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Sanitary-microbiological research of water, air, soil, food products and objects of external environmental

Value of sanitary microbiology and its task Sanitary microbiology is engaged in the study of microorganisms and processes, caused by them in an environment. The basic task of sanitary microbiology is warning of origin of infectious diseases, realization of permanent control by water, air, soil, food products et cetera with the purpose of exposure of pathogenic microorganisms, or exposure of sanitary-indicatory microorganisms which are the indirect indexes of infection of environment.
Sanitary-indicatory microorganisms It is permanent inhabitants of surfaces and digestive tract of the human and animals, selected from an organism those ways, what pathogenic. Therefore, than sanitary-indicatory microorganisms are anymore exposed, the large probability of hit in the objects of external environment of pathogenic microorganisms.
Description of sanitary-indicatory microorganisms 1. Constantly selected in great numbers with excrement or drops of mucus from air-respiratory ways. 2. Does not have other habitats. 3. Able to be saved in an environment during those terms, what pathogenic bacteria, parasitic in an intestine and respiratory tracts. 4. Incapable intensively to propagate oneself out of organism of owner and change the properties.
The microflora of air The microflora of air depends on the microflora of water and soils which the layers of air are located above. In soil and water microbes can propagate oneself; they do not propagate oneself in mid air, and only saved some time. Lifted in air with a dust, they either settles with drops back onto a terrene or perish in mid air from innutrition and from the action of ultraviolet rays. However some of them more steady, for example, a tubercular stick, spores of Clostridia, fungus and other, can be protractedly saved in mid air. In addition, at a cough, sneeze shallow drops-aerosols, containing the exciters of diseases, are thrown out in air, such as a flu, measles, whooping-cough, tuberculosis and row other, transmissible via air from a sick man — to healthy, causing a disease.
Sanitary-bacteriological research of air The bacteriological examination of air environment provides for: it is determination of general amount of microbes in 1 m3 of air; it is determination of amount of S. aureus in 1 m3 of air.
Air for bacterial research it is selected in the followings apartments: operating blocks; bandaging; post-operation chambers; maternity halls; chambers for new-born; chambers for prematurely born children; post-births chambers; separations and chambers intensive therapy and other apartments, requiring aseptic terms.
Methods of sampling air There are two basic methods of sampling air for research: 1. sedimentation is based on the mechanical settling of microorganisms; 2. aspiration is based on the active drawing through of air (this method is given by possibility to define not only high-quality but also quantitative maintenance of bacteria).
Microbial number for air It is an incurrence of bacteria which are contained in 1m3 air.
What microorganisms are a sanitary-indicatory for air of the closed apartments? Staphylococcus spp., Streptococcus spp.
What pathogenic microorganisms can be passed through air? C. diphtheriae, M. tuberculosis, B. pertussis, Y. pestis, B. anthracis and other.
Microflora of water Water is the natural environment of dwelling of many microbes. The bulk of microbes act from soil. The amount of microbes in 1 ml of water depends on a presence in it nutritive. What water is stronger muddy debris’s; the more microbes are in it. The opened reservoirs and rivers are especially rich in microbes. The most of microbes in them is in the superficial layers (in a layer 10 see is from the surface of water) of off-shore areas. Pathogenic microbes get in the rivers and reservoirs with sewages. Exciters of such intestinal infections, as typhoid fiver, paratyphoid fiver, dysentery, cholera and other, can be saved in water long time. In this case water becomes the source of infectious diseases. The hit of morbific microbes is especially dangerous in a plumbing network. Therefore after the state of reservoirs and tap water given from them sanitary-bacteriological control is set.
Sanitary-indicatory microorganisms for water Bacteria are groups of coli bacillus, which behave to different genus of family of Enterobacteriaceae.
Indexes of sanitary-bacteriological research of water 1. Microbal number . 2. Coli-titer. 3. Coli-index.
Microbial number of water (determination) An amount of microorganisms is in 1 ml.
Coli-titer of water (determination) It is the least of water (ml), a coli form (Âacteria Group of Escherichia coli - BGEC) is revealed in which.
Coli-index of water (determination) Amount of bacteria of group of bacteria of Escherichia coli, which are contained in 1 liter of the probed water.
Methods which a coli-titer and coli-index of water is determined by Titration (fermenting) method. Method of diaphragm filters.
Normal indexes of coli-titer and coli-index for a drinking-water Coli-titer ≥ 333 ml. Coli-index ≤ 3.
Method of determination of coli phages For the lead through of current control of quality of drinking-water use the method of determination of coli phages. They are bacterial viruses, capable destroy E. coli and to form at a temperature 37°C through 18 - 20 h the area of lyses of bacterial lawn (name-plates) on a nourishing agar.
Microflora of soil Soil is mixture of particles of organic and inorganic matters, water and air. Soil is abundantly populated microorganisms, because in it there is all necessary for life: organic matters, moisture, sun screening. In soil there are all forms of microorganisms which are on Earth: bacteria, viruses, Actinomyces, yeasts, fungi, the simplest, plants.
Sanitary-indicatory microorganisms of soil (specify on fecal pollution contamination) Clostridium perfringens, C. sporogenes, S. faecalis, E. coli and other.
Indexes of sanitary-bacteriological research of soil Microbial number. Perfringens-titer. Coli-titer. Titer of termophilic bacteria.
Microbial number of soil (determination) A general amount of bacteria is in a 1 g of soil.
Coli-titer of soil (determination) Amount of coliforms - BGEC in a 1 g of soil.
Perfringens-titer of soil (determination) The minimal amount of soil, Clostridium perfringens is revealed in which.
Titer of termophilic bacteria Termophilic bacteria get in soil with rotting manure or compost; it is therefore expedient to expose them for finding out of character and remoteness of biopollution of soil. As far as decomposition of organic matters the amount of termophilic bacteria is increased. Titer of termophilic bacteria - amount of termophilic bacteria in 1 g of soil.
What is thermophilic bacteria? Bacteria that prefer temperatures above 55°C and can tolerate temperatures up to 75-80°C. Extreme thermophiles can live in boiling water, and have been isolated from hot springs.
Sanitary state of milk and dairy products About the sanitary state of milk and dairy products you can judge on a microbial number and coli-titer. For the different types of milk these indexes are different and regulated sanitary norms.
Diseases, transmissible via milk and dairy products Tuberculosis, brucellosis, salmonellosis. Food toxic-infections and food intoxications.
Change of microflora of milk at storage: bactericidal phase, phase of the mixed microflora, phase of lactobacillus, phase of yeasts and moulds. Bactericidal phase. Bactericidal properties of milk are conditioned being in him of lysocime, normal antibodies, leucocytes and other. Phase of the mixed microflora. Upon termination of bactericidal phase the not detained reproduction of all groups of microorganisms, being in milk and capable in him to propagate oneself under the conditions begins nothing. Intensity of their reproduction will be different. This phase is the period of the most rapid reproduction of microflora. During this period the microflora of milk increases from not many thousands which it has by the end of bacterial phase, to hundred millions. Phase of lactobacillus. This phase begins from the moment of noticeable growth of acidity and predominance of lactobacillus in milk. In future with the accumulation of suckling acid lactobacillus slow the rate of the reproduction and other groups of microorganisms die off gradually. Most sensible to the increase of acidity are fluorescent bacteria, putrid microorganisms perish after them, further — micrococcus, and also bacteria of group of coli bacillus, longer than all maintaining growth of acidity among non-lactobacillus bacteria. Suckling acid is not a ruinous factor for the spores of yeasts and moulds, being in milk. Consequently, during a phase of lactobacillus there is as though self-wiping of milk almost from all groups of microorganisms, except for lactobacillus’s the amount of which by the end of phase is approached by 100 % all microflora. Phase of development of yeasts and moulds. This phase is final in all process of microbiological changes of milk. After its complete completion the organic matter of milk suffers almost complete mineralized (decomposition on inorganic). The external picture of development of this phase is expressed in that as early as time of lactobacillus phase on-the-spot clot (if he is not exposed to interfusion) the separate yeast of suckling mould (Oidium lactis), gradually closing up in continuous white fluffy tape, appear. Yeasts of Mycoderma spp., participating in formation of tape, appear at this time. Moulds of Penicillium spp. and Aspergillus spp. appear later.

 



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Date: 2016-01-14; view: 304


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