High Concentrations Of Ciprofloxacin Research Articles

Fluorometric detection of quinolones via AIE and FRET with terbium-doped carbon dots and copper nanoclusters

Terbium and nitrogen co-doped carbon dots (Tb@N-CDs), combined with α-lipoic acid-functionalized copper nanoclusters (LA@CuNCs), were proposed for the ratiometric detection of quinolone (QA) antibiotics. In this system, Tb@N-CDs facilitate the aggregation of LA@CuNCs, enhancing its fluorescence emission at 670 nm via aggregation-induced emission enhancement (AIEE). Meanwhile, the fluorescence emission of Tb@N-CDs at 460 nm diminishes due to Förster resonance energy transfer (FRET). Upon the introduction of QA, the binding between Tb3+ ions and N-CDs weakens, disrupting both AIEE and FRET processes. This disruption results in a reduction in fluorescence emission at 670 nm and a concurrent increase at 460 nm. The fluorescence response ratio (F460/F670) increases with higher concentrations of ciprofloxacin (CFX), demonstrating a linear range from 0.008 to 120 μmol L−1 and LOD of 1.6 nmol L−1. The method successfully detected CFX in milk and urine samples, achieving recoveries between 97.7 % and 103.8 %, RSD of less than 3.79 %.

Effects of Ciprofloxacin on the Production and Composition of Cellular Microcystins in Microcystis aeruginosa.

Antibiotics can affect the photosynthetic system of Microcystis, potentially altering the balance of carbon and nitrogen, which may influence the synthesis of different microcystin (MC) congeners. However, the regulatory mechanisms by which antibiotics affect the synthesis of various MC congeners in Microcystis remain unknown. In this study, the effects of ciprofloxacin (CIP) on the growth, carbon and nitrogen balance, amino acid composition, mcyB gene expression, and production of different MC congeners were investigated in two toxin-producing strains of Microcystis aeruginosa. The results show that CIP exposure significantly inhibited the growth of both strains, achieving an inhibition rate of 71.75% in FACHB-315 and 41.13% in FACHB-915 at 8 μg/L CIP by the end of the cultivation. The intracellular C:N ratio in FACHB-315 increased by 51.47%, while no significant change was observed in FACHB-915. The levels of leucine, tyrosine, and arginine, as identified and quantified by UPLC-MS/MS, were significantly altered at higher CIP concentrations, leading to a reduction in leucine percentage and a notable increase in tyrosine in both strains, which contributed to a reduction in MC-LR proportion and an increase in MC-RR and MC-YR proportion. Additionally, the expression of the mcyB gene was upregulated by as much as 5.57 times, indicating that antibiotic stress could enhance MC synthesis at the genetic level, contributing to the increased toxicity of cyanobacteria. These findings emphasize the significant role of CIP in the biochemical processes of M. aeruginosa, particularly in MC synthesis and composition, providing valuable insights into the ecological risks posed by antibiotics and harmful cyanobacteria.

Veterinary antibiotics differ in phytotoxicity on oilseed rape grown over a wide range of concentrations

Residues of veterinary antibiotics are a worldwide problem of increasing concern due to their persistence and diverse negative effects on organisms, including crops, and limited understanding of their phytotoxicity. Therefore, this study aimed to compare the phytotoxic effects of veterinary antibiotics tetracycline (TC) and ciprofloxacin (CIP) applied in a wide range of concentrations on model plant oilseed rape (Brassica napus). Overall phytotoxicity of 1–500 mg kg−1 of TC and CIP was investigated based on morphological, biochemical, and physiological plant response. Photosystem II (PSII) performance was suppressed by TC even under environmentally relevant concentration (1 mg kg−1), with an increasing effect proportionally to TC concentration in soil. In contrast, CIP was found to be more phytotoxic than TC when applied at high concentrations, inducing a powerful oxidative burst, impairment of photosynthetic performance, collapse of antioxidative protection and sugar metabolism, and in turn, complete growth retardation at 250 and 500 mg kg−1 CIP treatments. Results of our study suggest that TC and CIP pollution do not pose a significant risk to oilseed rapes in many little anthropogenically affected agro-environments where TC or CIP concentrations do not exceed 1 mg kg−1; however, intensive application of manure with high CIP concentrations (more than 50 mg kg−1) might be detrimental to plants and, in turn, lead to diminished agricultural production and a potential risk to human health.

Deciphering Ciprofloxacin’s Impact on Growth Attributes and Antioxidant Compounds in Pasankalla Quinoa

The utilization of irrigation water contaminated with antibiotics can potentially affect the growth and production of metabolites in crops. Thus, the effect of Ciprofloxacin (CIP) in irrigation water on the morphological characteristics and polyphenol content in the Pasakalla variety of quinoa was evaluated. Quinoa seeds were sown and irrigated twice weekly with different CIP doses (1, 10, and 100 µg/L). The plant was divided into roots, leaves, panicles, and grain to measure their morphological characteristics and antioxidant properties (the content of total polyphenols, antioxidant capacity, and polyphenolic profile). Root length and biomass of the plant were not affected by the dosage of CIP during physiological maturity. On the contrary, plant growth was reduced (16%) when 10 ug/L of CIP was used. On the other hand, the presence of high CIP concentrations (100 ug/L) improved the biosynthesis of polyphenols and antioxidant capacity by 52 and 59% compared to the control. Profile polyphenols show that vanillic acid and procyanidins A2 and B2 were significantly increased. Thus, the use of CIP could promote a higher enzymatic activity to produce specific polyphenols in order to inhibit the presence of ROS. Finally, under CIP-controlled conditions, the production of polyphenols could be improved without altering the plant’s expected growth.

Influence of Growth Medium Composition on Physiological Responses of Escherichia coli to the Action of Chloramphenicol and Ciprofloxacin.

The ability of hydrogen sulfide (H2S) to protect bacteria from bactericidal antibiotics has previously been described. The main source of H2S is the desulfurization of cysteine, which is either synthesized by cells from sulfate or transported from the medium, depending on its composition. Applying electrochemical sensors and a complex of biochemical and microbiological methods, changes in growth, respiration, membrane potential, SOS response, H2S production and bacterial survival under the action of bactericidal ciprofloxacin and bacteriostatic chloramphenicol in commonly used media were studied. Chloramphenicol caused a sharp inhibition of metabolism in all studied media. The physiological response of bacteria to ciprofloxacin strongly depended on its dose. In rich LB medium, cells retained metabolic activity at higher concentrations of ciprofloxacin than in minimal M9 medium. This decreased number of surviving cells (CFU) by 2-3 orders of magnitude in LB compared to M9 medium, and shifted optimal bactericidal concentration (OBC) from 0.3 µg/mL in M9 to 3 µg/mL in LB. Both drugs induced transient production of H2S in M9 medium. In media containing cystine, H2S was produced independently of antibiotics. Thus, medium composition significantly modifies physiological response of E. coli to bactericidal antibiotic, which should be taken into account when interpreting data and developing drugs.

Activation of peroxydisulfate degradation of ciprofloxacin by nitrogen-doped modified graphitized iron-based carbon materials: The transition from free to nonfree radicals

Considering that high concentrations of ciprofloxacin (CIP) are generally ecotoxic and persistent in water bodies, the refractory degradability has not been addressed in depth. In this study, an N-doped modified graphitized iron-based carbon nanomaterial (0.8 N@FeCS) was prepared by hydrothermal synthesis for the rapid degradation of ciprofloxacin by activated peroxydisulfate. More importantly, the N-doped nitrogen configuration in the iron-based carbon material is pyridine nitrogen, pyrrole nitrogen and graphite nitrogen. The nitrogen modification imparts a new twist to the CIP degradation system: a shift from a common free radical reaction to a nonradical process (1O2 and electron transfer pathways). The degradation intermediates were identified by LC-MS analysis and density functional theory (DFT), it is suggested that the possible CIP degradation pathway. In conclusion, the process of catalytic activation results in removal of CIP, and this study provides a new perspective for the removal of antibiotics from aqueous solutions.

Intensified hydrodynamic cavitation using vortex flow based cavitating device for degradation of ciprofloxacin

The present work, for the first time, establishes degradation behavior of ciprofloxacin (CIP), a widely used fluoroquinolone group of antibiotics, using vortex flow based hydrodynamic cavitation (HC) for low to high concentrations of CIP (10 and 100 mg/L). Effect of pressure on the degradation of CIP and TOC reduction was investigated on pilot plant scale (capacity 1 m3/h). Process intensifications using aeration as well as hydrogen peroxide (H2O2) were also investigated. While aeration did not yield any significant enhancement, process intensification using H2O2 resulted in ∼ 200% enhancement in the CIP degradation as compared to HC alone. Excellent degradations, to an extent of 79 & 95%, were achieved corresponding to high cavitational yields of 7.2 × 10−4 mg/J and 86.8 × 10−4 mg/J for CIP concentrations of 10 and 100 mg/L respectively using the process intensified approach of HC and H2O2, not reported so far for cavitating devices without moving elements. The developed methodology demonstrated 4–7 times improvement in per-pass degradation and low cost with high efficiency compared to the conventional cavitation. The results clearly highlight utility of the process intensified approach using H2O2 for the degradation of CIP even at high concentrations, specifically important for pharmaceutical industries requiring zero liquid discharge norms.

Repeated Exposure of Escherichia coli to High Ciprofloxacin Concentrations Selects gyrB Mutants That Show Fluoroquinolone-Specific Hyperpersistence.

Recent studies have shown that not only resistance, but also tolerance/persistence levels can evolve rapidly in bacteria exposed to repeated antibiotic treatments. We used in vitro evolution to assess whether tolerant/hyperpersistent Escherichia coli ATCC25922 mutants could be selected under repeated exposure to a high ciprofloxacin concentration. Among two out of three independent evolution lines, we observed the emergence of gyrB mutants showing an hyperpersistence phenotype specific to fluoroquinolones, but no significant MIC increase. The identified mutation gives rise to a L422P substitution in GyrB, that is, outside of the canonical GyrB QRDR. Our results indicate that mutations in overlooked regions of quinolone target genes may impair the efficacy of treatments via an increase of persistence rather than resistance level, and support the idea that, in addition to resistance, phenotypes of tolerance/persistence of infectious bacterial strains should receive considerations in the choice of antibiotic therapies.

Antibiotic toxicity on human spermatozoa assessed using the sperm DNA fragmentation dynamic assay.

Sperm DNA fragmentation (SDF) dynamic assays were piloted on 4 fresh ejaculates to examine the possible sperm toxicity of three common antibiotics, ciprofloxacin, doxycycline and ampicillin, incubated at a concentration estimated to be reached in semen in vivo, and 100×, for 24h. SDF was assessed in terms of single-strand DNA breaks (SSBs) and double-strand DNA breaks (DSBs). Low and high concentrations of ciprofloxacin and high concentration of doxycycline significantly increased the SDF rate, due to sperm containing SSBs. Ampicillin did not affect SDF dynamics at any dose. Based on these results, the effect of antibiotics on the global-SDF dynamics was further examined in 21 ejaculates assessed at 0, 4 and 6h. Ciprofloxacin increased the rate of SDF at the low concentration in 17 from 21subjects; the high concentration resulted in a stronger effect in all individuals. A significant increase in the rate of SDF in 17 ejaculates was also noted when spermatozoa were incubated with the high concentration of doxycycline. The dynamic SDF assay is a rapid and sensitive tool to evidence sperm toxicity. Ciprofloxacin should be avoided when it is necessary to preserve sperm quality for reproductive purposes and as additive in semen diluents.

Toxicity effects of ciprofloxacin on biochemical parameters, histological characteristics, and behaviors of Corbicula fluminea in different substrates.

Antibiotic toxicity and antibiotic resistance have become significant challenges to human health. However, the potential ecotoxicity of sediment-associated antibiotics remains unknown. In this study, biochemical responses, histological changes, and behavioral responses of Corbicula fluminea exposed to sediment-associated ciprofloxacin (CIP) were systemically investigated. Special attention was paid to the influence of different substrate types. Biochemical analyses revealed that the balance of the antioxidant system was disrupted, eventually leading to oxidative damage to the gills and digestive gland with increasing CIP concentration. Severe histopathological changes appeared along with the oxidative damage. An enlargement of the tubule lumen and thinning of the epithelium in the digestive gland were observed under exposure to high CIP concentrations (0.5 and 2.5 μg/g CIP). In a behavioral assay, the filtration rate of C. fluminea in high concentration exposure groups was clearly inhibited. Moreover, from the integrated biomarker response (IBR) index, the toxicity response gradients of the digestive gland (no substrate--NOS > Sand > Sand and kaolinite clay-- SKC > Sand, kaolinite clay, and organic matter--SCO) and gills (NOS > SCO > SKC > Sand) were different among substrate exposure groups. The most serious histopathological damage and highest siphoning inhibition were observed in the NOS group. The changes in the morphological structure of digestive gland cells in C. fluminea were similar in the other three substrate groups. The inhibition of the filtration rate in the higher concentration groups decreased in the order Sand > SKC > SCO.

Evaluating iron-based nanoparticles for ciprofloxacin removal: Date seed extract as a biostabilizing and a bioreducing agent

Iron-based nanoparticles (FeNPs) are promising materials for the removal of pharmaceutical pollutants. In this study, the following FeNPs were evaluated for ciprofloxacin (CIP) removal: (a) nanoscale zerovalent iron (nZVI) prepared using chemical reduction method (b) nZVI coated with extracts from Phoenix dactylifera/date palm seeds (ds-coated-nZVI) (c) iron-sulfide nanoparticles prepared using date seed extract in a green synthesis approach (ds-FeS). The successful use of date seed extract as a biostabilizer and as a bioreductant was evaluated through multiple characterization techniques to determine nanoparticle morphologies, sizes, and surface chemistry. Batch experiments were used to assess CIP removal capacities and rates by nZVI, ds-coated-nZVI and ds-FeS. Among the three isotherm models investigated (i.e., Langmuir, Freundlich and Hill), the Hill model provided the best fit with maximum removal capacities (qm) of 196 mg g−1 for nZVI, 92 mg g−1 for ds-coated-nZVI and 100 mg g−1 for ds-FeS. The CIP removal kinetics was better represented by the pseudo-second-order model compared to pseudo-first-order and showed concentration dependent enhancements and decreases depending on the FeNP. While nZVI outperformed ds-coated-nZVI and ds-FeS particles in terms of removal rates and extents at higher CIP concentrations (>10 mg/L), the removal performance was similar for the three FeNPs at lower CIP concentrations. Liquid chromatography mass spectrometry and total organic carbon measurements indicated the involvement of both sorption and degradative transformation of CIP. Overall, results from this study suggest the strong capability of FeNPs for CIP removal and also indicate the potential of employing comparatively eco-friendly FeNP alternatives at lower environmentally relevant CIP concentrations.

Characterization of Ciprofloxacin Resistance Levels: Implications for Ototopical Therapy.

Ciprofloxacin-resistant pathogens are inhibited by high concentrations of ciprofloxacin found in commercially-available ototopical solutions. Ciprofloxacin-resistant pathogens in otitis media are currently treated with ototopical ciprofloxacin suspensions. This is done irrespective of laboratory-reported ciprofloxacin susceptibility, under the assumption that the high concentration of ciprofloxacin applied topically is sufficient to overcome antimicrobial resistance. We evaluated 34 ciprofloxacin-resistant isolates consisting of Staphylococcus aureus, Pseudomonas aeruginosa, Corynebacterium spp., and Turicella otitidis. Ciprofloxacin minimum inhibitory concentration (MIC) assays and clinical ototopical solution minimum bactericidal concentration (CMBC) assays were performed. Amongst the ciprofloxacin-resistant isolates, ciprofloxacin MICs ranged from 8 to 256 mcg/ml (mean: 87.1 mcg/ml) and CMBCs ranged from 23.4 to 1500 mcg/ml (mean: 237.0 mcg/ml). There were no significant differences with respect to MIC in comparing P. aeruginosa versus Corynebacterium spp. (mean: 53.3 versus 55.2, p = 0.86), S. aureus versus P. aeruginosa (mean: 128.0 versus 53.3, p = 0.34), and S. aureus versus Corynebacterium spp. (mean: 128.0 versus 55.2, p = 0.09). The correlation between ciprofloxacin MIC and CMBC was poor (Pearson's r = -0.08, p = 0.75). Ciprofloxacin-resistant pathogens commonly recovered from otitis media exhibit highly variable ciprofloxacin MIC and CMBC levels. Ciprofloxacin was able to inhibit growth in all isolates tested at MIC levels less than or equal to 256 mcg/ml; however, CMBC's up to 1500 mcg/ml were observed within that same group. The clinical relevance of these in vitro MICs is unclear due in part to higher bactericidal concentrations (CMBC) in several strains. Our results suggest that treatment failures may be due to a combination of factors rather than high-level resistance alone.

Stress-responses of microbial population and activity in activated sludge under long-term ciprofloxacin exposure

In this study, the effects of ciprofloxacin on activated sludge were evaluated based on the microbial community and metabolic characteristics. The results indicated that the metabolism of chemical oxygen demand (COD) and nitrogen were inhibited with ciprofloxacin at mg/L level compared to the control experiment, and the concentration of ciprofloxacin was slightly decreased. High-throughput sequencing (HTS) results showed that ciprofloxacin greatly shaped the microbial communities in activated sludge, especially for the Nitrospirae phylum and Nitrospira genus. High concentrations of ciprofloxacin stimulated the enrichment of Zoogloea, thus reducing the stability of the activated sludge. Moreover, quinolone resistance proteins in Aeromonas were enriched, which demonstrates their competitive advantage in these enrichment incubations. Finally, the functional profiles were predicted through Tax4Fun, which revealed the adaption to microbes in activated sludge to the ciprofloxacin selective pressure. This work demonstrates the influence of ciprofloxacin on the activated sludge process, and can provide a useful reference for the assessment of the ecological security of ciprofloxacin.

Bacterial persisters in long-term infection: Emergence and fitness in a complex host environment.

Despite intensive antibiotic treatment, Pseudomonas aeruginosa often persists in the airways of cystic fibrosis (CF) patients for decades, and can do so without antibiotic resistance development. Using high-throughput screening assays of bacterial survival after treatment with high concentrations of ciprofloxacin, we have determined the prevalence of persisters in a large patient cohort using 460 longitudinal isolates of P. aeruginosa from 39 CF patients. Isolates were classed as high persister variants (Hip) if they regrew following antibiotic treatment in at least 75% of the experimental replicates. Strain genomic data, isolate phenotyping, and patient treatment records were integrated in a lineage-based analysis of persister formation and clinical impact. In total, 19% of the isolates were classified as Hip and Hip emergence increased over lineage colonization time within 22 Hip+ patients. Most Hip+ lineages produced multiple Hip isolates, but few Hip+ lineages were dominated by Hip. While we observed no strong signal of adaptive genetic convergence within Hip isolates, they generally emerged in parallel or following the development of ciprofloxacin resistance and slowed growth. Transient lineages were majority Hip-, while strains that persisted over a clinically diagnosed ‘eradication’ period were majority Hip+. Patients received indistinguishable treatment regimens before Hip emergence, but Hip+ patients overall were treated significantly more than Hip- patients, signaling repeated treatment failure. When subjected to in vivo-similar antibiotic dosing, a Hip isolate survived better than a non-Hip in a structured biofilm environment. In sum, the Hip phenotype appears to substantially contribute to long-term establishment of a lineage in the CF lung environment. Our results argue against the existence of a single dominant molecular mechanism underlying bacterial antibiotic persistence. We instead show that many routes, both phenotypic and genetic, are available for persister formation and consequent increases in strain fitness and treatment failure in CF airways.

Valorization of biomass into amine- functionalized bio graphene for efficient ciprofloxacin adsorption in water-modeling and optimization study.

A green synthesis approach was conducted to prepare amine-functionalized bio-graphene (AFBG) as an efficient and low cost adsorbent that can be obtained from agricultural wastes. In this study, bio-graphene was successfully used to remove Ciprofloxacin (CIP) from synthetic solutions. The efficacy of adsorbent as a function of operating variables (i.e. pH, time, AFBG dose and CIP concentration) was described by a polynomial model. A optimal99.3% experimental removal was achieved by adjusting the mixing time, AFBG dose, pH and CIP concentration to 58.16, 0.99, 7.47, and 52.9, respectively. Kinetic model revealed that CIP diffusion into the internal layers of AFBG controls the rate of the process. Furthermore, the sorption process was in monolayer with a maximum monolayer capacity of 172.6 mg/g. Adsorption also found to be favored under higher CIP concentrations. The thermodynamic parameters (ΔG°<0, ΔH°>0, and ΔS°>0) demonstrated that the process is endothermic and spontaneous in nature. The regeneration study showed that the AFBG could simply regenerated without significant lost in adsorption capacity.

The Interactions between Ciprofloxacin and Parenteral Nutrition Admixtures

Background: Co-infusion of parenteral nutrition (PN) and other drugs increases the risk of the interaction between drug and PN admixtures that can cause embolization of small blood vessels, resulting in potentially fatal consequences, including pulmonary embolism, or liver and retina vascular damage. The present study aimed to determine the compatibility between ciprofloxacin (CF) and eighteen compounded PN admixtures in order to assess the possibility of their co-administration via Y-sites. Methods: CF and PN admixtures were mixed at two volume ratios (1:1 and 2:1) and potential interactions were examined using visual inspection, and measurements of pH, osmolality particle size, and zeta potential. The analyses were conducted immediately after sample preparation and after four hours of storage. Results: The compatibility tests showed that the addition of the CF to the PN admixtures did not cause any color change or sign of destabilization in the fat emulsion. However, precipitation was observed in formulations containing higher CF concentrations and, in the case of lower CF concentrations, in formulations containing magnesium and calcium ions at a molar ratio of 2:1. Conclusions: The administration of CF and PN admixtures via the Y-site should be avoided or performed only with PN admixtures for which compatibility has been confirmed and the CF concentration in samples is 1 mg/mL at a molar ratio of magnesium to calcium ions of 1:1.

Multi-parametric analysis of ciprofloxacin toxicity at ecologically relevant levels: Short- and long-term effects on Daphnia magna

The increased presence of emergent compounds, such as pharmaceuticals drugs, in the aquatic compartment has been acknowledged as an evolving environmental issue whose consequences are not yet fully characterized. Specific classes of pharmaceutical drugs, such as fluoroquinolone antibiotics, can exert toxic effects to non-target species with ecological significance, since these compounds are environmentally stable and persistent, and may interact with some of the key physiologic processes of organisms. Despite such characteristics, knowledge about the effects of these drugs is still scarce, especially to non-target organisms. The present study aimed to evaluate the effects of chronic and acute exposures of the cladoceran Daphnia magna to the fluoroquinolone antibiotic ciprofloxacin. Putative toxic effects were assessed, following acute and chronic exposures to ecologically relevant concentrations of ciprofloxacin, through enzymatic (cholinesterase – ChEs, catalase – CAT, glutathione S-transferases – GSTs) and non-enzymatic (thiobarbituric acid reactive substances – TBARS, glycogen – Gly) biomarkers. In addition, we also determined behavioural (swimming distance – SD) and morphological (body length of the first brood – BL1B) endpoints in animals exposed to this drug. Ciprofloxacin acute exposure resulted in increased CAT and ChEs activities, and inhibited GSTs activity. After chronic exposure, ChEs activity was significantly inhibited, while GSTs activity was significantly enhanced. TBARS levels were only increased at higher concentrations of ciprofloxacin. CAT activity and Gly content did not evidence a clear and significant pattern of variation. SD was slightly inhibited during dark cycles. BL1B presented a significant decrease for animals subjected to an intermediate concentration. Results showed that even ecologically relevant concentrations of ciprofloxacin may cause oxidative stress in individuals of D. magna. The present study showed important data that corroborate the occurrence of significant biochemical alterations in key features of an aquatic organism when exposed to relevant levels of a widely used antibiotic, establishing essential links between environmental exposure to this specific drug and putative toxic challenges that may result in irreversible changes and damages, especially at the individual level. However, changes in the size of neonates suggest that population alterations are likely to occur under real scenarios of chronic contamination by this drug.

The susceptibility of Proteus mirabilis and Enterococcus faecalis to various antimicrobial agents in polymicrobial biofilms formed using a drip flow reactor

Objectives: Interspecies interactions in poly-species biofilm are substantial. Our aim is to set up dynamic biofilm models ofEnterococcus faecalis and Proteus mirabilis using Drip Flow Biofilm Reactor (DFR) and to evaluate the effect of these dual populationon anti-biofilms of some antimicrobials.Materials and Methods: E.faecalis and P.mirabilis biofilms were formed in a DFR. Influences of the dual interactions on theirsusceptibilities to antimicrobial agents (disinfectants, antibiotics and probiotic strains) were determined.Results: Gluteraldehyde and quaternary ammonium compounds (QAC) effectively killed the cells in both biofilms of E.faecalis andP.mirabilis. However, the efficacy of hydrogen peroxide (H2O2) was dependant on the microbial species present. P. mirabilis was lesssusceptible to the ampicillin and ciprofloxacin in co-culture compared to when cultured alone. Here, the influence of the presenceof E.faecalis on P.mirabilis susceptibility was determined. For high concentrations of ciprofloxacin (1024 and 512 μg/ml), the logreduction in P.mirabilis cells was determined as approximately 4.5 and 3.5 in mono and dual-species biofilms respectively. Comparedto B.lactis, L.acidophilus was found to be more effective both on single and dual species.Conclusion: The effect of antimicrobial agents on microbial cells in a polymicrobial biofilm may depend on the composition of thebiofilm.

Raw wastewater irrigation for urban agriculture in three African cities increases the abundance of transferable antibiotic resistance genes in soil, including those encoding extended spectrum β-lactamases (ESBLs)

A study was conducted to investigate the impact of raw wastewater use for irrigation on dissemination of bacterial resistance in urban agriculture in African cities. The pollution of agricultural fields by selected antibiotic residues was assessed. The structure and functions of the soil microbial communities, presence of antibiotic resistance genes of human clinical importance and Enterobacteriaceae plasmid replicons were analysed using high throughput metagenomic sequencing. In irrigated fields, the richness of Bacteroidetes and Firmicutes phyla increased by 65% and 15.7%, respectively; functions allocated to microbial communities' adaptation and development increased by 3%. Abundance of antibiotic resistance genes of medical interest was 27% greater in irrigated fields. Extended spectrum β-lactamase genes identified in irrigated fields included blaCARB-3, blaOXA-347, blaOXA-5 and blaRm3. The presence of ARGs encoding resistance to amphenicols, β-lactams, and tetracyclines were associated with the higher concentrations of ciprofloxacin, enrofloxacin and sulfamethoxazole in irrigated fields. Ten Enterobacteriaceae plasmid amplicon groups involved in the wide distribution of ARGs were identified in the fields. IncQ2, ColE, IncFIC, IncQ1, and IncFII were found in both farming systems; IncW and IncP1 in irrigated fields; and IncY, IncFIB and IncFIA in non-irrigated fields. In conclusion, raw wastewater irrigated soils in African cities could represent a vector for the spread of antibiotic resistance, thus threatening human and animal health. Consumers of products from these farms and farmers could be at risk of acquiring infections due to drug-resistant bacteria.

Few-layer WS2 modified BiOBr nanosheets with enhanced broad-spectrum photocatalytic activity towards various pollutants removal

Herein, an efficient broad-spectrum WS2/BiOBr heterostructure with ultrathin nanosheet was successfully prepared by one-pot hydrothermal route. The self-assembled flower-like WS2/BiOBr nanostructure was formed by few-layer WS2 and BiOBr nanosheets. The optimized heterojunction presented broad-spectrum high-efficiency photocatalytic activity towards the removal of various pollutants under visible-light irradiation, including organic dyes, antibiotics and phenols. This efficiency was linked to high light harvesting combined with effective charge separation/transfer. Meanwhile, the degradation efficiencies varied with nature of the pollutant decreased in the following order: LR5B (99%) > MNZ (97%) > TC (92%) > OTC (92%) > RhB (90%) > CIP (83%) > MB (78%) > MO (62%) > bisphenol (42%) > phenol (40%). The photocatalytic process of ciprofloxacin was explored, and the results indicated that high ciprofloxacin concentrations, low pH values and elevated concentrations of ions (PO43−, HPO42‐, H2PO4−, and Cu2+) restrained the photocatalytic performances. Trapping experiments and ESR revealed the significant contribution of holes (h+) in the mechanism, where both superoxide radicals (O2−) and hydroxyl radicals (OH) acted as assistants. Overall, this work could offer a new protocol for the design of highly efficient heterostructure photocatalysts for environmental remediation.