Tetracycline belongs to a family of broad spectrum antibiotics that inhibit bacterial protein synthesis through the prevention of the binding of amino acyl to transfer ribonucleic acid to the ribosome. Tetracycline exists in a wide variety of derivatives but only a few derivatives have a proven usefulness in clinical drug therapy. Apart from tetracycline itself, oxytetracycline, chlortetracycline, doxycline and minocycline are some of the derivatives in common use (Chopra & Howe 1978).
Apart from being an alternative therapeutic option in human beings, tetracyclines constitute a large percentage of drugs used in veterinary medicine. This implies that just as its use in therapy is predominant, so does its excretion into the environment. The potential effects of such environmental availability have been incriminated in the development in drug resistance (Patenaude et al 2008).
From water sources to the soil antibiotic resistant gram positive and negative bacteria have been isolated hence creating a novel and worrying phenomenon on the use of tetracyclines and other broad spectrum antibiotics in the treatment of diseases of bacterial etiology. Staphylococci are Gram positive cocci that are observable as grape like structures. These organisms are ubiquitous as they are known to be the causative agents of suppurative lesions.
Their ability to employ internal genetic mechanisms to develop resistance to a wide range of antibiotics has thrust them at the forefront of dreaded human pathogens. First isolated in human pyogenic lesions in 1871 by Von Recklinghausen and Pasteur in 1880, they became christened kokkos or a bunch of grapes in Greek. Generally these organisms are identified as yellow colonies in lesions and white on solid media. Properties linked to virulence included gelatin liquefaction, hemolysis, lipolytic activity, production of phosphatase, urease among others (Panniker, & Ananthanarayan 2006).
These organisms also produce enzyme coagulase and to a lesser extent ferment mannitol. While many other species in this genus are commensals on the human skin, Staphylococcus aureas is the most pathogenic and widely distributed. The Genus Escherichia consists of microorganisms that can be described as fucultatively anaerobic gram positive bacteria. They are rod shaped and are normal commensals of the gastrointestinal tract from where it may spread contagious diseases or block the gastrointestinal; tract.
In this genus, the species Escherichia coli is the most common (Roy et al 2007). The level and diversity of the Staphylococcus community in the environment is very large compared with Escherichia. To avoid the digression into repetitive analysis of the proportions of Staphylococcus and Escherichia, the proportionality ration of one between the two organisms was used to eliminate Escherichia and concentrate on Staphylococcus proportions in cultures with varying concentrations of a strong selective agent; tetracycline.