RU1778179C - Method for distinguishing pneumococcus from a hemolytic streptococcus - Google Patents

Abstract

Usage: medical microbiologists, diagnostics, differentiation of pneumococci from other & гем-hemolytic (green) streptococci. SUMMARY OF THE INVENTION: as a medium for differentiation, a semi-liquid culture medium for, is used. sterility control of the following composition, g / l: enzymatic casein hydrolyate 15, vitamin preparation EKD 5; sodium chloride b, medical glucose 5.0; thioglycol t sodium 0.5; cysteine dihydrochloride 0.75 {agar powder 0.6; sodium carbonate 0.5-0.95. The medium is a commercial preparation and is available as a dry powder. Pneumococci are differentiated according to their arrow-shaped, homogeneous optical density nature of growth in the thickness. this environment.

Description

The invention relates to medical microbiology, in particular, to a method for differentiating pneumococci from other cvi-hemolytic (green) streptococci.

There is a method for differentiating pneumococci from other green ones. Streptococci, in which the studied strains are seeded on agar with 5% ram blood with simultaneous inoculation of staphylococcus, forming incomplete hemolysis of ram red blood cells, i After 20-24 hours of incubation at 37 ° C, the nature of hemolysis around staphylococcus, in the growth sector of pneumococcus there is an increase in hemolysis, in contrast to other ob-hemolytic streptococci, which do not change the nature of hemolysis.

However, the proposed method has a number of significant disadvantages:

- About 10 strains of Streptococcus pneuraoniae do not give a hemolysis enhancement zone in the first 24 hours;

- Fresh ram blood is necessary, which presents certain difficulties for most practical laboratories. The use of human red blood cells reduces the effectiveness of ro 5-10%;

- requires constant maintenance of museum strains of hemolytic staphylococcus, which is additionally spent on nutrient media, including scarce blood.

The purpose of the invention is to simplify and accelerate the dierenation of pneumococci from other green streptococci.

This is achieved by the fact that the seeding of the studied colonies is carried out on a semi-liquid nutrient medium to control the sterility of the following composition, g / l:

X | H

00

-AND

Vj

H)

twenty

25

Casein Hydrolyzate Enzyme15

Vitamin preparation

ECD5 5

Sodium chloride 6.4

Glucose Medical 5.0

Thioglycol T sodium 0.5

Cysteine Dihydrochloride 0.75

Powdered agar 0.6 Q

Sodium carbonate 0.5-0.95 This medium is a commercial preparation and is produced as a dry powder by the Enterprise of the Central Research Institute of Vaccines and Serums named after II Mechni- gova under the name: Nutrient medium for sterility control, dry.

After 18-24 hours, the crops are viewed. Of all the species of green streptococci, only for Str. pneumoniae is characterized by the following features: growth is observed in the form of a local, homogeneous, slight turbidity of the medium, the shape of which resembles an arrow, with its tip pointing upwards, up to 2 mm thick and 4 mm or more in length. The growth zone is clearly limited, uniform optical density. Several of these arrows can be connected at the base at the bottom of the tube, forming a continuous cloudy zone in the form of a cloud, with clear localization, the same consistency as the arrows and also without any fluctuation in optical density. The growth of other types of oi-hemolytic streptococci in this medium differs either due to growth in the form of a cloud in the absence of arrow-shaped growth, or due to the presence of optically dense inclusions in the growth zone (sizes from the smallest, on the verge of visibility, to large ones with a diameter of up to 2-3 mm and more).

Example. The commercial medium prepared according to the manufacturer's instructions is poured into 5-7 ml tubes. Selected colonies suspicious of pneumococcus, sow35

40

45

sensitivity to bile and in the reaction of agglutination with specific serum. Strains capable of forming optically dense structures in the growth zone of various diameters, as well as those whose growth in this medium takes the form of cloud-like opacities without the presence of arrow-shaped outgrowths, are excluded from further analyzes.

The author tested 1 34 reference and freshly isolated strains of pneumococcus, as well as reference and freshly isolated strains of microorganisms of the following species: Str.mitis, Str.sanquis, Str.nutans, Str.anginosus in a total of 347 specimens. Inoculation was performed in parallel into two tubes. In no case was the growth pattern of microorganisms not belonging to the species Str.pneumoniae consistent with the above. At the same time, out of 134 pneumococcal strains, only seven (5%) growth in one of the two tubes was not characteristic of this species, which was manifested by the absence of arrow-shaped growth.

Thus, the proposed method for differentiating pneumococcus from Streptococcus aureus by reseeding suspicious colonies on a sterility control medium significantly narrows the search for pneumococcal cultures, has high sensitivity, is quite economical, and does not require additional tools, devices and reagents. In particular, in comparison with the prototype, this method is more sensitive, eliminates the need to maintain museum cultures of hemolytic staphylococcus and the presence of fresh mutton blood. Preparation of a nutrient medium on the basis of a commercial preparation does not require a lot of time, and the medium is ready and poured into test tubes and can be stored for a long time (up to two months) in a refrigerator at 4 ° C. The method can be widely used in practical laboratories for etiological break up a loop in the thickness of the medium to a depth of 50 encryption of diseases caused

pneumococci.

3/4 of the filled volume from the upper edge of the medium. After 18-24 hours of incubation at 37 ° C, the crops are viewed. Culture growth in the form of characteristic

the arrow-shaped turbidity of the medium is one- 5 From the green streptococcus by means of the rock optical density, evidence of the material under investigation indicates the growth of pneumococcus. Such a live medium, incubations from the post-culture are microscopic, tested by identification of cultures according to the invention. Method for differentiating pneumococcus

0

5

5

Q

g

about

35

40

45

sensitivity to bile and in the reaction of agglutination with specific serum. Strains capable of forming optically dense structures in the growth zone of various diameters, as well as those whose growth in this medium takes the form of cloud-like opacities without the presence of arrow-shaped outgrowths, are excluded from further analyzes.

The author tested 1 34 reference and freshly isolated strains of pneumococcus, as well as reference and freshly isolated strains of microorganisms of the following species: Str.mitis, Str.sanquis, Str.nutans, Str.anginosus in a total of 347 specimens. Inoculation was carried out in parallel into two tubes. In no case was the growth pattern of microorganisms not belonging to the species Str.pneumoniae consistent with the above. At the same time, out of 134 pneumococcal strains, only seven (5%) growth in one of the two tubes was not characteristic of this species, which was manifested by the absence of arrow-shaped growth.

Thus, the proposed method for differentiating pneumococcus from Streptococcus aureus by reseeding suspicious colonies on a sterility control medium significantly narrows the search for pneumococcal cultures, has high sensitivity, is quite economical, and does not require additional tools, devices and reagents. In particular, in comparison with the prototype, this method is more sensitive, eliminates the need to maintain museum cultures of hemolytic staphylococcus and the presence of fresh mutton blood. Preparation of a nutrient medium on the basis of a commercial preparation does not require a lot of time, and the medium is ready and poured into test tubes and can be stored for a long time (up to two months) in a refrigerator at 4 ° C. The method can be widely used in practical laboratories for etiological pneumococci.

From green streptococcus by seeding the test material on an electric medium, incubation with subsequent identification of cultures according to the invention. Method for differentiating pneumococcus

5 17781796

The growth promoter, distinguishing — sowing is carried out in the thickness of the medium and so that, in order to simplify and - with the arrow-shaped optically uniform acceleration of the method, the culture of the identifying medium is used as a medium for clouding the medium. 5 are infectious as pneumococcus, and if not, steroid for controlling sterility, such as green streptococcus.