Antibiotic proliferation in the environment and their persistent nature is an issue of global concern as they induce antibiotic resistance threatening both human health and the ecosystem. Antibiotics have therefore been categorized as emerging pollutants. Fluoroquinolone (FQs) antibiotics are an emerging class of contaminants that are used extensively in human and veterinary medicine. The recalcitrant nature of fluoroquinolones has led to their presence in wastewater, effluents and water bodies. Even at a low concentration, FQs can stimulate antibacterial resistance. The main sources of FQ contamination include waste from pharmaceutical manufacturing industries, hospitals and households that ultimately reaches the wastewater treatment plants (WWTPs). The conventional WWTPs are unable to completely remove FQs due to their chemical stability. Therefore, the development and implementation of more efficient, economical, convenient treatment and removal technologies are needed to adequately address the issue. This review provides an overview of the technologies available for the removal of fluoroquinolone antibiotics from wastewater including adsorptive removal, advanced oxidation processes, removal using non-carbon based nanomaterials, microbial degradation and enzymatic degradation. Each treatment technology is discussed on its merits and limitations and a comparative view is presented on the choice of an advanced treatment process for future studies and implementation. A discussion on the commercialization potential and eco-friendliness of each technology is also included in the review. The importance of metabolite identification and their residual toxicity determination has been emphasized. The last section of the review provides an overview of the policy interventions and regulatory frameworks that aid in retrofitting antibiotics as a central key focus contaminant and thereby defining the discharge limits for antibiotics and establishing safe manufacturing practices.

Antibiotics have been widely used in human and veterinary medicine to both treat and prevent disease. Due to their high water solubility and low bioavailability, many antibiotic residues have been found in aquatic environments. Fish are an indispensable link between the environmental pollution and human health. However, the chronic effects of environmental concentrations of antibiotics in fish have not been thoroughly investigated. Sulfamethoxazole (SMX) and oxytetracycline (OTC) are frequently detected in aquatic environments. In this study, zebrafish were exposed to SMX (260 ng/L) and OTC (420 ng/L) for a six-week period. Results indicated that exposure to antibiotics did not influence weight gain of fish but increased the metabolic rate and caused higher mortality when treated fish were challenged with Aeromonas hydrophila. Furthermore, exposure to antibiotics in water resulted in a significant decrease in intestinal goblet cell numbers, alkaline phosphatase (AKP), acid phosphatase (ACP) activities, and the anti-oxidant response while there was a significant increase in expression of inflammatory factors. Antibiotic exposure also disturbed the intestinal microbiota in the OTC-exposed group. Our results indicated that environmental antibiotic concentrations can impair the gut health of zebrafish. The potential health risk of antibiotic residues in water should be evaluated in the future.

Fipronil, a phenyl-pyrazole insecticide, has a wide range of uses, from agriculture to veterinary medicine. Due to its large-scale applications, the risk of environmental and occupational exposure and bioaccumulation raises concerns. Moreover, relatively little is known about the intracellular mechanisms of fipronil in trophoblasts and the endometrium involved in implantation. Here, we demonstrated that fipronil reduced the viability of porcine trophectoderm and luminal epithelial cells. Fipronil induced cell cycle arrest at the sub-G1 phase and apoptotic cell death through DNA fragmentation and inhibition of DNA replication. These reactions were accompanied by homeostatic changes, including mitochondrial depolarization and cytosolic calcium depletion. In addition, we found that exposure to fipronil compromised the migration and implantation ability of pTr and pLE cells. Moreover, alterations in PI3K-AKT and MAPK-ERK1/2 signal transduction were observed in fipronil-treated pTr and pLE cells. Finally, the antiproliferative and apoptotic effects of fipronil were also demonstrated in 3D cell culture conditions. In summary, our results suggest that fipronil impairs implantation potentials in fetal trophectoderm and maternal endometrial cells during early pregnancy.

The extensive use of antibiotics in human and veterinary medicine and their subsequent release into the environment may have direct consequences for autochthonous bacterial communities, especially in freshwater ecosystems. In small streams and rivers, local inputs of wastewater treatment plants (WWTPs) may become important sources of organic matter, nutrients and emerging pollutants, such as antibiotic resistance genes (ARGs). In this study, we evaluated the effect of WWTP effluents as a source of ARGs in river biofilms. The prevalence of genes conferring resistance to main antibiotic families, such as beta-lactams (blaCTX-M), fluoroquinolones (qnrS), sulfonamides (sul I), and macrolides (ermB), was determined using quantitative PCR (qPCR) in biofilm samples collected upstream and downstream WWTPs discharge points in four low-order streams. Our results showed that the WWTP effluents strongly modified the hydrology, physico-chemistry and biological characteristics of the receiving streams and favoured the persistence and spread of antibiotic resistance in microbial benthic communities. It was also shown that the magnitude of effects depended on the relative contribution of each WWTP to the receiving system. Specifically, low concentrations of ARGs were detected at sites located upstream of the WWTPs, while a significant increase of their concentrations was observed in biofilms collected downstream of the WWTP discharge points (particularly ermB and sul I genes). These findings suggest that WWTP discharges may favour the increase and spread of antibiotic resistance among streambed biofilms. The present study also showed that the presence of ARGs in biofilms was noticeable far downstream of the WWTP discharge (up to 1 km). It is therefore reasonable to assume that biofilms may represent an ideal setting for the acquisition and spread of antibiotic resistance determinants and thus be considered suitable biological indicators of anthropogenic pollution by active pharmaceutical compounds.

Wound healing is one of the utmost medical issues in human and veterinary medicine, which explains the urgent need for developing new agents that possess wound healing activities. The present study aimed to assess the effectiveness of green and chemical zinc oxide nanoparticles (ZnO-NPs) for wound healing. ZnO-NPs (green using Lawsonia inermis leaf extract and chemical) were synthesized and characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and high-resolution transmission electron microscopy (HRTEM). The gels containing the nanomaterials were prepared and inspected. Forty-five albino rats were divided into three groups, the control group was treated with normal saline 0.9%, and the other two groups were treated with gels containing green or chemical ZnO-NPs, respectively. On the 3ʳᵈ, 7ᵗʰ, 14ᵗʰ, and 21ˢᵗ days post-treatment (PT), the wounds were clinicopathologically examined. Both nanomaterials have good crystallinity and high purity, but green ZnO-NPs have a longer nanowire length and diameter than chemical ZnO-NPs. The formed gels were highly viscous with a pH of 6.5 to 7. The treated groups with ZnO-NP gels showed clinical improvement, as decreased wound surface area (WSA) percent (WSA%), increased wound contraction percent (WC%), and reduced healing time (p < 0.05) when compared with the control group. The histological scoring showed that the epithelialization score was significantly higher at the 21ˢᵗ day post-treatment in the treated groups than in the control group (p < 0.05), but the vasculature, necrosis, connective tissue formation, and collagen synthesis scores were mostly similar. The green and chemical ZnO-NP gels showed promising wound healing properties; however, the L. inermis–mediated ZnO-NPs were more effective.

The quality of water resources can be altered by human activities carried out in watersheds. These changes can lead to the occurrence of antibiotic-resistant bacteria and compromise public health. The aim of the present study was to evaluate the presence and concentration of total coliforms and Escherichia coli in the water at the Ecological Park Tietê in São Paulo, the antibiotics resistance of isolated E. coli, and the interaction between season, collection points, and water quality variables. Sample localities were georeferenced and identified as P1—drinking water from the distribution system (23°29′33.46″S, 46°31′16.12″O); P2—main lagoon of the park (23°29′37.59″S, 46°31′28.22″O); and P3—connection between the main lagoon and the Tietê River (23°29′14.66″S, 46°31′26.57″O). Physical–chemical and microbiological variables were measured. Data were subjected to analysis of variance. The isolated effect or the interaction between season, collection points, and variables had the means compared to each other by the Scott-Knott test. The microbiological analysis was performed by inoculating the samples in 3 M™ Petrifilm™ E. coli/Coliform Count Plates (containing agar medium with Violet Red Bile nutrients), incubated at 37 °C for 48 h and the E. coli isolated had their antibiotic resistance profile tested by the disk diffusion technique using Mueller–Hinton agar. Total coliforms and E. coli were not identified at P1. Total coliforms were identified in 64% of the samples and E. coli was identified in 36% of the samples. The microbial contamination of the surface waters of the park presents seasonal variation with higher concentrations of E. coli in the hottest and rainiest seasons (spring and summer). The isolated E. coli showed greater resistance to erythromycin (82%) and amoxicillin (55%) in P2 and to erythromycin (82%) and amoxicillin (27%) in P3, with the presence of multiresistant isolates at both points. No strain showed resistance to amikacin. The high rate of resistance of E. coli to the antibiotics frequently used in human and veterinary medicine demonstrates that the contribution of these substances in aquatic ecosystems over the years has exerted a selection pressure on microorganisms, assisting the appearance and spread of resistant bacteria, changing the environmental biota, and turning these locations in possible reservoirs of antibiotic resistance.

Benzimidazoles (BZ) are among the most used drugs to treat parasitic diseases in both human and veterinary medicine. In this study, solutions fortified with albendazole (ABZ), fenbendazole (FBZ), and thiabendazole (TBZ) were subjected to photoperoxidation (UV/H₂O₂). The hydroxyl radicals generated by the process removed up to 99% of ABZ, and FBZ, in the highest dosage of H₂O₂ (i.e., 1.125 mmol L⁻¹; 4.8 kJ L⁻¹). In contrast, 20% of initial TBZ concentration remained in the residual solution. In the first 5 min of reaction (i.e., up to 0.750 mmol L⁻¹ of H₂O₂), formation of the primary metabolites of ABZ—ricobendazole (RBZ), albendazole sulfone (ABZ-SO₂), and oxfendazole (OFZ)—was observed. However, these reaction products were converted after the reaction time was doubled. The residual ecotoxicity was investigated using the Raphidocelis subcapitata microalgae and the marine bacteria Vibrio fischeri. The results for both microorganisms evidence that the residual solutions are less harmful to these microorganisms. However, after 30 min of reaction, the treated solution still presents a toxic effect for V. fischeri, meaning that longer reaction times are required to achieve an innocuous effluent.

Ivermectin (IVM) is a broad-spectrum antiparasitic drug that is regularly employed in veterinary medicine. In this work, the sorption and desorption of IVM in two Brazilian soils (N1-sand and S2-clay) as well as its leaching capacity, dissipation under aerobic conditions, and degradation in aqueous solution by photocatalysis with TiO₂ in suspension were evaluated. The kinetic sorption curves of IVM were adjusted to a pseudo-second-order model. The sorption and desorption data were well fitted with the Freundlich isotherms in the log form (r > 0.96). The Freundlich sorption coefficient (K F ᵃᵈˢ) and the Freundlich desorption coefficient (K F ᵈᵉˢ) were 77.7 and 120 μg¹⁻¹/ⁿ (cm³)¹/ⁿ g⁻¹ and 74.5 and 138 μg¹⁻¹/ⁿ (cm³)¹/ⁿ g⁻¹, for soils N1 and S2, respectively. A greater leaching capacity of IVM was observed for the sandy soil N1 than for the clay soil S2. Under aerobic conditions, the dissipation (DT₅₀) at 19.3 °C was 15.5 days (soil N1) and 11.5 days (soil S2). Photocatalysis with UVC and TiO₂ in suspension resulted in the degradation of 98 % of IVM (500 μg L⁻¹) in water in 600 s. The toxicity (Daphnia similis) of the solutions submitted to the photocatalytic process was completely eliminated after 10 min.

Effective treatment of dairy wastewater with efficient removal of antibiotic-resistant bacteria (ARB) is a great challenge for reuse of treated wastewater. Antibiotics are widely used in human and veterinary medicine, and antibiotics misuse has led to occurrence and spread of antibiotic-resistant bacteria (ARB). Reuse of treated wastewater for irrigation is a solution to deal with water shortage in developing countries. One of the major problems of treated wastewater reuse is the possible presence of ARB. Removal of ARB from dairy wastewater using a full-scale hybrid constructed wetland (CW) at Miyagi Prefecture, Japan, was studied. It was well-defined that hybrid CW caused a complete removal of ampicillin-, gentamicin-, kanamycin-, and streptomycin-resistant bacteria resulting in an effluent free of these resistant strains. Additionally, a significant decrease in the number of vancomycin-RB was definite with a final 3.2 log unit decrease in the effluent. This study addressed the remarkable efficiency of a full-scale hybridized CW in Kawatabi, Field Science Center, Tohoku University. It decreased the output of organic matter (COD), total suspended solids (SS), and ammonia-nitrogen. The performance of CW for the removal ARB from dairy wastewater was efficient to minimize the release of these contaminants into the environment and avoid the spread of antibiotic resistance with safe discharge and reuse of treated wastewater. Finally, the current study represents the first report about the assessment of ARB removal during treatment of dairy wastewater using CW.