Occurrence of antibiotic-resistant bacteria in household greywater discharged into the environment in Burkina Faso's Sahel region

The prevalence and antibiotic resistance of Salmonella spp. and Staphylococcus spp. from greywater were investigated in Africa's Sahel region, Burkina Faso. A total of 36 and 56 isolates of Salmonella spp. and Staphylococcus spp. were isolated from greywater, respectively. From the Salmonella spp. isolates, resistance was most frequently observed against vancomycin (69%), ampicillin (61%), cefoxitin (42%), trimethoprine/sulfamethoxazole (36%), amoxicillin-clavunal acid (33%) and tetracycline (33%). For all Staphylococcus spp. isolates, the highest rate of resistance was against penicillin (55.36%) followed by oxacillin (48.21%) and clindamycin (30.36%). In addition, 75% of the isolated Salmonella spp. strains were resistant to at least two antibiotics of different families, while 30.35% of Staphylococcus spp. strains were multidrug-resistant (MDR). Overall, this is one of the first studies reporting the presence of MDR bacteria in untreated greywater discharged from domestic activities in Burkina Faso. Our results show that untreated greywater can contain bacteria resistant to antibiotics used in therapeutic care. Therefore, uncontrolled discharge of untreated greywater into the environment could lead to the dissemination of resistant bacteria and resistance genes in the environment and increase the risk of human exposure to antimicrobial resistance.