Metal-organic frameworks-molecularly imprinted polymers (MOF-MIP): Synthesis, properties, and applications in detection and control of microorganisms

Microbial contamination poses a significant threat to human health, food safety, and the ecological environment. Its rapid spread and potential pathogenicity create an urgent global challenge for efficient detection and control. However, existing methods have several shortcomings such as traditional techniques like culture methods and polymerase chain reaction (PCR) are time-consuming, while nanomaterials and aptamers often lack selectivity, stability, and affordability. Additionally, conventional disinfectants can be inefficient, lead to drug resistance, and harm the environment. To address these challenges, developing new materials and technologies that are efficient, sensitive, and stable is crucial for microbial detection and control. In this context, metal-organic frameworks (MOF) and molecularly imprinted polymers (MIP) have emerged as promising functional materials due to their unique structural advantages. The high porosity of MOF provides ample imprinting sites for MIP, while MIP enhance selective adsorption and inactivation of target microorganisms by MOF. This synergistic combination results in a composite material that offers a novel solution for microbial detection, significantly improving sensitivity, selectivity, antibacterial efficiency, and environmental friendliness. This paper reviews the synthesis strategies of metal-organic frameworks-molecularly imprinted polymers (MOF-MIP), highlighting their structural properties and innovative applications in microbial detection, which aim to inspire researchers in related fields. Looking ahead, future advancements in material science and biotechnology are expected to lead to widespread use of MOF-MIP composites in food safety, environmental monitoring, medical diagnosis, and public health-providing robust support against microbial pollution. By studying the collaborative mechanisms of MOF and MIP while optimizing design processes will enhance precision speed cost-effectiveness in microbial detection technology significantly contributing to human health and environmental safety.

Divergent mitigation mechanisms of soil antibiotic resistance genes by biochar from different agricultural wastes

Biochar, produced from agricultural waste, provides a sustainable solution for effective waste management and soil remediation. The potential and mechanisms of biochar derived from primary agricultural sources (plant residues and animal manure) to mitigate the antibiotic resistance genes (ARGs) pollution in agricultural soil remain unexplored. To address this, a 60-day microcosm experiment was conducted, applying biochar derived from either corn straw (B1) or chicken manure (B2) to sulfamethazine and tetracycline-contaminated soil. The results demonstrated that B1 had richer functional groups than B2. B1 increased soil pH (+1.63 %) and total carbon (+24.56 %), but it decreased the abundance of norank_Vicinamibacteraceae (-35.71 %) and Haliangium (-42.11 %), and inhibited the dissemination of tetM and tetW by 57.76 % and 39.17 %, respectively. Comparatively, B2 significantly increased soil dissolved organic carbon (+161.66 %) and decreased the abundance of potential ARGs hosts (Acidibacter, -40.32 %), leading to reduced sul2 abundance (-33.47 %). Besides, B2 enhanced soil total nitrogen and bacterial diversity, and further reduced tetW abundance (-33.76 %). Overall, this study revealed divergent mechanisms and potential for mitigating soil ARGs transmission by biochar derived from corn straw and chicken manure. This study contributes to developing more effective strategies for managing ARGs in contaminated soil and mitigating their environmental risks.

A porridge-like hydrogel promoted the oral bioavailability of veterinary medicines

The administration of veterinary medicines via drinking water or feed ingredients is a widely adopted method in intensive livestock and poultry farming due to its convenience and cost-effectiveness. Among these drugs, antimicrobials are extensively used, with over 70% of global antimicrobial consumption attributed to veterinary applications. However, the misuse of antimicrobials in livestock has been identified as a significant driver of drug resistance, as well as contributing to other adverse health and environmental impacts. Moreover, certain antimicrobials, such as florfenicol, exhibit limited oral bioavailability due to their low water solubility and permeability, which can compromise their therapeutic efficacy. To address these challenges, this study introduces a novel porridge-like hydrogel designed to enhance the oral absorption of antimicrobials, thereby improving their therapeutic effectiveness. Sodium alginate (SA), a natural polysaccharide polymer, was employed as a protective barrier to shield the antimicrobials from degradation by gastric juices, ensuring drug integrity until release in the intestine. This formulation facilitates excellent mixing with feed, resulting in significantly increased oral bioavailability of the antimicrobials. In a Salmonella-infected chicken model, the orally administered florfenicol-loaded SA hydrogel significantly reduced mortality rates compared to conventional delivery methods. Furthermore, this SA hydrogel can enhance the oral bioavailability of a range of poorly absorbed medications, demonstrating its potential as a versatile oral delivery system. These findings suggest that the porridge-like hydrogel represents a novel promising approach for the oral delivery of veterinary medicines, offering a more effective alternative to traditional formulations.

Restoring tigecycline efficacy with lysine supplementation in tmexCD-toprJ-positive bacteria

OBJECTIVES

Antimicrobial resistance is one of the most pressing challenges to global public health. Tigecycline, a last-resort antibiotic, has been undermined by the emergence of the tmexCD1-toprJ1 gene cluster, a transferable RND-type efflux pump that confers resistance. Metabolite-enabled killing of antibiotic-resistant pathogens by antibiotics is an attractive strategy to tackle antibiotic resistance.

METHODS

The potentiation of lysine to tigecycline was evaluated through a series of in vitro studies, including bacterial viability assays, time-kill kinetics analysis, persister assays, and biofilm eradication experiments, as well as in vivo assessment using a murine systemic infection model. The underlying mechanisms of action were further explored through transcriptomic profiling and biochemical validation.

RESULTS

Herein, we show that lysine synergistically enhances the antibacterial efficacy of tigecycline against tmexCD-toprJ-positive bacteria. Mechanistic studies indicate that lysine supplementation promotes tigecycline uptake by upregulating ∆pH and disrupting membrane permeability. Transcriptomic analysis, coupled with phenotypic experiments, indicates that lysine not only triggers the generation of reactive oxygen species (ROS) by inhibiting hydrogen sulfide (H2S) production but also downregulates energy metabolism pathways essential for efflux pump function. These effects promote intracellular accumulation of tigecycline, thereby overcoming tmexCD-toprJ-mediated resistance. In mouse infection models, the combination of lysine and tigecycline shows improved therapeutic efficacy compared to tigecycline monotherapy.

CONCLUSION

Collectively, our findings indicate that lysine can serve as a promising tigecycline booster to tackle infections caused by tmexCD-toprJ-positive bacteria.

Environmental fate of antibiotic resistance genes in livestock farming

As emerging environmental pollutants, antibiotic resistance genes (ARGs) are prevalent in livestock farms and their surrounding environments. Although existing studies have focused on ARGs in specific environmental media, comprehensive research on ARGs within farming environments and their adjacent areas remains scarce. This review explores the sources, pollution status, and transmission pathways of ARGs from farms to the surrounding environment. Drawing on the "One Health" concept, it also discusses the potential risks of ARGs transmission from animals to human pathogens and the resulting impact on human health. Our findings suggest that the emergence of ARGs in livestock farming environments primarily results from intrinsic resistance and genetic mutations, while their spread is largely driven by horizontal gene transfer. The distribution of ARGs varies according to the type of resistance genes, seasonal changes, and the medium in which they are present. ARGs are disseminated into the surrounding environment via pathways such as manure application, wastewater discharge, and aerosol diffusion. They may be absorbed by humans, accumulating in the intestinal microbiota and subsequently affecting human health. The spread of ARGs is influenced by the interplay of microbial communities, antibiotics, heavy metals, emerging pollutants, and environmental factors. Additionally, we have outlined three control strategies: reducing the emergence of ARGs at the source, controlling their spread, and minimizing human exposure. This article provides a theoretical framework and scientific guidance for understanding the cross-media migration of microbial resistance in livestock farming environments.

SERS calibration substrate with a silent region internal standard for reliable simultaneous detection of multiple antibiotics in water

As the extensive use of antibiotics has led to the rapid spread of antibiotic resistance, there is an urgent need for quantitative assessment of antibiotic residues in the environment. Surface-enhanced Raman spectroscopy (SERS) has emerged as a rapid and cost-effective detection method, but it suffers from the high variability in signal intensities, its quantitative detection remains challenging. Herein, we have developed a SERS calibration substrate with a silent region internal standard, enabling simultaneous and reliable quantitative detection of three commonly antibiotics of penicillin potassium (PP), tetracycline hydrochloride (TCH) and levofloxacin (LEV). The calibration substrate is made by assembling Au @ 4-mercaptobenzonitrile (4-MBN) @ SiO2 on silicon wafer. The chemically-inert silica shell allows the substrate to remain SERS active for more than 24 weeks in the air. The vC ≡ N of 4-MBN in the silent region of 1800-2800 cm-1 provides an effective reference for correcting Raman signal fluctuations. The relative SERS intensity by normalizing to the internal standard (IS) of vC ≡ N shows a linear response against to the logarithmic concentration with a correlation coefficient of 0.997, 0.976, 0.998 and a limit of detection (LOD) of 26.9, 28.2, 2.4 nM for PP, TCH and LEV, respectively. Furthermore, simultaneous detection and principal component analysis (PCA) of these antibiotics in lake water with a concentration range of 1-100 mg/L can achieve a sensitivity and specificity of 100 %. This novel quantitative technique of using this SERS calibration substrate shows promises as a high-throughput platform for multiple trace antibiotics analysis.

LC-AMP-I1, a novel venom-derived antimicrobial peptide from the wolf spider Lycosa coelestis

Antibiotic resistance has become a critical concern in recent years, and antimicrobial peptides may function as innovative antibacterial agents to address this issue. In this work, we identified a novel antimicrobial peptide, LC-AMP-I1, derived from the venom of Lycosa coelestis, demonstrating substantial antibacterial properties and minimal hemolytic activity. LC-AMP-I1 was subjected to additional assessment for antibacterial efficacy, anti-biofilm properties, drug resistance, stability, and cytotoxicity in vitro. It exhibited comparable antibacterial efficacy to melittin against six common clinical multidrug-resistant bacteria, effectively inhibiting biofilm formation and disrupting established biofilms. Additionally, LC-AMP-I1 demonstrated minimal bacterial resistance, excellent stability, negligible mammalian cell toxicity, low hemolytic activity, and appropriate selectivity for both normal and tumor cells. When combined with traditional antibiotics, LC-AMP-I1 exhibited additive or synergistic therapeutic effects. In a neutropenic mouse thigh infection model, LC-AMP-I1 exhibited a therapeutic effect in inhibiting bacterial proliferation in vivo. The mechanistic investigation indicated that LC-AMP-I1 could influence bacterial cell membrane permeability at low concentrations and directly disrupt structure-function at high concentrations. The results of this work indicate that LC-AMP-I1 may function as a viable alternative to traditional antibiotics in addressing multidrug-resistant bacteria.

Fermented Astragalus Powder, a New Potential Feed Additive for Broilers to Improve the Growth Performance and Health

A total of 320 1-day-old broilers were randomly divided into five groups. The control group (CON) received a basal diet, while the FAP4, FAP2, and FAP1 groups were provided with the basal diet supplemented with 4%, 2%, and 1% fermented Astragalus powder, respectively. The unfermented Astragalus powder (UAP2) group was fed the basal diet supplemented with 2% UAP. Each group contained eight replicates of eight chicks each. The results revealed that the final BW and ADG in the FAP 1 and FAP2 were higher than those in the UAP2 and CON groups, while reducing F/G from day 14 to day 42. On day 42, the thymus index in the UAP and FAP groups as well as the bursa index in the FAP4 group showed significant increases compared to those in the CON group. Supplementation with 2% FAP elevated serum IgA levels in broilers on day 28 and day 42, and it also increased serum IgG levels on day 42. Furthermore, supplementation with 2% FAP elevated serum albumin (ALB) levels in broilers, while supplementation with 4% FAP increased serum (glucose) GLU levels in broilers on day 28. The serum biochemical parameters and pathological observation of the liver and kidney in the groups did not show any adverse effects on broilers' health. In addition, the serum total antioxidant capacity (T-AOC) level significantly increased in the FAP4 and FAP2 groups on day 28, and the malondialdehyde (MDA) level in both serum and liver tissue decreased in the FAP2 group on day 28 and day 42. Compared to the CON group, 2% FAP and 2% UAP supplementation reduced the relative abundance of Bacteroides and supplementation with 2% FAP increased the relative abundance of Alistipes on day 42. In conclusion, the dietary supplementation of FAP can enhance the growth performance, immune function, and antioxidant capacity and regulate microflora in broilers, of which 2% FAP is more effective. It indicates FAP exhibits significant application potential as a promising feed additive for broilers.

Extended-spectrum β-lactamases producing Enterobacteriaceae (ESBL-PE) prevalence in Nepal: A systematic review and meta-analysis

An alarming increase in the occurrence of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) has threatened the treatment and management of bacterial infections. This systematic review and meta-analysis aimed to provide a quantitative estimate of the prevalence of ESBL among the members of the Enterobacteriaceae family by analyzing the community-based and clinical studies published between 2011 and 2021 from Nepal and determine if ESBL-PE correlates with multidrug resistance (MDR). The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed for systematic review and meta-analysis and the articles' quality was assessed using the Newcastle-Ottawa scale. Of the 2529 articles screened, 65 articles were systematically reviewed, data extracted, and included in in-depth meta-analysis. The overall pooled prevalence of ESBL-producers in Enterobacteriaceae was 29 % (95 % CI: 26-32 %) with high heterogeneity (I2 = 96 %, p < 0.001). Escherichia coli was the predominant ESBL-producing member of the Enterobacteriaceae family, followed by Citrobacter spp. and Klebsiella spp. The prevalence of ESBL-PE increased from 18.7 % in 2011 to 29.5 % in 2021. A strong positive correlation (r = 0.98) was observed between ESBL production and MDR in Enterobacteriaceae. ESBL-PE isolates showed high resistance to ampicillin, cephalosporins, and amoxicillin-clavulanic acid, and blaCTX-M type was the most reported gene variant among ESBL-PE. In conclusion, this study demonstrated an increased prevalence of ESBL-PE in Nepal over the last decade, and such isolates showed a high level of MDR against the β-lactams and non-β-lactam antibiotics. Tackling the rising antibiotic resistance (AR) and MDR in ESBL-PE would require concerted efforts from all stakeholders to institute effective infection control programs in the community and clinical settings.

Specific nanoantibiotics for selective removal of antibiotic-resistant bacteria: New insights in bacterial imprinting based on interfacial biomimetic mineralization

Antibiotic resistance has been a worsening global concern and selective elimination of antibiotic-resistant bacteria (ARB) while retaining the co-existed beneficial bacteria has been essential in environmental protection, which having attracted considerable interest. In this work, by integrating the whole cell imprinting and epitope imprinting strategy, magnetic bacterial imprinted polymers (BIPs) towards ARB were synthesized with interfacial biomimetic mineralization followed by a screening process. The binding data showed that the BIPs owned highly specific affinity towards the target bacteria. Taking advantage of this specific binding ability of BIPs, a two-step selective antimicrobial approach was developed. Remarkably, the BIP nanoantibiotics (nAbts) could efficiently destroy ARB without harming the beneficial bacteria. In comparison with the non-bacterial imprinted polymers, the biocompatible BIP nAbts showed a 12.5-fold increase in the survival percentage for the beneficial bacteria in wastewater. To the best of our knowledge, this is the first time that bacterial imprinting via interfacial biomimetic mineralization was developed, and also the first report of killing ARB without harming the beneficial bacteria in wastewater. We believe that this strategy provides a new insight into the design of novel affinity materials for the selective elimination of ARB in biological treatment for environmental protection.

Prevalence of metallo-β-lactamases as a correlate of multidrug resistance among clinical Pseudomonas aeruginosa isolates in Nepal

Pseudomonas aeruginosa is an opportunistic human pathogen that has developed antibiotic resistance (AR) and causes a range of illnesses, including respiratory pneumonia, gastrointestinal infections, keratitis, otitis media and bacteremia in patients with compromised immune system. The production of metallo-β-lactamases (MBLs) is one of the major mechanisms of AR in this bacterium with ensuing infections difficult to treat. The main goal of this study was to provide a quantitative estimate of MBLs producing clinical P. aeruginosa isolates among the Nepalese patients and determine if MBL correlates with multi-drug resistance (MDR). Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline was followed for meta-analysis of relevant literature using PubMed, Research4Life, and Google Scholar. The prevalence of MBLs in P. aeruginosa from clinical samples was determined using R 4.1.2 for data pooled from studies published until 2021. The meta-analysis of a total of 19 studies selected (of 6038 studies for which titles and abstracts were reviewed) revealed the prevalence of MBLs producing P. aeruginosa (MBL-PA) was 14 % (95 % CI: 0.10-0.19) while MDR isolates among P. aeruginosa was 42 % (95 % CI: 0.30-0.55) in Nepal. Combined Disc Test was predominantly used phenotypic method for confirming MBLs phenotypes among the studies. Sputum was the most common specimen from which MBL-PA was recovered. A significant positive correlation was observed between MDR and MBL production in P. aeruginosa. We conclude that MBL producing strains are widespread among the clinical isolates of P. aeruginosa in Nepal and responsible for emerging MDR strains. It is paramount that antibiotics prescription against the bacterium should be monitored closely and alternative therapeutic modalities against MBL-PA explored.

Cationic Polysaccharide Conjugates as Antibiotic Adjuvants Resensitize Multidrug-Resistant Bacteria and Prevent Resistance

In recent years, traditional antibiotic efficacy has rapidly diminished due to the advent of multidrug-resistant (MDR) bacteria, which poses severe threat to human life and globalized healthcare. Currently, the development cycle of new antibiotics cannot match the ongoing MDR infection crisis. Therefore, novel strategies are required to resensitize MDR bacteria to existing antibiotics. In this study, novel cationic polysaccharide conjugates Dextran-graft-poly(5-(1,2-dithiolan-3-yl)-N-(2-guanidinoethyl)pentanamide) (Dex-g-PSS_n ) is synthesized using disulfide exchange polymerization. Critically, bacterial membranes and efflux pumps are disrupted by a sub-inhibitory concentration of Dex-g-PSS₃₀ , which enhances rifampicin (RIF) accumulation inside bacteria and restores its efficacy. Combined Dex-g-PSS₃₀ and RIF prevents bacterial resistance in bacteria cultured over 30 generations. Furthermore, Dex-g-PSS₃₀ restores RIF effectiveness, reduces inflammatory reactions in a pneumonia-induced mouse model, and exhibits excellent in vivo biological absorption and degradation capabilities. As an antibiotic adjuvant, Dex-g-PSS₃₀ provides a novel resensitizing strategy for RIF against MDR bacteria and bacterial resistance. This Dex-g-PSS₃₀ research provides a solid platform for future MDR applications.

Antibiotic resistance genes and bacterial community distribution patterns in pig farms

Antibiotic-resistant pathogens pose high risks to human and animal health worldwide. In recent years, many studies have been carried out to investigate the role of gut microbiota as a pool of antibiotic resistance genes (ARGs) in human and animals. Both the structure and function of the gut bacterial community and related ARGs in pig remain unknown. In this study, we characterized the gut microbiomes and resistomes of fecal samples collected from sixteen pig farms located in sixteen cities of Shandong Province by metagenomic sequencing. Alpha diversity indicated that fecal samples from Dezhou (DZ) and Jinan (J) showed higher alpha diversity, and the lowest was from pig farms of Rizhao (RZ). Other pig farms showed similar alpha diversity. Besides, we found that the composition of gut bacterial among these pig farms varied greatly. Helcococcus massiliensis was the dominant bacterial species in pig farms of RZ and Zibo (ZB), while Prevotella sp. P5-92 occupied a superior proportion in Binzhou (BZ) and Yantai (YT). The proportion of Lactobacillus johnsonii was similar among farms of Qingdao (QD), Linyi (LY), Taian (TA), Weifang (WF), Weihai (WH), and YT. In total, 1112 ARGs were obtained and classified into 69 groups from 48 fecal samples. ARG abundance was higher in farms of Dongying (DY) and WH than others, while the lowest farms in BZ and ZB. Interestingly, it is found that BZ pig farm was exclusive, so the tetQ gene showed a higher abundance. In contrast, the load of APH(3') - IIIa in fecal samples from DY, J-1, LC, WF, and WH was high. Meanwhile, the most relevant ARGs and the corresponding microbes were screened out. Our metagenomic sequencing data provides new insights into the abundance, diversity, and structure of bacterial community in pig farms. Meanwhile, we screened ARG-carrying bacteria and explored the correlation between ARGs and bacterial community, which provide a comprehensive view of the pig fecial ARGs and microbes in different farms of Shandong.

Monoterpene indole N-oxide alkaloids from Tabernaemontana corymbosa and their antimicrobial activity

Tabernaemontana corymbosa is a traditional folk medicine. In our research, six monoterpene indole N-oxide alkaloids and their parent alkaloids were obtained from the stem bark of T. corymbosa, including seven new alkaloids (1-7) and five known alkaloids (8-12). Their structures and absolute configurations were elucidated by extensive spectroscopy, quantum chemical calculations, and DP4+ probability analyses. The antimicrobial activity of the obtained compounds was evaluated, among which alkaloids 4, 8, 12 showed significant antimicrobial activity against Staphylococcus aureus with an MIC value of 6.25 μg/mL, while alkaloids 11, 12 showed moderate antimicrobial activity against Bacillus subtilis with an MIC value of 25 μg/mL.

Vermiculax drug effect on blood parameters, immune response, calcium and phosphorus, and weight of laying hens

This paper presents the experiment on 160 laying hens of the white Leghorn breed divided into 4 groups. Group I (taken as a control group) was given a basic diet (OR). Group II had OR + Vermiculax at a dosage of 30 mg per 1 kg of the laying hen weight. Group III had OR + Vermiculax at a dosage of 37 mg per 1 kg of the laying hen weight. Group IV consumed OR + Vermiculax at a dosage of 44 mg per 1 kg of the laying hen weight. According to the results of the study, we came to the following conclusions. The drug Vermiculax increases the content of erythrocytes (by 21.45%) and hemoglobin (by 4.94%), which indicates the prevention of anemia, increases the index of total protein by 30.57%, calcium by 0.7% and inorganic phosphorus in the blood by 4.16%. Thus, it affects phagocytic processes, increases the immune response and absorption processes; increases the activity of macrophages and affects the process of degranulation of polymorphonuclear neutrophils, which in turn increases lysozyme activity by 3.9%. This is a sign of strengthening the natural antibacterial barrier. There is an increase in the retention of calcium in the body by 115.32% and phosphorus by 107.94% (on the 30th day of the study). In addition, increased retention of calcium by 8.3% and phosphorus by 8.5% (on the 180th day of the study) was observed. There is an increase in the deposition of calcium in the body by 132.8% and phosphorus by 133.45% (on the 30th day of the study), and increased retention of calcium by 66.36% and phosphorus by 66.4% (on the 180th day of the study). There is a high dynamic in weight gain by the second month of the study (increased by 21.88%), as well as a decrease in the level of feed consumption per weight gain of 1 kilogram by 13.33%.

Onion leaf and synthetic additives in broiler diet: impact on splenic cytokines, serum immunoglobulins, cecal bacterial population, and muscle antioxidant status

BACKGROUND

The disadvantages associated with the use of synthetic additives in animal production could threaten human and animal health, and the safety of animal-derived foods. This study assessed the growth performance, blood chemistry, immune indices, selected caeca bacterial population, muscle antioxidant enzyme activities, and meat quality in broiler chickens fed diet supplemented with antibiotic (70% oxytetracycline +30% neomycin), tert-butylhydroxytoluene or onion leaf powder (OLP). One day old Ross 308 chicks (n = 240) were assigned randomly to either D-1, control diet (CD) without additives; D-2, CD + 0.3 g kg^-1 antibiotic +0.15 g kg^-1 tert-butylhydroxytoluene; D-3, CD + 2.5 g kg^-1 OLP; or D-4, CD + 5 g kg^-1 OLP for 42 days.

RESULTS

The D-2 and D-4 diets improved (P < 0.05) bodyweight gain and feed efficiency in broilers. Platelet and cecal Lactobacillus spp. counts were higher (P < 0.05) whereas muscle cholesterol was lower (P < 0.05) in the OLP-supplemented birds. Supplemented birds had higher (P < 0.01) splenic interleukin-10 and lower (P < 0.01) splenic tumor necrosis factor-α, immunoglobulin A, cecal E. coli and C. perfringens counts compared with the D-1 birds. The D-4 birds had the least (P < 0.05) splenic interleukin-1β. Dietary supplements increased (P < 0.05) catalase, glutathione peroxidase, and total antioxidant capacity, and lowered (P < 0.05) drip loss, malondialdehyde and carbonyl content in breast meat.

CONCLUSION

Dietary supplementation of 5 g kg^-1 OLP exerted antimicrobial, immunomodulatory, and antioxidant effects that were comparable to those of antibiotics and tert-butylhydroxytoluene in broiler chickens. © 2021 Society of Chemical Industry.

More diversified antibiotic resistance genes in chickens and workers of the live poultry markets

BACKGROUND

Poultry farms and LPMs are a reservoir of antimicrobial resistant bacteria and resistance genes from feces. The LPM is an important interface between humans, farm animals, and environments in a typical urban environment, and it is considered a reservoir for ARGs and viruses. However, the antibiotic resistomes shared between chicken farms and LPMs, and that of LPM workers and people who have no contact with the LPMs remains unknown.

METHODS

We characterized the resistome and bacterial microbiome of farm chickens and LPMs and LPM workers and control subjects. The mobile ARGs identified in chickens and the distribution of the mcr-family genes in publicly bacterial genomes and chicken gut metagenomes was analyzed, respectively. In addition, the prevalence of mcr-1 in LPMs following the ban on colistin-positive additives in China was explored.

RESULTS

By profiling the microbiomes and resistomes in chicken farms, LPMs, LPM workers, and LPM environments, we found that the bacterial community composition and resistomes were significantly different between the farms and the LPMs, and the LPM samples possessed more diversified ARGs (59 types) than the farms. Some mobile ARGs, such as mcr-1 and tet(X3), identified in chicken farms, LPMs, LPM workers, and LPM environments were also harbored by human clinical pathogens. Moreover, we found that the resistomes were significantly different between the LPM workers and those who have no contact with the LPMs, and more diversified ARGs (188 types) were observed in the LPM workers. It is also worth noting that mcr-10 was identified in both human (5.2%, 96/1,859) and chicken (1.5%, 14/910) gut microbiomes. Although mcr-1 prevalence decreased significantly in the LPMs across the eight provinces in China, from 190/333 (57.1%) samples in September 2016-March 2017 to 208/544 (38.2%) samples in August 2018-May 2019, it is widespread and continuous in the LPMs.

CONCLUSION

Live poultry trade has a significant effect on the diversity of ARGs in LPM workers, chickens, and environments in China, driven by human selection with the live poultry trade. Our findings highlight the live poultry trade as ARG disseminators into LPMs, which serve as an interface of LPM environments even LPM workers, and that could urge Government to have better control of LPMs in China. Further studies on the factors that promote antibiotic resistance exchange between LPM environments, human commensals, and pathogens, are warranted.

Chemically modified and conjugated antimicrobial peptides against superbugs

Antimicrobial resistance (AMR) is one of the greatest threats to human health that, by 2050, will lead to more deaths from bacterial infections than cancer. New antimicrobial agents, both broad-spectrum and selective, that do not induce AMR are urgently required. Antimicrobial peptides (AMPs) are a novel class of alternatives that possess potent activity against a wide range of Gram-negative and positive bacteria with little or no capacity to induce AMR. This has stimulated substantial chemical development of novel peptide-based antibiotics possessing improved therapeutic index. This review summarises recent synthetic efforts and their impact on analogue design as well as their various applications in AMP development. It includes modifications that have been reported to enhance antimicrobial activity including lipidation, glycosylation and multimerization through to the broad application of novel bio-orthogonal chemistry, as well as perspectives on the direction of future research. The subject area is primarily the development of next-generation antimicrobial agents through selective, rational chemical modification of AMPs. The review further serves as a guide toward the most promising directions in this field to stimulate broad scientific attention, and will lead to new, effective and selective solutions for the several biomedical challenges to which antimicrobial peptidomimetics are being applied.

Synthesis of multi-color fluorine and nitrogen co-doped graphene quantum dots for use in tetracycline detection, colorful solid fluorescent ink, and film

Fluorine-doped graphene quantum dots have unique chemical bonds and charge distribution, which can bring unexpected properties compared to other common atom-doped graphene quantum dots. In the present work, fluorine and nitrogen co-doped graphene quantum dots (F, N-GQDs) are synthesized from levofloxacin via a simple hydrothermal method. Systematic studies demonstrate that F, N-GQDs can emit various fluorescence with the wavelength ranging from blue to green by dispersing F, N-GQDs into different solvents. Moreover, multi-color fluorescence is available by simply changing the concentration of F, N-GQDs. In addition to these unique characteristics, F, N-GQDs also exhibit a sensitive fluorescence response to tetracycline with an ultralow detection limit of 77 nM in water. Because of high photostability and high quantum yield, the F, N-GQDs are exploited as a unique invisible ink, which is printable and writable on paper. Meanwhile, based on the solvatochromism of F, N-GQDs, we realized the color adjustable fluorescent ink. Finally, large-area flexible multi-color fluorescent films are realized. Our synthesized F, N-GQDs, with tunable fluorescence in wavelength and intensity, have numerous opportunities for optical molecular sensors, information security, flexible optics, and others.

Exploring the decentralized treatment of sulfamethoxazole-contained poultry wastewater through vertical-flow multi-soil-layering systems in rural communities

Sulfamethoxazole (SMX) is the most widely distributed sulfonamide antibiotics detected in decentralized poultry wastewater in rural communities. As an economically-feasible and eco-friendly technology for decentralized wastewater treatment in rural areas, vertical-flow multi-soil-layering (MSL) system was promising to mitigate the ecological and human health risks from SMX in such areas. The treatment of SMX-contained poultry wastewater by using MSL systems was investigated for the first time, and the main and interactive effects of related multiple variables on system performance were explored through factorial analysis, including material of permeable layer, concentration of SMX, and pH of influent. Results indicated that SMX concentration and pH of influent showed significantly negative effects on SMX removal. Medical stone used in MSL systems with larger surface area could intensify the SMX removal compared to anthracite. MSL systems showed stable performances on SMX removal with the best SMX removal efficiency more than 91%. A novel stepwise-cluster inference (SCI) model was developed for the first time to map the multivariate numeric relationships between state variables and SMX removal under discrete and nonlinear complexities. It was demonstrated that the effect of SMX in wastewater with high concentration was significant on the differentiation of soil bacteria composition in MSL systems based on microbial diversity analysis. These results can help better understand the mechanism of SMX removal in MSL systems from perspectives of factorial analysis, numeric modeling, and microbiological change.

Fe3O4–Au–polydopamine hybrid microcapsules with photothermal–photodynamic synergistic anti-bacterial performance

A novel magnetic Fe3O4–Au–PDA hybrid microcapsule with both photothermal (PTT) and photodynamic (PDT) anti-bacterial functions has been developed, and the product exhibits higher antibacterial performance by the combined PTT/PDT treatment.

Cationic π-Conjugated Polyelectrolyte Shows Antimicrobial Activity by Causing Lipid Loss and Lowering Elastic Modulus of Bacteria

Cationic, π-conjugated oligo-/polyelectrolytes (CCOEs/CCPEs) have shown great potential as antimicrobial materials to fight against antibiotic resistance. In this work, we treated wild-type and ampicillin-resistant (amp-resistant) Escherichia coli (E. coli) with a promising cationic, π-conjugated polyelectrolyte (P1) with a phenylene-based backbone and investigated the resulting morphological, mechanical, and compositional changes of the outer membrane of bacteria in great detail. The cationic quaternary amine groups of P1 led to electrostatic interactions with negatively charged moieties within the outer membrane of bacteria. Using atomic force microscopy (AFM), high-resolution transmission electron microscopy (TEM), we showed that due to this treatment, the bacterial outer membrane became rougher, decreased in stiffness/elastic modulus (AFM nanoindentation), formed blebs, and released vesicles near the cells. These evidences, in addition to increased staining of the P1-treated cell membrane by lipophilic dye Nile Red (confocal laser scanning microscopy (CLSM)), suggested loosening/disruption of packing of the outer cell envelope and release and exposure of lipid-based components. Lipidomics and fatty acid analysis confirmed a significant loss of phosphate-based outer membrane lipids and fatty acids, some of which are critically needed to maintain cell wall integrity and mechanical strength. Lipidomics and UV-vis analysis also confirmed that the extracellular vesicles released upon treatment (AFM) are composed of lipids and cationic P1. Such surface alterations (vesicle/bleb formation) and release of lipids/fatty acids upon treatment were effective enough to inhibit further growth of E. coli cells without completely disintegrating the cells and have been known as a defense mechanism of the cells against cationic antimicrobial agents.

Country Income Is Only One of the Tiles: The Global Journey of Antimicrobial Resistance among Humans, Animals, and Environment

Antimicrobial resistance (AMR) is one of the most complex global health challenges today: decades of overuse and misuse in human medicine, animal health, agriculture, and dispersion into the environment have produced the dire consequence of infections to become progressively untreatable. Infection control and prevention (IPC) procedures, the reduction of overuse, and the misuse of antimicrobials in human and veterinary medicine are the cornerstones required to prevent the spreading of resistant bacteria. Purified drinking water and strongly improved sanitation even in remote areas would prevent the pollution from inadequate treatment of industrial, residential, and farm waste, as all these situations are expanding the resistome in the environment. The One Health concept addresses the interconnected relationships between human, animal, and environmental health as a whole: several countries and international agencies have now included a One Health Approach within their action plans to address AMR. Improved antimicrobial usage, coupled with regulation and policy, as well as integrated surveillance, infection control and prevention, along with antimicrobial stewardship, sanitation, and animal husbandry should all be integrated parts of any new action plan targeted to tackle AMR on the Earth. Since AMR is found in bacteria from humans, animals, and in the environment, we briefly summarize herein the current concepts of One Health as a global challenge to enable the continued use of antibiotics.

Integrated metagenomic and metatranscriptomic profiling reveals differentially expressed resistomes in human, chicken, and pig gut microbiomes

Gut microbiota is a reservoir of antibiotic resistance genes (ARGs). Yet, limited information is available regarding the presence (metagenomic DNA level) and expression profiles (metatranscriptomic RNA level) of ARGs in gut microbiota. Here, we used both metagenomic and metatranscriptomic approaches to comprehensively reveal the abundance, diversity, and expression of ARGs in human, chicken, and pig gut microbiomes in China. Based on deep sequencing data and ARG databases, a total of 330 ARGs associated with 21 antibiotic classes were identified in 18 human, chicken, and pig fecal samples. Metatranscriptomic analysis revealed that 49.4, 66.5, and 56.6% of ARGs identified in human, chicken, and pig gut microbiota, respectively, were expressed, indicating that a large proportion of ARGs were not transcriptionally active. Further analysis demonstrated that transcript abundance of tetracycline, aminoglycoside, and beta-lactam resistance genes was mainly contributed by acquired ARGs. We also found that various biocide, chemical, and metal resistance genes were actively transcribed in human and animal guts. The combination of metagenomic and metatranscriptomic analysis in this study allowed us to specifically link ARGs to their transcripts, providing a comprehensive view of the prevalence and expression of ARGs in gut microbiota. Taken together, these data deepen our understanding of the distribution, evolution, and dissemination of ARGs and metal resistance genes in human, chicken, and pig gut microbiota.

Selective Entropy Gain-Driven Adsorption of Nanospheres onto Spherical Bacteria Endows Photodynamic Treatment with Narrow-Spectrum Activity

Narrow-spectrum antimicrobials specifically eradicate the target pathogens but suffer from significantly lagging development. Photodynamic therapy eliminates cells with reactive oxygen species (ROS) generated upon light irradiation but is intrinsically a wide-spectrum modality. We herein converted photodynamic therapy into a narrow-spectrum modality by taking advantage of a previously unnoticed physics recognition pathway. We found that negatively charged nanospheres undergo selective entropy gain-driven adsorption onto spherical bacteria, but not onto rod-like bacteria. This bacterial morphology-targeting selectivity, combined with the extremely limited effective radii of action of ROS, enabled photodynamic nanospheres to kill >99% of inoculated spherical bacteria upon light irradiation and <1% of rod-like bacteria under comparable conditions, indicative of narrow-spectrum activity against spherical bacteria. This work unveils the bacterial morphology selectivity in the adsorption of negatively charged nanospheres and suggests a new approach for treating infections characterized by overthriving spherical bacteria in niches naturally dominated by rod-like bacteria.

Prevention of antibiotic resistance - an epidemiological scoping review to identify research categories and knowledge gaps

BACKGROUND

Antibiotics have become the cornerstone for the treatment of infectious diseases and contributed significantly to the dramatic global health development during the last 70 years. Millions of people now survive what were previously life-threatening infections. But antibiotics are finite resources and misuse has led to antibiotic resistance and reduced efficacy within just a few years of introduction of each new antibiotic. The World Health Organization rates antibiotic resistance as a 'global security threat' impacting on global health, food security and development and as important as terrorism and climate change.

OBJECTIVES

This paper explores, through a scoping review of the literature published during the past 20 years, the magnitude of peer-reviewed and grey literature that addresses antibiotic resistance and specifically the extent to which "prevention" has been at the core. The ultimate aim is to identify know-do gaps and strategies to prevent ABR.

METHODS

The review covers four main data bases, Web of Science, Medline, Scopus and Ebsco searched for 2000-17. The broader research field "antibiotic OR antimicrobial resistance" gave 431,335 hits. Narrowing the search criteria to "Prevention of antibiotic OR antimicrobial resistance" resulted in 1062 remaining titles. Of these, 622 were unique titles. After screening of the 622 titles for relevance, 420 abstracts were read, and of these 282 papers were read in full. An additional 53 references were identified from these papers, and 64 published during 2018 and 2019 were also included. The final scoping review database thus consisted of 399 papers.

RESULTS

A thematic structure emerged when categorizing articles in different subject areas, serving as a proxy for interest expressed from the research community. The research area has been an evolving one with about half of the 399 papers published during the past four years of the study period. Epidemiological modelling needs strengthening and there is a need for more and better surveillance systems, especially in lower- and middle-income countries. There is a wealth of information on the local and national uses and misuses of antibiotics. Educational and stewardship programmes basically lack evidence. Several studies address knowledge of the public and prescribers. The lessons for policy are conveyed in many alarming reports from national and international organizations.

CONCLUSIONS

Descriptive rather than theoretical ambitions have characterized the literature. If we want to better understand and explain the antibiotic situation from a behavioural perspective, the required approaches are lacking. A framework for an epidemiological causal web behind ABR is suggested and may serve to identify entry points for potential interventions.

Excessive use of medically important antimicrobials in food animals in Pakistan: a five-year surveillance survey

Demand for poultry meat is rising in low- and middle-countries, driving the expansion of large commercial farms where antimicrobials are used as surrogates for hygiene, good nutrition. This routine use of antimicrobials in animal production facilitates the emergence and spread of antibiotic-resistant pathogens. Despite potentially serious consequences for the animal industry, few studies have documented trends in antimicrobial use (AMU) at the farm-level in low- and middle-income countries. The objective of this study was to estimate AMU in a broiler chicken farm in Pakistan over a five-year period and to extrapolate national AMU in commercial broiler farming. Between 2013 and 2017, we monitored AMU in 30 flocks from a commercial broiler farm in Punjab, the most populous province of Pakistan. The amount of antimicrobials administered was calculated in milligram/population unit of the final flock weight (mg/fPU) and in used daily dose (UDD). The annual on-farm antimicrobial use was 250.84 mg of active ingredient per kilogram of the final flock weight. This consumption intensity exceeds the amount of antimicrobial used per kilogram of chicken of all countries in the world except China. Measured in mg per kg of final flock weight or population unit (fPU), medically important drugs such as colistin (31.39 mg/fPU), tylosin (41.71 mg/fPU), doxycycline (81.81 mg/fPU), and enrofloxacin (26.19 mg/fPU) were the most frequently used antimicrobials for prophylactic or therapeutic use. Lincomycin was the most frequently used antimicrobial used in-feed (29.09 mg/fPU). Our findings suggest that the annual consumption of antimicrobials in the broiler sector in Pakistan could be as high as 568 tons. This alarmingly high consumption estimate is the first baseline study on antimicrobial use in animals in Pakistan. Our findings call for immediate actions to reduce antimicrobial use in Pakistan, and countries with comparable farming practices.