Identifying Currently Unaddressed Fluoroquinolone Antibiotic Complexes in Ground Water Systems

Fluoroquinolones, a class of powerful antibiotics, enter the environment via waste water effluent and soil applications of human sludge, or agricultural manure. The persistence of fluoroquinolones may pose a threat to aquatic organisms and promote bacterial resistance. Such negative impacts of fluoroquinolone contamination on the environment as well as public health demand that these bioactive components\u27 environmental fate and transport pathways be clearly defined. According to pharmaceutical literature, metalfluoroquinolone complexes are likely stable within soils and waste waters. Furthermore, metalfluoroquinolone complexes often have increased antimicrobial activity relative to the fluoroquinolones alone. However, minimal research has been conducted regarding the role metal-fluoroquinolone complexes may play in environmental systems. Results of previous research done in our laboratory showed that cadmium (Cd; a heavy metal found in animal wastes), Ciprofloxacin (a common veterinary fluoroquinolone antibiotic) and P-nitrophenol (PNP; an herbicidal degradation product) readily combine to form a temary complex. Current work extends to other transition metals (Fe, Cu, Zn) and various chlorinated nitrophenols, which stem from degradation of herbicides that are often chlorinated. Results point to the likely formation of both soluble and insoluble temary complexes. Iron, the most prevalent transition metal in natural waters, appears to form the sole soluble temary complex. Experiments involving the chlorinated nitrophenols are ongoing. Since the base forms of the nitrophenols appear to be required for complex formation, the lower pka values of chlorinated versus nonchlorinated nitrophenols ought to ensure the reactivity of these pesticide degradation products over the range of natural water pH