What are sulfa drugs?

          Sulfa drugs are synthetic chemicals that are used to treat many diseases caused by bacteria. The first sulfa drug was developed by a German bacteriologist, Gerhard Domagk, in 1930. He showed through experiments that a sulfa drug called Prontosil could kill streptococcus bacteria. Sulfanilamide was the active chemical in Prontosil which killed the bacteria. Since that time, scientists have experimented with thousands of similar chemicals, but only about 20 of these are being used as medicines. 

          How do sulfa drugs control the bacterial diseases? Sulfa drugs operate by interfering with the normal metabolism of the bacteria cells. All living cells need folic acid to grow and reproduce. Human beings and many other animals get folic acid from their food. Bacteria, however, make their own folic acid. For this most bacteria need a chemical called para-amino benzoic acid (PABA). Chemically sulfa drugs and PABA are almost the same. The only difference between the two is that the sulfa drugs have sulphur atoms whereas PABA has carbon atoms. Bacteria cannot make out the difference between the two and absorb sulfa drug. This prevents the production of folic acid. Without folic acid bacteria cannot grow and reproduce. Thus, the sulfa drugs do not actually kill the bacteria, but keep them away from reproducing and allow the body’s own defence to kill them.

          Unfortunately, the sulfa drugs do not act on all the bacteria that cause diseases. However, they are very effective in the treatment of pneumonia and meningitis. They have little effect on tuberculosis bacteria. Moreover, they are toxic and cause many side-effects such as nausea and skin blisters. Although these medicines are found in common use but the antibiotics have been proved more effective. The sulfa drugs and antibiotics save thousands of lives every year, throughout the world.