ which involves much disruption, unlike Chemex AntiBak. Such a combination also needs highly specialised and trained teams to apply it. Chlorine bleach is a combination of hypochlorous acid and sodium hypochlorite - a combination that reacts rather violently with hydrogen peroxide. It reacts particularly well (or badly, depending on your perspective) if the concentration of the hydrogen peroxide exceeds 15%. While such combinations can be more effective than disinfectants alone at killing pathogens, most hydrogen peroxide solutions are stabilised by acids. This can cause problems as acid combined with bleach leads to the formation of chlorine gas which is extremely dangerous. *6) “Steam Sterilisation Kills C. diff* Spores” True, provided it’s done correctly. Hospitals use steam sterilising ovens (autoclaves) for surgical instruments. Autoclaves used to use steam heated to 121 °C at 15 psi for at least 15 minutes or to 134 °C for a minimum of 3 minutes. This is sufficient to kill spores. Now the protocol is more commonly 121–132 °C for 60 minutes or 134 °C for at least 18 minutes to denature the prions thought to mediate conditions such as CJD / BSE. This has led to steam being used to sterilise surfaces in hospital environments. One of the problems with steam disinfection is that if the steam is overheated it becomes equivalent to dry heat which makes it far less efficient for disinfection or decontamination. Dry heat needs a far longer contact time to achieve the same result as saturated steam. Steam sterilisation outside an autoclave can fail to kill all the spores. 7) “Laundry at 60°C Kills C. diff Spores”** Any laundry cycle may remove C. diff spores through mechanical washing – that is, it washes them away rather than killing them. Although it has not been proved yet, there is a fear that C. diff spores may remain present in the internal pipes and sump of a washing machine, meaning they can re-infect future loads unless killed. To guarantee effectiveness against spores, laundry would need to run at very high temperatures, beyond the reach of most machines – even commercial ones – and would require a great deal of energy to reach the right temperature. Some industrial detergents have been shown to achieve a degree of spore reduction, sometimes up to log 3 (or 99.9% reduction). Chemex AntiBak has been proven to achieve far greater than log 5 or 99.9997% reduction. Home \| About Chemex \| Products and Services \| What's New \| Contact Us