Prevalence and molecular characteristics of intestinal pathogenic Escherichia coli isolated from diarrheal pigs in Southern China.

Intestinal pathogenic Escherichia coli (InPEC) is one of the most common causes of bacterial diarrhea in farm animals, including profuse neonatal diarrhea and post weaning diarrhea (PWD) in piglets. In this study, we investigated the prevalence of InPEC and associated primary virulence factors among 543 non-duplicate E. coli isolates from diarrheal pigs from 15 swine farms in southern China. Six major virulence genes associated with InPEC were identified among 69 (12.71 %) E. coli isolates and included est (6.62 %), K88 (4.79 %), elt (3.68 %), eae (1.47 %), stx2 (0.92 %) and F18 (0.55 %). Three pathotypes of InPEC were identified including ETEC (8.10 %), EPEC (1.29 %) and STEC/ETEC (0.92 %). In particular, K88 was only found in ETEC from breeding farms, whereas F18 was only present in STEC/ETEC hybrid from finishing farms. Whole genome sequence analysis of 37 E. coli isolates revealed that InPEC strains frequently co-carried multiple antibiotic resistance gene (ARG). est, elt and F18 were also found to co-locate with ARGs on a single IncFIB/IncFII plasmid. InPEC isolates from different pathotypes also possessed different profiles of virulence genes and antimicrobial resistance genes. Population structure analysis demonstrated that InPEC isolates from different pathotypes were highly heterogeneous whereas those of the same pathotype were extremely similar. Plasmid analysis revealed that K88 and/or est/elt were found on pGX18-2-like/pGX203-2-like and pGX203-1-like IncFII plasmids, while F18 and elt/est, as well as diverse ARGs were found to co-locate on IncFII/IncFIB plasmids with a non-typical backbone. Moreover, these key virulence genes were flanked by or adjacent to IS elements. Our findings indicated that both clonal expansion and horizontal spread of epidemic IncFII plasmids contributed to the prevalence of InPEC and the specific virulence genes (F4, F18, elt and est) in the tested swine farms.

Cat and dog feces as reservoirs of diverse novel antibiotic resistance genes.

Companion animals have the potential to greatly enhance the physical and mental health of humans, thus leading to an increased focus on the interactions between humans and pets. Currently, the inappropriate and excessive utilization of antimicrobial agents has become prevalent in veterinary clinical practice for pets. This antibiotic contamination phenomenon has a profound impact on the enrichment of antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs) in pets. However, the pet-associated resistome, especially the novel ARGs in pets, represents a relatively neglected area. In this study, we successfully constructed a total of 12 libraries using the functional metagenomics approach to assess the diversity of ARGs in pet cats and dogs from four pet hospitals. Through the integration of functional screening and high-throughput sequencing, a total of 122 antibiotic resistance determinants were identified, of which 15 were classified as putative novel ARGs originating from five classes. Functional assessment demonstrated that 6 novel ARGs including one ß-lactam, two macrolides, two aminoglycosides, and one rifamycin (RIF), namely blaPF, ermPF, msrPF, aac(6')PF, aph(3')PF, and arrPF, exhibited functionally activity in conferring bacterial phenotypic resistance by increasing the minimum inhibitory concentrations (MICs) with a 4- to 128-fold. Genetic context analysis demonstrated that, with the exception of aac(6')PF and arrPF, the remaining four novel ARGs were found adjacent to mobile genetic elements (MGEs) including IS elements or transposases, which provided a prerequisite for horizontal transfer of these novel ARGs, thereby offering an explanation for their detection in diverse samples collected from various sampling sites. The current study has unveiled the significant role of cat and dog feces as one source of reservoirs of diverse novel ARGs, while also highlighting the potential adverse consequences of their further spread to medically significant pathogens and human commensal organisms.

Cinnamaldehyde targets SarA to enhance ß-lactam antibiotic activity against methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is a current global public health problem due to its increasing resistance to the most recent antibiotic therapies. One critical approach is to develop ways to revitalize existing antibiotics. Here, we show that the phytogenic compound cinnamaldehyde (CIN) and ß-lactam antibiotic combinations can functionally synergize and resensitize clinical MRSA isolates to ß-lactam therapy and inhibit MRSA biofilm formation. Mechanistic studies indicated that the CIN potentiation effect on ß-lactams was primarily the result of inhibition of the mecA expression by targeting the staphylococcal accessory regulator sarA. CIN alone or in combination with ß-lactams decreased sarA gene expression and increased SarA protein phosphorylation that impaired SarA binding to the mecA promoter element and downregulated virulence genes such as those encoding biofilm, α-hemolysin, and adhesin. Perturbation of SarA-mecA binding thus interfered with PBP2a biosynthesis and this decreased MRSA resistance to ß-lactams. Furthermore, CIN fully restored the anti-MRSA activities of ß-lactam antibiotics in vivo in murine models of bacteremia and biofilm infections. Together, our results indicated that CIN acts as a ß-lactam adjuvant and can be applied as an alternative therapy to combat multidrug-resistant MRSA infections.

Daily occupational exposure in swine farm alters human skin microbiota and antibiotic resistome.

Antimicrobial resistance (AMR) is a major threat to global public health, and antibiotic resistance genes (ARGs) are widely distributed across humans, animals, and environment. Farming environments are emerging as a key research area for ARGs and antibiotic resistant bacteria (ARB). While the skin is an important reservoir of ARGs and ARB, transmission mechanisms between farming environments and human skin remain unclear. Previous studies confirmed that swine farm environmental exposures alter skin microbiome, but the timeline of these changes is ill defined. To improve understanding of these changes and to determine the specific time, we designed a cohort study of swine farm workers and students through collected skin and environmental samples to explore the impact of daily occupational exposure in swine farm on human skin microbiome. Results indicated that exposure to livestock-associated environments where microorganisms are richer than school environment can reshape the human skin microbiome and antibiotic resistome. Exposure of 5 h was sufficient to modify the microbiome and ARG structure in workers' skin by enriching microorganisms and ARGs. These changes were preserved once formed. Further analysis indicated that ARGs carried by host microorganisms may transfer between the environment with workers' skin and have the potential to expand to the general population using farm workers as an ARG vector. These results raised concerns about potential transmission of ARGs to the broader community. Therefore, it is necessary to take corresponding intervention measures in the production process to reduce the possibility of ARGs and ARB transmission.

Innovative Delivery System Combining CRISPR-Cas12f for Combatting Antimicrobial Resistance in Gram-Negative Bacteria.

Antimicrobial resistance poses a significant global challenge, demanding innovative approaches, such as the CRISPR-Cas-mediated resistance plasmid or gene-curing system, to effectively combat this urgent crisis. To enable successful curing of antimicrobial genes or plasmids through CRISPR-Cas technology, the development of an efficient broad-host-range delivery system is paramount. In this study, we have successfully designed and constructed a novel functional gene delivery plasmid, pQ-mini, utilizing the backbone of a broad-host-range Inc.Q plasmid. Moreover, we have integrated the CRISPR-Cas12f system into the pQ-mini plasmid to enable gene-curing in broad-host of bacteria. Our findings demonstrate that pQ-mini facilitates the highly efficient transfer of genetic elements to diverse bacteria, particularly in various species in the order of Enterobacterales, exhibiting a broader host range and superior conjugation efficiency compared to the commonly used pMB1-like plasmid. Notably, pQ-mini effectively delivers the CRISPR-Cas12f system to antimicrobial-resistant strains, resulting in remarkable curing efficiencies for plasmid-borne mcr-1 or blaKPC genes that are comparable to those achieved by the previously reported pCasCure system. In conclusion, our study successfully establishes and optimizes pQ-mini as a broad-host-range functional gene delivery vector. Furthermore, in combination with the CRISPR-Cas system, pQ-mini demonstrates its potential for broad-host delivery, highlighting its promising role as a novel antimicrobial tool against the growing threat of antimicrobial resistance.

Antimicrobial resistance and population genomics of emerging multidrug-resistant Salmonella 4,[5],12:i:- in Guangdong, China.

Salmonella 4,[5],12:i:-, a monophasic variant of Salmonella Typhimurium, has emerged as a global cause of multidrug-resistant salmonellosis and has become endemic in many developing and developed countries, especially in China. Here, we have sequenced 352 clinical isolates in Guangdong, China, during 2009-2019 and performed a large-scale collection of Salmonella 4,[5],12:i:- with whole genome sequencing (WGS) data across the globe, to better understand the population structure, antimicrobial resistance (AMR) genomic characterization, and transmission routes of Salmonella 4,[5],12:i:- across Guangdong. Salmonella 4,[5],12:i:- strains showed broad genetic diversity; Guangdong isolates were found to be widely distributed among the global lineages. Of note, we identified the formation of a novel Guangdong clade (Bayesian analysis of population structure lineage 1 [BAPS1]) genetically diversified from the global isolates and likely emerged around 1990s. BAPS1 exhibits unique genomic features, including large pan-genome, decreased ciprofloxacin susceptibility due to mutation in gyrA and carriage of plasmid-mediated quinolone resistance (PMQR) genes, and the multidrug-resistant IncHI2 plasmid. Furthermore, high genetic similarity was found between strains collected from Guangdong, Europe, and North America, indicating the association with multiple introductions from overseas. These results suggested that global dissemination and local clonal expansion simultaneously occurred in Guangdong, China, and horizontally acquired resistance to first-line and last-line antimicrobials at local level, underlying emergences of extensive drug and pan-drug resistance. Our findings have increased the knowledge of global and local epidemics of Salmonella 4,[5],12:i:- in Guangdong, China, and provided a comprehensive baseline data set essential for future molecular surveillance.IMPORTANCESalmonella 4,[5],12:i:- has been regarded as the predominant pandemic serotype causing diarrheal diseases globally, while multidrug resistance (MDR) constitutes great public health concerns. This study provided a detailed and comprehensive genome-scale analysis of this important Salmonella serovar in the past decade in Guangdong, China. Our results revealed the complexity of two distinct transmission modes, namely global transmission and local expansion, circulating in Guangdong over a decade. Using phylogeography models, the origin of Salmonella 4,[5],12:i:- was predicted from two aspects, year and country, that is, Salmonella 4,[5],12:i:- emerged in 1983, and was introduced from the UK, and subsequently differentiated into the local endemic lineage circa 1991. Additionally, based on the pan-genome analysis, it was found that the gene accumulation rate in local endemic BAPS 1 lineage was higher than in other lineages, and the horizontal transmission of MDR IncHI2 plasmid associated with high resistance played a major role, which showed the potential threat to public health.

Pharmacokinetic/pharmacodynamic evaluation of gamithromycin against rabbit pasteurellosis.

BACKGROUND: Gamithromycin is an effective therapy for bovine and swine respiratory diseases but not utilized for rabbits. Given its potent activity against respiratory pathogens, we sought to determine the pharmacokinetic profiles, antimicrobial activity and target pharmacokinetic/pharmacodynamic (PK/PD) exposures associated with therapeutic effect of gamithromycin against Pasteurella multocida in rabbits. RESULTS: Gamithromycin showed favorable PK properties in rabbits, including high subcutaneous bioavailability (86.7 ± 10.7%) and low plasma protein binding (18.5-31.9%). PK analysis identified a mean plasma peak concentration (Cmax) of 1.64 ± 0.86 mg/L and terminal half-life (T1/2) of 31.5 ± 5.74 h after subcutaneous injection. For P. multocida, short post-antibiotic effects (PAE) (1.1-5.3 h) and post-antibiotic sub-inhibitory concentration effects (PA-SME) (6.6-9.1 h) were observed after exposure to gamithromycin at 1 to 4× minimal inhibitory concentration (MIC). Gamithromycin demonstrated concentration-dependent bactericidal activity and the PK/PD index area under the concentration-time curve over 24 h (AUC24h)/MIC correlated well with efficacy (R2 > 0.99). The plasma AUC24h/MIC ratios of gamithromycin associated with the bacteriostatic, bactericidal and bacterial eradication against P. multocida were 15.4, 24.9 and 27.8 h in rabbits, respectively. CONCLUSIONS: Subcutaneous administration of 6 mg/kg gamithromycin reached therapeutic concentrations in rabbit plasma against P. multocida. The PK/PD ratios determined herein in combination with ex vivo activity and favorable rabbit PK indicate that gamithromycin may be used for the treatment of rabbit pasteurellosis.

Qualitative and Quantitative Analytical Techniques of Nucleic Acid Modification Based on Mass Spectrometry for Biomarker Discovery.

Nucleic acid modifications play important roles in biological activities and disease occurrences, and have been considered as cancer biomarkers. Due to the relatively low amount of nucleic acid modifications in biological samples, it is necessary to develop sensitive and reliable qualitative and quantitative methods to reveal the content of any modifications. In this review, the key processes affecting the qualitative and quantitative analyses are discussed, such as sample digestion, nucleoside extraction, chemical labeling, chromatographic separation, mass spectrometry detection, and data processing. The improvement of the detection sensitivity and specificity of analytical methods based on mass spectrometry makes it possible to study low-abundance modifications and their biological functions. Some typical nucleic acid modifications and their potential as biomarkers are displayed, and efforts to improve diagnostic accuracy are discussed. Future perspectives are raised for this research field.

Chitosan oligosaccharide accelerates the dissemination of antibiotic resistance genes through promoting conjugative plasmid transfer.

The dissemination of antibiotic resistance genes (ARGs), especially via plasmid-mediated horizontal gene transfer, poses a pervasive threat to global health. Chitosan-oligosaccharide (COS) is extensively utilized in medicine, plant and animal husbandry. However, their impact on microflora implies the potential to exert selective pressure on plasmid transfer. To explore the role of COS in facilitating the dissemination of ARGs via plasmid conjugation, we established in vitro mating models. The addition of COS to conjugation mixtures significantly enhanced the transfer of RP4 plasmid and mcr-1 positive IncX4 plasmid in both intra- and inter-specific. Phenotypic and transcriptome analysis revealed that COS enhanced intercellular contact by neutralizing cell surface charge and increasing cell surface hydrophobicity. Additionally, COS increased membrane permeability by inhibiting the Tol-Pal system, thereby facilitating plasmid conjugative transfer. Furthermore, COS served as the carbon source and was metabolized by E. coli, providing energy for plasmid conjugation through regulating the expression of ATPase and global repressor factor-related genes in RP4 plasmid. Overall, these findings improve our awareness of the potential risks associated with the presence of COS and the spread of bacterial antibiotic resistance, emphasizing the need to establish guidelines for the prudent use of COS and its discharge into the environment.

Dual-ROS Sensitive Moieties Conjugate Inhibits Curcumin Oxidative Degradation for Colitis Precise Therapy.

Curcumin, a natural bioactive polyphenol with diverse molecular targets, is well known for its anti-oxidation and anti-inflammatory potential. However, curcumin exhibits low solubility (<1 µg mL-1), poor tissue-targeting ability, and rapid oxidative degradation, resulting in poor bioavailability and stability for inflammatory therapy. Here, poly(diselenide-oxalate-curcumin) nanoparticle (SeOC-NP) with dual-reactive oxygen species (ROS) sensitive chemical moieties (diselenide and peroxalate ester bonds) is fabricated by a one-step synthetic strategy. The results confirmed that dual-ROS sensitive chemical moieties endowed SeOC-NP with the ability of targeted delivery of curcumin and significantly suppress oxidative degradation of curcumin for high-efficiency inflammatory therapy. In detail, the degradation amount of curcumin for SeOC is about 4-fold lower than that of free curcumin in an oxidative microenvironment. As a result, SeOC-NP significantly enhanced the antioxidant activity and anti-inflammatory efficacy of curcumin in vitro analysis by scavenging intracellular ROS and suppressing the secretion of nitric oxide and pro-inflammatory cytokines. In mouse colitis models, orally administered SeOC-NP can remarkably alleviate the symptoms of IBD and maintain the homeostasis of gut microbiota. This work provided a simple and effective strategy to fabricate ROS-responsive micellar and enhance the oxidation stability of medicine for precise therapeutic inflammation.

Targeted inhibition of gut bacterial ß-glucuronidases by octyl gallate alleviates mycophenolate mofetil-induced gastrointestinal toxicity.

Mycophenolate mofetil (MMF) is a viable therapeutic option against various immune disorders as a chemotherapeutic agent. Nevertheless, its application has been undermined by the gastrotoxic metabolites (mycophenolic acid glucuronide, MPAG) produced by microbiome-associated ß-glucuronidase (ßGUS). Therefore, controlling microbiota-produced ßGUS underlines the potential strategy to improve MMF efficacy by overcoming the dosage limitation. In this study, the octyl gallate (OG) was identified with promising inhibitory activity on hydrolysis of PNPG in our high throughput screening based on a chemical collection of approximately 2000 natural products. Furthermore, OG was also found to inhibit a broad spectrum of BGUSs, including mini-Loop1, Loop 2, mini-Loop 2, and mini-Loop1,2. The further in vivo experiments demonstrated that administration of 20 mg/kg OG resulted in predominant reduction in the activity of BGUSs while displayed no impact on the overall fecal microbiome in mice. Furthermore, in the MMF-induced colitis model, the administration of OG at a dosage of 20 mg/kg effectively mitigated the gastrointestinal toxicity, and systematically reverted the colitis phenotypes. These findings indicate that the OG holds promising clinical potential for the prevention of MMF-induced gastrointestinal toxicity by inhibition of BGUSs and could be developed as a combinatorial therapy with MFF for better clinical outcomes.

The History and Prediction of Prebiotics and Postbiotics: A Patent Analysis.

Prebiotics and postbiotics have gained attention as functional food additives due to their substantial influence on the gut microbiome and potential implications for human health on a broader scale. In addition, the number of patents for these additives has also increased, yet their functional classification has been problematic. In this study, we classified 2215 patents granted from 2001 to 2020 by functionality to enable predictions of future development directions. These patents encompassed subjects as diverse as feed supplementation, regulation of intestinal homeostasis, prevention of gastrointestinal ailments, targeted drug administration and augmentation of drug potency. The progression of patents issued during this time frame could be divided into three phases: occasional accounts prior to 2001, a period from 2001 to 2013 during which an average of 42 patents were issued annually, followed by a surge exceeding 140 patents annually after 2013. The latter increase has indicated that pre- and post-biotics have been recognized as biologically relevant. Patent mining therefore can enable forecasts of the future trajectory of these biologics and provide insights to evaluate their advancement. Moreover, this research is the first attempt to generalize and predict the directions of prebiotics and postbiotics using patent information and offers a comprehensive perspective for the potential utilization of prebiotics and postbiotics across a wide variety of fields.

Distribution of antibiotic resistance genes and their pathogen hosts in duck farm environments in south-east coastal China.

Livestock farms are major reservoirs of antibiotic resistance genes (ARGs) that are discharged into the environment. However, the abundance, diversity, and transmission of ARGs in duck farms and its impact on surrounding environments remain to be further explored. Therefore, the characteristics of ARGs and their bacterial hosts from duck farms and surrounding environment were investigated by using metagenomic sequencing. Eighteen ARG types which consist of 823 subtypes were identified and the majority conferred resistance to multidrug, tetracyclines, aminoglycosides, chloramphenicols, MLS, and sulfonamides. The floR gene was the most abundant subtype, followed by sul1, tetM, sul2, and tetL. ARG abundance in fecal sample was significantly higher than soil and water sample. Our results also lead to a hypothesis that Shandong province have been the most contaminated by ARGs from duck farm compared with other four provinces. PcoA results showed that the composition of ARG subtypes in water and soil samples was similar, but there were significant differences between water and feces samples. However, the composition of ARG subtypes were similar between samples from five provinces. Bacterial hosts of ARG subtypes were taxonomically assigned to eight phyla that were dominated by the Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria. In addition, some human bacterial pathogens could be enriched in duck feces, including Enterococcus faecium, Acinetobacter baumannii, and Staphylococcus aureus, and even serve as the carrier of ARGs. The combined results indicate that a comprehensive overview of the diversity and abundance of ARGs, and strong association between ARGs and bacterial community shift proposed, and benefit effective measures to improve safety of antibiotics use in livestock and poultry farming. KEY POINTS: • ARG distribution was widespread in the duck farms and surroundings environment • ARG abundance on the duck farms was significantly higher than in soil and water • Human bacterial pathogens may serve as the vectors for ARGs.

Molecular characteristic of mcr-1 gene in Escherichia coli from aquatic products in Guangdong, China.

OBJECTIVES: Aquatic ecosystems serve as a dissemination pathway and a reservoir of both antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). This study aimed to determine the prevalence of colistin-resistant mcr-like genes in Enterobacteriales in aquatic products, which may be contribute to the transfer of ARGs in water environments. METHODS: The mcr-1-positive Escherichia coli were recovered from 123 freshwater fish and 34 cultured crocodile cecum samples from 10 farmers' markets in Guangdong, China. Minimum inhibitory concentration (MIC) was determined using the agar dilution method. Genotyping was performed using pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Conjugation assay was carried out to investigate the transferability of mcr-1. Genomic information was obtained by whole genome sequencing (WGS) and bioinformatic analysis. RESULTS: Forty-four mcr-1 positive isolates showed co-resistance to tetracycline, trimethoprim/sulfamethoxazole, and gentamicin, while they were all sensitive to tigecycline, meropenem, and amikacin. They were typed into sixteen PFGE clusters. ST10 and ST117 were the most popular sequence types, followed by ST1114. S1-PFGE verified the presence of the mcr-1 gene on plasmids in sizes of ∼60 kb (n = 1) and ∼240 kb (n = 3). Whole genome sequencing-based analysis identified mcr-1 integrated in IncHI2 plasmid (n = 3), IncI2 plasmid (n = 2), and bacterial chromosome in two copies (n = 1). In addition to mcr-1, they carried several other antibiotic resistance genes, such as blaCTX-M-14, fosA3, and aac(6')-Ib-cr. CONCLUSION: These data suggest that aquatic products are an important antibiotic resistance reservoir and highlight possible risks regarding food safety.

Spatio-temporal evolutionary analysis of surface ecological quality in Pingshuo open-cast mine area, China.

The open-pit mining area is highly affected by human activities, which aggravate soil erosion and disturb surface ecology, bringing many problems and challenges to its environmental management and restoration, which has received widespread attention. The establishment of an objective, timely and quantitative remote sensing monitoring, and evaluation system for the spatio-temporal evolution of the surface ecological environment in the open-pit mining area is of great significance for its environmental protection, management decisions, and sustainable social development. Based on the Google Earth Engine (GEE) platform, this paper uses Landsat images to construct and calculate the remote sensing ecological index (RSEI) of the Pingshuo open-cast mine area (POMA) from 1990 to 2020 and monitor and evaluate its surface ecological environment. Combined with the Theil-Sen median, Mann-Kendall test, and Hurst index, the spatio-temporal process was analyzed. The results showed that the ecological environmental quality of the mining area first decreased and then increased from 1990 to 2020. 1990-2000 was a period of serious ecological degradation, followed by improvement. The overall improvement area reached 87.03%, and the degradation was concentrated in the coal mining area. Between 1990 and 2020, the Hurst index of the mining area was 0.452, indicating that the region has a fragile ecological environment and has difficult maintaining its stability. The global Moran's I mean value of the RSEI of the study area is 0.92, which combined with Moran's scatter plot to indicate that there is a strong positive spatial correlation rather than a random distribution of its ecological environment. During the study period, the impact on the climate of the ecological environmental change of POMA was weak, and human factors such as coal mining, land reclamation, and social construction were the main driving forces for the change in ecological quality. The results of this study reveal the changing trend of surface ecology in the mining area over the past 30 years, which is helpful for understanding its impact mechanism on ecological quality and provides support for the management of the region.

Self-assembly of H2S-responsive nanoprodrugs based on natural rhein and geraniol for targeted therapy against Salmonella Typhimurium.

Salmonellosis is a globally extensive food-borne disease, which threatens public health and results in huge economic losses in the world annually. The rising prevalence of antibiotic resistance in Salmonella poses a significant global concern, emphasizing an imperative to identify novel therapeutic agents or methodologies to effectively combat this predicament. In this study, self-assembly hydrogen sulfide (H2S)-responsive nanoprodrugs were fabricated with poly(α-lipoic acid)-polyethylene glycol grafted rhein and geraniol (PPRG), self-assembled into core-shell nanoparticles via electrostatic, hydrophilic and hydrophobic interactions, with hydrophilic exterior and hydrophobic interior. The rhein and geraniol are released from self-assembly nanoprodrugs PPRG in response to Salmonella infection, which is known to produce hydrogen sulfide (H2S). PPRG demonstrated stronger antibacterial activity against Salmonella compared with rhein or geraniol alone in vitro and in vivo. Additionally, PPRG was also able to suppress the inflammation and modulate gut microbiota homeostasis. In conclusion, the as-prepared self-assembly nanoprodrug sheds new light on the design of natural product active ingredients and provides new ideas for exploring targeted therapies for specific Enteropathogens. Graphical  illustration for construction of self-assembly nanoprodrugs PPRG and its antibacterial and anti-inflammatory activities on experimental Salmonella infection in mice.

Increased Activity of ß-Lactam Antibiotics in Combination with Carvacrol against MRSA Bacteremia and Catheter-Associated Biofilm Infections.

ß-Lactam antibiotics are the mainstay for the treatment of staphylococcal infections, but their utility is greatly limited by the emergence and rapid dissemination of methicillin-resistant Staphylococcus aureus (MRSA). Herein, we evaluated the ability of the plant-derived monoterpene carvacrol to act as an antibiotic adjuvant, revitalizing the anti-MRSA activity of ß-lactam antibiotics. Increased susceptibility of MRSA to ß-lactam antibiotics and significant synergistic activities were observed with carvacrol-based combinations. Carvacrol significantly inhibited MRSA biofilms and reduced the production of exopolysaccharide, polysaccharide intercellular adhesin, and extracellular DNA and showed synergistic biofilm inhibition in combination with ß-lactams. Transcriptome analysis revealed profound downregulation in the expression of genes involved in two-component systems and S. aureus infection. Mechanistic studies indicate that carvacrol inhibits the expression of staphylococcal accessory regulator sarA and interferes with SarA-mecA promoter binding that decreases mecA-mediated ß-lactam resistance. Consistently, the in vivo experiment also supported that carvacrol restored MRSA sensitivity to ß-lactam antibiotic treatments in both murine models of bacteremia and biofilm-associated infection. Our results indicated that carvacrol has a potential role as a combinatorial partner with ß-lactam antibiotics to address MRSA infections.

Genomics analysis of KPC-2 and NDM-5-producing Enterobacteriaceae in migratory birds from Qinghai Lake, China.

The study examined the epidemiological characteristics of carbapenem-resistant Enterobacteriaceae (CRE) isolated from migratory birds and surroundings in Qinghai Lake, China. We identified 69 (15.7%) CRE isolates from a total of 439 samples including 29 (6.6%) blaNDM-5 Escherichia coli and 40 (9.1%) blaKPC-2 Klebsiella pneumoniae. WGS analysis indicated that ST746, ST48, ST1011, and ST167 were the primary sequence types (ST) for blaNDM-5 E. coli, while all blaKPC-2 K. pneumoniae were ST11 and harbored numerous antibiotic resistance gene types including blaCTX-M, qnrS, and rmtB. A phylogenetic tree based on core genomes revealed that blaNDM-5 E. coli was highly heterogeneous while the blaKPC-2 K. pneumoniae was highly genetically similar within the group and to human Chinese isolates. IncX3, IncHI2, and IncFIB-HI2 plasmid replicon types were associated with blaNDM-5 spread, while IncFII-R and IncFII plasmids mediated blaKPC-2 spread. We also identified IncFII-R hybrid plasmids most likely formed by IS26-mediated integration of IncFII into IncR plasmid backbones. This also facilitated the persistence of IncFII-R plasmids and antibiotic resistance genes including blaKPC-2. In addition, all of the blaKPC-2 K. pneumoniae isolates harbored a pLVKP-like virulence plasmid carrying a combination of two or more hypervirulence markers that included peg-344, iroB, iucA, rmpA, and rmpA2. This is the first description of ST11 K. pneumoniae that co-carried blaKPC-2- and pLVKP-like virulence plasmids from migratory birds. The blaKPC-2 K. pneumoniae carried by migratory birds displayed high genetic relatedness to human isolates highlighting a high risk of transmission of these K. pneumoniae. KEY POINTS: • Multidrug resistance plasmids (blaKPC-2, bla436NDM-5, bla CTX-M, qnrS, and rmtB). • Co-occurrence of plasmid-mediated resistance and virulence genes. • High similarity between migratory bird genomes and humans.

Impact of regional accessibility on urban residents' income in China: A bidirectional-fixed panel model.

The income gap between regions and its expansion are the main manifestations of the imbalanced and inadequate economic development in China. High-speed railway (HSR) construction is regarded as an important method to drive domestic demand, drive the pulse of the economy, and promote the coordinated development of regions. Based on the opening of HSR and the acceleration of ordinary railways, we used the weighted average travel time model and accessibility coefficient to estimate the changes on accessibility in 286 cities at prefecture-level and above from 2000 to 2018. Then, the influence mechanisms of improving regional accessibility on urban residents' income were estimated by using the bidirectional-fixed effects panel model and the recursive model respectively. We found that: (1) The accessibility of urban areas has been greatly improved due to the opening of HSR and the acceleration of ordinary railway, among which the improvement of HSR cities is greater. (2) The improvement of regional accessibility significantly promoted the income growth of urban residents, and the increase of the regional accessibility coefficient by 1 unit led to an average increase of 2140 yuan in the per capita disposable income of urban residents. (3) There is regional heterogeneity in the impact of improving regional accessibility on urban residents' income, and it has a significant effect on the eastern and northeastern regions. It has a greater positive effect on improving the income of residents in central cities compared with peripheral cities. (4) Regional accessibility can promote urban income growth through regional employment and fixed asset investment. In the future, the transportation network should be further improved to facilitate the regional economic cycle, strengthen the coordination and complementarity of regional economies, and promote regional economic integration so as to promote the improvement of resident income level and the common prosperity of the people.