Introduction

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 et al., 2000). Most bacterial pathogens potentially transmitted by water infect the gastrointestinal tract and are excreted in the faeces of infected humans and other animals. However, there are also some waterborne bacterial pathogens, such as Legionella, Burkholderia pseudomallei and atypical Mycobacteria that can grow in water and soil.

The Safety of Bottled Drinking Water

While the term bottled water is widely used, the term packaged water is perhaps more accurate. Water sold in countries for consumption can come in cans, laminated boxes and even plastic bags. However, bottled water is most commonly sold in glass or disposable plastic bottles. Bottled water also comes in various sizes from single servings to large carbouys holding up to 80 litres.

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

Sterilization of Apparatus and Culture Media.

Culture Media Used

Total Heterotrophic Bacterial Count

Total Coliform Count

Characterization of Isolates

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.

Figure 1

Table 1: Various tests and Reaction involved in API-20E Kit.

Interpretation of Results

Results

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; Pseudomonas aeruginosa, Pseudomonas fluorescens, Chryseomonas luteola, Citrobacter freundii, Enterobacter sp., Cedecea sp., Citrobacter sp., Salmonella sp., Chromobacter violaceum, Providencia rettgeri, and Escherichia coli. Table 3 shows the frequency of occurrence of the isolates. Pseudomonas aeruginosa and Escherichia coli had the highest frequency of occurrence of 16 %

Figure 2

TABLE 2: TOTAL HETEROTROPHIC COUNT ON PLATE COUNT AGAR

Figure 3

TABLE 3: FREQUENCY OF OCCURRENCE OF ISOLATES

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 acute health risk. In contrast, a meaningful health risk from chemical contaminants such as arsenic, radon, or benzene, to name only a few, requires a long period of exposure, typically over many years.

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.