Antibiotic Pollution in the Environment: From Microbial Ecology to Public Policy

Mechanistic pathways for the degradation of SMX drug and floatation of degraded products using F–Pt co-doped TiO2 photocatalysts

This work presents smart pathways to enhance the photocatalytic activity of TiO₂via co-doping with fluorine (F) and platinum (Pt) to form F–Pt co-doped TiO₂ photocatalysts and investigates the unique and unusual fluorination of the floated products. Our investigations indicate that the crystalline structure of the photocatalysts was a mixture of anatase and brookite phases and that the nanoparticles of the synthesized nanocomposites had nanometric sizes (4–25 nm). The F–Pt co-doped TiO₂ nano-photocatalysts demonstrated degradation of sulfamethoxazole (SMX) drug of >93% within 90 min under direct solar light and 58% degradation within 360 min under a solar simulator. Thus, co-doping TiO₂ with F and Pt atoms to form F–Pt co-doped TiO₂ nanocomposite is an efficient pathway to achieve high photocatalytic performance escorted with the formation of floating metal-fluoropolymer, unlike pristine TiO₂ which has less photocatalytic degradation and no generation of a floating polymer. Our photocatalytic protocol demonstrates that the degradation of SMX started with redox reactions of oxygen and water absorbed on the surface of the prepared nanocomposites to form superoxide anions (O₂˙⁻) and hydroxy radicals (˙OH) which have oxidation superpower. The resultant products were subsequently fluorinated by fluoride radical ions and floated as metal-fluoropolymer.

This work presents smart pathways to enhance the photocatalytic activity of TiO₂via co-doping with fluorine (F) and platinum (Pt) to form F–Pt co-doped TiO₂ photocatalysts and investigates the unique and unusual fluorination of the floated products.

Antibiotic resistance: Tools for effective translational research

The rising emergence of bacterial resistances has led to a crisis which threatens human, animal and environmental health. The impact of the emergency is enormous in terms of public health and economics. Although there is a global awareness of the warnings and programmes supporting innovative actions to combat fight against antibiotic resistance, it must be admitted that proposed new antibiotics fail to find the economic profitability necessary for them to reach the market and become available for patients and the community. Moreover, it is necessary to develop tools/indicators to define effective interventions against antibiotic resistance. The work of the think-tank reported in this article concentrated on two aspects of translational research: - prevention and the impact on health of the antibiotic resistance issue, and - the specific requirements of clinical research leading to innovation in the fight against antibiotic resistance. This article, which reflects the thoughts of a group of French experts, proposes directly operational solutions which could be rapidly implemented and radically transform the quality and quantity of our resources available for the combat.

In vitro selection of DNA aptamers and their integration in a competitive voltammetric biosensor for azlocillin determination in waste water

The uncontrolled usage of veterinary antibiotics has led to their widespread pollution in waterways and milk products. Potential impact of antibiotic residues on the environment and human health such as increased antibiotic resistance of microorganisms and triggering allergic reactions in humans have been reported. In this work, we developed a highly selective and sensitive voltammetric aptasensor for on-step, sensitive and low cost detection of azlocillin antibiotic, one of the broad spectrum β-lactam antibiotics. The successful selection of DNA aptamers against azlocillin was accomplished using systemic evolution of ligands by exponential enrichment (SELEX) method. Fluorescence-binding assays showed dissociation constant of 55 nM for one of the selected aptamers (Az9). This aptamer was used to construct a competitive voltammetric aptasensor for azlocillin. A limit of detection of 1.2 pg/mL as well as remarkable selectivity against potential interfering agents, including amoxicillin, were achieved. This signal-off competitive sensor takes 30-50 min to complete the quantification of the target antibiotic. The sensor was challenged by detecting the target directly in complex environments such as tap and waste water where good recovery percentages were achieved.

Susceptibility of Multidrug-Resistant and Biofilm-Forming Uropathogens to Mexican Oregano Essential Oil

Antibiotic resistance along with biofilm formation increases the difficulty for antibiotic therapy in urinary tract infections. Bioactive molecules derived from plants, such as those present in essential oils, can be used to treat bacterial infections. Oregano is one of the spices to have antimicrobial activity. Therefore, three Mexican oregano essential oils (two Lippia berlandieri Schauer and one Poliomintha longiflora) were tested for antimicrobial capacity against multidrug-resistant, biofilm-forming bacterial isolates. Clinical isolates from urinary tract infections were tested for antibiotic resistance. Multidrug-resistant isolates were evaluated for biofilm formation, and Mexican oregano antimicrobial effect was determined by the minimal inhibitory (CMI) and minimal bactericidal concentrations (CMB). The selected isolates were identified by molecular phylogenetic analysis. Sixty-one isolates were included in the study; twenty were characterized as multidrug-resistant and from those, six were strong biofilm formers. Three isolates were identified as Escherichia coli, two as Pseudomonas aeruginosa and one as Enterococcus faecalis based on the phylogenetic analysis of 16 S rRNA gene sequences. The antimicrobial effect was bactericidal; E. faecalis was the most susceptible (<200 mg/L CMI/CMB), and P. aeruginosa was the most resistant (>2,000 mg/L CMI/CMB). There was a range of 500-1000 mg/L (CMI/CMB) for the E. coli isolates. Mexican oregano essential oils demonstrated antimicrobial efficacy against multidrug-resistant clinical isolates.