Antibiotics And Vaccines

                      Antibiotics And Vaccines  

Two important medicinal drugs are antibiotics and vaccines. 

 Antibiotics:

                  An antibiotic is a drug that kills or retards the growth (reproduction) of bacteria. They are the chemicals produced by or derived from microorganisms (bacteria and fungi)

Bactericidal and Bacteriostatic antibiotics:

                                                                  Antibiotics are used to treat many different bacterial infections. Some antibiotics are ‘bactericidal’, meaning that they kill bacteria. Others are ‘bacteriostatic’, meaning that they work by stopping bacterial growth. Antibiotics are among the most frequently prescribed medications in modren medicine.

Three major groups of antibiotics are described below:

1. Cephalosporins:

                             Cephalosporins interfere with synthesis of bacterial cell wall and so are bactericidal. Cephalosporins are used to treat pneumonia, sore throat, tonsillitis, bronchitis etc.

2. Tetracyclines:

                          These are broad-spectrum bacteriostatic antibiotics and inhibit bacterial protein synthesis. Tetracyclines are used in the treatment of infections of respiratory tract, urinary tract, intestine etc. Tetracyclines are not used in children under the age of 8, and specifically during periods of tooth development.

3. Sulpha Drugs - Sulfonamides: 

                                                                                 Sulpha drugs are synthetic antibiotics that contain sulfonamide group. Sulfonamides are broad spectrum bacteriostatic antibiotics. They inhibit the folic acid synthesis in bacteria. They are used to treat pneumonia and urinary tract infections. 

       Some  antibiotics can be  used to  treat a wide  range  of 

       infections and are called ‘Broadspectrum’ antibiotics. 

       Others are only effective against a few types of bacteria                        and are called ‘Narrowspectrum’ antibiotics.

Antibiotic Resistance:

                                 Antibiotics are extremely important in medicine, but unfortunately bacteria are capable of developing resistance to them. Such bacteria are not affected by commonly used antibiotics. Bacteria have number of ways of developing resistance. Sometimes, their internal mechanism stops the working of antibiotic. Bacteria can also transfer the genes responsible for antibiotic resistance between them. So such resistant bacteria make it possible for other bacteria to acquire resistance.

         Another reason for increasing antibiotic resistance in bacteria is their use in diseases in which they have no efficacy (e.g. antibiotics are not effective against infections caused by viruses). Resistance to antibiotics poses a serious and growing problem, because some infectious diseases are becoming more difficult to treat. Some of the resistant bacteria can be treated with more powerful antibiotics, but there are some infections that do not eliminate even with new antibiotics.

                Expired drugs can cause damage to kidneys.

 Vaccines:

                    A vaccine is a material containing weakened or killed pathogens and is used to produce immunity to a disease by stimulating the production of antibodies. In 1796, a British physician, Edward Jenner, infected a young boy with cowpox, by injecting pus cells. After the boy had recovered from cowpox, Jenner injected the pus cells from a smallpox patient into him. The boy did not get smallpox. So it became clear that intentional infection with cowpox protected people from smallpox.

 This method was named “vaccination” and the substance used to vaccinate was called a “vaccien”.

          

The Mode of Action of Vaccines:

Pathogens contain special proteins called “antigens”. When pathogens enter the body (blood) of host, these proteins stimulate the immune response in host i.e. synthesis of “antibodies”. Antibodies bind to pathogens and destroy them. In addition, “memory cells” are produced, which remain in blood and provide protection against future infections with the same pathogen. When a vaccine i.e. weakened or dead pathogen is introduced into bloodstream, the white blood cells are stimulated.

        B-lymphocytes recognize the weakened or dead pathogens as enemies and start producing antibodies against them. These antibodies remain in blood and provide protection against pathogens. If real pathogens enter blood, the already present antibodies kill them.