Department of microbiology microbial food technology group a diploma in quality assurance in microbiology diploma

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First attested in English in 1670s, the word hygiene comes from the French hygiène, theromanization of the Greek "ὑγιεινή (τέχνη)" - hugieinē technē, meaning "(art) of health", from ὑγιεινός (hugieinos), "good for the health, healthy",[1] in turn from ὑγιής (hugiēs), "healthful, sound, salutary, wholesome".[2] In ancient Greek religionHygeia (Ὑγίεια) was the personification of health.[3]

Concept of hygiene

well as to personal and professional care practices related to most aspects of living. In medicine and in home (domestic) and everyday life settings, hygiene practices are employed as preventative measures to reduce the incidence and spreading of disease. In the manufacture of food, pharmaceutical, cosmetic and other products, good hygiene is a key part ofquality assurance i.e. ensuring that the product complies with microbial specifications appropriate to its use. The terms cleanliness (or cleaning) and hygiene are often used interchangeably, which can cause confusion. In general, hygiene mostly means practices that prevent spread of disease-causing organisms. Since cleaning processes (e.g., hand washing) remove infectious microbes as well as dirt and soil, they are often the means to achieve hygiene. Other uses of the term appear in phrases including: body hygiene, personal hygiene, sleep hygiene, mental hygiene, dental hygiene, and occupational hygiene, used in connection with public healthHygiene is also the name of a branch of science that deals with the promotion and preservation of health, also called hygienics. Hygiene practices vary widely, and what is considered acceptable in one culture might not be acceptable in another.

Medical hygiene

Medical hygiene pertains to the hygiene practices related to the administration of medicine, and medical care, that prevents or minimizes disease and the spreading of disease.

Medical hygiene practices include:

  • Isolation or quarantine of infectious persons or materials to prevent spread of infection.

  • Sterilization of instruments used in surgical procedures.

  • Use of protective clothing and barriers, such as masksgownscapseyewear and gloves.

  • Proper bandaging and dressing of injuries.

  • Safe disposal of medical waste.

  • Disinfection of reusables (i.e. linen, pads, uniforms)

  • Scrubbing up, hand-washing, especially in an operating room, but in more general health-care settings as well, where diseases can be transmitted[4]

Most of these practices were developed in the 19th century and were well established by the mid-20th century. Some procedures (such as disposal of medical waste) were tightened up as a result of late-20th century disease outbreaks, notably AIDS and Ebola.

[edit]Home and everyday life hygiene

Home hygiene pertains to the hygiene practices that prevent or minimize disease and the spreading of disease in home (domestic) and in everyday life settings such as social settings, public transport, the work place, public places etc.

Hygiene in home and everyday life settings plays an important part in preventing spread of infectious diseases.[5] It includes procedures used in a variety of domestic situations such as hand hygiene, respiratory hygiene, food and water hygiene, general home hygiene (hygiene of environmental sites and surfaces), care of domestic animals, and home healthcare (the care of those who are at greater risk of infection).

At present, these components of hygiene tend to be regarded as separate issues, although all are based on the same underlying microbiological principles. Preventing the spread of infectious diseases means breaking the chain of infection transmission. The simple principle is that, if the chain of infection is broken, infection cannot spread. In response to the need for effective codes of hygiene in home and everyday life settings the International Scientific Forum on Home Hygiene has developed a risk-based approach (based on Hazard Analysis Critical Control Point (HACCP), which has come to be known as “targeted hygiene”. Targeted hygiene is based on identifying the routes of spread of pathogens in the home, and applying hygiene procedures at critical points at appropriate times to break the chain of infection.

The main sources of infection in the home[6] are people (who are carriers or are infected), foods (particularly raw foods) and water, and domestic animals (in western countries more than 50% of homes have one or more pets). Additionally, sites that accumulate stagnant water—such as sinks, toilets, waste pipes, cleaning tools, face cloths—readily support microbial growth, and can become secondary reservoirs of infection, though species are mostly those that threaten “at risk” groups. Germs (potentially infectious bacteria, viruses etc.) are constantly shed from these sources via mucous, faeces, vomit, skin scales, etc. Thus, when circumstances combine, people become exposed, either directly or via food or water, and can develop an infection. The main “highways” for spread of germs[6] in the home are the hands, hand and food contact surfaces, and cleaning cloths and utensils. Germs can also spread via clothing and household linens such as towels. Utilities such as toilets and wash basins, for example, were invented for dealing safely with human waste, but still have risks associated with them, which may become critical at certain times, e.g., when someone has sickness or diarrhea. Safe disposal of human waste is a fundamental need; poor sanitation is a primary cause of diarrhoeal disease in low income communities. Respiratory viruses and fungal spores are also spread via the air.

Good home hygiene means targeting hygiene procedures at critical points, at appropriate times, to break the chain of infection i.e. to eliminate germs before they can spread further.[6] Because the “infectious dose” for some pathogens can be very small (10-100 viable units, or even less for some viruses), and infection can result from direct transfer from surfaces via hands or food to the mouth, nasal mucosa or the eye, 'hygienic cleaning' procedures should be sufficient to eliminate pathogens from critical surfaces. Hygienic cleaning can be done by:

  • Mechanical removal (i.e. cleaning) using a soap or detergent. To be effective as a hygiene measure, this process must be followed by thorough rinsing under running water to remove germs from the surface.

  • Using a process or product that inactivates the pathogens in situ. Germ kill is achieved using a “micro-biocidal” product i.e. a disinfectantor antibacterial product or waterless hand sanitizer, or by application of heat.

  • In some cases combined germ removal with kill is used, e.g. laundering of clothing and household linens such as towels and bedlinen.

Hand hygiene

Defined as hand washing or washing hands with soap and water or using a waterless hand sanitizer.

Hand hygiene is central to preventing spread of infectious diseases in home and everyday life settings.[7]

In situations where hand washing with soap is not an option (e.g. when in a public place with no access to wash facilities), a waterless hand sanitizer such as an alcohol hand gel can be used. They can also be used in addition to hand washing, to minimise risks when caring for “at risk” groups. To be effective, alcohol hand gels should contain not less than 60%v/v alcohol. Hand sanitizers are non-options in most developing country settings; in situations where availability of water is a problem, there are appropriate solutions such as tippy-taps, which use much less water and are very low-cost to make, with local materials. In low income communities mud or ash is sometimes used as an alternative to soap.

Respiratory hygiene

Correct respiratory and hand hygiene when coughing and sneezing reduces the spread of germs particularly during the cold and flu season.

  • Carry tissues and use them to catch coughs and sneezes

  • Dispose of tissues as soon as possible

  • Clean your hands by hand washing or using an alcohol hand sanitizer.

Food hygiene at home

Food hygiene pertains to the hygiene practices that prevent food poisoning . The five key principles of food hygiene, according to WHO, are:

Prevent contaminating food with pathogens spreading from people, pets, and pests.

  1. Separate raw and cooked foods to prevent contaminating the cooked foods.

  2. Cook foods for the appropriate length of time and at the appropriate temperature to kill pathogens.

  3. Store food at the proper temperature.

  4. Use safe water and raw materials

Household water treatment and safe storage

Household water treatment and safe storage are practices which can be used by the family at home and in the community to ensure that drinking water is safe for consumption.

Drinking water quality remains a significant problem, not only in developing countries[9] but also in developed countries[10]; even in the European region it is estimated that 120 million people do not have access to safe drinking water. Point-of-use water quality interventions can reduce diarrhoeal disease in communities where water quality is poor, or in emergency situations where there is a breakdown in water supply. Since water can become contaminated during storage at home (e.g. by contact with contaminated hands or using dirty storage vessels), safe storage of water in the home is also important.

Methods for treatment of drinking water [13],[12] include:

  1. Chemical disinfection using chlorine or iodine

  2. Boiling

  3. Filtration using ceramic filters[14][15]

  4. Solar disinfection - Solar disinfection is an effective method, especially when no chemical disinfectants are available.[16][17]

  5. UV irradiation - community or household UV systems may be batch or flow-though. The lamps can be suspended above the water channel or submerged in the water flow.

  6. Combined flocculation/disinfection systems – available as sachets of powder which act by coagulating and flocculating sediments in water followed by release of chlorine.

  7. Multibarrier methods – Some systems use two or more of the above treatments in combination or

Hygiene in the kitchen, bathroom and toilet

Routine cleaning of “contact” (hand, food and drinking water) sites and surfaces (such as toilet seats and flush handles, door and tap handles, work surfaces, bath and basin surfaces) in the kitchen, bathroom and toilet reduces the risk of spread of germs.[13] The infection risk from the toilet itself is not high, provided it is properly maintained, although some splashing and aerosol formation can occur during flushing, particularly where someone in the family has diarrhoea. Germs can survive in the scum or scale left behind on baths and wash basins after washing and bathing.

Water left stagnant in the pipes of showers can be contaminated with germs that become airborne when the shower is turned on. If a shower has not been used for some time, it should be left to run at a hot temperature for a few minutes before use.

Thorough cleaning is important in preventing the spread of fungal infections.[19] Moulds can live on wall and floor tiles and on shower curtains. Mould can be responsible for infections, cause allergic responses, deteriorate/damage surfaces and cause unpleasant odours. Primary sites of fungal growth are inanimate surfaces, including carpets and soft furnishings.[20] Air-borne fungi are usually associated with damp conditions, poor ventilation or closed air systems.

Cleaning of toilets and hand wash facilities is important to prevent odours and make them socially acceptable. Social acceptability is an important part of encouraging people to use toilets and wash their hands, particularly in low income communities.

Laundry hygiene

Laundry hygiene pertains to the practices that prevent or minimize disease and the spreading of disease via soiled clothing and household linens such as towels.[13] Items that are most likely to be contaminated with pathogens are those which come into direct contact with the body e.g. underwear, personal towels, facecloths, nappies. Micro-organisms can also be transferred between contaminated and uncontaminated items of clothing and linen during laundering. Of concern are the new “community” strains of MRSA.[21] Experience in the USA suggests that these strains are transmissible within families, but also in community settings such as prisons, schools and sport teams. Skin-to-skin contact (including unabraided skin) and indirect contact with contaminated objects such as towels, sheets and sports equipment seem to represent the mode of transmission.[21]

Two processes are considered suitable for hygienic cleaning of clothing and linen:[13]

  • Washing or laundering at 60°C or above

  • Washing or laundering at 30-40°C using a bleach-based product: This produces decontamination of fabrics by a combination of physical removal and chemical inactivation. However, some types of fungi and viruses that are harder to inactivate, may not be removed.

Washing at temperatures of 40°C or below with a non-bleach product is considered to carry a risk of inadequate decontamination.

Medical hygiene at home

Medical hygiene pertains to the hygiene practices that prevents or minimizes disease and the spreading of disease in relation to administering medical care to those who are infected or who are more “at risk” of infection in the home. Across the world, governments are increasingly under pressure to fund the level of healthcare that people expect. Care of increasing numbers of patients in the community, including at home is one answer, but can be fatally undermined by inadequate infection control in the home. Increasingly, all of these “at-risk” groups are cared for at home by a carer who may be a household member who thus requires a good knowledge of hygiene. People with reduced immunity to infection, who are looked after at home, make up an increasing proportion of the population (currently up to 20%).[5] The largest proportion are the elderly who have co-morbidities, which reduce their immunity to infection. It also includes the very young, patients discharged from hospital, taking immuno-suppressive drugs or using invasive systems, etc. For patients discharged from hospital, or being treated at home special “medical hygiene” (see above) procedures may need to be performed for them e.g. catheter or dressing replacement, which puts them at higher risk of infection.

Antiseptics may be applied to cuts, wounds abrasions of the skin to prevent the entry of harmful bacteria which can cause sepsis.

Day-to-day hygiene practices, other than special medical hygiene procedures[22] are no different for those at increased risk of infection than for other family members. The difference is that, if hygiene practices are not correctly carried out, the risk of infection is much greater.

Home Hygiene in low income communities

In the developing world, for decades, universal access to water and sanitation has been seen as the essential step in reducing the preventable ID burden, but it is now clear that this is best achieved by programmes that integrate hygiene promotion with improvements in water quality and availability, and sanitation. About 2 million people die every year due to diarrhoeal diseases, most of them are children less than 5 years of age.[23] The most affected are the populations in developing countries, living in extreme conditions of poverty, normally peri-urban dwellers or rural inhabitants. Providing access to sufficient quantities of safe water, the provision of facilities for a sanitary disposal of excreta, and introducing sound hygiene behaviours are of capital importance to reduce the burden of disease caused by these risk factors.

Research shows that, if widely practiced, hand washing with soap could reduce diarrhoea by almost fifty percent[24][25][26] and respiratory infections by nearly twenty-five percent[27][28] Hand washing with soap also reduces the incidence of skin diseases[29][30], eye infections like trachoma and intestinal worms, especially ascariasis and trichuriasis.[31]

Other hygiene practices such as safe disposal of waste, surface hygiene, care of domestic animals are also important in low income communities in order to break the chain of infection transmission.[32]

Disinfectants and antibacterials in home hygiene

Chemical disinfectants are products that kill germs (harmful bacteria, viruses and fungi). If the product is a disinfectant, the label on the product should say “disinfectant” and/or “kills” germs or bacteria etc. Some commercial products, e.g. bleaches, even though they are technically disinfectants, say that they “kill germs”, but are not actually labelled as “disinfectants”. Not all disinfectants kill all types of germs. All disinfectants kill bacteria (called bactericidal). Some will also kill fungi (fungicidal), bacterial spores (sporicidal) and/or viruses (virucidal).

An antibacterial product is a product that acts against bacteria in some unspecified way. Some products labelled “antibacterial” will kill bacteria whilst others may contain a concentration of active ingredient which will only prevent them multiplying. It is therefore important to check whether the product label states that it “kills” bacteria” An antibacterial is not necessarily anti-fungal or anti-viral unless this is stated on the label.

The term sanitizer has been used to define substances which both clean and disinfect. More recently this term has been applied to alcohol-based products which are used to disinfect the hands (alcohol hand sanitizers). Alcohol hand sanitizers however are not considered to be effective on soiled hands.

The term biocide is a broad term for a substance that kills, inactivates or otherwise controls living organisms. It includes antiseptics and disinfectants, which combat micro-organisms, and also includes pesticides.

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