Title: Antibiotic Resistance Profiles and Prevalence of Aeromonas in Post-chlorinated Wastewater and Surrounding Recreational Beaches
Name: Anthony Craig
Primary Presenters: Anthony Craig
College of Health Sciences
Masters
Faculty Sponsor(s): Dr. Troy Skwor

Antibiotic Resistance Profiles and Prevalence of Aeromonas in Post-chlorinated Wastewater and Surrounding Recreational Beaches

1 Anthony Craig, 1 Max Blumenthal, 1 Anamarie Lynn Leduc, Barbara Mayo, 1 Troy Skwor
1 Department of Biomedical Sciences, University of Wisconsin – Milwaukee, Milwaukee, WI, USA

Antibiotic resistance (ABR) has presented significant and growing problems for both global human health and the world economy. Approximately 2.8 million ABR infections occur each year, resulting in 35,000 deaths and an annual $3 trillion-dollar loss in global domestic product. Aeromonas is an environmentally ubiquitous, highly adaptable, pathogenic organism and has been implicated in the dissemination of ARGs in the environment. ABR Aeromonas is detectable across the wastewater pathways and effluent recipients; however, the prevalence and ABR profiles of Aeromonas in potential downstream receiving environments, such as recreational beaches, remains poorly characterized. To address this, we assessed prevalence and ABR profiles of Aeromonas from potentially impacted sand samples in Milwaukee, WI and compared it to post-chlorinated (POC) wastewater from Milwaukee, WI. Dislodging and water filtration followed by colony counting and Kirby-Bauer disk diffusion methods were used to accomplish these aims. Aeromonas, on average, represented 47.6% ± 6.6% of culturable bacteria across all 3 beaches examined. We found that Aeromonas isolates from POC samples showed significantly higher amounts of resistance to amoxicillin/clavulanic acid (89% to 25%), cefazolin (93% to 63%), nalidixic acid (45% to 0%) and sulfamethoxazole/trimethoprim (18% to 5%) compared to beach isolates. While 52% of POC isolates displayed multi-drug resistance (MDR), only 1% of beach sand isolates displayed MDR. Although most beach isolates displayed low ABR levels, few isolates displayed intermediate resistance to gentamicin, tetracycline, chloramphenicol, and meropenem. Importantly, one beach isolate displayed resistance to cefotaxime, a 3rd generation cephalosporin. It remains unclear if ABR Aeromonas on the beach comes from WWTPs, however, our results suggest Aeromonas represents the majority of culturable bacteria in this environment. This work underscores the need for further research addressing the risk that POC WWTP effluents pose for human health in the context of potentially pathogenic, ABR Aeromonas infection acquired from recreational beaches.