Contamination of groundwater with sulfamethoxazole and antibiotic resistant Escherichia coli in informal settlements in Kisumu, Kenya
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Abstract
High frequency of antibiotic detection in groundwater in informal settlements is attributed to increased usage and improper disposal, thus difficult to identify sources of antibiotic resistance in the environment, worsened by inadequate sanitation facilities and increased population density, particularly in developing-countries. Reliance on groundwater exposes them to pollutants and risk of antibiotic resistance, in addition to experiencing inequities in accessing vital services. Sulfamethoxazole and trimethoprim, used for prophylaxis by HIV/AIDS patients were tested in 49 groundwater sources in Kisumu, Kenya. Only Sulfamethoxazole (SMX) was found, with a detection frequency of 14.3% and concentrations ranging from below limit of quantification (LOQ) to 258.2 ng/L. Trimethoprim (TMP), marketed in combination with sulfamethoxazole, was not detected, owing to its high distribution coefficient (kPa7.12) and, generally, being a bigger molecule with modest water mobility and solubility. Furthermore, TMP ratio in cotrimoxazole is low (5:1), it is expected that mass loading will be lower, as well as influence of the study area’s hydrogeology, where soil is clayey with high porosity and permeability. Escherichia coli was recovered in 98% (n = 48) of water samples, with counts ranging from 16 to 8,850 MPN/100ml. Additionally, resistance to sulfamethoxazole was identified in 6% (n = 3) samples with Inhibition Zone Diameters of 0.8mm(resistant), 10.5mm (resistant), and 11.5mm (intermediate), but not among samples where SMX was detected. Antibiotic concentrations in water that can cause resistance are unknown because antibiotic-resistant E. coli was not found in water samples where sulfamethoxazole was identified, raising concerns about f environmental resistance spread. Concentration of SMX was lower in a previous research, which only collected water from one groundwater source, than the current study, which included additional samples (49). Presence of SMX and Escherichia coli resistance is of concern and necessitates greater attention and regular monitoring for potential contaminants and resistance trigger to avert potential risks to human health.
Introduction
Proliferation of urban informal settlements is as a result of increased urbanization, which has an impact on the limited resources available like improved water and sanitation facilities [1]. This happens in Low and Medium income Countries, and at least 50% of the urban population reside in those types of settlements [2]. The settlements have seen increased levels of inequality and exclusion, and lack of access to opportunities, employment, health, education, technology, municipal services and private goods [2, 3], a recipe for social unrest. To compensate for water scarcity, informal settlement dwellers utilize the readily available groundwater through construction of boreholes and shallow wells [4], without necessarily subjecting the water any form of treatment.
Higher prevalence of infectious diseases in informal settlements is s major driver for increased antibiotic use, leading to increased demand for antibiotics due to low capacity to access information to make informed health choices particularly in developing nations [5]. Antibiotic use in the informal settlement was found to be 43%, with the majority acquiring antibiotics without a prescription for a qualified health practitioner, choosing to self-medicate, which may accelerate selection and spread of antibiotic resistant microbes [6]. Access to antibiotics in informal settlements without a prescription is easy, where the health practitioners are not necessarily qualified or are not competent [7]. The unqualified practitioners are likely not to recognize infections that require further medical attention, thus resort to dispense different types of antibiotics at a more expensive cost. In such cases, residents whose purchasing power is limited end up either buying part of the dose, that may also be counterfeit or low quality [7]. As a result, the cycle of antibiotic self-medication leads to poverty and also antimicrobial resistance in general.
The efficacy of any antibiotics used to prevent and treat bacterial infection is critical in current human health practice [8]. However, the rise in antibiotic use particularly in the informal settlements is a reason to worry about due to the way the antibiotics are disposed bearing in mind possible negative impact on the environment, particularly on human health, due to the unknown influence of active pharmacological compounds in the environment from numerous sources. Antibiotics detected in the environment are largely attributed to improper use and disposal practices, coupled with incomplete metabolism of the pharmaceuticals in the human body, resulting in their excretion in urine and feces either unchanged or as active derivatives [9]. Antibiotics have been discovered to pollute groundwater sources via leaching from sanitation facilities such as pit latrines, waste disposal facilities in the subsurface in places where the aquifer is shallow, and sensitive to rainfall recharge, all of which impair the region’s sanitation system [4]. Even at sub-optimal levels, cumulative continuous exposure to Active Pharmaceutical Ingredients (APIs) to non-target organisms may have detrimental eco-toxicological effects
It is also known that current antibiotic removal technologies are not economically viable [10], and for many countries around the world, is yet to be made a regulatory requirement, so this water is not necessarily subjected to any form of treatment before consumption, exposing residents to the novel risk of antibiotics and their derivatives in drinking water, and selection for resistance in the environment. Health protection in a polluted environment is critical because there is a complex connection between humans, animals, and the environment [11] interface that necessitates a one-health, multi-sector collaboration to obtain better public health outcomes.
The presence of antibiotics sulfamethoxazole (SMX) and trimethoprim (TMP) was investigated, as well as an antibiotic sensitivity test against Escherichia coli in groundwater sources. The World Health Organization recommends antibiotics for the prevention and treatment of infections in people living with HIV/AIDS [12]. Most infections, such as urinary tract infections (UTI) caused by enteric pathogen Escherichia coli and pneumocystis pneumonia caused by Pneumocystis jirovecii, can progress from asymptomatic to severe disease and death due to the increased susceptibility to disease in people living with HIV/AIDS [13]. This study location is reported to have a high HIV prevalence of 16.3% [14] (NACC, 2018) and the population is at risk of being exposed to antibiotic resistant Escherichia coli. It is also Sulfamethoxazole and trimethoprim are found together in a fixed dose of Cotrimoxazole, where each tablet includes 80mg Trimethoprim BP and 400mg Sulfamethoxazole BP, resulting in a 5:1 ratio [12]. Escherichia coli was also isolated from the water and antibiotic resistance determined.
Escherichia coli are generally harmless organisms that are members of the gut flora in both humans and warm blooded animals. They are also known to be an opportunistic pathogen and have been linked to intestinal illness, urinary tract infections, newborn meningitis, and gastroenteritis [15–17]. Contamination of water supplies by coliforms like Escherichia coli mostly is as a result of lack of adequate sanitation, which is a common phenomenon in informal settlements [18, 19]. The bacteria are reported as an indicator of fecal contamination in the assessment of water quality deterioration. There is however rising worry about the prevalence of antibiotic-resistant bacteria and antibiotic-resistant genes in aquatic environments, with industries, agriculture, and domestic antibiotic usage have all been identified as sources of aquatic pollution [20, 21]. Studies focusing on antibiotic resistance have concentrated in aquatic environments heavily contaminated with antibiotics as a result of activities like wastewater treatment and anthropogenic activities such as farming [22, 23]. Presence and spread of antibiotic resistance in natural water used for irrigation, aquaculture, recreation, drinking and other domestic purposes are ignored whereas the importance to human life is well known. The direct or indirect use of the water contaminated by antibiotic resistant bacteria could have an effect on the health of human beings, animals and contaminate the environment [24, 25].
The goal of assessing the extent of contamination in chosen informal settlements and antibiotic resistance is to enable for the evaluation of preventative measures for harmful health consequences especially among the HIV/AIDS patients whose immunities are compromised. This not only is of benefit to humans but also on animals and the general environment.
