1. Introduction
Antimicrobial resistance (AMR) is a serious public health problem, that threatens human health and can cause large economic losses. Infections caused by multidrug resistant bacteria challenge the hospital practices, since they may be associated with increased severity of infections and with a high mortality rate. Recently, in 2019, approximately 4.95 million deaths were associated to AMR, with 1.27 million directly attributable to multidrug resistant bacteria with the highest number recorded in western Sub-Saharan Africa, with 27.3 deaths per 100,000 population [
1]. Moreover, the economic cost of AMR will continually increase over the next 10 years [
2]. However, there are data gaps in many low-income settings, including Burkina Faso. ESBL and carbapenemase-producing
Enterobacterales, particularly
Escherichia coli (ESBL-
Ec) and
Klebsiella pneumoniae (ESBL
-Kp)
, contribute to exacerbate the AMR crisis in healthcare and community in low- and middle income countries (LMICs), due to their resistance to beta-lactams, commonly used antibiotics in treatment of bacterial infections [
4,
5,
6].
Estimated 131,109 tons of antimicrobials were used for food animals in 2013 [
5]. Since 2000 to 2017, the demand for animal protein in Africa has increased by 64%, driven by demand for protein-rich diets, consumer preferences and population growth, accelerating transfer to both more intensive and extensive animal production [
6]. With regard to livestock production in Africa, cattle accounted for 53% of the total population produced in 2017. The quantity of antimicrobials used for animal production was estimated at 4.279 tonnes [
7]. In Burkina Faso, cattle farming significantly contributes to rural households’ income, estimated at 71 to 115 million dollars [
8]. The intensification of animal production has led to an increased use of veterinary medicines including antimicrobials, accelerating the rise of AMR [
4,
8]. Antimicrobials are used to treat sick animals, but also for prophylaxis, as growth promoters and to compensate inadequate hygiene on the farm [
9]. The misuse or excessive use of antimicrobials contribute to the emergence and dissemination of resistant bacteria including resistant
Enterobacterales, which can be transferred to people through the food chain [
10]. ESBL production is one of the most common mechanisms of multidrug resistance in
Enterobacterales and occurrence of ESBL-producing bacteria on farms has been documented in many parts of the world [
11]. From African countries, the occurrence of ESBL-producing
Enterobacterales (ESBL-
E) in cattle have been reported, for example, from Egypt, Madagascar, Nigeria, South Africa and Tunisia [
12,
13,
14,
15,
16]. In Nigeria, the horizontal transfer of ESBL genes from cattle to slaughterhouse workers was reported [
17]. In Burkina Faso, ESBL-
E were previously isolated from farms, ESBL-
Ec and ESBL-
K being the most common isolates [
18]. Studies carried out in 2014 in three regional hospitals in Burkina Faso showed that 58% of enterobacterial isolates were ESBL producers and
E. coli and
Klebsiella pneumoniae were the most frequently isolated ones [
19]. However, data on the occurrence of ESBL-producing bacteria at the human-animal-environment interface on Burkinabe farms remains limited. Therefore, this study assessed the occurrence of ESBL-
Ec and ESBL-
K on farms near the capital city Ouagadougou, among cattle, farmers, their drinking water and soil using a One Health approach.
4. Discussion
Antimicrobial resistance poses a serious threat to health globally, and the World Health Organisation (WHO) classifies ESBL-
Ec and ESBL-
K among the highest priority pathogens [
21]. Multidrug-resistant
E. coli can be considered as indicator of antibiotic resistant bacteria in general, as
E. coli is a ubiquitous and commensal species in animals and can provide relevant indication of the spread of antibiotic resistance [
22]. Our study assessed the presence of ESBL-
Ec and ESBL-
K in animals, soil, humans and drinking water on two types of farms located in the semi-urban area in Burkina Faso. The study revealed that 58% of all the samples from farms yielded at least one ESBL
-Ec or ESBL
-K isolate. Researchers from other parts of Africa have reported lower rates, on the average 25% occurrence of ESBL-
Ec and ESBL-
K in animals, environment and humans in Egypt [
23], Nigeria [
17] , Ghana [
24] and in Uganda [
25]. Likewise, a study conducted in Rwanda among livestock, environment, community members and farm products showed a relatively low prevalence of 14.8% [
26]
. In Burkina Faso and other LMICs, the occurrence of resistant bacteria correlates with poor sanitation, close interactions with livestock, easy access and irrational use of antibiotics [
27]. Misuse of antibiotics in humans and animals has been documented in the literature to promote a selective increase in some bacterial populations as well as dissemination of resistant strains [
28].
In the cattle faeces, the detected prevalence of 85.3% was detected for ESBL-
Ec and/or ESBL-
K, which is higher than previously reported from Burkina Faso [
18] and Cote d’Ivoire [
29]. A study on cattle faeces reported 45.4% prevalence of ESBL
-Ec among animals in Nigerian slaughterhouses[
17]. In Ghana, the prevalence of ESBL
-Ec was 31% in cattle faeces [
30] and in Egypt 42.8%[
12]., while ESBL-
Ec and ESBL-
K prevalence on cattle farms were reported to be 76.4% in South Africa [
15]. In Burkina Faso, antibiotics are used by farmers to treat animals, for prophylactic purposes, and more critically, as growth promoters [
8] and, consequently, the selection pressure on commensal and pathogenic microorganisms has led to the proliferation of antibiotic resistant bacteria. These bacteria can be transferred to humans through direct contact with animals or indirectly via the food chain or environmental pollution from agricultural effluents [
31].
In the farmers’ stools, the prevalence of ESBL-
Ec and ESBL-
K was 76.5% and 25.0 %, respectively. Two previous studies carried out in Burkina Faso reported a prevalence of 22% and 53% of ESBL-
E in healthy volunteers, and 42% and 56% among inpatients [
32,
33]. Among slaughterhouse workers in Nigeria, 50% prevalence of ESBL-
Ec was detected [
34]. A study conducted among poultry workers in Nigeria reported as low prevalence as 2.7 % of ESBL-
Ec [
35]. Over the last 20 years, the prevalence of community-acquired ESBL carriage has increased tenfold worldwide, reaching 26% in 2016-2020 [
36]. Cumulative prevalence was highest in South-East Asia (35.1%, 95% CI, 10.3%–60.0%)and lowest in Europe (6.0%, 95% CI, 4.6%–7.5%) , whereas it was 21.4% (95% CI, 12.7%–30.1%)in Africa [
36]. Compared to these figures, the prevalence we detected in farmer’s stools is high. This could be due to common use of antibiotics on the studied farms and farmers being in contact with farm animals and sharing the same environment with them. Resistant bacteria can be transmitted between humans, cattle and their environment through contact with faeces or via the food chain, including raw milk and contaminated meat [
37]. Several studies have highlighted the potential contribution of poor hygienic practices, lack of personal protective equipment and an abundance of bacterial pathogens in the environment to contamination especially with ESBL
-Ec [
19,
36,
37,
38]
.
In drinking water collected from farmers’ taps our study found prevalence of 37.9 % of ESBL-producing bacteria. The prevalence of ESBL-
Ec was 7.6% and of ESBL-
K 33.3%. A study conducted in Kenya found an association between domestic animal presence and ownership and household drinking water contamination, reporting
approximately 70% of water samples to be contaminated by
enterococci in different peri-urban areas [
39]. The prevalence of ESBL-
K and ESBL-
Ec in the current study aligns with results from Ethiopia [
40], whereas a study in Nigeria reported a prevalence of 7.14% of ESBL-
E in drinking water sources [
41]. The general poor quality of drinking water in Ouagadougou was reported by a study on borehole water in the city, with 59% of water samples being contaminated by coliforms, including
E. coli, indicating faecal contamination [
42]. ESBL-producing
Proteus, Klebsiella spp and
Bacillus were isolated from the treated water, municipal water and raw water in a study in Nigeria [
43,
44]. Indeed, the spread of ESBL-
E via drinking water poses a serious health risk to consumers and can compromise empirical treatment of invasive infections such as urinary tract and bloodstream infections [
43].
ESBL-
Ec and ESBL-
K were also found in farm soil, with a prevalence of 47% and 19%, respectively. The recent study in Burkina Faso reported a prevalence of 28.0% and 36.0% of ESBL-
Ec and ESBL-
K in manure from cattle markets from two livestock markets [
45]. A study from Nigeria on ESBL-
Ec in drainage and washing water in slaughterhouses showed prevalence of 40% and 22%, respectively [
46]. The presence of ESBL-
Ec and/or ESBL-
K in slaughterhouses can lead to contamination of meat, which is a risk for consumers if good hygiene and proper cooking conditions are not respected. Livestock production wastewater, soil and manure from dairy and beef production can also add AMR genes and bacteria into the environment [
47]. Wastewater, humans, pets, domestic animals, and industry have all been identified as potential sources of resistant bacteria in the African environment [
48].
The present study also compared the prevalence of ESBL-
Ec and ESBL-
K on semi-intensive and traditional farms. The prevalence of ESBL-
Ec and/or ESBL-
K was 92% on semi-intensive farm and 85% on traditional farms, not a significant difference between these two types. This is possibly because cattle on semi-intensive farms also graze in the surroundings of the farm during the day. Our figures from the traditional farms are much higher than that reported from Tanzanian traditional cattle farm, where the prevalence was 10% [
49]. At the global level, in 2022, the prevalence of AMR varied between 18% and 28%, depending on the farming system [
50]. In comparison to these figures, the AMR on cattle farms in Burkina Faso seems very high. We can speculate that here animals that roam free in the environment are exposed to various AMR sources resulting from deficient sanitation and waste management, exposing free-roaming animals to eg. human and abattoir solid waste and wastewaters that contain resistant bacteria and antibiotic residues.
The multidrug resistance rates we detected were high, close to 70% of ESBL-
Ec and ESBL-
K isolates were multidrug resistant, with highest resistance rates against tetracycline and cotrimoxazole. Tetracycline and cotrimoxazole antibiotics are relatively cheap and readily available over the counter in LMICs. Tetracycline belongs to one of the most commonly used classes of antimicrobial agents in veterinary medicine due to their broad spectrum of activity [
29] and it contributed 63% of the quantity of antibiotics used in 2016, 11.6% in 2017, 31.7% in 2018 and 28.7% in 2020 [
7]. Our results showed that 3.1% of the animal faeces and 1.4% of the human stools contained ESBL-
Ec and ESBL-
K resistant to all the groups of antibiotics tested, except carbapenems. Carbapenems are used to treat serious human infections and their use is not licensed in livestock or veterinary fields [
51,
52]. However, One Health approach is needed to prevent dissemination of carbapenem resistance from humans to animals and the environment.
Author Contributions
Conceptualization, D.S., I.J.O.B., F.B.J.D K.H.; methodology, I.J.O.B., D.S., F.B.J.D and Z.G.; formal analysis, S.D., writing—original draft preparation, S.D.; writing—review and editing, D.S., I.J.O.B., K.H., F.B.J.D., Z.G, N.S., and N.S.S., E.B., M.E.M.N, supervision, Z.G. and I.J.O.B.; project administration, I.J.O.B.; funding acquisition, I.J.O.B and K.H. All authors have read and agreed to the published version of the manuscript.