Heavy Metals Help Superbugs Hatch in Sewage

By Paula MeltonCombining heavy metals and excreted antibiotics in wastewater is a formula for breeding antibiotic-resistant “superbugs,” according to a study presented to the American Chemical Society. The scientists found that copper alone, without any antibiotics, increases resistance to ciprofloxacin in bacteria, while zinc amplifies resistance to tetracycline. Tetracycline with no metals caused 44% of bacteria to become resistant, and tetracycline plus zinc caused 68% of bacteria to become resistant. Heavy metals are prevalent in industrial wastewater, and domestic wastewater tends to contain high levels of antibiotics: mixing the two in treatment plants is a common but risky practice, according to the researchers. Previous studies have established that copper could increase antibiotic resistance in microbes living in soil, according to Chemical & Engineering News, but scientists have yet to determine whether the effects of heavy metals are passed on genetically to subsequent generations of microbes.