Bacteriological Quality and antimicrobial susceptibility of some isolates of Well Waters Used for Drinking in Jimma Town, Southwest Ethiopia

Well waters could be polluted with fecal materials due to inadequate protection, depth of wells, distance and position relative to latrine ho use, unhygienic practice at the source and poor environmental sanitation. The objectives o f this study were to assess the current bacteriological safety of well waters being used for drinking and other domestic uses; and also to evaluate the antibiotic susceptib ili y patterns of bacterial species isolated from some of the wells in Jimma town, sout hwestern Ethiopia. Accordingly, bacteriological quality and safety, as well as phys ico-chemical properties of water samples collected from 30 purposively selected well s were assessed following the standard microbiological methods. Pure isolates wer e characterized to species level using API 20 E kit and evaluated for resistance pat terns towards ten antimicrobial agents being used for human medication. The finding of the study showed that the mean pH (6.646.8) of all the studied well water sample s was within acceptable range (pH= 6.5-8.5), while the mean temperature was not. Likew ise, the mean microbial counts (cfu/ml) of the samples were beyond the value recom mended by World Health Organization. Accordingly, the mean count (cfu/ml) of aerobic mesophilic bacteria (AMB) was 908 (360 – 1490), while those of Entrobac teriaceae and coliforms were 332 and 234, respectively. A total of 15 representative bacterial species including Aeromonas hydrophilia (3), Enterobacter cloacae(1), Serratia liqueofaciens(1), Enterobacter sakazaki(1), Serratia marcesense(1), Klebsella orit hinolytica(4), and Escherichia coli(1) were identified to species level. All isolates were sensitive to Amikacin (AK), Norfloxacin (Nx), Kanamycin (K), Bacitracin (B) and Tetracyclin (T). On the other hand, all isolates were resistant to Methicillin (M) and Pencillin G ( P). Stains of Klebsella ornithinolytica showed the highest resistance against most of the a ntibiotics tested. In general, the well water samples analyzed in this study were found in unacceptable condition in terms of bacteriological quality. Moreover, the identificati on of Escherichia coli in some of the wells indicates the safety problem of the water for human consumption. Therefore, it calls for proper disinfection and monitoring of the water sources besides awareness creation to the well owners. Key words/phrases: Antimicrobial sensitivity, Bacte riological safety, Jimma, Well water Department of Biology, College of Natural Sciences, Jimma University, P. O. Box 378, Jimma, Ethiopia *Ketemabacha2002@yahoo.com Tel: +251917800789 Ethiop. J. Educ. & Sc. Vol. 6 No 2 INTRODUCTION Well water is one of the potential sources for human consumption. Over 15 million U.S. households regularly depend on private ground water wells (U.S. Census Bureau, 2008). In developing countries, the share of well water could be even higher. For instance, 37.4% of households have access to piped water sources in Benin (Balk et al., 2003). However, improperly constructed or poorly maintained wells and well water could be the source of some waterborne diseases. Many diseases like diarrhea, gastroenteritis, keratoconjunctivitis, respiratory infections, and hepatitis are associated with viruses, often found in environmental samples including groundwater, surface water, and costal water (Borchardt et al., 2003, Borchardt et al., 2004; Xagoraraki et al., 2007). Pathogenic bacteria such as Salmonella spp. , Shigella spp. , pathogenic Escherichia coli, Vibrio cholerae, Yersinia enterocolitica, Campylobacter jejuni, and Campylobacter coli can contaminate a drinking water via fecal material, domestic and industrial sewage and agricultural and pasture runoff (Geldreich, 1991: Wiggins, 1996). If water used for drinking or bathing contains sufficient numbers of pathogens such as Pseudomonas aeruginosa and species of Flavobacterium, Acinetobacter, Klebsiella, Serratia, Aeromonas and certain slow-growing non-tuberculous mycobacteria, they can create several infections of the skin and the mucus membranes of the eye, ear, nose and throat (WHO, 1993). Recent report by Verheyen et al. (2009) showed the possible isolation of viruses from well water. About 80% of the disease cases in developing countries are attributed to inadequate sanitation and use of polluted water (Epstein et al. 1994). Similarly, about three-quarter of the health problems of children in Ethiopia are communicable diseases arising from the environment, specially water and sanitation (http://www.unicef.org/ethiopia/wes. html ). The most communicable wide spread health risk associated with drinking water is microbial contamination (WHO, 1993). Thus, it is necessary to make a regular test the safety status of water being used for drinking and domestic uses. Water test could be done for the four most common indicators of trouble: bacteria, nitrate, pH, and total dissolved solids (TDS). Access to potable drinking water is not dependable in Jimma town. Despite the availability of pipe lines for tap water in the majority of the households, people get water in a very intermittent condition. The poor access to safe water could be due to inconsistency in water supply and/or total lack of access to treated water for one or many reasons. Therefore, some population of the town, especially those living on peripheral part of the town are highly dependent on private well waters for various purposes such as cleaning utensils, washing clothes, bathing and drinking. This fact necessitates evaluation of the magnitude of risks associated with frequent dependence on well water. To this effect, this study was conducted to assess the bacteriological quality and safety of well water being used for drinking in Jimma town and also to determine the current antimicrobial sensitivity patterns of the isolates. MATERIALS AND METHODS Description of the study area The study was conducted in Jimma town, located 353 km southwest of Addis Ababa. The town has an area of 220 Km . It is located at 07 39’ latitude, 3650’longitude, Bacteriological Quality Hussen Ali, Ketema Bacha and Tsige Ketema and altitude ranging between 1700-1750 meter above sea level. Preliminary survey Socio-demographic data of the study population and the current status of wells and well water being used for different purposes were gathered through administration of pre-designed structured questionnaire (with both open and closeended questions) and interview. Well water owners in Jimma town were selected purposely and a total of thirty well waters were assessed in this study. The study was conducted from February to June, 2010. Sample collection and processing About 100ml water samples from each 30 purposely selected wells were collected using sterile flask of 250 ml capacity . From each well, water samples were collected twice during the study period, making a total of sixty samples. Physico-chemical analysis The temperature and pH of well waters were determined on the spot of sampling using thermometer and digital pH meter (HANNA-211 meter, Portugal), respectively. Microbiological Analysis From appropriate dilution (1:10), 0.1ml of aliquots were spread plated in duplicate on pre-dried surfaces of plates of Violet Red Bile Agar (Oxoid), Plate Count Agar (Oxoid), and MacConkey agar (Oxoid) for the counts of coliforms, aerobic mesophilic bacteria and members of the family Enterobacteriaceae, respectively. Colonies were counted after the plates were incubated under aerobic condition at 3032C for 24 hours. Purplish red colonies surrounded by reddish zone of precipitated bile were counted as coliforms. Pink to purple mucoid colonies were enumerated as members of