1 INTRODUCTION OF
Antibiotics, in today’s most up-to-date therapeutic armamentarium, occupy strategically the most coveted and key position during the span of past half-century across the globe. This conglomeration of drugs affords an effective management and critical control of a host of deadly human related pathogenic microorganisms which previously caused pathetic prolonged human sufferings orultimately leading to death irrespective of the physical condition, age factor or economic status of an individual.
The word ‘antibiotic’ has been coined from the term antibiosis that evidently means ‘against life’ (anti—against and bios—life).
Over the years various versions of ‘definitions’ for an antibiotic have been postulated which are enumerated as under.
The most widely accepted definition of an antibiotic accepted by the scientific jargons is—‘a chemical substance produced by a microorganism, that has the capacity, in low concentration, to inhibit or kill, selectively, other microorganisms.’ This definition lays particular emphasis on the terminology ‘selectivity’ or ‘selective toxicity’ that explicitly suggests that the substance either checks the growth of pathogens or exerts a bactericidal action on the microbes without displaying a likewise action on the host organism i.e.., the human beings.
The above definition clearly excludes the compounds having the pure synthetic genesis (origin).
However, in a rather broader perspective these ‘synthetic substances’ are virtually treated at par with the natural compounds along with their corresponding derivatives under the terminology ‘antimicrobials’ which may be further categorized into antifungals and antibacterials based on the particular type of microbe undergoing inhibition. Hence, in order to circumvent the practical aspects, both the terminologies viz., ‘antibiotic’ and ‘antimicrobial’ may be employed interchangeably irrespective of the particular source of the compound.
Even in the ancient and primitive era, dating back to 2500 years, the anti-infective characteristic features of fungi and moulds usually observed in various food products like: mouldy bread, yoghurt, and soybean curds, and other similar materials to wounds and boils to curb their infection. This sort of age-old treatment one may regard as a folk-medicine style of antibiotic therapy.
It is, however, pertinent to mention here that the real impetus and legitimate recognition of the antibiotics in the so called ‘modern drugs’ was virtually accomplished by the famous french scientist Louis Pasteur. The epoch making introduction of pyocyanase interestingly extracted from Pseudomonas aeruginosa as a prominent therapeutic agent under the ‘antibiotics’ is indeed one of the greatest achievements in the history of medicine. This event was immediately followed by another historic invention of Alexander Fleming for the drug penicillin; and the subsequent antimicrobial activity of Penicillium notatum discovered by Chain Florey and his co-workers.
In fact, the most effective and wonderful class of life saving antibiotics comprise of a plethora of active substances that are found to be effective on either Gram +ve or Gram –ve micro-organisms; besides the ones that are invariably known as the broad-spectrum antibiotics.
In general, the antibiotics are produced on a large scale by three known methods, namely:
(a) fermentation process; (b) semi-synthetic process; (c) synthetic process. Recently, with the advent of a tremendous quantum jump and diversification in the specific field of ‘biotechnology’, the first two processes stated above have not only gained an enormous increase in the rate of production but also improved their yield and purity. Nevertheless, the fermentation process is further categorized into two types: (a) surface method; (b) submerged method. It is worthwhile to mention here that the second method has a much greater efficiency limit and hence used commercially. Over the years, a vast number of altogether newer, purer, and high-yielding microbial strains have been developed, tried and tested for evaluating their antibiotic yielding strength besides the efficiency in their extraction.
