Antibiotic Mixture Research Articles

Competitive adsorption of oxytetracycline and sulfamethoxazole by nanosized activated carbon in aquatic environments: Experimental analysis and DFT calculations

Nanosized activated carbon (NAC) is an emerging carbonaceous nanomaterial for water treatment, while oxytetracycline (OTC) and sulfamethoxazole (SMX) coexisting in aquatic environments may undergo competitive adsorption to influence its removal efficiency. This study investigated the competitive adsorption of OTC and SMX onto NAC under different interaction sequence, pH, electrolyte, and water matrix conditions, using experimental analysis and density function theory (DFT) calculations. Adsorption kinetics show that increasing concentration of one antibiotic inhibited the adsorption of another. Faster equilibrium was attained in binary systems than single systems due to competitive adsorption, with pseudo-second-order model providing the best fit in both systems. Adsorption isotherms suggest that NAC exhibited stronger affinity towards OTC (395.26 mg/g) than SMX (232.02 mg/g), with Langmuir model showing satisfactory fitting in both single and binary systems. Sequential adsorption of [NAC + OTC] + SMX was more favored than binary adsorption, aligning with the optimum configuration of SMX--[NAC-OTC±] with binding energy of −57.25 kcal/mol from DFT calculations. Competitive adsorption was preferred within pH 3.2–5.6, where electrostatic attraction existed between NAC and cationic antibiotics. Salting-out, charge screening, and complexation effects from Na+ and Ca2+ influenced competitive adsorption. Optimal removal of OTC and SMX by NAC was achieved in wastewater effluent among four water matrices in both single and binary systems. Hydrogen bonding, π − π electron donor–acceptor interactions, electrostatic interactions, and hydrophobic interactions contributed to adsorption. Sequential change in functional groups of NAC followed − OH → C − H → C − O → C = C and C = C → C − O → C − H → − OH in single and binary systems, respectively. The findings provide valuable insights into the competitive adsorption mechanisms of antibiotics on NAC, highlighting its potential for remediating mixtures of antibiotics in complex aquatic environments.

Kinetic modelling of UVC and UVC/H2O2 oxidation of an aqueous mixture of antibiotics in a completely mixed batch photoreactor

The removal kinetics of an aqueous mixture of thirteen antibiotics (i.e., ampicillin, cefuroxime, ciprofloxacin, flumequine, metronidazole, ofloxacin, oxytetracycline, sulfadimethoxine, sulfamethoxazole, sulfamethazine, tetracycline, trimethoprim and tylosin) by batch UVC and UVC/H2O2 processes has been modeled in this work. First, molar absorption coefficients (ε), direct quantum yields (Φ) and the rate constants of the reaction of antibiotics with hydroxyl radical (kHO•) (model inputs) were determined for each antibiotic and compared with literature data. The values of these parameters range from 0.3 to 21.8 mM−1 cm−1 for ε, < 0.01 to 67.8 mmol·E−1 for Φ and 3.8 × 109 to 1.7 × 1010 M−1 s−1 for kHO•. Second, a regression model was developed to compute the rate constants of the reactions of the antibiotics with singlet oxygen (k1O₂) from experimental data obtained in batch UVC experiments treating a mixture of the antibiotics. k1O₂ values in the 1–50 × 106 M−1 s−1 range were obtained for the antibiotics studied. Finally, a semi-empirical kinetic model comprising a set of ordinary differential equations was solved to simulate the evolution of the residual concentration of antibiotics and hydrogen peroxide (model outputs) in a completely mixed batch photoreactor. Model predictions were reasonably consistent with the experimental data. The kinetic model developed might be combined with computational fluid dynamics to predict process performance and energy consumption in UVC and UVC/H2O2 applications at full scale.

Mixture of oxytetracycline and erythromycin antibiotics enhances nutritional quality of a commercial feed, effluent quality, and but not water quality in catfish culture, Clarias gariepinus

Mixture of oxytetracycline and erythromycin antibiotics enhances nutritional quality of a commercial feed, effluent quality, and but not water quality in catfish culture, Clarias gariepinus

Lesion Sterilization and Tissue Repair in Pediatric Endodontics: A Review

Dentists treating patients have long been concerned about residual infections in the root canal system. Lesion sterilization and tissue repair (LSTR) therapy is a type of endodontic treatment in which root canal systems are disinfected by placing an antibiotic mixture after minimum or no equipment is used. It is increasingly being used to treat nonvital teeth instead of extractions, root canal treatments, and conventional pulpectomies. The content of this article covers the technique's development, purpose, indications, applications, and clinical steps that are required to use it.

Voltammetric electronic tongue for the discrimination of antibiotic mixtures in tap water

The identification and quantification of antibiotics in different types of water is of growing interest due to the resistance their presence can induce in many bacterial species. Although the electrochemical analysis of electroactive antibiotics via voltammetric techniques is rapid, simple and cost-effective, their simultaneous detection is often challenging due to their overlapping oxidation peaks. To address this issue, we have developed a voltammetric electronic tongue for the discrimination and quantification of antibiotic mixtures in tap water. For that purpose, three different screen-printed carbon electrodes were modified with “green”-synthesized metallic nanoparticles (NPs) of copper and silver, and commercial titanium dioxide NPs. The electrochemical behavior of the electrodes against the detection of six antibiotics was first investigated by cyclic voltammetry, proving the catalytic effect of the selected NPs. Next, principal component analysis and artificial neural networks (ANNs) were used to achieve the accurate discrimination and quantification of three selected antibiotics, cefepime, daptomycin, and vancomycin, at the mg/L level with a normalized root mean square error (NRMSE) of 0.055 for the test subset. Finally, after validation of the ANN model, the analysis of tap water samples spiked with the three selected antibiotics was carried out to test its applicability for water quality monitoring, showing a good agreement with the expected values (average recovery of 95 %, and NRMSE of 0.034).

A microbiome-biochar composite synergistically eliminates the environmental risks of antibiotic mixtures and their toxic byproducts

This study developed a continuous reactor system employing a hybrid hydrogel composite synthesized using a complex sludge microbiome and an adsorbent (HSA). This HSA-based system effectively eliminated the environmental risks associated with a mixture of the antibiotics ciprofloxacin and sulfamethoxazole, which exhibited higher toxicity in combination than individually at environmentally relevant levels. Analytical chemistry experiments revealed the in-situ generation of various byproducts (BPs) within the bioreactor system, with two of these BPs recording toxicity levels that surpassed those of their parent compound. The HSA approach successfully prevented the functional microbiome from being washed out of the reactor, while HSA efficiently removed antibiotic residues in their original and BP forms through synergistic adsorptive and biotransformation mechanisms, ultimately reducing the overall ecotoxicity. The use of HSA thus demonstrates promise not only as a mean to reduce the threat posed by toxic antibiotic residues to aquatic ecosystems but also as a practical solution to operational challenges, such as biomass loss/washout, that are frequently encountered in various environmental bioprocesses.

Plantlet Regeneration from Callus Cultures of Kappaphycus alvarezii for Cultivation in Coastal Waters at Myeik Archipelago, Myanmar.

&lt;b&gt;Background and Objective:&lt;/b&gt; The cultivation of &lt;i&gt;Kappaphycus alvarezii&lt;/i&gt;, the most economically valuable rhodophyte seaweed species, began in Myanmar in 2004, primarily on islands in the Myeik Archipelago. Since &lt;i&gt;K. alvarezii&lt;/i&gt; is not native to Myanmar, it was initially imported from the Philippines and Indonesia. This study aimed to develop a tissue culture procedure for the generation of &lt;i&gt;K. alvarezii&lt;/i&gt; plantlets to ensure a continuous supply of seaweed for commercial farming in the coastal waters of Myanmar. &lt;b&gt;Materials and Methods:&lt;/b&gt; Specimens of &lt;i&gt;K. alvarezii&lt;/i&gt;, two-month-old, were procured in the Myeik Archipelago, Myanmar. After being cleared epiphytes and clinging materials, the specimens were placed in glass aquarium tanks with circulating seawater. Axenic explant culture was established using 1% povidone-iodine for 1 min and a 1% antibiotic mixture for 24 hrs. Plant growth regulators, 6-benzyl aminopurine (BAP) and indole 3 acetic acid (IAA) were supplemented in solid Provasoli's enriched seawater (PES) media to induce callus formation and somatic embryogenesis. &lt;b&gt;Results:&lt;/b&gt; The optimal culture conditions were incubation at 22-25°C under cool-white fluorescent-light (15-20 μmol photons/m&lt;sup&gt;2&lt;/sup&gt;/sec) with a 12:12 hrs light and dark cycle. Water quality during the culturing process was maintained at a pH of 8 and salinity of 30 PSU. The tissue-cultured &lt;i&gt;K. alvarezii&lt;/i&gt; plantlets exhibited an average daily growth rate of 9.70±0.25% over the growth period. &lt;b&gt;Conclusion:&lt;/b&gt; Therefore, plantlet regeneration from &lt;i&gt;K. alvarezii&lt;/i&gt; callus cultures can be utilized as seedlings for revenue-generating cultivation along the Myanmar coastline.

Antibiotic feeding changes the bacterial community of Chilo suppressalis and thereby affects its pesticide tolerance

BackgroundOwing to the widespread use of chemical pesticides to control agricultural pests, pesticide tolerance has become a serious problem. In recent years, it has been found that symbiotic bacteria are related to pesticides tolerance. To investigate the potential role of microorganisms in the pesticide tolerance of Chilo suppressalis, this study was conducted.ResultsThe insect was fed with tetracycline and cefixime as the treatment group (TET and CFM, respectively), and did not add antibiotics in the control groups (CK). The 16S rDNA sequencing results showed that antibiotics reduced the diversity of C. suppressalis symbiotic microorganisms but did not affect their growth and development. In bioassays of the three C. suppressalis groups (TET, CFM, and CK), a 72 h LC50 fitting curve was calculated to determine whether long-term antibiotic feeding leads to a decrease in pesticide resistance. The CK group of C. suppressalis was used to determine the direct effect of antibiotics on pesticide tolerance using a mixture of antibiotics and pesticides. Indirect evidence suggests that antibiotics themselves did not affect the pesticide tolerance of C. suppressalis. The results confirmed that feeding C. suppressalis cefixime led to a decrease in the expression of potential tolerance genes to chlorantraniliprole.ConclusionsThis study reveals the impact of antibiotic induced changes in symbiotic microorganisms on the pesticide tolerance of C. suppressalis, laying the foundation for studying the interaction between C. suppressalis and microorganisms, and also providing new ideas for the prevention and control of C. suppressalis and the creation of new pesticides.

Rapid and Simple Morphological Assay for Determination of Susceptibility/Resistance to Combined Ciprofloxacin and Ampicillin, Independently, in Escherichia coli.

Current antibiograms cannot discern the particular effect of a specific antibiotic when the bacteria are incubated with a mixture of antibiotics. To prove that this task is achievable, Escherichia coli strains were treated with ciprofloxacin for 45 min, immobilized on a slide and stained with SYBR Gold. In susceptible strains, the nucleoid relative surface started to decrease near the MIC, being progressively condensed as the dose increased. The shrinkage level correlated with the DNA fragmentation degree. Ciprofloxacin-resistant bacilli showed no change. Additionally, E. coli strains were incubated with ampicillin for 45 min and processed similarly. The ampicillin-susceptible strain revealed intercellular DNA fragments that increased with dose, unlike the resistant strain. Co-incubation with both antibiotics revealed that ampicillin did not modify the nucleoid condensation effect of ciprofloxacin, whereas the quinolone partially decreased the background of DNA fragments induced by ampicillin. Sixty clinical isolates, with different combinations of susceptibility-resistance to each antibiotic, were co-incubated with the EUCAST breakpoints of susceptibility of ciprofloxacin and ampicillin. The morphological assay correctly categorized all the strains for each antibiotic in 60 min, demonstrating the feasible independent evaluation of a mixture of quinolone and beta-lactam. The rapid phenotypic assay may shorten the incubation times and necessary microbial mass currently required for evaluation.

Classification and regression machine learning models for predicting the combined toxicity and interactions of antibiotics and fungicides mixtures

Antibiotics and triazole fungicides coexist in varying concentrations in natural aquatic environments, resulting in complex mixtures. These mixtures can potentially affect aquatic ecosystems. Accurately distinguishing synergistic and antagonistic mixtures and predicting mixture toxicity are crucial for effective mixture risk assessment. We tested the toxicities of 75 binary mixtures of antibiotics and fungicides against Auxenochlorella pyrenoidosa. Both regression and classification models for these mixtures were developed using machine learning models: random forest (RF), k-nearest neighbors (KNN), and kernel k-nearest neighbors (KKNN). The KKNN model emerged as the best regression model with high values of determination coefficient (R2 = 0.977), explained variance in prediction leave-one-out (Q2LOO = 0.894), and explained variance in external prediction (Q2F1 = 0.929, Q2F2 = 0.929, and Q2F3 = 0.923). The RF model, the leading classifier, exhibited high accuracy (accuracy = 1 for the training set and 0.905 for the test set) in distinguishing the synergistic and antagonistic mixtures. These results provide crucial value for the risk assessment of mixtures.

Electrophoretically deposited TiO2 layers for efficient photocatalytic degradation of antibiotic mixture in greywater

Efficient removal of pharmaceuticals from greywater is crucial to enable its application for non-potable use. TiO2 photocatalysis is a promising environmentally friendly way of streamlining their complete degradation. However, dispersed TiO2 nanopowders are unsuitable for greywater treatment procedures because they require separation and may aggregate, thereby losing photocatalytic activity. Thus, TiO2 nanopowders (anatase 5 and 100 nm, AEROXIDE® P 25) were immobilized into layers by quantitative electrophoretic deposition. The layer ability to degrade the commonly used antibiotics ampicillin and sulfathiazole in deionized water was monitored using HPLC-PDA analysis and compared with that of the respective nanopowders. All layers attained total conversion of the initial antibiotics (limit of detection 50–100 μg L−1) with the highest degradation rate constant corresponding to 66 × 10−4 min−1 for AEROXIDE® P25 layer. To evaluate the efficiency of the prepared layers under more realistic conditions, collected greywater was treated in a membrane bioreactor, spiked with an equimolar antibiotic mixture, and subjected to photocatalysis. The overall reaction rate constants were calculated as 54, 15 and 75 × 10−4 min−1 for 5 and 100 nm anatase and AEROXIDE® P25 layers, respectively; the best-performing layer achieved complete removal and 68 % total mineralization of the antibiotic mixture in greywater within 7 and 24 h, respectively. For this layer, the developed regeneration method recovered min. 94 % of the original photocatalytic activity, enabling its reusability. These results suggest that our presented deposition method provides layers capable of degrading antibiotic mixtures in greywater effectively and is suitable for upscaling due to its low cost and simplicity.

Effect of Multiantibiotic-Loaded Bone Cement on the Treatment of Periprosthetic Joint Infections of Hip and Knee Arthroplasties-A Single-Center Retrospective Study.

Two-stage septic revision is the prevailing method for addressing late periprosthetic infections. Using at least dual-antibiotic-impregnated bone cement leads to synergistic effects with a more efficient elution of individual antibiotics. Recent data on the success rates of multiantibiotic cement spacers in two-stage revisions are rare. We conducted a retrospective follow-up single-center study involving 250 patients with late periprosthetic hip infections and 95 patients with prosthetic knee infections who underwent septic two-stage prosthesis revision surgery between 2017 and 2021. In accordance with the antibiotic susceptibility profile of the microorganisms, a specific mixture of antibiotics within the cement spacer was used, complemented by systemic antibiotic treatment. All patients underwent preoperative assessments and subsequent evaluations at 3, 6, 9, 12, 18, and 24 months post operation and at the most recent follow-up. During the observation period, the survival rate after two-step septic revision was 90.7%. Although survival rates tended to be slightly lower for difficult-to-treat (DTT) microorganism, there was no difference between the pathogen groups (easy-to-treat (ETT) pathogens, methicillin-resistant staphylococci (MRS), and difficult-to-treat (DTT) pathogens). Furthermore, there were no differences between monomicrobial and polymicrobial infections. No difference in the survival rate was observed between patients with dual-antibiotic-loaded bone cement without an additional admixture (Copal® G+C and Copal® G+V) and patients with an additional admixture of antibiotics to proprietary cement. Employing multiple antibiotics within spacer cement, tailored to pathogen susceptibility, appears to provide reproducibly favorable success rates, even in instances of infections with DTT pathogens and polymicrobial infections.

Influence of Four Veterinary Antibiotics on Constructed Treatment Wetland Nitrogen Transformation.

The use of wetlands as a treatment approach for nitrogen in runoff is a common practice in agroecosystems. However, nitrate is not the sole constituent present in agricultural runoff and other biologically active contaminants have the potential to affect nitrate removal efficiency. In this study, the impacts of the combined effects of four common veterinary antibiotics (chlortetracycline, sulfamethazine, lincomycin, monensin) on nitrate-N treatment efficiency in saturated sediments and wetlands were evaluated in a coupled microcosm/mesocosm scale experiment. Veterinary antibiotics were hypothesized to significantly impact nitrogen speciation (e.g., nitrate and ammonium) and nitrogen uptake and transformation processes (e.g., plant uptake and denitrification) within the wetland ecosystems. To test this hypothesis, the coupled study had three objectives: 1. assess veterinary antibiotic impact on nitrogen cycle processes in wetland sediments using microcosm incubations, 2. measure nitrate-N reduction in water of floating treatment wetland systems over time following the introduction of veterinary antibiotic residues, and 3. identify the fate of veterinary antibiotics in floating treatment wetlands using mesocosms. Microcosms containing added mixtures of the veterinary antibiotics had little to no effect at lower concentrations but stimulated denitrification potential rates at higher concentrations. Based on observed changes in the nitrogen loss in the microcosm experiments, floating treatment wetland mesocosms were enriched with 1000 μg L-1 of the antibiotic mixture. Rates of nitrate-N loss observed in mesocosms with the veterinary antibiotic enrichment were consistent with the microcosm experiments in that denitrification was not inhibited, even at the high dosage. In the mesocosm experiments, average nitrate-N removal rates were not found to be impacted by the veterinary antibiotics. Further, veterinary antibiotics were primarily found in the roots of the floating treatment wetland biomass, accumulating approximately 190 mg m-2 of the antibiotic mixture. These findings provide new insight into the impact that veterinary antibiotic mixtures may have on nutrient management strategies for large-scale agricultural operations and the potential for veterinary antibiotic removal in these wetlands.

Effects of sulfamonomethoxine and trimethoprim co-exposures at different environmentally relevant concentrations on microalgal growth and nutrient assimilation

In aquaculture around the world, sulfamonomethoxine (SMM), a long-acting antibiotic that harms microalgae, is widely employed in combination with trimethoprim (TMP), a synergist. However, their combined toxicity to microalgae under long-term exposures at environmentally relevant concentrations remains poorly understood. Therefore, we studied the effects of SMM single-exposures and co-exposures (SMM:TMP=5:1) at concentrations of 5 μg/L and 500 μg/L on Chlorella pyrenoidosa within one aquacultural drainage cycle (15 days). Photosynthetic activity and N assimilating enzyme activities were employed to evaluate microalgal nutrient assimilation. Oxidative stress and flow cytometry analysis for microalgal proliferation and death jointly revealed mechanisms of inhibition and subsequent self-adaptation. Results showed that exposures at 5 μg/L significantly inhibited microalgal nutrient assimilation and induced oxidative stress on day 7, with a recovery to levels comparable to the control by day 15. This self-adaptation and over 95 % removal of antibiotics jointly contributed to promoting microalgal growth and proliferation while reducing membrane-damaged cells. Under 500 μg/L SMM single-exposure, microalgae self-adapted to interferences on nutrient assimilation, maintaining unaffected growth and proliferation. However, over 60 % of SMM remained, leading to sustained oxidative stress and apoptosis. Remarkably, under 500 μg/L SMM-TMP co-exposure, the synergistic toxicity of SMM and TMP significantly impaired microalgal nutrient assimilation, reducing the degradation efficiency of SMM to about 20 %. Consequently, microalgal growth and proliferation were markedly inhibited, with rates of 9.15 % and 17.7 %, respectively, and a 1.36-fold increase in the proportion of cells with damaged membranes was observed. Sustained and severe oxidative stress was identified as the primary cause of these adverse effects. These findings shed light on the potential impacts of antibiotic mixtures at environmental concentrations on microalgae, facilitating responsible evaluation of the ecological risks of antibiotics in aquaculture ponds.

Lactose-free milk powder can effectively relieve diarrhea symptoms in weaning SD rats and children

Diarrhea has become the leading cause of illness and death among infants and young children in developing countries. Clinically, patients with diarrhea showed damaged intestinal epithelial villi, usually accompanied by lactase deficiency. In this study, we evaluated the therapeutic effects of lactose-free milk powder on rats and children with diarrhea. Antibiotic-associated diarrhea ¹(AAD) model was established by gavage with antibiotic mixture in SD rats, followed by administration of milk powder containing lactose or not. The results showed that lactose-free milk powder ameliorated AAD-related diarrhea symptoms, and accelerated the recovery from diarrhea. And 16S sequencing results indicated lactose-free milk powder contributed to increase the α and β diversity of intestinal flora, and restore the intestinal microbiota disorder. In conclusion, our data demonstrate that lactose-free milk powder could alleviate diarrhea by restoring gut microbiota and intestinal barrier function.

Floating MIL-88A(Fe)@expanded perlites catalyst for continuous photo-Fenton degradation toward tetracyclines under artificial light and real solar light

In this work, MIL-88A(Fe) was immobilized onto the expanded perlites to fabricate the floating MIL-88A(Fe)@expanded perlites (M@EP) catalyst via high throughput batch synthesis method under room temperature. The as-prepared M@EP could efficiently activate H2O2 to achieve 100% tetracycline antibiotics (TCs) removal under both artificial low power UV light (UVL) and real sunlight (SL) irradiation. The toxicological evaluation, growth experiment of mung beans and antimicrobial estimation revealed the decreasing aquatic toxicity of the TCs intermediates compared to those of the pristine TCs. A self-designed continuous bed reactor was employed to investigate the long-term operation of the M@EP. The findings demonstrated that the antibiotics mixture can be continuously degraded up to 7 days under UVL and 5 daytimes under SL irradiation, respectively. More importantly, ca. 76.9% and 81.6% of total organic carbon (TOC) removal efficiencies were accomplished in continuous bed reactor under UVL and SL irradiation, respectively. This work advances the immobilized MOFs on floating supports for their practical application in large-scale wastewater purification through advanced oxidation processes. Environmental implicationThis work presented the high throughput production and photo-Fenton degradation application of floating MIL-88A(Fe)@expanded perlites (M@EP). Three tetracycline antibiotics (TCs) were selected as model pollutants to test the degradation ability of M@EP in batch experiment and continuous operation under artificial light and solar light. The complete TCs degradation could be accomplished in self-designed device up to 7 d under UV light and 5 d under real solar light. This work tapped a new door to push MOFs-based functional materials in the real water purification.

The Effect of Adding Various Antibiotics on the Push-out Bond Strength of a Resin-based Sealer: An In Vitro Study.

This study aimed to compare the bond strength of AH Plus sealer to root canal dentin when used with or without various antibiotics including amoxicillin, clindamycin, and triple antibiotic mixture (TAM). A total of 80 single-rooted extracted human teeth were instrumented and obturated with gutta-percha and four different sealer-antibiotic combinations (n = 20). Group I: AH Plus without any antibiotics, Group II: AH Plus with amoxicillin, Group III: AH Plus with clindamycin, and Group IV: AH Plus with TAM. After seven days, the roots were sectioned perpendicular to their long axis and 1 mm thick slices were obtained from the midroots. The specimens were subjected to a push-out bond strength test and failure modes were also evaluated. Data was analyzed using Kruskal-Wallis and Dunn's post hoc tests. Group IV had significantly higher bond strength compared to other groups (p ≤ 0.05). No significant differences were found between other groups. While the sealer-antibiotic groups predominantly showed cohesive failure modes, the control group displayed both cohesive and mixed failure modes. Within the limitations of this study, the addition of TAM increased the push-out bond strength of AH Plus. Amoxicillin, clindamycin, or TAM can be added to AH Plus for increased antibacterial efficacy without concern about their effects on the bond strength of the sealer. How to cite this article: Adl A, Shojaei NS, Ranjbar N. The Effect of Adding Various Antibiotics on the Push-out Bond Strength of a Resin-based Sealer: An In Vitro Study. J Contemp Dent Pract 2024;25(3):231-235.

Climate warming promotes collateral antibiotic resistance development in cyanobacteria

Both cyanobacterial blooms and antibiotic resistance have aggravated worldwide and posed a great threat to public health in recent years. As a significant source and reservoir of water environmental resistome, cyanobacteria exhibit confusing discrepancy between their reduced susceptibility and their chronic exposure to antibiotic mixtures at sub-inhibitory concentrations. How the increasing temperature affects the adaptive evolution of cyanobacteria-associated antibiotic resistance in response to low-level antibiotic combinations under climate change remains unclear. Here we profiled the antibiotic interaction and collateral susceptibility networks among 33 commonly detected antibiotics in 600 cyanobacterial strains isolated from 50 sites across four eutrophicated lakes in China. Cyanobacteria-associated antibiotic resistance level was found positively correlated to antibiotic heterogeneity across all sites. Among 528 antibiotic combinations, antagonism was observed for 62 % interactions and highly conserved within cyanobacterial species. Collateral resistance was detected in 78.5 % of pairwise antibiotic interaction, leading to a widened or shifted upwards mutant selection window for increased opportunity of acquiring second-step mutations. We quantified the interactive promoting effect of collateral resistance and increasing temperature on the evolution of both phenotypic and genotypic cyanobacteria-associated resistance under chronic exposure to environmental level of antibiotic combinations. With temperature increasing from 16 °C to 36 °C, the evolvability index and genotypic resistance level increased by 1.25 – 2.5 folds and 3 – 295 folds in the collateral-resistance-informed lineages, respectively. Emergence of resistance mutation pioneered by tolerance, which was jointly driven by mutation rate and persister fraction, was found to be accelerated by increased temperature and antibiotic switching rate. Our findings provided mechanic insights into the boosting effect of climate warming on the emergence and development of cyanobacteria-associated resistance against collateral antibiotic phenotypes.

Binary hetero-structured PVDF/TiO2@MXene composite membranes for the removal of antibiotics from wastewater

The presence of pharmaceuticals in hospital wastewaters has generated significant interest among researchers. Current membrane technologies face limitations in effectively removing these emerging contaminants, which has led to continuous advancements in the field. Two-dimensional (2D) nanomaterial-based membranes have proved their ability in providing high water permeability without compromising separation performance. In this study, a binary hetero-structured PVDF/TiO2@MXene composite 2D membrane was prepared and utilized for the rejection of antibiotics, namely tetracycline and meropenem. Vacuum-assisted filtration was employed to fabricate the photocatalytic and highly selective multi-layer TiO2@MXene stacked sheets on hydrophilic PVDF microfilters. The attachment of TiO2 nanoparticles in the MXene structure has significantly improved the wettability and permeation of the PVDF/TiO2@MXene membrane, with a water contact angle of 19.5° and a permeation capacity of 293 L.m−2.h−1.bar−1. In terms of antibiotic rejection, the developed membrane demonstrated a rejection of 87.8% and 60.7% for tetracycline and meropenem solutions, respectively, through interlayer sieving, adsorption, and photocatalysis. The membrane also performed ideally in neutral pH conditions often present in hospital wastewaters, when compared to acidic and alkaline conditions, aiding in the membrane's adsorptive interactions under UV irradiation. When studied in antibiotic mixtures and spiked real hospital wastewater feed solutions, the membrane exhibited a rejection rate of 77.4% and 70.1% for tetracycline, respectively. This research represents a promising approach to addressing the challenges posed by pharmaceuticals in hospital wastewaters through the synergistic utilization of MXene and anatase TiO2.

Inadvertent antibiotic exposure during pregnancy may increase the risk for neural tube defects in offspring

BackgroundAs emerging environmental contaminants, antibiotics pose potential threats to human health, in particular to pregnant women and infants. However, the potential harm of inadvertent antibiotic exposure (IAE) is often disregarded in light of the focus on intentional antibiotic use during pregnancy. Currently, little is known about the effects of IAE during pregnancy on fetal neural tube development. MethodsIn this case-control study, we used questionnaire data from 855 subjects to investigate the effects of intentional antibiotic use in early pregnancy on neural tube defects (NTDs). Then we tested for placental antibiotics in mothers who had not intentionally used antibiotics, and the compounds were detected in 379 subjects; these were considered IAE cases. We assessed the association between IAE during pregnancy and fetal NTDs using both multivariable logistic and multi-pollutant exposure models. We also analyzed the correlation between maternal dietary habits and placental antibiotics to explore possible sources of IAE. ResultsOnly 50 of 855 participants (5.8%) intentionally used antibiotics and such use showed no significant association with NTD risk (odds ratio [OR] = 1.92, confidence interval [95%CI] = [0.66, 5.59]). However, 14 of 15 placental antibiotics were detected in 378 of 379 subjects (99.7%) and multivariable logistic analysis indicated that high levels of placental macrolides were significantly associated with increased NTD risk (4.42 [2.01–10.45]). Multi-pollutant exposure analysis suggested an increase in NTD risk with an increase in exposure to a mixture of placental antibiotics, among which macrolides were the most important contributor. In addition, the level of placental macrolides was positively correlated with the intake frequency of milk. Finally, mothers who drank river, well, or pond water had higher levels of placental macrolides than those who drank only tap water. ConclusionsIntentional antibiotic use during early pregnancy may not be associated with NTDs, while IAE during pregnancy is associated with higher NTD risk in offspring. Macrolides are crucial risk factors. Milk, and river, well, or pond water may be important sources of IAE.