Microflora of the Air

The composition of the microbes of the air is quite variable. Then more dust, smoke, and soot in the air, the greater the number of microbes. Each particle of dust or smoke is able to adsorb on its surface numerous microbes. The number of microbes in the air varies from a few specimens to many tens of thousands per 1 m³. Depending on the time of the year, the composition and the amount of microflora change. If the total amount of microbes in winter is accepted as 1, then in spring it will be 1.7, in summer— 2 and in autumn — 1.2.

The number of microbes in factories and homes is associated closely with the sanitary hygienic conditions of the building. At poor ventilation and natural lighting and if the premises are not properly cleaned, the number of microbes increases.

Pathogenic species of microbes (pyogenic cocci, tubercle bacilli, anthrax bacilli, bacteria of tularaemia, rickettsiac of Q-fever, etc.) may be found in the surroundings of sick animals and humans, infected arthropods and insects, and in dust. The causative agents of influenza, measles, scarlet fever, diphtheria, whooping cough, meningococcal infections, tonsillitis, acute catarrhs of the respiratory tract, tuberculosis, smallpox, pneumatic plague, and other diseases can be transmitted through the air together with droplets of mucus and sputum during sneezing, coughing, and talking.

The air is an unfavourable medium for microbes. The absence of nutrient substances, the presence of moisture, optimal temperature, the lethal activity of sunlight, and desiccation do not create conditions for keeping microbes viable and most of them perish. However, the relatively short period during which the microbes are in air is quite enough to bring about the transmission of pathogenic bacteria and viruses from sick to healthy persons, and to cause extensive epidemics of diseases such as influenza.

The laboratory investigation of air is carried out to determine the qualitative and quantitative composition of its microflora. This is achieved by using simple and complex methods. For a more accurate investigation of microbial contents of the air special apparatus are used.

At present Streptococcus viridans serves as sanitary indices for the air of closed buildings, and haemolytic streptococci and pathogenic staphylococci are a direct epidemiological hazard.

So, sanitary-indicative bacteria of air of closed buildings are

1)Streptococcus viridans,

2)Streptococcus haemolyticus,

3) Staphylococcus aureus.

These bacteria are indicators of contamination by oral droplets.

Microbiological investigation of the air. The sanitary - bacteriological investigation of air includes: 1) determination the total number of microbes in 1 m³ of the air - a total microbial number (TMN); 2) presence of sanitary-indicative bacteria — Str. viridans, Str. haemolyticus , S. aureus.

For taking the samples sedimentation and aspiration methods are used.

Plate method (sedimentation method). The Petri’s dishes with meat-peptone agar or another special nutrient media for staphylococci and streptococci, for example blood agar, yolk- salt agar are used. They are opened and are stayed in investigated room. Term of exposition depends on prospective quantity of microbes in the air. With a plenty of microorganisms a plate is opened for 5-10 minutes to detect a total microbial number, with a little - for 20 — 40 minutes for detection of cocci.

Then the dishes put into thermostat at 37 °C for 24 hrs. After incubation all colonies are accounted (for determination of total number of microorganisms). Number of grown colonies indicates degree of air contamination.

According to Omeliansky’s data in 5 minutes on a surface of 100 cm² so many microbes sedimentate, as they present in 10 L of air. For example, on the dish surface with MPA after 5 minute exposure 32 colonies have grown. It is necessary to calculate amount of microbes which are present in 1 nr³ of the air, applying the Omeliansky’s formula. The plate has 100 cm² . 32 colonies of microbes contain in 10 L of the air, and in 1 m³ (1000 л) there will be (32 • 1000): 10 = 3200.

Aspiration method. Krotov’s apparatus is used for this purpose. It give us the possibility to let pass 50 -100 L of air with a speed of 25 L per minute through clinoid chink in the special glass above the open dish with MPA. The rotation of Petry’s dish (1 rotation/sec) provides uniform dispersion of microorganisms on all surface of a medium. Then dish is incubated in a thermostat at 37 °C for 18-24 hrs.

For example, 250 colonies are revealed on the surface of dish after 2-minutes exposure with a 25 1/min speed. Thus the number of microbes (x) in 1 m³ of the air is: x = (250 • 1000): 50 = 5000.

Determination of staphylococci and streptococci. Using Krotov’s apparatus 250 L of air are seeded on the surface of open Petri dish with yolk- salt agar for staphylococci and with blood agar for streptococci. Then dishes are incubated in a thermostat at 37 °C for 18-24 hrs. After incubation growing up colonies are accounted and the number of staphylococci or streptococci in 1 m³ of the air is calculated.

To the air environment of pharmacies strict hygienic requirements are imposed, which is reflected in normative documents. Sources of air pollution pharmacies: • - visitors; • -employees; • -infected material (recipes, dishes, packaging material); • - poor-quality medicinal plant raw materials.

The permissible standards of the microbial number of air in various pharmacy premises have also been developed.

Normal microflora of the human body and its meaning. The concept of gnotobiology. Disbiosis. Preparations used to restore normal microflora.

In a healthy animal, the internal tissues, e. g. blood, brain, muscle, etc., are normally free of microorganisms. On the other hand, the surface tissues, e. g. skin and mucous membranes, are constantly in contact with environmental organisms and become readily colonized by certain microbial species.