Michael C Dodd

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Antibiotic resistance genes (ARGs), in association with antibiotic resistant bacteria (ARB), have been identified as widespread contaminants of treated drinking waters and wastewaters. As a consequence, concerns have been raised that ARB or ARG transport between aquatic compartments may enhance the spread of antibiotic resistance amongst non-resistant(More)
Ozone and hydroxyl radical (*OH) reaction kinetics were measured for 14 antibacterial compounds from nine structural families, to determine whether municipal wastewater ozonation is likely to result in selective oxidation of these compounds' biochemically essential moieties. Each substrate is oxidized by ozone with an apparent second-order rate constant,(More)
Kinetics and mechanisms of As(III) oxidation by free available chlorine (FAC-the sum of HOCl and OCl-), ozone (O3), and monochloramine (NH2Cl) were investigated in buffered reagent solutions. Each reaction was found to be first order in oxidant and in As(III), with 1:1 stoichiometry. FAC-As(III) and O3-As(III) reactions were extremely fast, with(More)
A wide variety of antibacterial compounds is rapidly oxidized by 03 and hydroxyl radical (*OH) during aqueous ozonation. Quantitative microbiological assays have been developed here or adapted from existing methods and utilized to measure the resulting changes in antibacterial potencies during O3 and *OH treatment of 13 antibacterial molecules(More)
Sulfamethoxazole (SMX)--a member of the sulfonamide antibacterial class--has been frequently detected in municipal wastewater and surface water bodies in recent years. Kinetics, mechanisms, and products of SMX in reactions with free chlorine (HOCl/OCl-) were studied in detail to evaluate the effect of chlorination processes on the fate of sulfonamides in(More)
Trimethoprim (TMP), one of the antibacterials most frequently detected in municipal wastewaters and surface waters, reacts readily with free available chlorine (i.e., HOCl) at pH values between 3 and 9 (e.g., the pH-dependent apparent second-order rate constant, k''(app)=5.6 x 10(1)M(-1)s(-1), at pH 7). Solution pH significantly affects the rate of TMP(More)
OBJECTIVE To estimate performance of a single-nucleotide polymorphism-based noninvasive prenatal screen for fetal aneuploidy in high-risk and low-risk populations on single venopuncture. METHODS One thousand sixty-four maternal blood samples from 7 weeks of gestation and beyond were included; 1,051 were within specifications and 518 (49.3%) were low risk.(More)
OBJECTIVE This study aims to develop a noninvasive prenatal test on the basis of the analysis of cell-free DNA in maternal blood to detect fetal aneuploidy at chromosomes 13, 18, 21, X, and Y. METHODS A total of 166 samples from pregnant women, including 11 trisomy 21, three trisomy 18, two trisomy 13, two 45,X, and two 47,XXY samples, were analyzed using(More)
Previous work demonstrates that widely used fluoroquinolone antibacterial agents, including ciprofloxacin, are degraded by means of aqueous ultraviolet photolytic and titanium dioxide (TiO(2)) photocatalytic (using both ultraviolet-A (UVA) and visible light (Vis) irradiation) treatment processes. In this study, we investigate the effects of photolytic and(More)
Kinetics, products, and mechanistic aspects of reactions between free available chlorine (HOCl/OCl-), ciprofloxacin (CF), and enrofloxacin (EF) were extensively investigated to elucidate the behavior of fluoroquinolone antibacterial agents during water chlorination processes. Although the molecular structures of these two substrates differ only with respect(More)