Uses of Antibiotics
Antibiotics are used in medicine to treat diseases that are caused by bacteria, while some are also effective against fungi and protozoa. The majority of bacteria are harmless to human body but the rest of them are pathogenic and responsible for numerous diseases and infections through out the world many of which are still fatal in some parts of the world, especially in Subsaharan Africa. Bacteria were also responsible for one of the deadliest pandemics in human history the Black Death in the Middle Ages. The pandemic of bubonic plague that was caused by bacterium Yersinia pestis caused about 70 millions of dead worldwide.
Bacteria are large group of unicellular microorganisms which are invisible with the naked eye. There are many species of bacteria which are either harmless or pathogenic in human body. Pathogenic bacteria are usually divided on Gram-positive which have no outer membrane and Gram-negative bacteria in which outer membrane is present. Most pathogenic bacteria in human body are Gram-negative microorganisms, while only six Gram-positive bacteria are pathogenic in humans. Either way, any pathogenic bacterium is harmful for human health and if left untreated it can be fatal. As other unicellular organisms bacteria grow and reproduce extremely fast, in ideal environment doubling in every 20 minutes what means that one bacterium can produce several millions bacteria in 24 hours.
Bacterial infections can be treated with antibiotics which either eliminate the bacteria (bacteriocidal) or inhibit their growth (bacteristatic). There are many different types of antibiotics which are used for treatment of diseases caused by bacteria which also distinguish themselves by the effective range. Antibiotics that eliminate or block the growth of particular bacteria are commonly referred as the narrow-spectrum antibiotics, while antibiotics which target wider range of bacteria are known as broad-spectrum antibiotics.
Besides humans bacteria also affect animal and plants. For that reason antibiotics are besides in medicine for treatment of bacterial infections also used in agriculture to treat or prevent diseases of animals and plants what greatly contributed to the resistance of bacteria against some prescribed antibiotics in humans.