Searching for microbes Part V. Microbes and outer influences Decontamination methods, and how to assess their effectivity Ondřej Zahradníček To practical for VLLM0421c Contacts to me: 777 031 969 zahradnicek@fnusa.cz, ICQ 242-234-100 Content of this slideshow What we know already • We know how to use three diagnostic methods – microscopy as Wet mount, simple staining, Gram staining and capsular staining – culture of microbes on solid and liquid media (using solid media, we can get and strain) – biochemical (and other) identification methods for cultured strains • Today we will fight microbes using decontamination methods. Tale • There was and king with three sons. He had an awful pyogene ulcus of his leg, and in the meantime he wanted to decide, who will be his follow him to the throne. So he decided, that the future king will be the prince, that will definitivelly destroy his ulcus. What the first two princes have done • First prince sterilized the scalpel. He sterilized enough time, but at too low temperature. The scalpel was not sterile enough, and when the prince had cut the ulcus, it was reinfected soon. • Second prince sterilized the scalpel, too. He used sufficient temperature, but too short time. So the result was the same as in the case of the first prince. What the third prince has done • He sterilized the scalpel for sufficient temperature and time. So he cut his father‘s ulcus, it was OK, he became king, he married and sexy princess, and if he have not died, he lives there, having a lot of children. What to learn of it • When we try to kill microbes by physical or chemical factors, we have to use correct parameters. • These parameters are mutually related, i. e. the necessary value of one changes in relation with the other • Time uses to be one of very important parameters Microbes and outer influences Microbes and outer influences I Practical check of growth and survival limit • If we want to find survival limit of bacteria, we have to remove the tested extreme parameters to the conditions and to let them then in optimal conditions for a sufficient time (to recover, if they are inhibited only). • If we want to demonstrate growth limit only, we let them all the time in the extreme conditions (without chance to recover). Methodological difference Microbes and outer influences II A factor, allways combined with the other factors: TIME • Remark: The lower the temperature is, the longer the time should be, to obtain a sufficient sterilization effect. This is also expressed in the intimation for sterilization saying what temperature and time should be used at steam sterilization and hot air sterilization. Deconta-mination methods: survey Decontamination methods • Those are physical and chemical approaches of destroying microbes, insects and rodents outside the organism. (Some public health researchers put methods of destroying insects and rodents aside, and call them “assanation methods“) • Destroying microbes in organism, altough local (use of antiseptics), does not belong to decontamination methods. An antiseptic is a drug. A disinfectant is not a drug Survey of decontamination methods (Czech intimation 195/2005) Asepsis and antisepsis • Asepsis: approaches passivelly defending an area against microbes • Antisepsis: approaches, activelly acting against microbes • Basics of assepsis and antisepsis were introduced – to surgery by lord Joseph Lister – to obstetrics by Ignaz Semmelweis How to perform decontamination properly (not regarding the type of method) • To choose a proper sterilization/disinfection method/medium. „Proper“ means: – it should destroy (St) all organisms, or (Df) all pathogens that might be found in such an environment – it should not destroy disinfected or sterilized material – it should be practically applicable • To use sufficient intensity of a factor (temperature, intensity, concentracion) • The factor should act enough time Before and and after decontamination • Before decontamination often preparation is necessary – mechanical cleaning, ensuring of a proper process. All the procedures take part in legal acts concerning decontamination methods • After decontamination often some steps should be done (e. g. let the remaining gases to flow out). It is necessary to keep rules for storage of decontaminated objects. • Storage of decontaminated objects (exspiration) is described in intimations, too. Decontamination and cleaning Tools, that are mechanically dirty, should be cleaned before decontamination. Without cleaning it would not be effective enough. Disinfection Disinfection – examples 1 • A. PHYSICAL methods • 1. Boiling: • a) at normal pressure – in medicine at least 30 minut. (For coocing, less is enough, but the meal should be boiled profoundly!!!) • b) in pressure vessels – shorter time – even in this case it is NOT a sterilisation! • 2. Other physical methods – filtration, sun rays, ultraviolet rays etc. Disinfection – examples 2 • B. DISINFECTANTS • Oxidation reagents • 3. Peroxides: peracetic acid (CH[3]COOOH, in Czechia Persteril). For spores, fungi and tuberculosis; 0.5% solution = higher level disinfection. Disadvantage: agressivity, decoloration of textils, instability of solutions • 4. Hydrogen peroxide (H[2]O[2]) – simillar, less agressive, but also less effective Disinfection – examples 3 • 5. Halogen preparations – hypochloates: – chlorine bleach (NaOCl), Savo in Czechia – calcium hypochlorite (Ca(OCl)[2] • 6. Chloramin (Chloramin B in Czechia). • 7. Iodine solutions (in Czechia mostly Jodonal B, Jodisol and Betadine). Unlike ancient iodine tincture, iodine is bound in a komplex. At non-alergic pacients iodine preparations should be used rather than detergents (Ajatin) Disinfection – examples 4 • 8. Kalium permanganate has no more use. • 9. Formaldehyde – in mixtures • 10. Kresol (lysol) is effective, but for aggresivity and bad smell not used at all • 11. Ethylalcohol – in mixtures; alone not enough effectifity; the most effective is 70 % solution • 12. Detergents: Orthosan BF 12 • 13. Ajatin – for skin disinfection • 14. Septonex – rather an antiseptic. • 15. Anorganic acids and hydroxydes, heavy metals • 16. Combined agents, e. g. Incidur Effectivity of disinfection to various microorganisms • In booklets and other materials, usually alphabetical system is used: • A = effective to (vegetative forms of) bacteria and yeasts • B = effective against viruses • C = effective against bacterial endospores • T = effective against TB mycobacteria • M = effective against atypical mycobacteria • V = effective against filamentous fungi Suitability to various purposes Some disinfectants are only suitable for disinfection of surfaces, other are only for skin. Usually disinfectants are classified for • disinfectants for tools • disinfectants for surfaces • disinfectants for hands (+ disinfection soaps) • disinfectants for pipes in food industry • disinfectants suitable for kitchens Hand washing and disinfection Washing and disinfection of hands For hands, the rules are different than for tools of surfaces. Usually there is no thick layer of dirtiness on your hands Recent legislative uses following terms: • Mechanic hand wash (as a part of personal hygiene, or as a step preceding surgical hand rub) • Hygienic hand wash (using antimicrobial soap; better than mechanic hand wash, but worse thand hygienic hand rub) • Hygienic hand rub (recommended for medicine) • Surgical hand rub (before operations) Normal course of working day of a nurse or a medic • When comming at work: washing one‘s hands and use alcohol disinfection • During working day: use alcohol disinfection only, eventualy hand care preparations • At finishing work: wash one‘s hands again. During the working day, it is recommended rather to disinfect one‘s hands and not to wash them too often Proper hand rub / wash technique • 1^st step: Rub hands together palm to palm • 2^nd step: Left palm over back of right hand and vice versa • 3^rd step: Palm to palm, fingers interlaced • 4^th step: Backs of fingers to opposing palms with fingers interlocked • 5^th step: Clasp right thumb in left palm and vice versa • 6^th step: Using a circular motion rub fingertips of right hand in left palm and vice versa • (7^th step: Wrist of one hand using the other hand) How to wash/rub your hands 1. Rub hands together palm to palm 2. Left palm over back of right hand and vice versa 3. Palm to palm, fingers interlaced 4. Backs of fingers to opposing palms with fingers interlocked 5. Very important: Clasp right thumb in left palm and vice versa 6. Using a circular motion rub fingertips of right hand in left palm and vice versa A urban legend „when using gloves, washing and disinfection is not necessary“ There exist systems for disinfection checking using UV rays Stuff behaviour complexely • Important for all stuff • Proper technique of hand washing is not as obvious as supposed, it should be trained • Use of gloves and other barrier tools • Proper manipulation with needles after use • Work organisation (division of „clean“ and „dirty“ manipulation by place and/or time at all levels: dirty and clean trays, area for infusion preparation and a different one for biological material etc.) Higer level disinfection Higher level disinfection • „Something between sterilization and disinfection“ • It is not sterilization, because protozoan cysts and helming eggs are not always destroyed. • Glutaraldehyde, Secusept or Persteril • Concentration always higher then for common disinfection • For flexible endoscopes, where no sterilization methods can be used. Sterilization Sterilization – examples I • 1. Hot steam sterilization under pressure. Steam should be just saturated. It is suitable for objects made of glass, metal, ceramics, china, textile, rubber and some plastics. Temperatures 121–134 °C. (No more 115 °C!) • 2. Hot air sterilization (in apparates with artificial air circulation 180 °C 20 min or 170 °C 30 min or 160 °C an hour). For metal, glass, china. • 3. Hot water sterilization under pressure – not used anymore Sterilization – examples II • 4. Gamma ray sterilization: in industrial production, e. g. for single use gloves. • 5. Plasma sterilization in high-frequency electromagnetic field (a modern method) • 6. Chemical sterilization by vapors of formaldehyde or by ethylenoxide (the procedure should be peformed according to the shedule). In situations disabling use of physical methods. Sterilization – examples III (not in health care) • 7. Fire sterilization for microbiological loops only. Incineration for waste. • 8. Pascalisation is a pressure sterilization, used in alimentary industr • 9. Other methods: fractionated sterilization, solution filtration etc., used in research, not in practical medicine What method should be used? • Suitability of methods is related with material resistance to various temperature, humidity, chemicals and other factors • Do not forget, that parameters should be sufficient (temperature in °C, pressure in kPa, radiation dose in Gy etc.) and time has to be sufficient, too! Checking effectivity of deconta-mination Checking up, whether sterilisation was done, and its quality assessment • Orientation checking up – e. g. by typical smelling • Assessment of real concentration of disinfectants (chemically) • Chemical check up of sterilization uses indicators that change colour at a certain temperature • Biological way uses resistant strains of Bacillus genus. These absolve the whole cycle and then their survival is assessed. The end Lord Joseph Lister (5 April 1827 – 10 February 1912) English surgeon Lister became aware of a paper published by Louis Pasteur. Lister used carbolic acid (phenol) as a means of deodorizing sewage. He also made surgeons wear clean gloves and wash their hands before and after operations with 5% carbolic acid solutions. As the germ theory of disease became more widely accepted, it was realised that infection could be better avoided by preventing bacteria from getting into wounds in the first place. This led to the rise of sterile surgery. Some consider Lister "the father of modern antisepsis." In 1879 Listerine mouthwash was named after him for his work in antisepsis. Also named in his honour is the bacterial genus Listeria, typified by the food-borne pathogen Listeria monocytogenes. http://en.wikipedia.org/wiki/Joseph_Lister,_1st_Baron_Lister Ignaz Fülöp Semmelweis (1818 – 1865) Hungarian physician. He discovered that cases of puerperal fever, also known as childbed fever, could be cut drastically if doctors washed their hands in a chlorine solution before gynaecological examinations. While employed at the Vienna General Hospital in Austria, Semmelweis introduced hand washing with chlorinated lime solutions for interns who had performed autopsies. This immediately reduced the incidence of fatal puerperal fever. Semmelweis' hypothesis, that there was only one cause, was largely ignored, rejected or ridiculed. He was dismissed from the hospital and harassed by the medical community in Vienna, which eventually forced him to move to Budapest. Semmelweis' practice only earned widespread acceptance years after his death, when Louis Pasteur developed the germ theory of disease. He is considered a pioneer of antiseptic procedures. http://en.wikipedia.org/wiki/Ignaz_Semmelweis