SEWAGE INDICATOR AND CULTURABLE ANTIBIOTIC-RESISTANT BACTERIA SHOW INCREASED CONCENTRATIONS IN URBAN STREET STORM RUNOFF AS COMPARED TO SUBURBAN STREET STORM RUNOFF

Urban surface water bodies receive combined sewer overflows (csos) during rain events. Csos are combined mixtures of both urban geographic runoff and household and commercial sewage, which contribute high levels of potentially harmful antibiotic-resistant bacteria into the receiving water bodies, thereby creating ecological and public health concerns. We examined culturable total and antibiotic-resistant bacteria concentrations in storm runoff in both urban and suburban streets (in both queens and nassau counties). Enterococcus (bacteria associated with the mammalian gut and used as a microbial sewage indicator) concentrations were calculated using idexx methods. Enterococcus concentrations differ significantly (p<0.05) between urban and suburban street runoff. Samples were cultured on four different media types using r2a media and r2a with one of three commonly used antibiotics added (sulfamethoxazole (smx), ampicillin (amp), and tetracycline (tet)), to determine concentrations and relative ratios of antibiotic-resistant bacteria. Total bacteria, smx resistant, amp resistant, and tet resistant bacteria, all increase by one order of magnitude between urban and suburban street runoff samples. Samples were also filtered for dna to examine broad bacterial presence based on 16s sequencing.