Impact of biochar on plant growth and uptake of ciprofloxacin, triclocarban and triclosan from biosolids.

Application of municipal biosolids in agriculture present a concern with potential uptake and bioaccumulation of pharmaceutical compounds from biosolids into agronomic plants. We evaluated the efficacy of biochar as a soil amendment to minimize uptake of antimicrobial agents (ciprofloxacin, triclocarban, and triclosan) in lettuce (Lactuca sativa) and carrot (Daucus carota) plants. Biochar reduced the concentration of ciprofloxacin and triclocarban in lettuce leaves and resulted in a 67% reduction of triclosan in carrot roots. There was no substantial difference in pharmaceutical concentrations in carrot and lettuce plant matter at low (2.0 g kg-1 soil) and high (20.4 g kg-1 soil) rates of applied biochar. The co-amendment of biochar and biosolids increased soil pH and nutrient content which were positively correlated with an increase in lettuce shoot biomass. Our results demonstrate the potential efficacy of using walnut shell biochar as a sorbent for pharmaceutical contaminants in soil without negatively affecting plant growth.

The Widely Used Antimicrobial Triclosan Induces High Levels of Antibiotic Tolerance In Vitro and Reduces Antibiotic Efficacy up to 100-Fold In Vivo.

The antimicrobial triclosan is used in a wide range of consumer products ranging from toothpaste, cleansers, socks, and baby toys. A bacteriostatic inhibitor of fatty acid synthesis, triclosan is extremely stable and accumulates in the environment. Approximately 75% of adults in the United States have detectable levels of the compound in their urine, with a sizeable fraction of individuals (>10%) having urine concentrations equal to or greater than the minimal inhibitory concentration for Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). Previous work has identified connections between defects in fatty acid synthesis and accumulation of the alarmone guanosine tetraphosphate (ppGpp), which has been repeatedly associated with antibiotic tolerance and persistence. Based on these data, we hypothesized that triclosan exposure may inadvertently drive bacteria into a state in which they are able to tolerate normally lethal concentrations of antibiotics. Here we report that clinically relevant concentrations of triclosan increased E. coli and MRSA tolerance to bactericidal antibiotics as much as 10,000-fold in vitro and reduced antibiotic efficacy up to 100-fold in a mouse urinary tract infection model. Genetic analysis indicated that triclosan-mediated antibiotic tolerance requires ppGpp synthesis but is independent of growth. These data highlight an unexpected and certainly unintended consequence of adding high concentrations of antimicrobials in consumer products, supporting an urgent need to reevaluate the costs and benefits of the prophylactic use of triclosan and other bacteriostatic compounds.

Solid lipid nanoparticles for targeted delivery of triclosan into skin for infection prevention.

Healthcare-associated infections (HAIs) are a concern for health service providers, exacerbated by poor delivery of antimicrobials to target sites within the skin. The dermal route is attractive for local and systemic delivery of drugs, however; permeation, penetration, and access to deeper skin layers are restricted due to the barrier function of the stratum corneum (SC). Solid lipid nanoparticles present several benefits for topical delivery for therapeutic applications, especially via the follicular route. Hair follicles, surrounded by a close network of blood capillaries and dendritic cells, are an important target for delivery of antimicrobials and present a unique microbial nidus for endogenous infections in situations where the barrier is disrupted, such as after surgery, for example, triclosan, a broad-spectrum antimicrobial agent, was encapsulated into nanoparticles using glyceryl behenate and glyceryl palmitostearate (GP) solid lipids, and incorporating Transcutol P, a known permeation enhancer at different ratios. Optimised formulation was stable over 90 d and in vitro permeation studies using full thickness porcine ear skin showed that the lipid-based nanoparticles enhanced delivery of triclosan into the skin and could direct the agent towards hair follicles, indicating their potential as a carrier system for antiseptic dermal delivery.

Triclosan exhibits a tendency to accumulate in the epididymis and shows sperm toxicity in male Sprague-Dawley rats.

Triclosan (TCS) is considered a potent endocrine disruptor that causes reproductive toxicity in non-mammals, but it is still unclear exactly whether TCS has adverse effects on the sperm or reproductive organs in mammals. In this study, we aimed to evaluate the distribution status of TCS in male reproductive organs of rats, and seek the correlation with the TCS-induced sperm toxicity or reproductive organ damage. Male rats were intragastrically administered with TCS at a dose of 50 mg/kg, the kinetics of TCS in the plasma and reproductive organs were investigated. TCS in testes and prostates both showed a lower-level distribution compared to that in the plasma, which indicates it has no tendency to accumulate in those organs. However, TCS in the epididymides showed a longer elimination half-life (t1/2 z), a longer the mean retention time (MRT), and a lower clearance (CLZ /F) compared with those in the plasma. Besides, the ratios of mean area under the concentration-time curve (AUC)(0-96 h(epididymides/plasma)) and AUC(0-∞(epididymides/plasma)) were 1.13 and 1.51, respectively. These kinetic parameters suggest TCS has an accumulation tendency in the epididymides. Based on this, we investigated the TCS-induced sperm toxicity and histopathological changes of reproductive organs in rats. TCS was given intragastrically at doses of 10, 50, and 200 mg/kg for 8 weeks. Rats treated with the high dose (200 mg/kg) of TCS showed a significant decrease in daily sperm production (DSP), changes in sperm morphology and epididymal histopathology. Considering the histopathological change in the epididymides, TCS may induce the epididymal damage due to the epididymal accumulation of that.

Treated wastewater irrigation: uptake of pharmaceutical and personal care products by common vegetables under field conditions.

Global water shortage is placing an unprecedented pressure on water supplies. Treated wastewater is a valuable water resource, but its reuse for agricultural irrigation faces a roadblock: the public concern over the potential accumulation of contaminants of emerging concern (CECs) into human diet. In the present study, we measured the levels of 19 commonly occurring pharmaceutical and personal care products (PPCPs) in 8 vegetables irrigated with treated wastewater under field conditions. Tertiary treated wastewater without or with a fortification of each PPCP at 250 ng/L, was used to irrigate crops until harvest. Plant samples at premature and mature stages were collected. Analysis of edible tissues showed a detection frequency of 64% and 91% in all vegetables from the treated wastewater and fortified water treatments, respectively. The edible samples from the two treatments contained the same PPCPs, including caffeine, meprobamate, primidone, DEET, carbamazepine, dilantin, naproxen, and triclosan. The total concentrations of PPCPs detected in edible tissues from the treated wastewater and fortified irrigation treatments were in the range of 0.01-3.87 and 0.15-7.3 ng/g (dry weight), respectively. Annual exposure of PPCPs from the consumption of mature vegetables irrigated with the fortified water was estimated to be only 3.69 µg per capita. Results from the present study showed that the accumulation of PPCPs in vegetables irrigated with treated wastewater was likely limited under field conditions.

Polymeric nanospheres as strategy to increase the amount of triclosan retained in the skin: passive diffusion vs. iontophoresis.

The aim of this study was to evaluate the passive and iontophoretic permeation of triclosan in human skin using a triclosan solution and triclosan-loaded cationic nanospheres in order to determine which of the two strategies is more effective in allowing the deposition of triclosan within the skin. Triclosan-loaded nanospheres were prepared by the emulsification-solvent displacement technique using aminoalkyl methacrylate (Eudragit® RL 100) as polymer matrix. Nanospheres of 261.0 ± 15.1 nm with a positive surface charge (Ψz = 26.0 ± 3.2 mV) were obtained. Drug loading was 62.0 ± 1.7%. Results demonstrated that the amount of triclosan retained within the skin was significantly greater (8.5-fold) when this was encapsulated into cationic nanospheres and administered by passive diffusion than when the triclosan solution was employed. The amount of triclosan retained within the skin when the cationic nanospheres were administered by iontophoresis was 3.1-fold greater than when the triclosan solution was administered by passive diffusion. Iontophoresis proved to be effective in enhancing the passage of triclosan in solution throughout the skin, whereas the triclosan nanospheres could achieve a local effect by forming a controlled release dermal depot.

Metabolization of the bacteriostatic agent triclosan in edible plants and its consequences for plant uptake assessment.

Persistent environmental contaminants may enter agricultural fields via the application of sewage sludge, by irrigation with treated municipal wastewater or by manuring. It has been shown that such contaminants can be incorporated into crop plants. The metabolism of the bacteriostatic agents triclocarban, triclosan, and its transformation product methyl triclosan was investigated after their uptake into carrot cell cultures. A fast metabolization of triclosan was observed and eight so far unknown phase II metabolites, conjugates with saccharides, disaccharides, malonic acid, and sulfate, were identified by liquid chromatography-mass spectrometry. Triclocarban and methyl triclosan lack a phenolic group and remained unaltered in the cell cultures. Phase I metabolization was not observed for any of the compounds. All eight triclosan conjugates identified in the cell cultures were also detected in extracts of intact carrot plants cultivated on triclosan contaminated soils. Their total amount in the plants was assessed to exceed the amount of the triclosan itself by a factor of 5. This study shows that a disregard of conjugates in studies on plant uptake of environmental contaminants may severely underestimates the extent of uptake into plants and, eventually, the potential human exposure to contaminants via food of plant origin.

Triclosan: environmental exposure, toxicity and mechanisms of action.

Triclosan [5-chloro-2-(2,4-dichlorophenoxy)phenol; TCS] is a broad spectrum antibacterial agent used in personal care, veterinary, industrial and household products. TCS is commonly detected in aquatic ecosystems, as it is only partially removed during the wastewater treatment process. Sorption, biodegradation and photolytic degradation mitigate the availability of TCS to aquatic biota; however the by-products such as methyltriclosan and other chlorinated phenols may be more resistant to degradation and have higher toxicity than the parent compound. The continuous exposure of aquatic organisms to TCS, coupled with its bioaccumulation potential, have led to detectable levels of the antimicrobial in a number of aquatic species. TCS has been also detected in breast milk, urine and plasma, with levels of TCS in the blood correlating with consumer use patterns of the antimicrobial. Mammalian systemic toxicity studies indicate that TCS is neither acutely toxic, mutagenic, carcinogenic, nor a developmental toxicant. Recently, however, concern has been raised over TCS's potential for endocrine disruption, as the antimicrobial has been shown to disrupt thyroid hormone homeostasis and possibly the reproductive axis. Moreover, there is strong evidence that aquatic species such as algae, invertebrates and certain types of fish are much more sensitive to TCS than mammals. TCS is highly toxic to algae and exerts reproductive and developmental effects in some fish. The potential for endocrine disruption and antibiotic cross-resistance highlights the importance of the judicious use of TCS, whereby the use of TCS should be limited to applications where it has been shown to be effective.

Consideration of dosimetry in evaluation of ToxCast™ data.

The US Environmental Protection Agency (US EPA) Toxcast™ program has the stated goal of predicting hazard, characterizing toxicity pathways and prioritizing the toxicity testing of environmental chemicals through the use of in vitro high-throughput screening (HTS) assays. This analysis integrates data from biomonitoring and from in vivo toxicity and pharmacokinetic studies to examine the physiological relevance of the tested and responding in vitro concentrations for five case study chemicals: triclosan, 2,4-dichlorophenoxyacetic acid, perfluorooctanoic acid, monobutyl phthalate and mono-2(ethylhexyl)phthalate. This analysis also examines the ToxCast™ phase 1 data set for approximately 50 chemicals belonging to four 'common mechanism groups' which have been the subject of cumulative risk assessments by the US EPA for both the pattern of key responses and the relative potencies of included chemicals compared with the in vivo relative potencies. Responding concentrations in vitro were generally in the range of serum or plasma concentrations associated with no-observed to lowest-observed effect levels for the case study chemicals, while available biomonitoring data demonstrating actual exposures were generally lower. ToxCast™ assay endpoints related to acetylcholinesterase (AChE) inhibition had low sensitivity for detecting organophosphate pesticides but good sensitivity for detecting N-methyl carbamates. However, in vitro relative potencies did not correlate with in vivo potency. Both qualitative and quantitative predictive power is probably affected by the lack of comprehensive metabolic activity in most current in vitro systems explored in the ToxCast™ program, and this remains a fundamental challenge for high-throughput toxicity screening efforts.

Absorption, pharmacokinetics, and safety of triclosan after dermal administration.

We evaluated the pharmacokinetics and safety of the antimicrobial agent triclosan after dermal application of a 2% triclosan-containing cream to six volunteers. Percutaneous absorption calculated from urinary excretion was 5.9% +/- 2.1% of the dose (mean +/- standard deviation). The amount absorbed suggests that daily application of a standard adult dose would result in a systemic exposure 890 times lower than the relevant no-observed-adverse-effect level. Triclosan can be considered safe for use in hydrophobic creams.

Biomonitoring Equivalents for triclosan.

Recent efforts worldwide have resulted in a growing database of measured concentrations of chemicals in blood and urine samples taken from the general population. However, few tools exist to assist in the interpretation of the measured values in a health risk context. Biomonitoring Equivalents (BEs) are defined as the concentration or range of concentrations of a chemical or its metabolite(s) in a biological medium (blood, urine, or other medium) consistent with an existing health-based exposure guideline, and are derived by integrating available data on pharmacokinetics with existing chemical risk assessments. This study reviews available health-based exposure guidance values for triclosan based on recent evaluations from the United States Environmental Protection Agency (US EPA), the European Commission's Scientific Committee on Consumer Products (EC SCCP) and the Australian National Industrial Chemicals Notification and Assessment Scheme (NICNAS). BE values corresponding to the reference dose (RfD) or margin of safety (MOS) targets from these agencies were derived based on kinetic data (urinary excretion and plasma clearance) from human studies and measured blood concentration data in animal studies. Estimated BE values for urinary total triclosan (free plus conjugates) corresponding to the US EPA RfD and the EC-identified margin of safety target from the NOAEL are 6.4 and 2.6 mg/L, respectively (corresponding to 8.3 and 3.3mg/g creatinine, respectively). Plasma BE values corresponding to the US EPA, EC, and Australian NICNAS values are 0.3, 0.9, and 0.4 mg/L, respectively. These values may be used as screening tools for evaluation of population biomonitoring data for triclosan in a risk assessment context.

Biomarkers for the toxicity of sublethal concentrations of triclosan to the early life stages of carps.

Accumulation, contents of protein, non-enzymatic antioxidant glutathione (GSH and GSSG), lipid peroxidation product (melondialdehyde-MDA) and organic acids (fumarate, succinate, malate and citrate), and activities of neurological (acetylcholinesterase-AChE), detoxification (glutathione S-transferase-GST) and metabolic (lactate dehydrogenase-LDH, aspartate transaminase-AST and alanine transaminase-ALT) enzymes were recorded in the hatchlings of Cyprinus carpio, Ctenopharyngodon idella, Labeo rohita and Cirrhinus mrigala after 7 and 14 days exposure and 10 days post exposure (recovery period) to sublethal concentrations (0.005, 0.01, 0.02 and 0.05 mg/L) of triclosan, a highly toxic and persistent biocide used in personal care products. Accumulation was maximum between 7-14 days at 0.01 mg/L for C. carpio and L. rohita but at 0.005 mg/L for C. idella and C. mrigala. No triclosan was observed at 0.005 mg/L in C. carpio and C. mrigala after recovery. Significant decline in protein, glutathione and acetylcholinesterase but increase in glutathione S-transferase, lactate dehydrogenase, aspartate transaminase, alanine transaminase, melondialdehyde and organic acids over control during exposure continued till the end of recovery period. Integrated biomarker response (IBR) analysis depicted higher star plot area for glutathione and glutathione S-transferase during initial 7 days of exposure, thereafter, during 7-14 days of exposure and the recovery period, higher star plot area was observed for acetylcholinesterase, aspartate transaminase, alanine transaminase and organic acids. Higher star plot area was observed for protein in all the species throughout the study. The study shows that L. rohita is most sensitive and glutathione, acetylcholinesterase, aspartate transaminase and alanine transaminase are the biomarkers for the toxicity of sublethal concentrations of TCS.

Investigation of triclosan retention and dental plaque viability with a triclosan/PVM/MA copolymer mouthrinse in a Thai population.

This investigation studied triclosan retention and plaque viability in a group of healthy human subjects from Bangkok, Thailand, 12 hours after using a mouthrinse containing a triclosan/PVM/MA copolymer system. The results show the retained triclosan in the dental plaque was with in or higher than the minimum inhibitory concentration (MIC range 0.27-6.25 microg/ml), indicating the triclosan in this product remains at an effective concentration in dental plaque. The 12-hour post-application evaluation demonstrated only 36.5% viability of oral bacteria in dental plaque after a one-time use of the mouthrinse. This study shows the benefits of using a mouthrinse containing a triclosan/PVM/MA copolymer system for providing 12 hours long-lasting anti-bacteria and dental plaque control.

Nationwide reconnaissance of five parabens, triclosan, triclocarban and its transformation products in sewage sludge from China.

China's rapid growth of both population size and sanitation infrastructure have created a heightened need for responsible management of sewage sludge. We applied liquid chromatography in conjunction with isotope dilution tandem mass spectrometry to measure multiple endocrine disrupting antimicrobials and their transformation products in 100 sewage sludge samples collected across 21 Chinese provinces/districts. Occurrences (detection frequencies) and concentrations (ng/g dry weight) were as follows: triclosan (99%; <4-4870), triclocarban (95%; <3-43,300), 2'-hydroxy-triclocarban (94%; <1-2340), 3'-hydroxy-triclocarban (91%; <1-1250), 3,3',4,4'-tetrachlorocarbanilide (100%; 22-580), dichlorocarbanilide (94%; <2-23,890), monocarbanilide (92%; <2-120), carbanilide (90%; <3-1,340), and five parabens: methyl- (98%; <2-630), ethyl- (96%; <2-170), propyl- (99%; <2-27), butyl- (89%; <2-11) and benzyl-paraben (7%; <2-12). The transformation products of triclocarban were measured for the first time in Chinese wastewater system, and ratios of transformation products to parental triclocarban indicate ongoing triclocarban dechlorination during wastewater treatment. Contaminant profiles and concentrations differed by region, treatment capacity, and wastewater type. Extrapolation of collected data yielded an estimate for the total mass of 13 analytes sequestered in Chinese sewage sludge of 68 t/y with an upper bound of 400 t/y. This China-wide survey established baseline levels of selected antimicrobials in sludges whose current disposal is performed with little regulatory oversight and enforcement.

The effect of temperature on Triclosan and Lead exposed mussels.

Interest on the effects of emerging contaminants over aquatic organisms has increased in the last years. Nonetheless, the toxic action of classical natural and anthropogenically-driven metals has also to be monitored, especially because they reflect real environmental situations. For that, in the present study we focused on the effects on the marine mussel Mytilus galloprovincialis of the personal care product Triclosan (TCS) and Lead (Pb), as toxic metal, under separate and co-exposure situations at environmentally relevant concentrations: TCS (1 µg/L) and Pb (50 µg/L). The consideration of an additional factor such as an increase in ambient temperature was also included to provide a forecasted scenario of climate change: from the ambient temperature at actual conditions (17 °C) to a predicted warming situation (22 °C). Water chemical characterization and some physical properties and bioaccumulation of TCS and Pb in mussels at the end of the experiment (28 days) was considered. The parameters followed up comprise the energy related system production (electron transport system) and glycogen and protein reserves. Antioxidant enzymatic defences towards reactive oxygen species (ROS) and the consequences of ROS damage over endogenous lipids (LPO) and proteins (PC). Overall the results suggested only particular responses to chemical exposures at 17 °C whereas at 22 °C the detoxification machinery was set up and this prevented the occurrence of LPO. Nonetheless, PC formation occurred under Pb and TCS + Pb co-exposure at the highest temperature. Due to the complexity of the study: 4 chemical conditions, 2 temperatures and 10 biomarkers considered, a principal component ordination (PCO) analysis was included. The results of this integrative analysis confirmed a clear effect of the temperature, more responsiveness to drugs at 22 °C and in all likelihood due to Pb presence.

Immobilization of triclosan and erythrosine in layer-by-layer films applied to inactivation of microorganisms.

The use of layer-by-layer (LbL) deposition technique allows materials, such as drugs, to be self-assembled in multilayers with other electrolytes by combining their properties in a nanostructured system. Triclosan (TCS) is commonly used as a drug because of its bactericidal action, while erythrosine (ERY) has been used as a photosensitizer in photodynamic therapies because of its high light absorptivity in the visible region of the electromagnetic spectrum. The major advantage of investigating systems immobilized in LbL films is the benefit of characterizing the interaction through available substances in solid state techniques. It was possible to immobilize in LbL films, ERY, and ERY + TCS. The results show that the growth of the films was linear, indicating the deposition of the same amount of material from the first bilayer without substrate interference. The release analysis showed slow kinetics, which occurred more rapidly for ERY LbL films, probably due to apparent activation energy, which were higher for films with TCS. The combination of TCS, ERY, and laser light (532 nm) for photodynamic inactivation of the fungus Candida albicans was analyzed, and the results were promising for future studies in applications, such as coating surfaces of dental implants.

Triclosan and triclocarban exposure, infectious disease symptoms and antibiotic prescription in infants-A community-based randomized intervention.

BACKGROUND: Triclosan and triclocarban (TCs) are broad-spectrum antimicrobials that, until recently, were found in a wide variety of household and personal wash products. Popular with consumers, TCs have not been shown to protect against infectious diseases. OBJECTIVES: To determine whether use of TC-containing wash products reduces incidence of infection in children less than one year of age. METHODS: Starting in 2011, we nested a randomized intervention of wash products with and without TCs within a multiethnic birth cohort. Maternal reports of infectious disease symptoms and antibiotic use were collected weekly by automated survey; household visits occurred every four months. Antibiotic prescriptions were identified by medical chart review. Urinary triclosan levels were measured in a participant subset. Differences by intervention group in reported infectious disease (primary outcome) and antibiotic use (secondary outcome) were assessed using mixed effects logistic regression and Fisher's Exact tests, respectively. RESULTS: Infectious illness occurred in 6% of weeks, with upper respiratory illness the predominant syndrome. Among 60 (45%) TC-exposed and 73 (55%) non-TC-exposed babies, infectious disease reports did not differ in frequency between groups (likelihood ratio test: p = 0.88). Medical visits with antibiotic prescriptions were less common in the TC group than in the non-TC group (7.8% vs. 16.6%, respectively; p = 0.02). CONCLUSIONS: Although randomization to TC-containing wash products was not associated with decreased infectious disease reports by mothers, TCs were associated with decreased antibiotic prescriptions, suggesting a benefit against bacterial infection. The recent removal of TCs from consumer wash products makes further elucidation of benefits and risks impracticable.

Triclosan loaded polyurethane micelles with pH and lipase sensitive properties for antibacterial applications and treatment of biofilms.

Three different kinds of polyurethane (PU) micelles, i.e. PEG-c-PU, PEG-g-PU and PEG-b-PU, with hydrophobic PCL core and hydrophilic PEG corona were prepared by self-assembly method. DLS studies illustrated that PEG-g-PU micelles showed pH dependent surface charge switching properties while no obvious surface charge switching activities were found for PEG-b-PU and PEG-c-PU micelles. Triclosan was loaded into PCL core by dialysis method with pretty high encapsulate content and efficiency and the payloads were released at an accelerate rate in the presence of lipase. MIC and MBC studies demonstrated an enhanced antibacterial activity of encapsulated Triclosan against planktonic bacteria than free Triclosan. CLSM images of S. aureus biofilms treated with Nile red loaded PU micelles illustrated the penetration and accumulation of PEG-g-PU micelles inside the bacterial biofilms at an acidic environment. In addition, Triclosan loaded into PEG-g-PU micelles showed more potent antibiofilm activities than that loaded into PEG-c-PEG and PEG-b-PU micelles. Therefore, the PEG-g-PU micelles can be potentially used as hydrophobic antibiotic carriers to treat bacterial infections and biofilms.

A triclosan-ciprofloxacin cross-resistant mutant strain of Staphylococcus aureus displays an alteration in the expression of several cell membrane structural and functional genes.

Triclosan is an antimicrobial agent found in many consumer products. Triclosan inhibits the bacterial fatty acid biosynthetic enzyme, enoyl-ACP reductase (FabI). Decreased susceptibility to triclosan correlates with ciprofloxacin resistance in several bacteria. In these bacteria, resistance to both drugs maps to genes encoding multi-drug efflux pumps. The focus of this study was to determine whether triclosan resistance contributes to ciprofloxacin resistance in Staphylococcus aureus. In S. aureus, triclosan resistance maps to a fabI homolog and ciprofloxacin resistance maps to genes encoding DNA gyrase, topoisomerase IV and to the multi-drug efflux pump, NorA. Using a norA overexpressing mutant, we demonstrated that upregulation of NorA does not lead to triclosan resistance. To further investigate triclosan/ciprofloxacin resistance in S. aureus, we isolated triclosan/ciprofloxacin-resistant mutants. The mutants were screened for mutations in the genes encoding the targets of triclosan and ciprofloxacin. One mutant, JJ5, was wild-type for all sequences analyzed. We next monitored the efflux of triclosan from JJ5 and determined that triclosan resistance in the mutant was not due to active efflux of the drug. Finally, gene expression profiling demonstrated that an alteration in cell membrane structural and functional gene expression is likely responsible for triclosan and ciprofloxacin resistance in JJ5.

Responses of earthworms and microbial communities in their guts to Triclosan.

Responses of the earthworm (Eisenia fetida) and compositions of associated microbial communities were determined after exposure to various concentrations of Triclosan (TCS) for 7 d. Concentrations of TCS were greater in intestines than in epidermis of earthworms, which suggested that earthworms accumulate TCS mainly by ingestion rather than by epidermic penetration. Exposure to TCS caused a concentration-dependent increase in activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) and in malondialdehyde (MDA) in E. fetida. Analyses of both the bacterial and eukaryotic community by next generation sequencing (NGS), demonstrated that TCS caused a concentration-dependent decrease in sensitive genera. While relative abundances of Pseudomonas, Stenotrophomonas, and Achromobacter were increased. Nine susceptible microbial groups were more sensitive to exposure to TCS, than were activities of enzymes in earthworms. Thus, rapid genomic measures of gut flora can be used as indicators to assess adverse effects of chemicals on earthworms.