Antibacterial effect of Costus spiralis leaves extract on pathogenic strains of Vibrio cholerae

The use of remedies from plant origin covers a wide variety of maladies and constitutes an alternative way to antibiotic therapy, which otherwise seems to be no longer promising due to antibiotics widespread resistance among pathogenic microorganisms. Active principles having antimicrobial activity may be extracted and purified from plants for developing new drugs. Among several illnesses that have historically scourged man, Cholera has been potentially epidemic and one of the most outstanding. The bacterium Vibrio cholerae, the causal agent, can be eliminated with antibiotics so that besides the traditional treatment of rehydration via oral or intravenous, antibiotics such as tetracycline, ciprofloxacin, norfloxacin or azithromycin are commonly applied. The antimicrobial effect of Costus spiralis (Roscoe) leaves extracts on various pathogenic strains of Vibrio cholerae was assayed in vitro by means of the agar plate diffusion technique. Fresh leaves from this plant were picked up, ovendried for 48 h at 50 oC, powdered and finally ethanol-extracted. After drying, the remaining residue was suspended in distilled water up to 100 mg/mL (w/v) and the antimicrobial assays carried out. The pathogenic strains representing the pandemics of the 20th Century: C7258 (O1, El Tor, Ogawa), C6706 (O1, El Tor, Inaba), O395 (O1, Classic, Ogawa), CRC266 (O139) and 569B (O1, Classic, Inaba) were apparently killed, as judged by halos of inhibition of growth in the assays. Furthermore, minimal inhibitory concentrations (MICs) of the extracts for the various strains were also attempted. The above results were similar to those from Ampicillin, suggesting that Costus spiralis may be used as a source of active principles against Vibrio cholerae. INTRODUCTION Knowledge on medicinal properties of plants has extensively been applied all over the World to cure or ameliorate suffering of mankind. The use of remedies from plant origin covers a wide variety of maladies and constitutes an alternative way to antibiotics, which is otherwise no longer promising due to the generalized antibiotic resistance among pathogenic microorganisms.1 Theoretically, active principles having antimicrobial activity can be extracted and purified from plants for developing new drugs.2,3 Among several illnesses that have historically scourged man, Cholera has been potentially epidemic and one of the most outstanding. It is characterized by life-threatening secretory diarrhea with voluminous watery stools, often accompanied by vomiting, and resulting in hypoglycemic shock and acidosis.4 The bacterium Vibrio cholerae, the causal agent, can be eliminated with antibiotics so that besides the traditional treatment of rehydration via oral or intravenous, antibiotics such as tetracycline, ciprofloxacin, norfloxacin or azithromycin are commonly applied.5 The World Revista CENIC Ciencias Biológicas, Vol. 39, No. 1, 2008. 71 Health Organization recommends antibiotics treatment only in cases of severe dehydration.6 The risk of the illness is currently higher in underdeveloped areas, with no enough sanitary conditions, unsuitable or non-existing water purification systems and elimination of residual waters. Although cholera has effectively been treated everywhere and even vaccination developed, plant medicines must be considered, mostly in such areas where the above strategies might not be available. In fact, there are several reports elsewhere concerning the matter.3,7 The medicinal properties of Costus spiralis have been used for treating a wide variety of illnesses, mostly dealing with the urinary tract and kidney disturbances.8 This report intends to demonstrate the antimicrobial effect of Costus spiralis on Cholera. Here are the results of an in vitro antimicrobial assay from leaves extract of this plant on pathogenic strains of Vibrio cholerae, which represent the pandemics of the XX Century. MATERIALS AND METHODS Microorganisms The epidemic strains of Vibrio cholerae were used throughout this study. Table 1 shows the corresponding phenotypes.