Fecal Coliform Source Identification Using Chemical Tracers

Fecal sterols and fluorinated whitening agents (FWA) were used as chemical tracers for fecal coliform source tracking in Cane and Little Cane creeks in Walhalla, SC. Fecal sterols were quantifiable in both stream sediments and suspended particulates using an extraction, clean-up, and analytical method modified from Isobe et al. (2002) with a N,O-Bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization scheme. Only human sterol source identification ratios were able to be calculated using the chosen sterol suite. Human fecal signatures were seen in both the sediment and the water column at various points along both creeks, indicating human fecal pollution is contributing to the fecal coliform pollution. Because there was little deposition of sediment at sampling sites along the creeks and the sterol loading on suspended particulates was about the same or greater than that in the sediment, it is recommended that future studies on this system concentrate on quantifying fecal sterol loadings in the water column. Further, water column samples will provide an instantaneous picture of fecal loadings. Sediment samples are easier to process and may be useful for specific investigations. Results were compared to microbial source tracking (MST) methods by a collaborating researcher and showed consistencies for only some of the sample sites, which may have been due to false negatives or differences in sampling dates and matrices. FWA was never above presumptive sewage detection levels in the creeks even when sediment samples indicated some historical human fecal pollution at sites. Due to its specificity for human input and the apparent requirement of significant levels to give a positive signal, it is suggested that FWA analysis be discontinued unless a significant human fecal input is suspected. An expanded study is recommended to compare fecal sterols in the water column during base and storm flow using the method developed here and an expanded sterol suite to correlate fecal loadings with different sources in the watershed. Using this information, BMPs could be implemented with a focus on addressing actual fecal loadings. The method could also be used to help quantify surface water quality improvements after BMP implementation

Viability and Ecology Based tools for Studying Antibiotic Resistance

Over 2 million people are sickened and at least 23,000 people die in the U.S. of antibiotic resistant infections each year. Community acquired infections in humans have been linked with environmental sources of antibiotic resistance. Mitigating the risk of environmental AR infections requires understanding hot spots for AR as well as the potential for horizontal gene transfer. A series of case studies will be presented towards understanding hot spots of antibiotic resistance genes in viable cells

Fecal Coliform Bacteria TMDL Implementation on Cane Creek and Little Cane Creek in Oconee County, South Carolina

2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio

Mathematical modelling of antimicrobial resistance in agricultural waste highlights importance of gene transfer rate

Antimicrobial resistance is of global concern. Most antimicrobial use is in agriculture; manures and slurry are especially important because they contain a mix of bacteria, including potential pathogens, antimicrobial resistance genes and antimicrobials. In many countries, manures and slurry are stored, especially over winter, before spreading onto fields as organic fertilizer. Thus these are a potential location for gene exchange and selection for resistance. We develop and analyze a mathematical model to quantify the spread of antimicrobial resistance in stored agricultural waste. We use parameters from a slurry tank on a UK dairy farm as an exemplar. We show that the spread of resistance depends in a subtle way on the rates of gene transfer and antibiotic inflow. If the gene transfer rate is high, then its reduction controls resistance, while cutting antibiotic inflow has little impact. If the gene transfer rate is low, then reducing antibiotic inflow controls resistance. Reducing length of storage can also control spread of resistance. Bacterial growth rate, fitness costs of carrying antimicrobial resistance and proportion of resistant bacteria in animal faeces have little impact on spread of resistance. Therefore effective treatment strategies depend critically on knowledge of gene transfer rates

Fate and transport of tylosin-resistant bacteria and macrolide resistance genes in artificially drained agricultural fields receiving swine manure

Application of manure from swine treated with antibiotics introduces antibiotics and antibiotic resistance genes to soil with the potential for further movement in drainage water, which may contribute to the increase in antibiotic resistance in non-agricultural settings. We compared losses of antibiotic-resistant Enterococcus and macrolide-resistance (erm and msrA) genes in water draining from plots with or without swine manure application under chisel plow and no till conditions. Concentrations of ermB,ermC and ermF were all \u3e 109 copies g− 1 in manure from tylosin-treated swine, and application of this manure resulted in short-term increases in the abundance of these genes in soil. Abundances of ermB, ermC and ermF in manured soil returned to levels identified in non-manured control plots by the spring following manure application. Tillage practices yielded no significant differences (p \u3e 0.10) in enterococci or erm gene concentrations in drainage water and were therefore combined for further analysis. While enterococci and tylosin-resistant enterococci concentrations in drainage water showed no effects of manure application, ermB and ermF concentrations in drainage water from manured plots were significantly higher (p \u3c 0.01) than concentrations coming from non-manured plots. ErmB and ermF were detected in 78% and 44%, respectively, of water samples draining from plots receiving manure. Although ermC had the highest concentrations of the three genes in drainage water, there was no effect of manure application on ermC abundance. MsrA was not detected in manure, soil or water. This study is the first to report significant increases in abundance of resistance genes in waters draining from agricultural land due to manure application

Increasing temperature and pH can facilitate reductions of cephapirin and antibiotic resistance genes in dairy manure slurries

Quantifying antibiotics and antibiotic resistance genes (ARGs) in manure exposed to various temperature and pH treatments could guide the development of cost-effective manure handling methods to minimize the spread of antibiotic resistance following land application of manure. This study aimed to investigate the effect of various temperatures and initial pH shocks on the persistence of a cephalosporin antibiotic and ARGs in dairy manure slurries. Feces and urine were collected from five healthy dairy cows administered with cephapirin (cephalosporin antibiotic) at dry-off via intramammary infusion, and mixed with sterile water to generate manure slurries. In a 28-day incubation study, dairy manure slurries were either continuously exposed to one of three temperatures (10, 35, and 55ºC) or received various initial pH (5, 7, 9, and 12) shocks. Cephapirin was detected in the initial samples and on day 1 following all treatments, but it was undetectable thereafter. This indicates that cephapirin can be rapidly degraded irrespective of temperature and pH treatments. However, degradation was greater on day 1 with the mesophilic (35ºC) and thermophilic (55ºC) environments compared to the psychrophilic environment at 10ºC (P < 0.001). Increasing pH beyond neutral also accelerated degradation as cephapirin concentrations were lower on day 1 after initial alkaline adjustments (pH 9 and 12) than neutral and acidic adjustments (pH 7 and 5; P < 0.001). No significant effect of temperature or initial pH was observed on abundances of a beta-lactam ARG, cfxA, and a tetracycline ARG, tet(W), implying that bacteria that encoded cfxA or tet(W) genes were not sensitive to temperature or pH in dairy manure slurries. However, abundances of a macrolide ARG, mefA, were decreased in the psychrophilic and thermophilic environments, and also following exposure to a strong alkaline shock (pH 12). Our results suggest that increasing temperature or pH during storage of dairy manure slurries could be used together with other on-farm practices that are tailored to reduce the transfer of ARGs from manure to the environment following land application

Microplastics in Mediterranean coastal area: toxicity and impact for the environment and human health

The so-called marine litter, and in particular microplastics (MPs) and nanoplastics (NPs), are ubiquitously distributed and recognised as an emerging risk for the environment and human health. It is known that marine environments are one of the most impacted areas and among them; coastal zones are the most contaminated ones. They are subjected to population pressure, tourism, harbours, desalination plants, marine traffic and fish farms. This review is focused on the Mediterranean Sea, currently considered one hot spot of microplastics pollution in the world, as a consequence of the high number of plastic marine litter generating activities and its characteristic morphology of semi-enclosed sea. MPs and NPs have been detected not only in surface water and water columns but also in sediments, deep seafloor, and biota including fish and seafood for human consumption. Because of this, different European legislation initiatives have been launched during the last years in order to prevent MPs and NPs contamination and to face derived problems. Finally, this review summarises the main problems and shortcomings associated to MPs and NPs analyses such as their identification and quantification or the necessity of standardised protocols.Postprin