Spatio-temporal dynamics of antibiotic-resistant ESKAPE bacteria in the man-made lake of Ayamé 1 (Côte d’Ivoire)

Background: The man-made lake of Ayamé 1 in southeastern Côte d’Ivoire (197 km^²) provides key socio-economic services but faces pressures from population growth, pollution, and water level fluctuations, leading to environmental degradation in related to the growing resistance of ESKAPE bacteria. 
Aim: This study analyzed the spatio-temporal dynamics of antibiotic-resistant ESKAPE bacteria in relation to the physicochemical water quality parameters in the lacustrine ecosystem of Ayamé 1, with a view to assessing the potential hazard to public health and the environment to address the problem of antimicrobial resistance and in particular, the potential link between the use of antimicrobial agents and the development of resistance among these pathogens.
Study Design:  Six campaigns were carried out at two stations (Témin site (S1) and Ayamé 1 site (S2)) distributed along the lake, during the dry season (low water) and the rainy season (high water), in order to meet different hydrological conditions. 
Methodology: From March to July 2024, physicochemical parameters, water and biofilm samples were collected each two weeks at the beginning (T0), 15 days after (T15) and 30 days after (T30) at two stations (Ayamé and Témn). Bacteria isolation was performed on selective and differential culture media. Identification was based on colonial morphology, Gram staining, and a battery of biochemical tests. Antibiotic susceptibility testing (AST) was conducted following the CA-SFM recommendations based on the bacterial species tested, using a panel of antibiotics from drug classes.
Results: The physicochemical parameters of Ayamé 1 man-made lake showed no statistically significant differences between stations or between seasons (Kruskal-Wallis, p > 0.05), with temperature, pH, dissolved oxygen, and conductivity remaining broadly uniform. Only nutrient concentrations were higher during the dry season at both stations, reflecting a reduced dilution effect. Findings showed that Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus were the most represented species in water samples, with maximum proportions of 96.86%, 89.53%, and 63.83%, respectively. In biofilms, Klebsiella pneumoniae decreased at station Ayamé 1 site (S2) from 25.28% at T0 to 1.15% at T30, whereas a strong increase was observed at station Témin site (S1), from 50.57% to 98.82%. Staphylococcus aureus occurred at low levels, while Pseudomonas aeruginosa, Escherichia coli, and intestinal enterococci were consistently less abundant. Regarding resistance profiles, Acinetobacter baumannii exhibited 100% resistance to penicillins, cephalosporins, quinolones, and sulfonamides, while remaining fully sensitive (100%) to carbapenems. Enterococcus faecalis showed complete resistance (100%) to sulfonamides and quinolones, with partial sensitivity to carbapenems (50%) and aminoglycosides (50%). Klebsiella pneumoniae demonstrated 100% resistance to penicillins and sulfonamides, but retained full sensitivity (100%) to carbapenems, cephalosporins, aminoglycosides, and fosfomycin. Pseudomonas aeruginosa presented 100% resistance to sulfonamides and intrinsic resistance to third-generation cephalosporins, yet remained fully sensitive (100%) to carbapenems, aminoglycosides, and quinolones. Finally, Staphylococcus aureus was entirely sensitive (100%) to penicillins, cephalosporins, aminoglycosides, and quinolones, but resistant to sulfonamides and fosfomycin (100%). These findings highlight a significant public health risk associated with bacterial exposure in the Ayame 1 man-made lake (Côte d’Ivoire). Strengthening sanitation, regulating human activity, and educating fisherfolk are vital to safeguard the lake’s ecosystem.