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The use of ultraviolet germicidal radiation for disinfecting air and surfaces in medical institutions. Guidelines
The guidelines provide basic guidelines for the organization and conduct of air and surface disinfection in health care facilities using ultraviolet bactericidal radiation, as well as hygienic and microbiological control over the use of bactericidal radiation. The document discusses the use of bactericidal irradiators, the characteristics and properties of basic technical means for disinfection, measures and conditions of operation of irradiators, including those ensuring the safety of staff and patients, as well as the principles of organizing and monitoring the use of bactericidal radiation.
Guidelines are intended for specialists of hygiene and epidemiology centers, medical institutions, as well as research and educational institutions involved in organizing and conducting disinfection of surfaces and indoor air using ultraviolet radiation.
Guidelines approved by the Ministry of Health of the Republic of Belarus as an official document.
1. GENERAL PROVISIONS
The problem of prevention of nosocomial infections (HBI) is important in terms of solving biomedical and socio-economic problems of health care. Nosocomial and nosocomial nosocomial infections, mainly due to infection during their stay in medical institutions, when performing medical and diagnostic procedures by medical staff, occur with an average frequency of 6–15%. VBI aggravate the course of the underlying disease, increase mortality, increase the cost of additional treatment, increase the duration of employment of a hospital bed. The incidence of nosocomial infection varies depending on the type of hospital. The largest proportion of nosocomial infections is in maternity hospitals, outpatient clinics, and surgical hospitals. In the Republic of Belarus, according to statistics, up to 1,100 cases of nosocomial infection are recorded annually, but, according to some authors, these data do not reflect the true picture. Periodically there are outbreaks of diseases caused by Salmonella, Shigella, Staphylococcus and other pathogens. Mortality from nosocomial infection can reach 25%. The urgency of the problem requires an increase in the effectiveness of the fight against nosocomial infection, the development of new and improvement of the known methods for the prevention of nosocomial infections.
2. APPLICATION OF ULTRAVIOLET IRRADIATION OF AIR AND
SURFACES FOR COMBATING NOSOCOMIAL INFECTIONS
To combat nosocomial infections, a whole set of various complementary sanitary-hygienic and anti-epidemic measures, physical, chemical, mechanical and combined methods of prevention are used. The method of chamber disinfection, steam-formalin, hot-air, steam and other physical methods of disinfection and sterilization are widely used. The importance is given to the disinfection of air and surfaces using ultraviolet rays.
Ultraviolet (UV) bactericidal radiation, which is part of the spectrum of electromagnetic waves in the optical range, is used as a preventive sanitary and anti-epidemic agent aimed at suppressing the vital activity of microorganisms on surfaces and in the air environment of the premises. It provides a reduction in the prevalence of infectious diseases and complements the mandatory compliance with relevant hygienic regulations on the design and maintenance of premises of health facilities. UV irradiation is used to disinfect air in rooms, fencing surfaces (ceilings, walls, floors) and equipment in rooms with an increased risk of spreading airborne droplets and intestinal infections. Its use is effective in operating rooms of hospitals, premises of maternity hospitals, bacteriological and virological laboratories, at blood transfusion stations, in dressing hospitals and clinics, in tambours of infectious diseases hospitals, in emergency departments of hospitals, childcare facilities. In the period of influenza epidemics, it is advisable to use bactericidal lamps in group rooms of children's institutions, gyms, cinemas, canteens, public transport, waiting rooms at railway stations and airports and other rooms with large and long crowds of people, including industrial enterprises, consumer services enterprises. population.
3. BACTERICIDAL ACTION OF ULTRAVIOLET RADIATION
The disinfecting effect of ultraviolet radiation with high biological activity is mainly due to photochemical damage to the DNA and RNA molecules of microorganisms, which leads to the death of the microbial cell in the first or subsequent generation. Viruses and bacteria in the vegetative form (sticks, cocci) are more sensitive to the effects of UV radiation. Fungi and the simplest microorganisms are less sensitive, and the most resistant are spore forms.
The degree of inactivation of microorganisms, the bactericidal efficiency of UV irradiation depends on the type of microflora, is proportional to the energy and exposure to radiation, and is determined by the bactericidal dose of radiation. Quantitative assessment of the bactericidal action or bactericidal efficacy is characterized by the ratio of the number of dead microorganisms to their initial number (in percent). When evaluating the bactericidal efficacy of UV irradiation, Staphylococcus aureus (Staphylococcus aureus) is taken as a sanitary-indicative microorganism.
The values of surface and bulk bactericidal doses (J / m 2, J / m 3) that ensure the efficiency of disinfection up to 90, 95 and 99.9% upon irradiation of various types of microorganisms are given in Appendix 1. A significant reduction in these doses can stimulate microbial growth, their reactivation.
The same value of the indicated doses is achieved by a different combination of the magnitude of the bactericidal flow and the duration of irradiation, but to maintain a given level of bactericidal efficacy, 5–10-fold variation of these parameters is allowed. For example, for a dose equal to 120 J / m 2, the optimal ratio will be the value of the incident flow of 0.5 W / m 2, created by the OBN-150 irradiator at a distance of 1 m with an irradiation time of 240 s. The same bactericidal efficacy at a dose of 120 J / m 2 will remain under irradiation for 1200 s and a flux density of 0.1 W / m 2 at a distance of 2 m (the conditional multiplicity of variation of parameters is 5). However, with a flow rate of 0.03 W / m 2 (the distance to the source is about 3 m) and an irradiation time of 4000 s (the multiplicity of parameter variations is already over 17), the decontamination efficiency will be much lower, although it corresponds to a dose of 120 J / sq.m. Consequently, at a specified distance, a given level of efficiency can hardly be achieved for any duration of irradiation, and an insufficient amount of UV flux (subbactericidal dose) may even stimulate the growth of microflora.
When carrying out the above dose calculations and determining bactericidal efficacy, the values of the irradiance parameters of the bactericidal feed used, indicated in the passport, operating instructions or irradiance results obtained directly from the instrumental measurements, should be taken as the basis.
Taking into account the high biological activity of UV radiation, the safety of personnel of health facilities, including those directly serving bactericidal irradiators, and patients is important. UV radiation due to low penetration affects only the surface layers: the skin, visible areas of the mucous membranes and eye tissue, which together with the immune system are critical organs or target organs. Human reactions to the influence of UV radiation are diverse and heterogeneous. There are examples of both positive effects (the formation of vitamin D, an increase in nonspecific resistance, therapeutic effects in a number of diseases), and negative manifestations of UV irradiation (burns and diseases of the skin and eyes, carcinogenic and other effects).
4. TECHNICAL MEANS FOR DISINFECTING BY ULTRAVIOLET RADIATION
4.1. Technical means that provide UV disinfection of air and indoor surfaces include: sources of ultraviolet bactericidal radiation (bactericidal lamps), in the radiation of which there is a spectral range with wavelengths (l) of 205-315 nm; bactericidal irradiators and bactericidal installations.
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l - the Greek letter "lambda"
4.2. The sources of ultraviolet radiation are low-and high-pressure discharge mercury lamps, as well as xenon flash lamps, which emit a bactericidal effect in the course of electrical discharge.
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l - the Greek letter "lambda"
Low-pressure (ND) mercury lamps are fluorescent lamps whose bulbs are made of special quartz or UV glass with a high transmittance of UV rays. When operating mercury lamps, ND of more than 60% of the radiation falls on the line with l = 254 nm, which has the maximum bactericidal effect. They have a long service life (3000 - 10,000 hours) and are ready to work almost immediately after their ignition; lamp power - from 6 to 75 W and more.
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l - the Greek letter "lambda"
The flask of high-pressure mercury lamps (HP) is also made of quartz glass. With small dimensions, these lamps have a high unit power from 100 to 1000 W, which makes it possible to reduce the number of lamps in the room, but they have low bactericidal efficiency and a short service life, and the necessary combustion mode occurs 5 to 10 minutes after their ignition. HP mercury lamps are not recommended for widespread use because of their low economic efficiency, since the fraction of radiation in this range is no more than 10%, and the service life is about 10 times less than that of ND mercury lamps.
Pulsed xenon lamps also create short-term high-power radiation pulses; with possible destruction, they do not pollute the indoor air with mercury vapor. The disadvantage of these lamps is the need to use for their work additional complex and expensive equipment.
The required mode of ignition and combustion of bactericidal mercury lamps is ensured by the presence of a control gear in the electrical circuit.
Bactericidal lamps (BL) are divided into ozone and zoneless. The radiation spectrum of a BL contains spectral lines with l less than 200 nm. Radiation with a specified wavelength in ozone lamps extends beyond the limits of the bulb and can cause the formation of ozone in air. Ozone poses a serious risk to human health, especially of children, as well as of persons suffering from lung diseases. This requires monitoring the concentration of ozone in rooms where irradiators are installed, equipped with ozone germicidal lamps. Ozone lamps are used in premises in the absence of people, followed by airing after the irradiation session. In bactericidal lampless lamps, the radiation output from l less than 200 nm is absent due to the design of the bulb or the use of a special material that delays the radiation.
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l - the Greek letter "lambda"
Many factors affect the performance of germicidal lamps. Reducing the temperature of the air makes it difficult to start the lamps, increases the atomization of the electrode materials, which reduces the service life. At temperatures less than 10 degrees. C a significant number of lamps may not light up; This effect is enhanced at lower network voltage. A feature of the BL is the dependence of their parameters on the voltage fluctuations of the network, and with a voltage increase of 20%, the service life decreases to 50%; When the mains voltage drops by more than 20%, the lamps start to burn unstably and may even go out. When new BL operate, the radiation flux first decreases, especially in the first tens of hours of combustion, which can reach 10%. In the future, the decay rate of the radiation flux slows down. The number of inclusions also affects the lamp life: each switch reduces the total lamp life by approximately 2 hours.
At the end of the life of the germicidal lamp should be replaced with new ones. The reason for the replacement is a significant decrease in the flux density of the lamp below the set limit (55% of the nominal value of the initial bactericidal flow specified in the technical documentation). Records of the operating time of the irradiators and the duration of exposure should be recorded in the “Register of the registration and control of the operation of bactericidal irradiators” (hereinafter referred to as the journal; see Appendix 7).
To compensate for the reduction in bactericidal flow during lamp operation, it is recommended that after the expiration of 1/3 of the service life, the established duration of exposure is increased by 1.2 times and after 2/3 of the period - by 1.3 times.
4.3. Bactericidal irradiators and installations. Bactericidal feed (BO) is an electrical device containing a bactericidal lamp as a radiation source and intended to disinfect air and / or surfaces in a room. The irradiator consists of a body in which a bactericidal lamp, a gear, a reflector, and fixtures for mounting and installation are installed. Bactericidal device (CU) - a set of bactericidal irradiators installed in the same room. The design of germicidal irradiators and installations must ensure compliance with the conditions of electrical, fire and mechanical safety, as well as other requirements.
By location, BOs are divided into ceiling, overhead, floor, wall and mobile, and, according to placement conditions, irradiators intended for use in premises or on vehicles.
By design, they can be open, closed and combined. Open-type irradiators are designed for the irradiation of air and surfaces in rooms by direct bactericidal flow in the absence of people. For such BOs installed on the ceiling or wall, a direct bactericidal stream covers a wide area in the irradiated space. Open-type irradiators include mobile bactericidal irradiators, as well as barrier-mounted BO (“ultraviolet doors”) installed in doorways, the main purpose of which is to create ultraviolet “curtains” by directing radiation into the lower zone by a narrow beam.
The irradiators of the closed type (recirculators) are designed to disinfect the air by passing it through a closed chamber, the internal volume of which is irradiated by bactericidal lamps, while the ultraviolet flux does not have a direct exit to the outside. Movement, exchange of air inside the chamber is provided by natural convection or with the help of a fan.
The irradiation of air and surfaces when using combined irradiators is carried out by direct, directed flux created by open lamps and / or reflected when operating screened lamps. Combined BOs have different separately switched-on lamps for direct and reflected radiation, or a movable reflector, which allows using a rotating screen to use a bactericidal stream for direct (in the absence of people) or for reflected (in the presence of people) irradiation of the room.
The main technical characteristics of BO (type of lamps used, amount of bactericidal flow, service life and date of manufacture), as well as parameters characterizing the efficiency of the irradiators - efficiency (for open BO), irradiator performance, utilization of the bactericidal flux of lamps, bactericidal irradiance are listed in the accompanying product documentation (passport, instruction manual).
In annexes 2 and 3 the main parameters and characteristics of germicidal mercury lamps and irradiators are given.
4.4. The quality of air and surface disinfection depends on two main parameters: the surface (bulk) flux density of UV radiation at different points in the room and the time of irradiation, i.e. determined by the dose. During air decontamination, the mobility of air, movement of its flows inside a room due to temperature differences, etc., are of particular importance. For example, during the cold season, with the onset of the heating season, flow changes, air circulation is achieved by convection of warm flow from heating devices and other sources. In the summertime, the speed of movement of air flow in the irradiated areas is usually insufficient for uniform and constant mixing of air masses. In these cases, the use of fans and other additional means for forced air exchange is recommended.
4.5. Other factors that are important for disinfecting various surfaces, besides influencing the disinfection efficiency of the above conditions, are other factors. One of them is the direction, the angle of incidence of the ultraviolet flux. At the same time, the maximum bactericidal efficiency is achieved at an angle of incidence close to 90 degrees. (perpendicular flow). When the device's sensor is located perpendicular to the incident flux, the UV radiation density was 3.7 W / m2, and when the sensor is parallel to the irradiated surface (inclined flow, the angle of incidence is about 40 degrees), it is already only 0.93 W / m2 . These results were obtained under the following irradiation conditions: the distance to the source is 1.5 m, the radiation source is mobile OBP-450, the reference point for measurements is on the floor surface. In this regard, when disinfecting surfaces of tables, equipment, floor and other horizontally located surfaces, it is most efficient to use ceiling and other BOs with a predominantly perpendicular falling stream relative to the irradiated surface.
When disinfecting surfaces, surfaces are most effectively decontaminated at a distance from a UV irradiator up to 3 m. When placing irradiated surfaces at a distance of more than 3 m, bactericidal efficiency (92–95%) with respect to cultures of Staphylococcus aureus and Escherichia coli was reached only after 120 minutes SSB-450; radiation flux density of 0.22 W / m2).
4.6. In conditions of high air humidity, as well as during the irradiation of microorganisms in liquid media, the latter noticeably weaken the bactericidal effect of radiation. So, when irradiating Petri dishes with a suspension of Escherichia coli cultures (concentration - 100 cells in 1 ml), the bactericidal effect was obtained after 30 min. Of UV irradiation (distance 0.7 m, flux density 6.0 W / sq. M), while upon irradiation of the culture applied directly to the surface of the nutrient medium, bactericidal efficacy was achieved already after 3 minutes under similar irradiation conditions.
In case of inactivation, it should be noted that the greatest effect is observed on the disinfected surfaces of light color - as a result of additional redistribution, diffuse reflection of the UV flux; significantly reduce the bactericidal effect of UV irradiation of roughness, pollution on the treated surfaces and other various obstacles that create micro-shades that impede the penetration of UV radiation to the objects of disinfection, which reduces the bactericidal effect.
4.7. Disinfection of premises with BO is accompanied by a sufficiently high energy consumption. When designing the CU is determined by the minimum duration of exposure, which should provide a given level of bactericidal efficiency. The most economical version of the BU is determined by calculation. The method of the necessary calculations for the design of bactericidal irradiators and installations is given in “Methodological guidelines on the use of bactericidal lamps for disinfecting air and surfaces in rooms” N 11-16 / 03-06 (approved by the Ministry of Healthcare of the Russian Federation on February 28, 1995).
Approximate number of bactericidal lamps for each specific room is determined at the rate of 1 W of bactericidal lamp power per 1 cubic meter. For example, to inactivate microorganisms in the room air (width - 2.6 m, length - 4.0 m, height - 2.7 m; volume - 28.1 cubic meters), you must use one 30 W lamp or two lamps of 15 W each. The emerging flow of UV radiation allows, taking into account the required irradiation time, to achieve different levels (90, 95 and 99.9%) of bactericidal efficiency and disinfection of the air environment and surfaces of a given room (Annexes 1 and 4).
After the installation of the bactericidal installation (irradiator), it is necessary to measure the actual irradiance and determine the bactericidal efficiency, and in case of discrepancy, adjust the irradiation time or, if necessary, install additional BOs to achieve compliance with the specified requirements.
5. BASIC OPERATION RULES AND SAFETY MEASURES FOR MAINTENANCE OF BACTERICIDESCURACES AND INSTALLATIONS
5.1. Disinfection with the use of ultraviolet bactericidal radiation is carried out in accordance with the nature of the work carried out in the room, taking into account its category, type and mode of irradiation (Annexes 4 and 5), which ensures a given level of bactericidal efficiency.
5.2. Decontamination of air and surfaces in hospitals is carried out in the following ways: a) directional, direct flow, which is achieved by using open BOs, in which the UV flux is directed to the entire volume of the room; b) reflected flux from the ceiling and walls (provided when shielded lamps of combined BO work), while the fraction of the reflected flux depends on the optical properties, reflectance of finishing and construction materials (Appendix 6); c) at the same time direct and reflected flow during operation of open and shielded lamps of combined bactericidal irradiators. When using BO closed type air disinfection is carried out.
5.3. The list of premises in which bactericidal irradiators are to be installed is determined according to Appendix 4; if necessary, it can be expanded with sectoral sanitary rules for the installation, equipment and maintenance of these premises, or scientific, technical and regulatory documentation agreed with State sanitary control authorities.
The height of the room where BOs are installed must be at least 3 m; it must be equipped with a supply and exhaust ventilation or have conditions for intensive ventilation with the help of natural ventilation, which provides a single air exchange in no more than 15 minutes.
The use of BO must be carried out taking into account the passport data on the product, instructions for use, as well as in accordance with these guidelines. To work on the maintenance of bactericidal irradiators and installations allowed personnel who have passed the necessary instructions on safety and operating rules of BO and BU.
5.4. By purpose and nature of the work carried out the premises are divided into three groups. The first includes premises in which disinfection is carried out in the presence of people, the second - in the absence of people, the third - with a short-term stay of people.
For disinfection of premises with a permanent stay of people should be used irradiating installation of a closed type, with no direct emission of radiation into the external space (recirculators), or a system of supply and exhaust ventilation. When using the latest BL are placed in the output chamber. In the specified rooms the continuous mode of radiation is applied. If according to the nature of the work in the room short-term removal of people is possible, it is allowed to disinfect the room with a directional flow only in the absence of people using BW working in an intermittent mode, and the specified level of bactericidal efficiency should be established within 2 h in order to maintain this level constantly in accordance with the multiplicity of natural or forced air exchange.
Recirculators should be placed indoors on the walls along the main air flow (in particular, near heating appliances) at a height of at least 2 m from the floor.
If according to the nature of the work in the room, short-term removal of people is possible, then it is advisable to use an irradiation unit of mixed type, which allows you to disinfect the air by using recirculators or forced-air ventilation in continuous mode with people staying and disinfecting the rooms with directed radiation short term mode. In this case, the time of the next exposure can be reduced to 5 minutes, and the interval between successive exposures can be increased to 3 hours. The use of mixed-type irradiation facilities allows an increase in the level of room disinfection during the preoperative preparation process.
In the absence of people, disinfection can be carried out using open (including mobile) and combined irradiators operating in an intermittent mode, and the exposure time should not exceed 25 minutes, provided that during this period the specified level of bactericidal efficiency is reached, and the interval between successive exposures shall not exceed 2 hours.
The power supply of a bactericidal system with open BW should be carried out using separate switches located outside the entrance door, which are blocked with a light panel above the door: "Do not enter. Danger. UV disinfection is underway." It is recommended that in order to avoid accidental exposure of personnel to UV radiation, install a device that blocks the power supply when the door is opened. Switches for installations with closed irradiators are installed in any convenient place. Above each switch should be the inscription: "Bactericidal irradiators."
The premises of the second group should provide for the storage of personal protective equipment for personnel against direct UV exposure (goggles, face masks and gloves), used when people need to stay in this room during the work of irradiators.
Allowed as an exception is time-limited work in such premises without the use of personal protective equipment; the limiting residence time of staff (seconds) is determined by the formula: 3.6 / E, where E is the irradiance (W / m2) in the service area on a horizontal surface at a height of 1.5 m from the floor. At the same time, the irradiance of the reflected flux from the ceiling and walls on the conditional surface at a height of 1.5 m from the floor should not exceed 0.001 W / m2, and the total exposure time during a shift should not exceed 60 minutes. The work of open lamps in the presence of people is not allowed ("Sanitary standards of ultraviolet radiation in industrial premises", N 4557-88, USSR Ministry of Health, 1988; Methodology for the hygienic assessment of industrial sources of ultraviolet radiation, N 105-9807, MH RB, 1999).
When combined irradiators are used, bactericidal flux from shielded lamps should be directed to the upper zone of the room so as to exclude the direct flow from the lamp or reflector to the lower zone.
Combined feeds should have separate switches to control shielded and open lamps. Open lamps are used only for disinfecting the premises in the absence of people.
Irradiation of premises with mobile irradiators should be carried out by personnel when they use a facial mask, glasses and gloves that protect the eyes and skin from UV radiation, in the absence of unauthorized people and patients. During the irradiation session, a sign should be posted on the entrance door: “Do not enter. Ultraviolet irradiation in progress.”
Irradiation installations for decontamination by reflected radiation are used only in places where people stay for a short time, for example, aisles, toilets, storage rooms and other areas, and hygiene standards must be observed in terms of exposure, duration of exposure, and total exposure time. The irradiators should be placed in such a way as to completely eliminate the exposure of people to a direct, direct stream of radiation.
If the room is not provided for the stay of people, then for disinfection can be used with any type of irradiators operating in continuous mode.
5.5. For disinfection of dishes, cutlery, toys and other household items used boxes, cabinets or small containers with trellised shelves, the design of which should provide disinfection with a UV flux of irradiated objects from all sides.
5.6. The use of barrier irradiators ("ultraviolet doors") in vestibules or doorways allows to exclude the penetration of airborne pathogens from one room to another due to the ultraviolet "veil"; for their maintenance, frequent transitions from one room to another, personnel must apply personal protective measures against direct exposure.
5.7. The dust from the surfaces of the reflector and the lamp bulb should be cleaned weekly, since even a small layer of dust reduces the output of the bactericidal stream by 10–12%. Cleaning of dust and replacement of lamps in irradiators and installations should be carried out when they are disconnected from the network.
Mobile feeds with open lamps outside of work should be stored in a separate room and closed with a cover.
5.8. During the operation of BW and CU, the danger associated with the possible release into the air of the treated premises of ozone, as well as, in violation of the integrity of germicidal lamps, mercury vapor should be taken into account. If ozone odor is detected, it is necessary to turn off the irradiators, remove people from the room and ventilate it, as well as identify ozone lamps and replace them, eliminate other causes of increased ozone formation and ozone penetration into the rooms where the staff and patients may be located. The ozone content in the indoor air environment should not exceed 0.03 mg / cubic meter (medium shift maximum allowable concentration (MPCss) for atmospheric air); Ozone concentration measurement results are recorded in a logbook. It is prohibited in the premises for children and pulmonary patients to use irradiators with ozone lamps. The frequency of control - in consultation with the state control authorities.
In case of violation of the integrity of the BL, it is necessary to exclude the ingress of mercury and its vapors into the room, and when mercury enters, the room must be demercurated. The content of mercury vapors in the room should not exceed 0.0003 mg / cubic meter (MPCss for atmospheric air).
Broken or expired BL must be kept packed and in a separate room. It is prohibited to discharge waste and broken mercury lamps into the garbage bins; Disposal of such lamps is carried out in accordance with applicable law.
6. MICROBIOLOGICAL CONTROL AND EVALUATION OF THE EFFICIENCY OF THE USE OF BACTERICIDE IRRADIATION
6.1. The necessary conditions for anti-epidemic protection should be ensured by the achievement of a given level of bactericidal efficacy of radiation established for premises of various purposes (see Appendix 1). The effectiveness of UV-irradiation of the room is estimated by the degree of reduction of microbial contamination of air, surfaces of fences and equipment under the influence of irradiation (Appendix 4). Monitoring of radiation efficiency indicators is carried out by measuring the actual levels of bactericidal flow in the premises; these measurements are also carried out at the workplaces of the personnel servicing the CI and BO
6.2. In the study of microbial contamination of air, bacteriological control provides for the determination of the total content of microorganisms in 1 cubic meter and is determined by the content of Staphylococcus aureus per 1 cubic meter of indoor air. To determine the total content of microorganisms, 100 l of air is pumped in, and for Staphylococcus aureus - 250 l (speed - 25 l / min). Air samples are taken by the aspiration method using the Krotov instrument. The use of a PAB-2 sampler and other devices is allowed.
To determine the total microorganism content in 1 cubic meter of air, samples are taken on a 2% nutrient agar. After incubation of crops at 37 degrees. C for 24 hours and 24 hours at room temperature, the grown colonies are counted and converted into 1 cubic meter of air.
To determine the content of Staphylococcus aureus in 1 cubic meter of air, samples are taken on yolk-salt agar (JSA). After incubation of crops at 37 degrees. C for 24 hours and an additional 24 hours at room temperature, suspicious colonies are subjected to further research in accordance with the "Instructions for the organization and conduct of epidemiological surveillance of nosocomial infections in obstetric hospitals" inflammatory diseases in newborns and puerperas ") or" Instructions on the organization and conduct of sanitary and hygienic measures for the prevention of nosocomial infection in medical institutions (departments) of the surgical profile, in max and intensive care units and intensive care "(supplement to the order of the Ministry of Health of the USSR N 720 from 07.31.1978).
To control the contamination of air in boxed and other premises that require aseptic working conditions, a sedimentation method is used. In accordance with this method, two Petri dishes with 2% nutrient agar are placed on the desktop and opened for 15 minutes. Crops are incubated at 37 degrees. C for 48 hours. With a growth of no more than 3 colonies per cup, the level of microbial contamination of air is considered acceptable.
6.3. Bacteriological study of the microbial contamination of the surfaces of premises and equipment provides for the detection of microorganisms of the family Enterobacteriaceae, Staphylococcus aurens, Pseudomonas aeruginosa.
Sampling from surfaces is carried out by a flush method. Washout is made from an area of 100 sq. Cm, carefully wiping the surface with a sterile cotton swab on sticks, mounted in test tube stoppers with 5.0 ml of sterile 1% peptone medium. Tampons moistened with nutrient medium, after taking the washout, will be placed in the same tube with peptone water. When analyzing the washout for the presence of bacteria of the coliform group, a swab is placed on Kessler or Coda. Further research and identification is carried out according to the standard technique.
Determining the presence of pathogenic Staphylococcus aureus is carried out by seeding the washings of the liquid in a test tube with 5 cc 6.5% saline broth. Further studies are carried out in accordance with Appendix 2 to Order No. 720 of July 31, 1978. Bacteria of the group of Escherichia coli and pathogenic staphylococci are not allowed in washes. When analyzing the wash for the Pseudomuscular Ornithis, special crops can be avoided, since the growth of colonies can be detected on Endo medium or nutrient agar.
To isolate Enterobacteriaceae and Pseudomonas aeruginosa, culture is carried out on Endo medium from tubes with 1% peptone water after incubating them at 37 degrees. C for 18-20 hours
Further research is carried out according to the "Instructions on the organization and conduct of epidemiological surveillance of nosocomial infections in obstetric hospitals" (order of the Ministry of Health of the Republic of Belarus N 178 of December 21, 1995 "On the prevention of nosocomial pyoinflammatory diseases in newborns and puerperas"), "Microbiological guidelines diagnosis of diseases caused by enterobacteria "(Ministry of Health of the USSR N 04-723 / 3 dated December 17, 19884) and" Guidelines for the determination of gram-negative potentially pathogenic bacteria that cause nosocomial infections "(Ministry of Health USSR, 1986).
In assessing the effectiveness of ultraviolet bactericidal exposure to mold fungi, bacteriological studies are carried out using the Saburo medium.
Monitoring compliance with the parameters of microbiological purity of the air environment and surfaces in the premises of health facilities is carried out by bacteriological laboratories of relevant institutions, as well as by the State Sanitary Inspectorate.
6.4. For the microbiological method of evaluating the effectiveness of open-type irradiators on the day of the study, a daily agar culture of Escherichia coli testis or Staphylococcus aureus is sown on a lawn with a bacteriological loop on a Petri dish with a nutrient medium. After removing the lid, one half of the Petri dish with the seed culture of the test strain is covered with a sheet of black paper. Then the cup is placed perpendicular to the incident bactericidal flux of ultraviolet radiation at a distance of 1 m from the source for 15 to 20 minutes. After the irradiation time has passed, the Petri dish is placed in a thermostat at 37 degrees. C for 24 hours. The BO operation is considered satisfactory if there is no growth of the culture test strain on the half-filled Petri dish irradiated with UV flow (single growth is allowed up to 10 colonies) and there is growth on the other part of the control, shaded part of the Petri dish.
7. SANITARY AND EPIDEMIOLOGICAL SUPERVISION OF USE
UV BACTERICIDE RADIATION FOR
DECOMPOSITION OF AIR AND SURFACES IN PREMISES OF LPU
7.1. Hygiene and epidemiology centers supervise and control bactericidal plants in accordance with these guidelines and other applicable regulatory and methodological documents. The device and operation of bactericidal irradiation facilities without the consent of the State Sanitary Inspectorate is not allowed.
The need for the use of UV bactericidal installations for disinfecting air and indoor surfaces is determined at the design stage of buildings or structures in accordance with these guidelines and design tasks agreed with the State Sanitary Supervision Authority.
Sanitary and epidemiological surveillance provides for monitoring the sanitary and hygienic indicators of premises equipped with BO, including room characteristics, standards and a list of requirements aimed, on the one hand, at achieving a given level of epidemiological protection, and on the other, at ensuring conditions that exclude the adverse effects of UV - radiation, ozone and mercury on the staff and patients of medical institutions.
It is prohibited to use UV germicidal irradiators that are not authorized by the Ministry of Health of the Republic of Belarus and without a hygienic certificate.
At the design stage and the equipment of the premises with bactericidal irradiation facilities, the list of facilities of medical facilities subject to bactericidal irradiation is determined, the nomenclature of the BOs used is calculated, the required lamp power and the number of BOs are calculated, the locations and height of the suspension of stationary irradiators are determined, as well as the radiation dose provided and the possible adverse effects of radiation, the device of the exhaust ventilation in the irradiated areas.
When commissioning and periodically during the operation of bactericidal irradiation facilities, sanitary and epidemiological supervision is carried out, during which the conformity of the irradiation unit to the project, types of BOs and lamps, their serviceability, mode of use, quality of care, timeliness of lamp replacement in accordance with the established hours of work are determined. , as well as the order of storage and disposal of failed BL.
7.2. In the course of the current sanitary and epidemiological surveillance, exposure control is carried out, including in the area where people are likely to stay, the concentration of ozone in the room air and the bacteriological control of the bactericidal efficiency of irradiators and installations used. The high biological activity of UV radiation requires careful monitoring of bactericidal irradiation in the workplace. Measurements of the bactericidal radiation intensity are carried out in the order of current supervision, as well as when new equipment is accepted for operation, and changes are made to the design of existing equipment. The frequency of control is determined by agreement with the State Inspectorate. Measurements are carried out using UV radiometers (Argus, ROI-82, UV meters, etc.), spectroradiometers (SRP-86), dosimeters DAU-81, and other certified and state-tested instruments. Measurements should be carried out with an established operating mode of the equipment and with the exclusion of influence, the elimination of other sources of radiation. When measuring the irradiance created by BL and BO, the sensor of the device should be positioned perpendicular to the axis of the bactericidal lamp, the irradiator (radiation flux), with the search for maximum values, in the bactericidal spectral range (UV-C). Measurements are carried out at a distance of 1 m. In addition to measurements of the direct directed flux, measurements of the bactericidal flux of reflected radiation are also carried out. Measurement of UV intensity parameters should be carried out with the obligatory use of a face mask, goggles and gloves that protect the eyes and skin from excessive UV radiation. Instrumental measurements and monitoring of the parameters of the flux density of UV radiation in the area of possible presence of personnel are carried out in accordance with the current regulatory documents ("Sanitary standards of ultraviolet radiation in industrial premises", N 4557-88, USSR Ministry of Health, 1988; Methods for hygienic assessment of production sources ultraviolet radiation, N 105-9807, MH RB, 1999).
To reduce the time spent in irradiation conditions when measuring, measuring points are determined in advance, taking into account the actual location of personnel when working in the area of possible UV exposure (when servicing mobile, open irradiators, determining compliance with the specified irradiators specified in the documentation for bactericidal irradiators values).
To monitor the levels of bactericidal irradiance, the state of the lamps, you can also use UV-radiation indicators, direct-staining photosensitive paper as an indicator of the intensity of radiation of BO, a microbiological method for determining the bactericidal efficiency of lamps (see section 6.4).
The State Sanitary Inspectorate's authorities during the control of premises with BOs check the availability of the act of commissioning the irradiator, the logbook and monitoring its operation, as well as personal protective equipment (for rooms where disinfection is carried out in the absence of people). Further, the correspondence of the efficiency of irradiation to the requirements of sanitary-hygienic indicators, which are subject to registration in rooms with bactericidal irradiators according to the present methodical recommendations, is revealed.
The identified parameters are correlated with current regulations and are recorded in a journal (Appendix 7). Monitoring of the control unit should be carried out at least once a year. Based on the results of the control, a conclusion is made, which is recorded in a journal. In case of non-compliance with the requirements of these guidelines and other applicable regulatory documents, the deadline for bringing the control unit into compliance with the requirements of regulatory documents is appointed or it is prohibited to operate the premises until the detected deficiencies are eliminated.
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