Resistant Bacteria Research Articles

Performance and potential mechanisms for reactive electrochemical ceramic membrane system to inhibit resistance transmission in antibiotic-resistant contaminated wastewater: From a microbial perspective

Due to the widespread presence of antibiotic resistance genes (ARGs) in traditional biological wastewater treatment systems, electrochemical disinfection techniques have received extensive attention. The rTNA/Sb-SnO2/PbO2 Reactive Electrochemical Ceramic Membrane (RECM) system has demonstrated outstanding performance in effectively removing refractory antibiotics. However, its capacity to remove antibiotic resistant bacteria (ARB) remains unclear. In this study, an antibiotic resistant strain of Escherichia coli (AR E. coli) was employed to investigate the disinfection efficiency of the RECM system at a macroscopic level, along with its disinfection mechanism at a microscopic level. Furthermore, the secondary effluent from an antibiotic production wastewater treatment plant was collected to validate the disinfection performance of this system against ARB in actual wastewater. In the RECM system, the inactivation of AR E. coli and the removal of ARGs were primarily governed by the electrocatalytic process, with notable influences from critical factors such as current density, electrolyte type, and hydraulic retention time. Morphological observation and flow cytometry experiments confirmed that the AR E. coli in the RECM system was inactivated by alterations in cell morphology, leading to fragmentation, and by improvement in cell membrane permeability. More significantly, this system exhibited noteworthy efficiency in treating wastewater contaminated with antibiotic resistant pollutants, effectively eliminating both antibiotics and ARGs from the secondary effluent. Overall, our study comprehensively investigated the performance and underlying mechanisms of the RECM system in mitigating the dissemination of ARGs, as well as its potential feasibility of practical application.

An early and stable mouse model of polymyxin-induced acute kidney injury

BackgroundPolymyxins have been revived as a last-line therapeutic option for multi-drug resistant bacteria and continue to account for a significant proportion of global antibiotic usage. However, kidney injury is often a treatment limiting event with kidney failure rates ranging from 5 to 13%. The mechanisms underlying polymyxin-induced nephrotoxicity are currently unclear. Researches of polymyxin-associated acute kidney injury (AKI) models need to be more standardized, which is crucial for obtaining consistent and robust mechanistic results.MethodsIn this study, male C57BL/6 mice received different doses of polymyxin B (PB) and polymyxin E (PE, also known as colistin) by different routes once daily (QD), twice daily (BID), and thrice daily (TID) for 3 days. We continuously monitored the glomerular filtration rate (GFR) and the AKI biomarkers, including serum creatinine (Scr), blood urea nitrogen (BUN), neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1). We also performed histopathological examinations to assess the extent of kidney injury.ResultsMice receiving PB (35 mg/kg/day subcutaneously) once daily exhibited a significant decrease in GFR and a notable increase in KIM-1 two hours after the first dose. Changes in GFR and KIM-1 at 24, 48 and 72 h were consistent and demonstrated the occurrence of kidney injury. Histopathological assessments showed a positive correlation between the severity of kidney injury and the changes in GFR and KIM-1 (Spearman’s rho = 0.3167, P = 0.0264). The other groups of mice injected with PB and PE did not show significant changes in GFR and AKI biomarkers compared to the control group.ConclusionThe group receiving PB (35 mg/kg/day subcutaneously) once daily consistently developed AKI at 2 h after the first dose. Establishing an early and stable AKI model facilitates researches into the mechanisms of early-stage kidney injury. In addition, our results indicated that PE had less toxicity than PB and mice receiving the same dose of PB in the QD group exhibited more severe kidney injury than the BID and TID groups.

Characterization of KPC-type drug resistance in bacteria

One of the main problems of modern medicine is the phenomenon of drug resistance. Inappropriate use of antibiotics is considered to be the most important reason for the emergence of new resistance mechanisms in microorganisms. Carbapenems, which belong to the β-lactams, are considered the most effective group of antimicrobial agents. Unfortunately, as a result of prolonged exposure to the aforementioned drugs, bacteria have developed several mechanisms for survival. The most important of these is the production of hydrolytic enzymes (carbapenemases), which cleave the β-lactam ring and inactivate the antibiotics. The mentioned enzymes are encoded by blaKPC genes, which are located in so-called mobile genetic elements (i.e. plasmids and transposons). Such localization is associated with their ease of transfer between different bacterial species in the process of horizontal gene transfer.

Investigation of dual inhibition of antibacterial and antiarthritic drug candidates using combined approach including molecular dynamics, docking and quantum chemical methods

Emerging antibiotic resistance in bacteria threatens immune efficacy and increases susceptibility to bone degradation and arthritic disorders. In our current study, we utilized a three-layer in-silico screening approach, employing quantum chemical methods, molecular docking, and molecular dynamic methods to explore the novel drug candidates similar in structure to floroquinolone (ciprofloxacin). We investigated the interaction of novel similar compounds of ciprofloxacin with both a bacterial protein S. aureus TyrRS (1JIJ) and a protein associated with gout arthritis Neutrophil collagenase (3DPE). UTIs and gout are interconnected through the elevation of uric acid levels. We aimed to identify compounds with dual functionality: antibacterial activity against UTIs and antirheumatic properties. Our screening based on several methods, sorted out six promising ligands. Four of these (L1, L2, L3, and L6) demonstrated favorable hydrogen bonding with both proteins and were selected for further analysis. These ligands showed binding affinities of −8.3 to −9.1 kcal/mol with both proteins, indicating strong interaction potential. Notably, L6 exhibited highest binding energies of −9.10 and −9.01 kcal/mol with S. aureus TyrRS and Neutrophil collagenase respectively. Additionally, the pkCSM online database conducted ADMET analysis on all lead ligand suggested that L6 might exhibit the highest intestinal absorption and justified total clearance rate. Moreover, L6 showed a best predicted inhibition constant with both proteins. The average RMSF values for all complex systems, namely L1, L2, L3 and L6 are 0.43 Å, 0.57 Å, 0.55 Å, and 0.51 Å, respectively where the ligand residues show maximum stability. The smaller energy gap of 3.85 eV between the HOMO and LUMO of the optimized molecule L1 and L6 suggests that these are biologically active compound. All the selected four drugs show considerable stabilization energy ranging from 44.78 to 103.87 kcal/mol, which means all four compounds are chemically and physically stable. Overall, this research opens exciting avenues for the development of new therapeutic agents with dual functionalities for antibacterial and antiarthritic drug designing.

Ozone-Resistant Bacteria, an Inconvenient Hazard in Water Reclamation: Resistance Mechanism, Propagating Capacity, and Potential Risks.

Resistant bacteria have always been of research interest worldwide. In the urban water system, the increased disinfectant usage gives more chances for undesirable disinfection-resistant bacteria. As the strongest oxidative disinfectant in large-scale water treatment, ozone might select ozone-resistant bacteria (ORB), which, however, have rarely been reported and are inexplicit for their resistant mechanisms and physiological characteristics. In this study, six strains of ORB were screened from a water reclamation plant in Beijing. Three of them (O7, CR19, and O4) were more resistant to ozone than all previously reported ORB or even spores. The ozone consumption capacity of extracellular polymeric substances and cell walls was proved to be the main sources of bacterial ozone resistance, rather than intracellular antioxidant enzymes. The transcriptome results elucidated that strong ORB possessed a combined antioxidant mechanism consisting of the enhanced transcription of protein synthesis, protein export, and polysaccharide export genes (LptF, LptB, NodJ, LivK, LviG, MetQ, MetN, and GltU). This study confirmed the existence of ORB in urban water systems and brought doubts to the idea of a traditional control strategy against chlorine-resistant bacteria. A salient "trade-off" effect between the ozone resistance and propagation ability indicated the weakness and potential control approaches of ORB.

Molecular Docking Studies and Antibacterial Evaluation of Urtica massaica Leaves

Bacterial resistance is at its peak challenging humankind and researchers dealing with microorganisms. To prevent further risk due to microbial infections, there is an emergency to solve this problem. The practice of using herbs in treating diseases is from ancient years, especially in African countries with rich natural remedies resources. Urtica Massaica from the Urticaceae family is abundantly found in Africa. Methanolic extract of leaf powder was tested against resistant microorganisms (Acinetobacter baumannii and MRSA (Methicillin-resistant Staphylococcus aureus). Ciprofloxacin was used as the standard antibacterial drug. Molecular docking studies were performed for the selected flavonoids of the plant from literature against penicillin-binding protein 2a and DNA gyrase subunit B. The results from the antimicrobial studies indicated the zone of inhibitions ranging from 6±0.00 mm to 11.67±0.33 mm. Molecular docking studies revealed the ability of Urtica flavonoids to bind with the selected target receptors. Kaempferol was found to have a higher docking score with a less binding energy of -11.25kCal/Mol and 9.83Kcal/Mol against PBP2a and DNA gyrase respectively. The results of the current study strongly indicate the need for further studies involving the isolation of pure compounds and their use against resistant bacteria.

Dissecting Molecular Pathways and Intricate Mechanisms Underpinning Antibiotic Resistance in Gram-Negative Bacteria: An Exhaustive and Integrative Review

Dissecting Molecular Pathways and Intricate Mechanisms Underpinning Antibiotic Resistance in Gram-Negative Bacteria: An Exhaustive and Integrative Review

Synthesis of metal(II) acetate complexes with a heterocyclic azo dye ligand: Characterization, geometrical molecular structures, antioxidant, biological activities, DNA binding and molecular docking studies

A series of Cu(II), Co(II), Ni(II), Mn(II), and UO2(II) complexes have been prepared from the ligand 4-(2’,4’-dihydroxybenzaldehyde phenylazo)antipyrine (H2L). FT-IR spectra demonstrated that the ligand under investigation behaves as a bi-and tridentate centre ligand through the phenolic oxygen of aldehydic, azo nitrogen atoms and carbonyl oxygen of antipyrine and forms a stable five- and six-membered chelating ring. From the X-ray crystallographic analysis (XRD) patterns of the ligand and complexes showed the polycrystalline phases are indicated by the multiple diffraction peaks in the 1igand and its complex (5). The HOMO‒LUMO energy gaps (∆E) were used to create theoretical models for the structure and confirmation barriers in molecular systems for the ligand (H2L) and metal complexes. It was found that the Cu(II), Co(II), Ni(II), and Mn(II) complexes have lower values for HOMO‒LUMO energy gaps (∆E), indicating that they are more stable than the 1igand. The biological activities of ligand (H2L) and its metal complexes showed that ligand was stronger antimicrobial and antioxidant agent than its metal complexes. 50 µg/ml H2L caused inhibition zones ranged from 13 to 20 mm against the tested bacteria and 13 to 16 against fungi. In addition, the present study tested metal (II) acetate complexes with a heterocyclic azodye ligand for their application in the textile industry as antimicrobial dyed fabrics. All obtained results confirmed the possibility of using the prepared compounds in different industrial applications. The 1igand (H2L) and its metal complexes showed moderate to strong antimicrobial activities in agar well diffusion, MIC, and antioxidant tests. Ligand and its metal complexes revealed inhibition zones against all tested microbes ranged between 6 to 24 mm. The MIC values of ligand and its metal complexes were recorded at 20 to 30 μg/ml and 30 to 145 μg/ml, respectively. 50 µg/ml of 1igand and its metal complexes was enough to complete inhibit Gram negative E. coli moreover they could inhibit the multidrug resistant bacteria K. pneumoniae and Pseudomonas sp. By molecular docking study, it was found that the complex (1) showed the highest and better binding affinity (-8.38874 and -7.74442 kcal/mol) than other 1igand (H2L) and complexes (2–5) for the breast cancer (3HB5) protein central activity and the colon cancer (2HQ6) protein central activity.

Antibiotic resistance and pathogen spreading in a wastewater treatment plant designed for wastewater reuse

Climate change significantly contributes to water scarcity in various regions worldwide. While wastewater reuse is a crucial strategy for mitigating water scarcity, it also carries potential risks for human health due to the presence of pathogenic and antibiotic resistant bacteria (ARB). Antibiotic resistance represents a Public Health concern and, according to the global action plan on antimicrobial resistance, wastewater role in selecting and spreading ARB must be monitored.Our aim was to assess the occurrence of ARB, antibiotic resistance genes (ARGs), and potential pathogenic bacteria throughout a wastewater treatment plant (WWTP) designed for water reuse. Furthermore, we aimed to evaluate potential association between ARB and ARGs with antibiotics and heavy metals.The results obtained revealed the presence of ARB, ARGs and pathogenic bacteria at every stage of the WWTP. Notably, the most prevalent ARB and ARG were sulfamethoxazole-resistant bacteria (up to 7.20 log CFU mL−1) and sulII gene (up to 5.91 log gene copies mL−1), respectively. The dominant pathogenic bacteria included Arcobacter, Flavobacterium and Aeromonas. Although the abundance of these elements significantly decreased during treatment (influent vs. effluent, p < 0.05), they were still present in the effluent designated for reuse. Additionally, significant correlations were observed between heavy metal concentrations (copper, nickel and selenium) and antibiotic resistance elements (ampicillin-resistant bacteria, tetracycline-resistant bacteria, ARB total abundance and sulII) (p < 0.05).These results underscore the importance of monitoring the role of WWTP in spreading antibiotic resistance, in line with the One Health approach. Additionally, our findings suggest the need of interventions to reduce human health risks associated with the reuse of wastewater for agricultural purposes.

Applications of Nanotechnology in Treating Infections Caused by Multidrug Resistance Bacteria

Applications of Nanotechnology in Treating Infections Caused by Multidrug Resistance Bacteria

The removal of antibiotic resistance bacteria and genes and inhibition of RP4 plasmid-mediated conjugative transfer by citric acid chelated Fe(II) catalyzing peroxymonosulfate systems: Performance and mechanisms

The excessive and inappropriate usage of antibiotics accelerated the appearance and proliferation of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs), posing a considerable threat to human health and ecological systems. The objectives of this study were to construct Fe(II) chelated by citric acid (CA) catalyzing peroxymonosulfate (PMS) systems with different dosages for the elimination of ARB (E. coli DH5α) and ARGs (tetA, tetR, and blaTEM-1), and to reveal the mechanisms on ARGs conjugation transfer. The processes still maintained high ARB/ARGs removal rates in various water matrices (tap water, river water, sewage, and farm wastewater). The results demonstrated Fe(II)-CA/PMS system in high dosages ([Fe(Ⅱ)] = 0.10 mM; [CA] = 0.08 mM; [PMS] = 0.40 mM) significantly enhanced the removal of ARB (8-log) and ARGs (5.11-log tetA, 1.01-log tetR, and 0.62-log blaTEM-1) by promoting the production of reactive oxygen species (ROSs), thereby inhibiting conjugative transfer completely. Interestingly, Fe(II)-CA/PMS treatment at low dosages ([Fe(Ⅱ)] = 0.0025 mM; [CA] = 0.002 mM; [PMS] = 0.02 mM) still inhibited the transfer of ARGs (2.26 × 10−4, 0.65-fold), mainly through downregulation of genes related with ROS synthesis, DNA damage repair (SOS response), ATP synthesis, and transfer-related genes, as well as upregulation of globally regulatory genes. These results presented a hopeful strategy for holding back the dissemination of antibiotic resistance in environments.

Bismuth-gold nanohybrid based nano photosensitizer to combat antimicrobial resistance

Antimicrobial resistance (AMR) leads to a decrease in the adequacy of antimicrobial agents and an increase in the rate of adverse effects and mortality. The main objective of this project is to investigate the synergistic effect of BiAu@NCLin-T1 and its substructures as an antimicrobial photodynamic therapy (aPDT) agent to combat microbial resistance. In addition, the effect of photothermal therapy (PTT) on some of the designed nanostructures at a temperature of 40 °C was also tested. The antimicrobial test was carried out using the growth curve method against Escherichia coli and Staphylococcus aureus. Computational methods were used to investigate the stability and entropy of oligonucleotide sequence structures. Various analyses were performed to identify the nanostructures, including Ultraviolet–visible (UV–vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS) and fluorescence analysis. The BiAu@NCLin-T1 appeared the significant aPDT impact against the gram-negative E.coli strain at two distinctive oligonucleotide concentrations (1, and 1.5 micromolar (µM)). Based on the results, the outlined nanostructures can act as a photosensitizer (PS), a photothermal treatment (PTT) agent, and an antimicrobial agent to combat resistant bacteria.

Removal of antibiotic resistant bacteria and antibiotic resistance genes: a bibliometric review

Removal of antibiotic resistant bacteria and antibiotic resistance genes: a bibliometric review

Airborne antibiotic resistome from sludge dewatering systems: Mobility, pathogen accessibility, cross-media migration propensity, impacting factors, and risks

Bioaerosol contamination was considered as a potential health threat in sludge dewatering systems (SDSs), while emission and risk of airborne antibiotic resistome remain largely unclear. Herein, seasonal investigations of fine particulate matter (PM2.5) were conducted using metagenomics-based methods within and around different SDSs, together with an analysis of sewage sludge. Featured with evident seasonality, antibiotic resistance genes (ARGs) in SDS-PM2.5 also possessed greater accumulation, transfer, and pathogen accessibility than those in ambient air PM2.5. Mobile ARGs in SDS-PM2.5 mainly encoded resistance to tetracycline, and most were flanked by integrase. Some pathogenic antibiotic resistant bacteria (PARB), including Enterobacter asburiae, Escherichia coli, Enterococcus faecium, and Staphylococcus aureus, also carried mobile genetic elements in SDS-PM2.5. Dewatering behavior actuated > 50.56% of ARG subtypes and > 42.86% of PARB in sewage sludge to aerosolize into air. Relative humidity, temperature, and PM2.5 concentration collectively drove the evolution of bacterial community and indirectly promoted the antibiotic resistance of SDS-PM2.5. SDS-PM2.5 posed more serious resistome risks than sewage sludge and ambient air PM2.5, and the highest levels were discovered in winter. These findings underline the role of dewatering behavior in facilitating resistome's aerosolization, and the need to mitigate this potential air pollution.

Potential MRSA inhibitory activity of some new benzofuran-pyrazolo[1,5-a]pyrimidine hybrids attached to arene units via methylene or azo linkage

MRSA, a resistant bacteria causing severe infections, is targeted by researchers developing new anti-resistance compounds. The study aimed to investigate the MRSA inhibitory activity of two series of benzofuran-pyrazolo[1,5-a]pyrimidines 1 and 2, attached to arene units via methylene or azo linkage, respectively. The desired products were prepared, in 82–92% yields, by reacting benzofuran-based enaminone 4 with the appropriate 1H-pyrazole-3,5-diamines 5 in pyridine at reflux for 5–6 h. The new hybrids showed a wide spectrum of antibacterial activity against different ATCC strains. Products with azo linkage and para-substituted arene units with electron-releasing groups demonstrated higher antibacterial activity. 3-((4-Methoxyphenyl)diazenyl)-linked pyrazolo[1,5-a]pyrimidine 2e demonstrates activity that exceeded the reference ciprofloxacin with MIC/MBC values of 1.8/3.6 µM against S. aureus and E. coli strains. Also, it demonstrated more effective MRSA inhibitory activity than the reference linezolid, with MIC/MBC values of 3.6/14.4 and 1.8/7.2 µM against MRSA ATCC:33591 and ATCC:43300 strains, respectively.

Appropriateness of antibiotic prescribing among patients treated for dental diseases in Mekelle city, Northern Ethiopia: a cross sectional study

BackgroundLocal operative treatments are generally preferred for most dental diseases, with antibiotics only recommended as an adjunct in specific cases. Misuse and overuse of antibiotics has been shown to significantly contribute to the development of resistant bacteria. However, the antibiotic prescribing practices of dentists in Ethiopia have not been thoroughly studied. This study aimed to assess the appropriateness of antibiotic prescribing for patients with dental diseases at dental clinics in Mekelle City, Northern Ethiopia.MethodsA cross sectional study was conducted in April and May 2020 among patients visiting dental clinics in Mekelle City. Data were collected through patient medical record reviews and dentist interviews. The appropriateness of antibiotic prescription was evaluated based on guidelines from the American Dental Association and the European Society of Endodontology. Data were analyzed using SPSS Statistics, version 29. Binary logistic regression analysis was performed, and the results were presented as odds ratios with 95% confidence intervals. A p value less than 0.05 was considered statistically significant.ResultsTwo hundred and thirty-one patients with dental diseases participated in the study. The mean age was 30.6 years with a standard deviation of 16.1. Most participants had dental pulp related disease. 89% of patients were prescribed antibiotics, with amoxicillin being the most common. Inappropriate antibiotic prescribing was identified in 175 (75.8%) of the study participants. The most common inappropriate prescribing was unnecessary antibiotic prescribing for dental conditions without systemic signs, assessed in 141 (80.1%) participants. Patients diagnosed with pulp related disease without systemic signs and those who had tooth extractions were significantly associated with inappropriate antibiotic prescription (p value < 0.001).ConclusionsThe study findings show that antibiotics are over-prescribed for dental conditions in this resource constrained setting, especially in patients who have had tooth extractions. Dentists need training on appropriate antibiotic use and antimicrobial stewardship interventions should be implemented in dental setting to reduce unnecessary antibiotic prescriptions and prevent antibiotic resistance development.

Antimicrobial Use in Cats in a University Veterinary Hospital in Central Italy: A Retrospective Study.

Background: Monitoring antimicrobial use is crucial for understanding current prescribing practices. Such information helps in establishing stewardship programs for effectively using antimicrobials and combating resistance to them. Objectives: This study describes how antimicrobials are prescribed at the Veterinary Teaching Hospital of the University of Pisa and compares how the internal medicine and intensive care units differ in their usage of antimicrobials. Methods: The study involved cats that were presented in the units in 2021 and 2022. Antimicrobial prescriptions were obtained via the hospital's management software (OCIROE). Results: In a population of 1164 non-surgical cats with 397 antimicrobials prescribed, the most prescribed ones were amoxicillin-clavulanic acid in the internal medicine unit and ampicillin in the intensive care unit. Twenty-five percent of all antimicrobials were Highest-Priority Critically Important Antimicrobials or Antimicrobial Advice Ad Hoc Expert Group Category B. The oral route was the main route of administration in the internal medicine unit, while parenteral was the most common route used in the intensive care unit. Most antimicrobials were prescribed to treat pathologic conditions affecting the urinary (39%), gastroenteric (21%), respiratory (13%), and integumentary (12%) systems. A diagnosis, accurate dosage, and the use of species-approved medications were recorded in the antimicrobial prescriptions. However, only 11% of these prescriptions were supported by antimicrobial susceptibility tests. Conclusions: These results suggest room for improvement, particularly in increasing the use of antimicrobial susceptibility testing to ensure more targeted antimicrobial therapy. Given the importance of antimicrobial resistance and the One Health approach, the study also highlights the need to consider the broader impact of antimicrobial use in animals, including the potential contribution to resistance in bacteria that affect both animal and human health.

Private benefit of β-lactamase dictates selection dynamics of combination antibiotic treatment

β-lactam antibiotics have been prescribed for most bacterial infections since their discovery. However, resistance to β-lactams, mediated by β-lactamase (Bla) enzymes such as extended spectrum β-lactamases (ESBLs), has become widespread. Bla inhibitors can restore the efficacy of β-lactams against resistant bacteria, an approach which preserves existing antibiotics despite declining industry investment. However, the effects of combination treatment on selection for β-lactam resistance are not well understood. Bla production confers both private benefits for resistant cells and public benefits which faster-growing sensitive cells can also exploit. These benefits may be differentially impacted by Bla inhibitors, leading to non-intuitive selection dynamics. In this study, we demonstrate strain-to-strain variation in effective combination doses, with complex growth dynamics in mixed populations. Using modeling, we derive a criterion for the selection outcome of combination treatment, dependent on the burden and effective private benefit of Bla production. We then use engineered strains and natural isolates to show that strong private benefits of Bla are associated with increased selection for resistance. Finally, we demonstrate that this parameter can be coarsely estimated using high-throughput phenotyping of clonal populations. Our analysis shows that quantifying the phenotypic responses of bacteria to combination treatment can facilitate resistance-minimizing optimization of treatment.

Swine wastewater co-exposed with veterinary antibiotics enhanced the antibiotic resistance of endophytes in radish (Raphanus sativus L.)

The widespread utilization of antibiotics in livestock has promoted the accumulation and diffusion of antibiotics and antibiotic resistance in agricultural soils and crops. Here we investigated the mechanisms of antibiotic uptake and accumulation in swine wastewater (SW)-treated radish (Raphanus sativus L.) and subsequent impacts on endophyte antibiotic resistance. Under SW treatments, exposure to 500 μg/L sulfamethazine (SMZ) and enrofloxacin (EFX) significantly affected radish biomass, with SMZ causing 63.0% increases and EFX causing 36.3% decreases relative to the untreated control. EFX uptake by radish were from 5 to 100-folds over SMZ. Passive diffusion through anion channel proteins on cell membranes was an important route for SMZ uptake, while both passive diffusion and energy-dependent processes contributed to the uptake of EFX. Bacterial community was time-dependent as a function of both antibiotics and SW, the bacterial alpha diversity in liquid solution co-treated with antibiotics and SW increased over time. The abundance of antibiotic resistance genes (ARGs) in the roots was positively correlated with ARGs in the Hoagland's solution under antibiotic-alone treatments. EFX co-exposure with SW enhanced the dissemination of ARGs from swine wastewater into plant roots, and significant correlations existed between ARGs and integrons in both Hoagland's solution and roots. These findings increased our understanding of the fate of antibiotics in crops and their subsequent impacts on antibiotic resistance of endophytic bacteria.

Chemical composition and antimicrobial activity of Plinia rivularis essential oil against multidrug-resistant bacteria

IntroductionThe increasingly common occurrences of multidrug-resistant bacteria represent a global health threat and the discovery of new alternative remedies is necessary. The use of essential oils (EOs) in the treatment of many pathogenic bacteria is promising and several examples have already been highlighted regarding their inhibitory action. Among the botanical families, Myrtaceae stands out for presenting important species that supply bioactive products. MethodsIn this work we investigate the chemical composition of Plinia rivularis (Myrtaceae) leaf EO and its antibacterial activity against resistant and non-resistant bacteria. The EO was obtained by two methods, hydrodistillation and steam distillation. Gas chromatography-flame ionization detector (GC-FID), gas chromatograph-mass spectrometry (GC-MS), nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR) were the techniques used in the EO chemical characterization. ResultsThe EOs were obtained with yields of 0.37 and 0.16% by hydrodistillation and steam distillation methods, respectively. The analyzes revealed the EOs chemical profile showing the compounds 2H-benzocyclohepten-2-one,3,4,4a,5,6,7,8,9-octahydro-4a-methyl (synonym: 4a-methyl-3,4,4a,5,6,7,8,9-octahydro-2H-benzo[7]annulen-2-one), rosifoliol, β-eudesmol and the diterpene kaurene as main constituents. Through preparative thin-layer chromatography (PTLC), it was possible to obtain the diterpene kaurene with a content of 91%, which was also characterized by NMR. The minimum inhibitory concentrations of EO against bacteria ranged from 0.56 to 2.25 mg.ml−1 and 2.25–36 mg.ml−1 for sensitive and resistant bacteria, respectively. Also, EO showed synergistic activity with amikacin and cefotaxime against carbapenem-resistant Pseudomonas aeruginosa (KPC). ConclusionsThis is the first report on the chemical composition of P. rivularis EO. Comparison of extraction methods showed variation in yields and small changes in component content. The EO demonstrated activity against resistant and non-resistant bacteria. In addition, the synergistic effect of EO against resistant bacteria may be explored in future studies.