Mine Spills and Antibiotic Resistance: What is the Connection? Jean E. McLain, Associate Director and Research Scientist University of Arizona Water Resources Research Center 2 nd Annual Conference on Environmental Conditions of the Animas and San Juan Watersheds June 22, 2017
Outline What is antibiotic resistance? Correlations between resistance and heavy metal concentrations Case studies Need for enhanced monitoring
Antibiotic Resistant Bacteria The ability of a bacterium to prevent an antibiotic from adversely affecting that isolate, strain, or group.
Antibiotic Resistant Bacteria The ability of a bacterium to prevent an antibiotic from adversely affecting that isolate, strain, or group. Horizontal Gene Transfer confers antibiotic resistance in response to selective pressure Clinical settings High antibiotic dosages
Antibiotic Resistant Bacteria Earliest antibiotics: naturally produced (e.g., Penicillin)
Antibiotic Resistant Bacteria Earliest antibiotics: naturally produced (e.g., Penicillin) Antibiotic resistant bacteria isolated from deep terrestrial subsurface (>250 m deep caves) and prehistoric (120,000+ YBP) ice cores
Antibiotic Resistant Bacteria Earliest antibiotics: naturally produced (e.g., Penicillin) Antibiotic resistant bacteria isolated from deep terrestrial subsurface (>250 m deep caves) and prehistoric (120,000+ YBP) ice cores Resistance genes evolved in absence of selective pressure from humans Competition for scarce resources
Antibiotic Resistance 2,000,000 infections and more than 23,000 deaths per year in the United States alone World Health Organization: one of the most critical human health challenges of the next century
Natural occurrence, though relatively scarce in the Earth s crust iron, copper, tin, silver, gold, platinum Some required for biological processes (e.g., iron) Heavy Metals Many are hazardous as contaminants (e.g., lead, nickel)
Natural occurrence, though relatively scarce in the Earth s crust iron, copper, tin, silver, gold, platinum Some required for biological processes (e.g., iron) Heavy Metals Many are hazardous as contaminants (e.g., lead, nickel) Leaching with sulfuric acid extracts and condenses heavy metals
Heavy Metals and Antibiotic Resistance Natural processes for bacterial tolerance to heavy metals are the same for antibiotic resistance
Heavy Metals and Antibiotic Resistance Natural processes for bacterial tolerance to heavy metals are the same for antibiotic resistance Peer reviewed literature Strong correlations between metal abundance and levels of antibiotic resistance Problem metals include mercury, cadmium, copper, and zinc
Gold King Mine Spill August 2015. EPA estimates that 540 tons of metals entered the river. Mostly iron and aluminum, also manganese, copper, lead, arsenic, zinc, cadmium
Gold King Mine Spill August 2015. EPA estimates that 540 tons of metals entered the river. Mostly iron and aluminum, also manganese, copper, lead, arsenic, zinc, cadmium
Gold King Mine Spill August 2015. EPA estimates that 540 tons of metals entered the river. Mostly iron and aluminum, also manganese, copper, lead, arsenic, zinc, cadmium Effects on antibiotic resistance in environmental bacteria = UNKNOWN
Case Studies 1978: Long Island (New York) and New Jersey shoreline Dumping ground for sewage sludge, acid wastes Numbers of antibiotic-resistant Bacillus isolates were directly correlated to heavy metal waste (mercury); 6X higher in dumping sites
2012: Shanghai, China Soils collected from multiple feedlots Case Studies Significant positive correlations between bacterial resistance genes and copper, mercury, and zinc Noted that metals do not degrade and thus, risk does not lower with time
2004: Iron-oxidizing bacteria isolated from acid mine drainage in Australia Tolerant to cadmium, copper, and arsenic Case Studies Levels of resistance to ampicillin, chloramphenicol, kanamycin, and tetracycline were correlated with presence of metals
Resistance Related to Gold King Mine Spill Effects of heavy metals antibiotic resistance in environmental bacteria = UNKNOWN
Resistance Related to Gold King Mine Spill Effects of heavy metals antibiotic resistance in environmental bacteria = UNKNOWN Potential risk is very real bathing, irrigation, drinking water for humans and animals
Resistance Related to Gold King Mine Spill Effects of heavy metals antibiotic resistance in environmental bacteria = UNKNOWN Potential risk is very real bathing, irrigation, drinking water for humans and animals Environmental monitoring would protect human health education programs to enhance awareness of any risk
Jean McLain mclainj@email.arizona.edu Questions?