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LABORATORY DIAGNOSIS OF CHOLERA

Actuality of the theme.Vibrios are among the most common bacteria in surface waters worldwide. They are curved aerobic rods and are motile, possessing a polar flagellum. V. cholerae serogroups O1 and O139 cause cholera in humans, while other vibrios may cause sepsis or enteritis. The epidemiology of cholera closely parallels the recognition of V. cholerae transmission in water and the development of sanitary water systems.

Primary objective:to be able to conduct and evaluate the microbiological diagnostics of cholera.

QUESTIONS FOR DISCUSSION

1. Biological properties of Cholera spp.

2. Epidemiology and pathogenesis of the diseases caused by Cholera spp. Specific features of immunity in such cases.

3. Microbiological diagnostics of Cholera.

4. Basic measures of prophylaxis and treatment of Cholera.

PROCEDURE OF PRACTICAL SESSION

Task 1. Study the preparation from the pure cultures of V. cholerae, microscopically; draw them in the protocol.

Task 2. Study biochemical properties of causative agents on Hiss media, to make conclusions and to mark the plan of the further researches.

Task 3. Study the tets for deferentiation of theV. cholerae . Make the conclusion and determine the biovar.

Task 4. Study the main antimicrobial drugs used for treat­ment, prevention and diagnostics of suppurative diseases. Write them in your copybook.

RECOMMENDATIONS FOR PRACTICAL WORK

Task 1.

At the microscopy of the preparations of V. cholerae is a comma-shaped, curved rod 2-4 μm long. It is actively motile by means of a polar flagellum. On prolonged cul­tivation, vibrios may become straight rods that resemble the gram-negative enteric bacteria.

 

 

Task 2.

In relation to manose, sucrose and arabinose (triad Hayberh) all vibrio divided into 8 groups. The result of fermentation of carbohydrates has diagnostic value. Causative agents of the cholera and refers to the I group of the Hayberh triad, ie V. cholerae fermente the manose to acid and sucrose, does not fermente arabinose. Latest Groups consists non-hemolytic vibrios.

Task 3.

Tests V. cholerae serogroup Ol V.cholerae O1 El Tor V.cholerae O139 non-01 /non-O139 V .cholerae
Agglutination by cholera Î1-serum agglutinate agglutinate do not agglutinate do not agglutinate
Agglutination by Ogáva and Inába serum. agglutinate agglutinate do not agglutinate do not agglutinate
Main tests:
Lysis by: bacteriophage El-Tor lyses do not lyses do not lyses lyses
Lysis by: Cholera monophagous C IV. do not lyses lyses do not lyses lyses
Resistance to the action of polymyxin B. sensetive(growth absent) resistent (growth present) resistent (growth present) resistent (growth present)
Agglutination of the chicken erythrocytes. do not not agglutinate ± (ophen +) ± (ophen +) agglutinate
Additional tests:
Hemolysis sheep erythrocytes. + +
Hexsamine test. + +
Fogesa-Proskauer test + + +

Task 4



Agglutination anti-O group 1 serum is diagnostic preparation, containing specific antibodies to O-antigens of cholera vibrios belonging to the O1 serogroup. The interaction of the specific antibodies with the corresponding antigens is formed agglutinates. Agglutinating serum obtained by hyperimmunisation of the rabbits with a mixture of G1-cholera antigens, followed by adsorption of nonspecific antibodies. It is used for setting agglutination test for bacteriological study of antigenic structure of the parasite and reaction of immobilization of vibrios.

Agglutination anti-H cholera serumis diagnostic preparation, containing specific antibodies to H-antigens of vibrio cholerae. Agglutination anti-H cholera serum obtained by hyperimmunisation of the rabbits with using V. cholera. It is followed by adsorption of nonspecific antibodies. It is used for setting agglutination test for bacteriological study of antigenic structure of the parasite.

Agglutination serum Ogávais diagnostic preparation, containing specific antibodies to O1-cholera antigens serovar Ogawa. Agglutinating serum obtained by hypperimmunisation of the rabbits with using V. cholera serovar Ogawa, followed by adsorption of nonspecific antibodies. It is used for setting agglutination test for bacteriological study of antigenic structure of the parasite

Cholera bacteriophage El Tor (liquid) is diagnostics preparation, containing a sterile filtrate of V. cholerae biovar eltor bacteriophages. It is used to phagotyping of the cholera vibrio biovar El Tor.

Cholera bacteriophages C (liquid) is diagnostics preparation, containing a sterile filtrate of V. cholerae bacteriophages. It is used to phagotyping of the cholera vibrio.

Ñholera fluorescent serum is diagnostics preparation, containing specific antibody labeled with fluorochrome (fluorescein isothiocyanates). In the formation of the complex Vibrio cholerae-specific antibodies observed to glow with fluorescent microscopy. A positive result is the identification of the even single vibrios and can be obtained within 1-2 hours from the start of the study with a content of not less than 106 vibrios in 1ml of the material. The preparation is used for the rapid identification of the causative agent in the material from the patient, in drinking water or in pure culture in bacteriological diagnosis of cholera.

Vibrio polyvalent bacteriophage (tablets)is preventive preparation containing a sterile filtrate of the bacteriophages that lyses V. cholerae. Available in the form of tablets with acid-coated. Appointed contact persons for prevention.

Corpuscular cholera vaccineis an inactivated dry.The preparation is used for specific prevention of the cholera. It is a suspension of equal amounts of pure cultures of V. cholerae O1 biovar eltor, Ogawa and Inaba serovars.

Cholera vaccine (choleragen-anatoxin + O-antigen)is preventive preparation.Itwas obtained by purification broth culture of the cholera vibrio serovar Inaba, inactivated with formalin. It contains choleragen-toxoid and somatic O-antigen. It is used for prevention of cholera by epidemiological indications.

Bivalent cholera vaccine chemical (pelletized)contains choleragen-anatoxin serovars Ogawa and Inába and somatic O-antigen serovars Inaba and Ogawa. It is used for prevention of epidemiological indications.

Choleragen-toxoidis used for specific prevention of cholera in epidemiologic testimonies (creation of active stress antitoxic immunity). It is a suspension of inactivated cholera vibrios, cultivated in liquid nutrient medium. The drug is purified from the ballast proteins. It is administered subcutaneously.

 

 

Addition 1


Date: 2016-01-14; view: 1033


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