Study of Drinking Water Quality of Kathmandu Metropolitan Areas and Evaluation of Antibacterial Property of Some Medicinal Plants Against Isolated Enteric Bacteria

Abstract

Present study was carried out to evaluate the quality of drinking water of the Kathmandu Metropolitan Areas in period of October2005 to November 2006.A total of one hundred and fourteen water samples with thirty eight each from three different sources namely stonespouts, taps and tube wells were collected. The physico-chemical and microbiological analysis of the samples were conducted. The pH of14.91 % of water samples were found to be below WHO guideline value. Similarly 24.56%, 26.32% and 31.58% of water samples were found to exceed WHO guideline value for conductivity, turbidity and iron content respectively. Hardness and the chloride content of all water samples were within the guideline value whereas22.81% of samples crossed ammonia permissible level. The nitrate content of all samples except one tube well sample was found within permissible level.Similarly,seven water samples(6.14%)exceeded the WHO guideline for arsenic level in the study.The bacteriological analysis of water samples revealed the presence of total coliformin90.35% of total samples (tube well-97.37 %, tap-73.68% and stone spout-100 %). Ten different kinds of enteric bacteria were isolated from the total contaminated samples.Among the isolates,Citrobacterspp (26.22%) was found to be maximum followed by Escherichiacoli (25%), Enterobacter spp (20.73%), Shigella spp(8.54%), Proteus vulgaris(7.93%)Pseudomonas aeruginosa(3.66%),Salmonella paratyphi(3.05%)Klebsiellaspp(2.44%),Proteus mirabilis (1.83%) and Salmonella typhi (0.61%). The water analysis data showed significant positive correlation between conductivity and hardness values for all water source types. Similarly,conductivity correlates significantly with chloride for tube well and stones pouts. The findings also showed a significant positive correlation of conductivity with nitrate, ammonia and iron in tap water and conductivity with nitrate in stone spouts. The turbidity and iron values for tap water exhibited significant positive correlation. Eight different medicinal plants were screened and evaluated for their antimicrobial activity against the enteric bacteria isolated from water on the basis of their common use among the different ethnic groups for common disorder.Among them,Punica granatum, Wood for diafruticosa, Psidium guajava and Syzygium cuminiwere found to be effective against all entericbacteria where as Mimosa pudica, Acorus calamus, Aegle marmelos and Anethum so wawerefoundto beineffective against all. The minimum bactericidal concentration (MBC) of these plant extracts found against Salmonella typhi,Salmonella paratyphi,Proteus mirabilis and Proteus vulgaris were lower(0.39-25mg/ml) so are more susceptible whereas the plants showed lethal effect against Pseudomonasspp, Citrobacterspp, Enterobacterspp, E. coli,Shigellaspp. and Klebsiellaspp. at MBC value ofaround25-50mg/ml. Key words:water,enteric bacteria,medicinal plants, minimum bactericidal concentration