Factors that influence the distribution of antibiotic resistant bacteria in the Mud River, West Virginia

Prior studies of the Ohio and Mud Rivers have shown that fecal contamination alone does not explain the distribution of antibiotic resistant bacteria (ARB) in surface waters. Water samples and physical parameters were collected twice per season in spring through fall at 12 sites on the Mud River. Aliquots were plated on R2A agar and R2A agar plus individual antibiotics for the enumeration of total cultivable bacteria, and cultivable bacteria resistant to ciprofloxacin, virginiamycin, or tetracycline respectively. The IDEXX Quanti-Tray/2000(TM) method was used to enumerate total coliforms, E. coli, and antibiotic resistant E. coli (AREc). Atomic absorption spectrometry was used for heavy metals analysis. Storm water runoff significantly increased the load of E. coli, which was always far below ARB, and ARB in surface waters, which were higher under conditions of lower dissolved oxygen/temperature and higher conductivity. Strong associations between ARB and urban/paved areas and pastures were observed.