National Survey of Stream Water Quality Revealing Threats to Antibio-Resistant Bacteria, Antibiotic Residues and Heavy Metals in Benin

Benin's waterways are affected by several forms of pollution that are linked in particular to anthropic activities. This study aims to detect the presence of antibiotic residues, the frequency of antibiotic resistant bacteria and the levels of heavy metals in Benin's waterways. 160 surface water samples from streams in Benin were collected. They were filtered by the membrane filtration method, then incubated on different media. The isolated bacterial species were identified by API 20E gallery and specific biochemical tests. After detection of the resistance profile of the latter, the antibiotic residues were quantified in the samples by the ELISA technique on plate and the physicochemical analyses were performed by Multi 3630 IDS SET KS2 multimeter. Finally, heavy metal levels were detected by the MERCK test kit method specific to each metal. The bacterial species mostly identified were Klebsiella pneumoniae (56.59%), Klebsiella spp. (18.68%), Enterobacter spp. (12.63%). The most abundant resistance of bacterial strains was to amoxicillin + clavulanic acid (92%), followed by metronidazole (86%). Metronidazole was the antibiotic with the highest residue concentration in the samples (6.578 to 6.829 mu g/L), followed by ciprofloxacin (2.142 to 9.299 mu g/L). Benin streams contain heavy metals such as mercury (0.454 +/- 0.129 mu g/L), lead (0.040 +/- 0.50 mg/L), zinc (6.120 +/- 16.017 mg/L), nickel (0.155 +/- 0.233 mg/L) and cadmium (0.154 +/- 0.132 mg/L). The analysis of the physico-chemical parameters showed that, apart from electrical conductivity, all parameters comply with Beninese and World Health Organization standards. Actions must be taken to clean up these rivers to preserve the integrity of aquatic ecosystems in Benin.