Bottled water brands are contaminated with multidrug resistant bacteria in Nairobi, Kenya

Introduction

Water is essential for the human body and mental functions^1–3 as well as for chronic disease prevention⁴. Water is essential for thermoregulation, protection and cushioning of body vital organs, as well as for breathing and transporting nutrients and oxygen throughout the body². It is not surprising therefore that water constitute 50–60% of the human body². Inevitably therefore, adequate total water intake of between 2 to 2.5 liters per day is recommended².

Achieving and maintaining good health requires the availability and consumption of clean, potable (drinkable) water. This requires that water must be devoid of pathogens, dissolved toxins, and disagreeable turbidity, odor, color and taste⁵. The current concerns about palatability and microbial and chemical contaminants in tap water⁶, have led to the proliferation in the consumption of bottled water reaching historical high accounting for billion gallons in consumption⁶. Bottled water offers a handy source of water for consumption both within and outside household settings. In developing countries such as Kenya, bottled water is habitually sold and consumed in hotel industries, markets places, streets, schools, and during mass gatherings such as wedding and spotting activities, workplaces, health care facilities, and emergency situations⁷. Unfortunately, bottled water is not always as sterile as perceived. Several reports are available showing contamination bottled water with heterotrophic bacteria and coliforms counts exceeding the national and international standards^8,9. Studies have isolated various bacterial contamination from bottled water such as Vibrio cholera and Salmonella spp.^10,11, Pseudomonas spp., Acinetobacter spp., Citrobacter spp. and C. violaceum⁹. As a result, several waterborne illnesses such as diarrhea account for significant morbidity and mortality among the young and the aged as well as immunocompromised populations^12,13.

The bottled drinking water in Kenya should meet the following minimum requirements: be free from pathogens and chemicals; clear (i.e. low turbidity); none saline and should not have offensive taste or smell¹⁴. The Kenyan Bureau of standard (KS EAS 153: 2014) reference criteria for packaged water requires the absence of total coliforms, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus faecalis, Shigella and Salmonella in 100 ml of water¹⁴. Microbiological contamination of drinking water can have an immediate and significant impact on human health and must therefore be analyzed frequently. Among the factors reported to influence the microbiological quality of bottled water include; material of bottles, color of bottles and the length of storage¹⁵. This study investigated the bacteriological quality of bottled water and the association with the processes and handling practices of water bottling companies sold in Nairobi Kenya.

Methods

Results

Discussion

Evaluation of bacteriological quality of bottled drinking water is important and urgent in Kenya given the current upsurge of different brands of bottled water, most of which are not regulated. This study was unique and among the first in Kenya to evaluate the role of the practices used by water bottling companies in relation to the bacterial quality of water in line with the WHO acceptability criteria. This was compared between those bottled waters approved and banned brands by Kenya Revenue Authority (KRA). The bacteriological quality of bottled water from approved brands was found to be better than those of banned brands. The total coliforms and fecal coliform present in 100 ml of water were detected cumulatively in 9.5% of all brands, and in 4% of KRA-approved and 17.6% of banned bottled water brands. The proportion of bottle water brands with unacceptable in line with WHO limits were lower than the 50% reported in Bangladesh²¹, 37.5% in India²², 26% reported in Nigeria¹⁶ and 25% in Nepal⁹. On the contrary, the proportion of unacceptable bottled water brands in our study was higher than the 4.6% reported in Tanzania²³ the 9% in Sri Lanka²⁴ and 0% reported in Saudi Arabia²⁵. Although KRA approval is based on tax payment rather than on scientific basis, the high number of KRA-banned bottled water brands points to the possibilities of ineffectiveness of the disinfection processes used in these brands. In a process likely to be mainly for financial benefit by the bottled water manufacturers, studies have cited the improper practice of filling the bottle directly from tap water and sealing it without any prior treatment as among the reasons responsible for higher brands of bottled water beyond the acceptable limits of bacteriological quality⁹. Longer storage periods, especially of already-contaminated bottled water, have been shown to worsen the bacteriological quality. As in many developing countries, the laxity by the government body responsible for monitoring the quality of bottled water has been shown to account for higher levels of bottled water brands with unacceptable microbiological limits⁹.

With regards to total plate count or heterotrophic bacteria, in this study, a total of 23.8% of the bottled water brands (40% KRA-approved and 60% banned brands) were contaminated. In other settings, higher percentages of between 20% to 100% of heterotrophic bacteria contamination of bottled drinking water have been reported^9,26,27. Studies have associated long storage duration with high levels of bacterial concentration mainly due to larger surface area for growth, higher temperature, and the nutrients arising in the container²⁸. This quantity of heterotrophic bacteria is shown to correlate with water pH. There were 35.5% of banned bottled water brands with a pH below the pH 6.5 minimum level recommended by WHO, which could account for the higher numbers of heterotrophic bacteria per milliliter detected in these brands. Similar results were also reported by Pant et al.⁹.

The presence of total coliforms and fecal coliforms in 4% KRA-approved and 17.6% KRA-banned bottled water brands exceeding WHO criteria is similar to that observed by other studies^23,29. This is worrying and a pointer to either poor water processing, introducing flakes of human skin or indigenously acquired by filling the bottles directly from the natural sources or taps²³.

E. coli (in 19.1%) was the most common bacteria found contaminating the bottled water brands. Others included Pseudomonas spp. (9.5%), Enterobacter spp. (4.8%), Klebsiella spp. (4.8%) and Proteus spp. (2.3%) and Aeromonas spp. (2.3%). In Nepal, Pant et al.⁹ isolated more of Pseudomonas spp. (87.5 %) and Acinetobacter spp. (87.5 %). In Iran Momtaz et al.,¹⁰ isolated E. coli, while in Brazil, Vasconcellos et al.³⁰ isolated Salmonella spp., and V. cholerae from bottled water.

Although all bacteria in our investigation were susceptible to ceftriaxone and ofloxacin, resistance to erythromycin, trimethoprim-sulfamethoxazole, doxycycline, tetracycline, gentamycin, chloramphenicol, kanamycin and ciprofloxacin were noted. Multidrug resistance (resistant to more than three drugs) in E. coli, Klebsiella spp. and Pseudomonas spp. from all bottle brands were also detected. The presence of different species of bacteria, including multidrug resistant strains, in supposedly bacteria-free bottled water is of important public health problem. Pathogenicity notwithstanding, their presence in bottled waters heavily consumed by those including the elderly, children and the immunocompromised, the hazards of contamination, and health risks to consumers should not be taken for granted^10,30.

This study incorporated a unique feature by investigating the manufacturing practices potentially associated with contamination of bottled water. In multivariable analysis, companies that used chlorine-based disinfectants for cleaning pipework/tankers and bottling equipment were less likely to have water brands exceeding WHO TCC limits compared to that that did not use any detergent for cleaning. Zamberlan et al.³¹ showed the importance of disinfection processes used by the water bottling companies as playing a key determinant of bacterial concentration in bottled water. In Nepal, Pant et al.⁹ showed that failure to disinfect water represents an important avenue for bacterial entry and colonization of water processing systems. Our study further showed that companies that had food safety programs, procedures for water sourcing and procedures for contamination protection were less likely produce bottled waters with unacceptable microbiological limits. As expected, if companies are set up in line with guidelines set by regulatory authorities, then the end product will be devoid or have a reduced microbial contamination. In this study, although more of companies producing approved brands had recommended water collection and transportation systems, water treatment procedures (filtration, UV and chlorination and reverse osmosis), packaged water using polycarbonate containers, used machine during bottling process, had batch tracing system, routinely tested their products according to the WHO guidelines and having recommended handling standard procedures than banned ones, these were not factors associated with the contamination of bottled water.

Our study had some limitations. First, due to limited resources available, the study could not process large enough numbers of the samples to include all brands sold in the country. Second, owing to the limited laboratory methods used, we were not able to identify all the potential pathogens that contaminated the water, including other pathogenic bacteria, viruses, fungi, and parasites. Third, the cross-sectional nature of our study only allowed us to describe associations between water company processes and procedures and bacterial quality and not a causal conclusion. Such outcomes can be confirmed in a longitudinal study. These limitations notwithstanding, one of the key outcomes of this investigation is the capacity to show that the perceived safe bottled water brands, including the top-selling and most expensive brands in Kenya, could be contaminated with bacteria beyond the WHO recommended limits. Additionally, some of these bacteria associated with significant disease outbreaks were multidrug-resistant. The study also showed that water bottling companies’ operations and processes are key avenue for bacterial water contamination. The Kenya Bureau of Standards is the Kenyan regulatory and monitoring authority for all water and packaged foods. Our results may suggest, however, that concerted efforts must be made to improve the ability of national governments to properly regulate and monitor these products which has been shown to improve product quality and safety^32,33.

Data availability