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ABSTRACT
This work was designed to study the effect of commercial antibiotics and herbal antimicrobials on development of resistant strain in the aquatic bacterial pathogens such as Vibrio harvi, Aeromonas hydrophila, Vibrio parahaemolyticus, Vibrio damselae and Vibrio angularium. The aquatic bacterial pathogens were treated with commercial antibiotics and partially purified herbal antimicrobials obtained from Adathoda zeylanica, Cynodon dactylon, Solanum trilobatum, Solanum surratense and Ocimum sanctum. The resistant strain developments in bacteria due to the treatment of antibiotic and herbal antimicrobials were studied by treating the pathogenic bacteria with Less than Threshold Concentration (LTC) of the antibiotics and herbal anti microbial for four subsequent treatments with uniform intervals. From this work, it was evidenced that apart from antibiotics, the herbal antimicrobials also induced resistant strain development in bacteria. The duration and concentration of treatment with commercial antibiotics and herbal antimicrobials were found effective for the development of resistant strain in bacteria. The commercial antibiotics and herbal antimicrobials when mixed and applied on bacteria, reduced the percentage of resistant strain development than applied them separately.
Keywords: Herbal Antimicrobials, Commercial Antibiotics, Resistant strain development, Aquatic pathogen, Threshold Concentration, Bio magnification.
INTRODUCTION
The use of herbals for drugs and dietary supplements derived from plants have accelerated in recent years. While 25 to 50% of current pharmaceuticals are derived from plants, none are used as antimicrobials. Traditional healers have long used plants to prevent or cure infectious conditions; western medicine is trying to duplicate their successes (Cowan,M.M, 1999). Plants are rich in a wide variety of secondary metabolites, such as tannins, terpenoids, alkaloids, and flavonoids, which have been found in vitro to have antimicrobial properties (Cowan,M.M, 1999).
Clinical microbiologists have two reasons to be interested in the topic of antimicrobial plant extracts. At first, it is very likely that these photochemicals will find their way into the arsenal of antimicrobial drugs prescribed by physicians; several among are already being tested in humans. It is reported that on average, two or three antibiotics derived from microorganisms are launched each year (Clark,1996). After a downturn in that pace in recent decades, the pace is again quickening as scientists realize that the effective life span of any antibiotic is limited. Worldwide spending on finding new anti-infective agents (including vaccines) is expected to...