BACTERIOLOGICAL LABORATORY

From Big Medical Encyclopedia

BACTERIOLOGICAL LABORATORY — the scientific and practical establishment which is carrying out bacteriological, immunological and other microbiological researches. According to differentiation of microbiology in general and bacteriology as one of its industries there are B. of l., the having various tasks and functions. Clinicodiagnostic B. of l. at hospitals conduct the researches necessary for statement or specification of the diagnosis of an infectious disease controlling efficiency of treatment.

B.'s specialization l. at hospitals is defined by a profile of hospital (acute infectious diseases, children's infectious diseases, venereal diseases, tuberculosis and so forth). B. l. at sanitary and epidemiologic stations, as well as clinical laboratories, are engaged in diagnostic work, servicing the hospitals which do not have own laboratories conduct preventive examination of the population and a sanitary and bacteriological research of foodstuff and water.

Except medical, there is a wide network of veterinary B. of l., the infectious diseases which are carrying out diagnostic and preventive testings at animals (see. Veterinary laboratory ). B. of l are highly specialized., the performing control functions, as, e.g., B. of l. at waterworks, control laboratories at the enterprises which are releasing vaccines, serums and other bacteritic drugs. Special B. of l. are organized at disinfection institutions. Their task is bacteriological quality control of the carried-out disinfection. Along with B. of l. a medical and veterinary profile there are specialized B. of l., the servicing needs of the food industry (the wine-making, baking, brewing and other enterprises), agriculture and so forth. Unlike the l transferred to B., solving practical problems, in structure of the relevant research institutes B. are provided by l. different profiles, intended for the solution of various research tasks. B. l. can be stationary and mobile. The last are used for sanitary and anti-epidemic service of military units, and also in forwarding, field conditions (see. Laboratory , in field conditions). Except mobile, in troops there are also stationary laboratories. Specifics of the researches conducted in B. by l., causes structure of laboratories and a duty in them.

The main requirement imposed to B. on l. and, creation of the conditions providing performance of researches in the most sterile conditions and guaranteeing personnel and people around against possible infection is following from specifics of its work. B.'s structure of l. includes: actually laboratory and number of divisions, additional to it. Treat them: sredovarnya, washing, preparatorsky, sterilizing and vivarium (see). The listed divisions as independent base units are large B.' part of l. In small B. of l. the vivarium and special preparatorsky are absent, and sredovarnya and sterilizing can be integrated in one room.

Device and equipment

Fig. 1. Bottles with pipettes for paints.
Fig. 2. Cornet's tweezers with a slide plate.
Fig. 3. Promyvatel for the painted smears.
Fig. 4. A mattress for cultivation of bacteria.
Fig. 5. Glass pallets. Fig. 6. The pallet from a platinum wire.

B.'s room of l. shall be light and rather spacious. Walls shall be painted by an oil paint, and a floor — not to have cracks. Windows of laboratory should be oriented to the North or the northwest. At orientation to the South of a window veil white curtains. In B. of l. there has to be a washing sink or a wash basin, over to-rymi the large bottle with solution for disinfection of hands is located on the shelf. A desktop of the bacteriologist, whenever possible, 1 m from a window have at distance and cover with linoleum or glass. On a table place a gas burner (in the absence of gas — spirit). The obligatory equipment of a workplace is bank for pipettes with disinfecting solution (3% solution carbolic to - you), the closed porcelain or glass cotton receptacle, a block — the holder for a bacterial loop, a set of bacterial standards, test-tube supports, the enameled ditches, tweezers, scissors and a scalpel, pure slide plates with holes and without them, and also cover glasses. Usually use slide plates of 26 X X 76 mm in size and 1 — 1,2 mm thick, cover glasses 18 x 18 or 20 x 20 mm. B. l. it has to be supplied with the metal trays for transfer of Petri dishes zinced with buckets or tanks for dumping of the infected ware or stock. Microscopes store in a case or under the bell jar. The desktop shall not be encumbered by excess objects. Usually in B. of l. equip an additional small table for coloring of the fixed drugs. On such table have: a set of necessary dyes and reactants in a block with pipettes and rubber barrels (fig. 1), the enameled ditch or a crystallizer with a support for drugs, wire tweezers or Cornet's (fig. 2) tweezers for fixing of slide plates, sheets of filter paper for removal of liquid from the washed-out drugs, a promyvatel (fig. 3) or a large bottle with water. B. l. it is equipped with the various ware necessary for carrying out researches. Except usual chemical ware (cylinders, flasks, beakers, measured pipettes and so forth), the special, intended for bacteriological and immunoassays ware is necessary: 1) the glass Petri dishes used for cultivation of bacteria on dense environments and receiving the isolated bacterial colonies; 2) bacterial mattresses (fig. 4) — flat bottles (the size 22 x 17 x 5 cm), to-rye are used for cultivation of a large number of bacteria; 3) test tubes of Ru with a banner for cultivation of bacteria on jambs of potatoes; 4) vassermanovsky test tubes 90 mm long and with an internal diameter of 9 — 10 mm for statement of reaction of binding complement and an agglutination test; 5) pretsipitatsionny test tubes 90 mm long and with a diameter of 3 — 5 mm for statement of a precipitation test; 6) the bacterial test tubes serving for cultivation of bacteria on solid and liquid nutrient mediums; 7) the pasterovsky pipettes used for crops of liquid materials, cultivation of liquids in the drop way, putting dyes and so forth; 8) pipettes Mora or pipettes with spherical expansion in a middle part for seeding of the infected liquid material, and also the automatic pipets or pipettes with rubber pears excluding a nasasyvaniye of material a mouth. For cultivation of cultures in liquid mediums, storage and pouring of mediums, reactants and so forth the usual laboratory glassware is applied. The ware used in B. by l., it has to be previously lixivious for what it is usually boiled in 1 — 2% solution salt to - you. Disinfection of bacteriological ware, in a cut microbes cultivate, it is necessary to carry out only by means of high temperature without use of any desinfectants since presence of the last even in the form of traces can slow down development of microbes further. Crops of microorganisms in B. of l. make by means of bacteriological loops, glass or platinum pallets (fig. 5 and 6). Cultivation of bacteria is carried out in air thermostat (see), and in large B. of l. — in special thermostately rooms.

In need of exact control of temperature and rather short-term cultivation of bacteria or at statement of immunological reactions it is convenient to use water ultrathermostats. Each B. of l., where research anaerobe bacterias, it has to be supplied anaerobic jar (see), exsiccators and vacuum pumps for deaerating. The last are used also during the carrying out filtering. For achievement of the best aseptic conditions necessary at carrying out crops, allocation or resowing of cultures, B. of l. equip with the special glazed boxes with predboksnik. In boxing there are a gas burner, a vessel with disinfecting solution and where it is possible, a germicidal uviol lamp. In case of lack of stationary boxing during the carrying out the nek-ry works demanding high degree of an asepsis it is possible to use figurative desktop boxing (see Boxes, microbiological).

Fig. 7. The automatic counter of colonies with television control adaptation: 1 — a Petri dish with the grown colonies; 2 — an electronic board with the figures specifying the number of colonies in a Petri dish; 3 — a TV screen for overseeing by the enlarged image of the colonies which grew in a Petri dish.

Bacterial cultures, medical and diagnostic serums, a phage and other substrates of biological character (serums, solutions of peptones and so forth) store in the refrigerator. Bacterial cultures need to be kept in the soldered test tubes or ampoules for what in B. of l. it is necessary to have a torch for soldering or a usual blowtorch. Obligatory accessory of any bacteriological laboratory is microscope (see). For the majority of researches use a microscope of MBI-3 and lighters. Research B. of l. are equipped also phase and contrast, luminescent and supermicroscopes. For the quantitative accounting of the bacterial clumps which grew on Petri dishes use counters of different systems. One of such counters is the automatic counter with the scanner and television control adaptation allowing to count up to 500 cups in an hour (fig. 7). Important elements of the equipment B. of l. the shaking machines used when it is necessary to provide hashing and stirring of material during certain time are (defibrinating of blood, homogenization of material and so forth). For sedimentation of dense particles (microbic cells, cells of the fabrics, a suspension of the studied material) which are in liquid use centrifuges (see). Most often use the centrifuges rotating with a speed of 3000 — 3500 rpm to carrying out the majority of researches. In the absence of electric centrifuges use hand centrifuges.

B.'s activity l. in many respects depends on observance of the main requirement — work in aseptic conditions with sterile objects (tools, mediums, ware). Therefore in B.'s equipment l. the important place is taken by the equipment for sterilizations (see). In each B. of l. is available autoclave (see), Koch's device, Pasteur's furnace (see. Pasteur furnace ), the device for coagulation of serum. Boiling apply the usual sterilizers (see) heated from electric network or other means to sterilization.

For sterilization of the liquid substrates changing at influence of temperature use bacterial filters (see). Drying of the humidified objects (ware, tools) after steam sterilization or under pressure is made in drying ovens (see). B.'s equipment l., necessary for preparation of the most common mediums, except the specified equipment, turns on devices for pouring of environments, sets of reactants and ware for carrying out nek-ry chemical analyses (definition of amine nitrogen, tryptophane, chlorides and so forth), and also devices and reactants for definition of pH of the environment; universal indicator, indicators and Mikhaelis's comparator or potentiometer.

Fig. 8. Device for fixing of rabbits.

Work with animals in B. of l. it is carried out in the special room — a vivarium. In actually B. of l. experiences with animals are not allowed. For carrying out the main works with animals (capture of blood, statement biol, tests, diagnostic reactions and so forth) it is necessary to have: scales for weighing of mice, pigs and rabbits, machines or devices for their fixing (fig. 8), a set of syringes, numbers for a tag of animals (or dyes), depilators.

Specifics of bacteriological work define especially high requirements to purity of rooms of B. of l. Purity of air has special value, in it raise dust absence. Cleaning of rooms of B. of l. it is better to make at the end of the working day or in several hours prior to work since dust which is kicked up in air during the cleaning increases the maintenance in it of microbes and complicates a possibility of sterile work. Reasonablly after cleaning of rooms before work to subject them to radiation by uviol germicidal lamps within 0,5 — 1 hours. For prevention of laboratory infection and a possibility of spread of an infection during the work in B. of l. it is necessary to carry out the following ground rules: 1) all persons which are in laboratory shall be in dressing gowns; 2) an excessive talk and circulations are not allowed; 3) each worker shall use only the workplace assigned to it; 4) in B. of l. meal and smoking is forbidden; 5) during the work with infectious material it is necessary to use tools (tweezers, needles, hooks) and not to touch it with hands at all; all stock which was in contact with infectious material is liable to sterilization or destruction; 6) at suction of liquid material it is recommended to use rubber pears; pipettes shall be closed by cotton stoppers; 7) transfusion of the infected liquids from a vessel in a vessel is made over the tray or a crystallizer filled with disinfecting liquid; 8) all work connected with crops, resowings, allocation of cultures and preparation of drugs from the infected material is carried out at a torch, burning at the same time edges of test tubes, loops, pallets and so forth; 9) test tubes, flasks, bottles and so forth where in the course of work the infected material is located, are immediately inscribed with the indication of character of material, the name and number of culture and date; 10) if infectious material got on surrounding objects, it is necessary to carry out careful disinfection immediately: to fill in this place with disinfecting solution, and then if it is possible, to burn a tampon with the burning alcohol; 11) the objects and materials infected in operating time register, collect in tanks or buckets, close, seal and on the same day will sterilize; 12) cultures if it is necessary, store in agar columns under oil in the soldered test tubes with labels; 13) registration and the accounting of all cultures, and also infected during work of animals is conducted in the magazine in a special form.

See also Bacteriological techniques , Virologic laboratory , Laboratory , Laboratory engineering , Laboratory business .


Bibliography: Meynell D. and Meynell E. Experimental microbiology, the lane with English, M., 1967, bibliogr.; Timakov V. D. and Guo ldfar D. M. Fundamentals of experimental medical bacteriology, M., 1958; F l όρη N with to and y A. V. New techniques of laboratory researches, M., 1954; Identification methods for microbiology, ed. by B. M. Gibbs a. F. A. Skinner, v. 1 — 2, L. — N. Y., 1966 — 1968.

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