Bacillus Calmette-Guérin (BCG) is a bacterium that was developed by Frenchmen Albert Calmette and Camille Guérin. It is used in some countries as an effective live vaccine against some forms of tuberculosis, but is also considered a promising immunotherapy in the fight against bladder cancer. Especially in children, Bacillus Calmette-Guérin positively influences the course of tuberculosis and prevents serious complications.
What is Bacillus Calmette-Guérin?
The bacterium Bacillus Calmette-Guérin, developed by continuous repeated breeding, belongs to the phylum Mycobacteria. The bacterium originally came from a cow that had contracted tuberculous mastitis. After it was discovered by Edmond Nocard in 1901, Frenchmen Albert Calmette and Camille Guérin continued the research. They cultured the strain of the mycobacterium in nutrient media and observed an attenuation of the infectious power. Thus, starting in 1921, the attenuated-virulent Bacillus Calmette-Guérin was successfully used as a live vaccine against tuberculosis and was genetically further developed. The vaccination is administered as a live intracuneiform vaccine, but cannot prevent infection or further spread of the tuberculosis germs. Today, BCG can protect children in particular against some forms of tuberculosis disease. However, its effectiveness is not sufficient against the most common form of tuberculosis, pulmonary tuberculosis, either in children or in adults. BCG vaccination, on the other hand, reliably prevents complications of tuberculosis, such as miliary tuberculosis or tuberculous meningitis, which are especially feared in children.
Occurrence, distribution, and characteristics
Tuberculosis (TB) is an infectious disease caused by bacteria. Different types of TB bacteria cause different courses of the disease. The most common type of TB is transmitted through the respiratory tract and causes a focus of infection in the lungs. Although tuberculosis is curable today with [antibiotics]], it can lead to complications – especially in immunocompromised patients – that are life-threatening. In the course of the disease, other organs such as the meninges, pleura, bones, urinary tract and skin can also be affected by the bacteria. The contagious infectious disease is transmitted primarily by airborne droplet infection. The Mycobacterium bovis tuberculosis pathogens can also be passed to humans through raw cow’s milk. About one-third of the world’s population carries tuberculosis. However, a healthy immune system can prevent the outbreak of the disease and also protects against infection. Frequent travelers should get tested regularly by a doctor
Significance and function
In the medical community today, the effectiveness of BCG vaccination is considered controversial. Several reasons account for this. Because its efficacy cannot be proven with certainty, the Standing Commission on Vaccination (STIKO) at the Robert Koch Institute has not recommended the use of the bacterium as a vaccine in Germany since 1998. The vaccine protection by the BCG vaccination could be proven in meta-analyses in only 50 percent of pulmonary tuberculosis cases in this country. Also due to frequently occurring undesirable side effects and complications, the vaccine is currently no longer licensed for this indication in Germany. Furthermore, altered test results have been observed in patients who were once vaccinated with the Bacillus Calmette-Guérin. In these patients, a positive test result is frequently observed in the tuberculin skin test, even in cases in which there is no tuberculosis infection. In addition, only a swelling larger than 15 mm in diameter is considered positive. Because the significance of a tuberculin skin test is limited, specialists in Germany use the gamma interferon blood test as an alternative for patients with BCG vaccination to detect an infection. In other countries, however, the use of the Bacillus Calmette-Guérin is considered reasonable, since in some cases different epidermiological conditions occur here. Those planning long-term stays in these countries should therefore undergo vaccination with BCG. However, BCG vaccination is not effective in people living in tropical and subtropical areas. Experts suspect that the reason for this lies in the immunity that the inhabitants have built up against the mycobacteria species that are widespread there.
Diseases and ailments
Since 1976, Bacillus Calmette-Guérin has been used successfully to combat bladder cancer. Many patients require effective immunotherapy after surgical removal of a tumor in the urinary bladder. It is intended to prevent a possible recurrence of this disease and also to stimulate the body’s own cells to fight the tumor. The cancer patient receives the prepared live BCG bacteria as an instillation directly into the bladder. BCG instillation is performed through a thin catheter that passes through the urethra. After about two hours, during which the solution remains in the bladder, the catheter is removed. Since the Bacillus Calmette-Guérin causes a local inflammation there, the body’s own defense cells can be activated in this way. If patients tolerate this treatment well, a total of six BCG treatments are administered at weekly intervals. Immunotherapy generally causes no side effects and elicits only a two-day bladder inflammation and brief flu-like symptoms, which are considered typical side effects of the treatment.
