Bacille Calmette-Guerin

[Audio] Bacille Calmette Guerin Vaccine against Tuberculosis Nupur Srivastava Roll no. 22-BT- 053 Semester 1 FYBT Microbiology Assignment.

[Audio] Introduction: What is the BCG vaccine? • Named after its inventors Albert Calmette and Camille Guerin, BCG is a vaccine used primarily against tuberculosis ( TB). Albert Calmette Camille Guerin.

[Audio] • It is a live attenuated vaccine ( LAV), created by reducing the virulence of the pathogen. • This vaccine was originally developed from Mycobacterium bovis, found in cattle, and though it has been weakened, it is still live. • First used medically in 1921, it is one of the World Heath Organisation's List of Essential Medicines. • This vaccine has existed for over a century, and is one of the most widely used of all current vaccines. Mycobacterium tuberculosis Mycobacterium bovis.

[Audio] History of the BCG vaccine • Following the success of vaccination in preventing smallpox, established during the 18th century, scientists sought to find a corollary in TB by drawing a parallel between bovine TB and cowpox: It was hypothesized that infection with bovine tuberculosis might protect against infection with human tuberculosis. • In the late 19th century, clinical trials using Mycobacterium bovis were conducted in Italy. The result was disastrous, as this pathogen was found to be just as virulent as Mycobacterium tuberculosis. • In 1908, a French Physician, Albert Calmette, and his assistant, Camille Guerin, a veterinarian, were working at the Institut Pasteur de Lille. • Their work included subculturing virulent strains of the tuberculosis bacillus and testing different culture media..

[Audio] • They noted that a glycerin-bile-potato mixture grew bacilli that seemed less virulent, and changed the course of their research to see if repeated subculturing would produce a strain that was attenuated enough to be considered for use as a vaccine. • The BCG strain was isolated after subculturing 239 times during 13 years from the virulent strain on glycerin potato medium. Calmette and Guerin.

[Audio] • The research continued throughout World War I until 1919, when the now avirulent bacilli were unable to cause tuberculosis in research animals. • Calmette and Guerin transferred to the Paris Pasteur Institute in 1919. • The BCG vaccine was first used in humans in 1921. • Public acceptance, however, was slow, owing to the Lubeck disaster, wherein 251 infants were vaccinated. 173 of them developed TB and 72 died. It was subsequently discovered that the BCG administered had been contaminated with a virulent strain being stored in the same incubator. French poster advertising the BCG vaccine.

[Audio] • Dr RG Ferguson, a pioneer in North America's fight against TB, was among the first to develop the practice of vaccination against tuberculosis. • In 1928, BCG was adopted by the Health Committee of the League of Nations ( predecessor to WHO). Because of opposition, however, it only became widely used after World War II. Dr RG Ferguson.

[Audio] Medical use • Target of the vaccine The BCG vaccine targets Mycobacterium tuberculosis, the etiological agent of tuberculosis, a bacterial infection that affects the lungs, and sometimes other parts of the body, such as the brain ( meningitis). TB is highly contagious, usually spreading by means of tiny droplets from the coughs or sneezes of an infected person. In children it decreases the risk of getting the infection by 20% and the risk of infection turning into active disease by nearly 60%. It is the most widely used vaccine worldwide, with more than 90% of all children being vaccinated. The immunity it induces decreases after about ten years. As tuberculosis is uncommon in most of Canada, Western Europe, and the United States, BCG is administered to only those people at high risk. Part of the reasoning against the use of the vaccine is that it makes the tuberculin skin test falsely positive, reducing the test's usefulness as a screening tool..

[Audio] • Preparation of the vaccine: A weakened strain of bovine tuberculosis bacillus, Mycobacterium bovis is specially subcultured in a culture medium, usually Middlebrook 7H9. Some BCG vaccines are freeze dried and become fine powder. Sometimes the powder is sealed with vacuum in a glass ampoule. Such a glass ampoule has to be opened slowly to prevent the airflow from blowing out the powder. Then the powder has to be diluted with saline water before injecting..

[Audio] • Administration of the vaccine This vaccine is available either as liquid fresh type or lyophilized type. The latter is more stable and is used currently after reconstituting it with normal saline. It is generally administered to infants at birth. A tuberculin skin test (or Mantoux test) is usually carried out before administering BCG. Tuberculin testing before BCG vaccination might be recommended on the grounds that it will detect tuberculosis and will prevent complications due to pre-existing immunity. Mantoux test.

[Audio] BCG is given as a single intradermal injection at the insertion of the deltoid. Site of the vaccine is not cleaned with spirit as it may kill the live component of the vaccine. The characteristic raised scar that BCG immunization leaves is often used as proof of prior immunization. BCG vaccination scar.

[Audio] Adverse effects • Scarring called keloids at the site of infection • If given subcutaneously, it may induce local abscess that can sometimes ulcerate • It can sometimes cause life-threatening infection, for example, in case of an immunocompromised patient. Keloid Abscess.

[Audio] Efficacy • BCG vaccine has a documented protective effect against meningitis and disseminated TB in children. It does not prevent primary infection, and more importantly, does not prevent reactivation of latent pulmonary infection. • Protective efficacy against some diseases: Pulmonary tuberculosis: 0[break]% Severe forms of tuberculosis (like miliary tuberculosis): 0- 80[ break]% Leprosy: 20- 40[break]%.

[Audio] Acknowledgment: I would like to sincerely thank Kinjal ma'am for giving me this opportunity to study this vaccine by the means of this assignment. The completion of this assignment would not have been possible without her guidance. Bibliography: The information and pictures for this assignment have been taken from the following sources: wikipedia.org who.int nhs.uk nbci.nlm.nih.gov unsplash.com Illustration drawn with Ibis PaintX.