Incidence Of Bacteria Of Public Health Importance In Drinking Water From Water Dispenser Systems In Homes And Offices In Lagos And Ibadan, Nigeria
F Ezekiel, O Abolade, O Adeniyi, O Motunrayo
coliform, water, water dispenser machine
F Ezekiel, O Abolade, O Adeniyi, O Motunrayo. Incidence Of Bacteria Of Public Health Importance In Drinking Water From Water Dispenser Systems In Homes And Offices In Lagos And Ibadan, Nigeria. The Internet Journal of Microbiology. 2008 Volume 7 Number 1.
The isolation and characterization of bacteria in drinking water samples from 11 water dispenser machines was carried out. The water samples were obtained from five homes in Ibadan, Oyo state and eight offices in Victoria Island, Lagos state.Twenty-five bacteria were isolated. They include
Water of good quality is of basic importance to human physiology and man’s continued existence depends very much on its availability (Lamikanra, 1999; FAO, 1997a and b). Before water can be described as portable, it has to comply with certain physical, chemical and microbiological standards, which are designed to ensure that the water is palatable and save for drinking ( Tebutt, 1983). Portable water is defined as water that is free from diseases producing organisms and chemical substances deleterious to health (Ihekoronye and Ngody, 1985). The effects of drinking contaminated water results in thousands of deaths every day, mostly in children under five years in developing countries (WHO, 2004). In addition, diseases caused through consumption of contaminated water, and poor hygiene practices are the leading cause of death among children worldwide, after respiratory diseases (WHO, 2003). Thus lack of safe drinking water supply, basic sanitation and hygienic practices is associated with high morbidity and mortality from excreta related diseases. Diarrhea illness remains a major killer in children and it is estimated that 80% of all illness in developing countries is related to water and sanitation; and that 15% of all child deaths under the age of 5 years in developing countries result from diarrhea diseases (WHO, 2000, 2004; Thompson and Khan, 2003).
There are many types of pollutants that can contaminate drinking water and cause illness and disease. Regardless of where drinking water comes from - a lake, a river, an underground aquifer, a well, a public water utility, and even bottled water - all can be contaminated by a number of impurities.
The pathogens most frequently transferred through water are those which cause infections of the intestinal tract (Pelczar
The Safety of Bottled Drinking Water
While the term
There has been a substantial increase, in recent years, in the use of water coolers and water dispensing machines in the workplace and even in some homes. Whilst these machines have a place, under certain circumstances, in providing suitable refreshment to people, their use is not without hazard and in many cases the perception of need for these machines is misguided. One of the main hazards associated with the use of bottled dispensers relates to the manual handling of the bottles themselves. The Health and Safety Executive and some Trades Unions have highlighted the number of over three-day absence injuries contributed to by the activity of bottle changing, this task often being left to the slightly built female secretary who has had no training in safe lifting techniques. The aims and objectives of this work are to ascertain the presence of bacteria of public health significance (enteric) from drinking water from water dispensers, to isolate and characterize the isolates and to recommend ways of improving the microbiological safety of the water dispenser systems.
Materials And Methods
Collection of Samples
The water samples were collected from five dispenser machines from homes in Ibadan, Oyo State and six dispenser machines from offices in Victoria Island, Lagos using sterile bottles. The samples were brought into the laboratory for analysis.
Sterilization of Apparatus and Culture Media.
All glass wares used were thoroughly washed with detergent and rinsed with water. They were air dried, wrapped in aluminium foil and sterilized in hot air oven at 170oC for 2 hours.
All culture media used were prepared according to manufacturer’s specification, homogenized and sterilized by autoclaving at 121 C for 15 minutes.
Culture Media Used
The culture media used for this research include Eosin Methylene Blue Agar, Plate Count Agar, MacConkey Agar, Salmonella Shigella Agar and Nutrient Agar.
Total Heterotrophic Bacterial Count
Plate Count Agar (PCA) was prepared, homogenized and sterilized according to the manufacturer’s specification. 1ml each serial dilution of the samples were placed in a sterile Petri dish. 15mls of the molten PCA was poured into the plate and swirled to mix with the sample. The mixtures were allowed to set and then incubated at 35oC for 48hours. Counting was done with Gallenkamp Colony Counter.
Total Coliform Count
MacConkey Agar (MCA) was prepared, homogenized and sterilized according to the manufacturer’s specification. 1ml each serial dilution of the samples were placed in a sterile Petri dish. 15mls of the molten MCA was poured into the plate and swirled to mix with the sample. The mixtures were allowed to set and then incubated at 35oC for 48hours. Counting was done with Gallenkamp Colony Counte
Characterization of Isolates
Characterization of isolates was carried out by
employing macroscopic, microscopic, physiological,
The API 20E kit is a standardized miniaturized version of conventional procedures for the identification of Enterobacteriaceae and other Gram negative rods. It is a microtube system designed for carrying out 21 standard biochemical tests on bacterial colonies isolated on plating media.
Principle of API 20E system
The API 20E strip consists of 20 microtubes containing dehydrated substrates. These tests are inoculated with a bacterial suspension that reconstitutes the media. During incubation, metabolism produces colour changes that are either spontaneous or revealed by the addition of reagents. The reactions are read according to the reading table and the identification is obtained by referring to the Analytical Profile Index or using the identification software.
The table below shows the 20 tests and the reactions involved in each test.
Interpretation of Results
Identification was carried out with the use of numerical profile. The numerical profile for each test isolate was looked up in the Analytical Profile Index supplied by the Kit manufacturer.
The water samples collected from the bottled water before being fixed on the dispenser machines showed no growth of any bacteria on the culture media. The results of the analysis of the water samples collected from the dispenser outlets are discussed below.
The total heterotrophic bacterial count on Plate Count Agar and the coliform bacterial count on MacConkey Agar is shown in Table 2. The mean values of the heterotrophic counts range between 63 x 10-2 cfu/ml and 272 x 10-2 cfu/ml. The mean values of the coliform counts range between 26 x 10-2 cfu/ml and 162 x 10-2 cfu/ml.
A total of 25 bacteria were isolated from the water samples collected from a total of 11 dispenser machines in Lagos and Ibadan. These include the following;
Discussion And Conclusion
Determining the bacterial quality of drinking water is the single most important water quality test, because one glass of water containing just a few disease initiating organisms can cause illness. When minimal exposure creates an immediate health risk, that factor is known as an
The total coliform test is the basic yardstick for determining a water supply's biological quality. This test is performed frequently because of the risk that disease causing organisms pose to health.
The public health effects of some of the coliforms isolated from the drinking water in this work are discussed as follows.
The result of this work showed that contamination of the drinking water is from the dispenser machine and not from the source of the water, therefore it is suggested that a maintenance agreement is entered into with the supplier of the equipment that will includes regular thorough cleaning of the internal and external components of the dispensers. Also, proper personal hygiene should be maintained by people using water dispenser machines like washing of hands after toilet breaks before handling and refilling of the dispenser water.