First Detection of blaNDM-1-Haboring IncHI2 Plasmid in Escherichia coli Strain Isolated from Goose in China.

Carbapenem-resistant Enterobacteriaceae infections are among the most serious threats to human and animal health worldwide. Of the 1013 strains of Escherichia coli isolated and identified in 14 regions of China from 2007 to 2018, seven strains were resistant to meropenem and all were positive for blaNDM. The seven New Delhi metallo-ß-lactamase (NDM)-positive strains belonged to five different sequence types, indicating that most of the NDM-positive strains were nonclonal. An IncHI2 plasmid carrying the blaNDM-1 element was identified in the C1147 strain from a goose source and reported for the first time, showing a specific structure. Conjugation experiments revealed that the IncHI2 plasmid was conjugatable, and the horizontal propagation of the plasmid led to the rapid propagation of NDM in the same and different strains. This study revealed that waterfowl, as a potential transmission factor for carbapenem-resistant blaNDM-1, poses a threat to human health.

Salmonella Typhimurium ST34 Isolate Was More Resistant than the ST19 Isolate in China, 2007 - 2019.

To disclose the antimicrobial susceptibility and wide adaptability of commonly occurring genotypes of Salmonella enterica serovar Typhimurium, the antimicrobial resistance and multilocus sequence typing (MLST) profiles of 196 Salmonella Typhimurium isolates (136 from food-producing animals, 19 from environments, 15 from markets, and 26 from humans) in China between 2007 and 2019 were analyzed. Tests of susceptibility to 19 antimicrobial agents using the broth microdilution method showed that 84.7% of the isolates were resistant to at least one antimicrobial. Antimicrobial susceptibility analysis demonstrated that 66.8% of the isolates were multidrug-resistant (MDR) strains, with resistance to three or more antimicrobials. The highest antidrug resistance was to ampicillin, amoxicillin/clavulanic acid, and tetracycline. Three MLST types were detected, and sequence type (ST) 19 was the most common ST. However, ST34 was associated with a higher MDR rate and more complex MDR patterns, than ST19 and ST99, although the exact mechanism has not been reported. Our study highlights the variation of drug resistance and STs from different sources and the association between STs and drug resistance, providing useful information for epidemiological research and developing a public health strategy.

Imides modified benzopicenes: synthesis, solid structure and optoelectronic properties.

Imide-modified polycyclic aromatic hydrocarbons can be widely applied in the field of optoelectronic materials. In this work, we have synthesized four novel functionalized benzopicenes and characterized their solid structures and optoelectronic properties. The fluorescence of the four functionalized benzopicenes showed red shifts with increasing solvent polarity; the quantum yields are high in the solution state and moderate in the solid state. The single crystal structures show that the benzopicenes adopt a lamellar motif π-stacking. Their good solubility and optoelectronic properties make them potential solution-processable candidates for organic devices, bioimaging and biolabeling.

"Ultrasound to Improve the Anatomical Approach of Temple and a Retrospective Study on the Efficacy of Large-Volume Autologous Fat Grafting".

BACKGROUND: Autologous fat grafting (AFG) has been widely used in temporal hollowing augmentation, while the efficacy and safety were unstable. To solve these problems, we suggested large-volume lipofilling with doppler-ultrasound (DUS) guided of the temporal region by the anatomical study. MATERIALS AND METHODS: To clarify the safe and stable levels of AFG of the temporal fat compartments, 5 cadaveric heads (10 sides) were dissected after dye was injected into targeted fat pads with DUS guided. We retrospectively analyzed 100 patients with temporal fat transplantation, including the groups of conventional autologous fat grafting (c-AFG, n=50) and DUS guided large-volume autologous fat grafting (lv-AFG, n=50). RESULTS: The anatomical study revealed the approach of five injection planes and two fat compartments in the temporal region: superficial and deep temporal fat pads. In clinical review of the two AFG groups, all genders were female and there were no statistical differences in age, body mass index (BMI), tobacco or steroids use and previous filling history, etc. Between the c-AFG group and the lv-AFG group, average volume of temporal lipofilling per side was (10.55±2.25 vs 22.32±5.19, p<0.001) ml/side, Likert scale score of surgeons was (2.86±0.97 vs 4.24±0.66, p<0.001), rate of satisfaction was (74% vs 92%, p=0.017 <0.05), and the three types of statistics had statistically significant differences. CONCLUSION: The anatomical approach of the main temporal fat compartment is feasible, and DUS guided large-volume AFG is an effective and safe way to improve temporal hollowing augmentation or aging. EVIDENCE LEVEL: III.

Efficient screening of adsorbed receptors for Salmonella phage LP31 and identification of receptor-binding protein.

The adsorption process is the first step in the lifecycle of phages and plays a decisive role in the entire infection process. Identifying the adsorption mechanism of phages not only makes phage therapy more precise and efficient but also enables the exploration of other potential applications and modifications of phages. Phage LP31 can lyse multiple Salmonella serotypes, efficiently clearing biofilms formed by Salmonella enterica serovar Enteritidis (S. Enteritidis) and significantly reducing the concentration of S. Enteritidis in chicken feces. Therefore, LP31 has great potential for many practical applications. In this study, we established an efficient screening method for phage infection-related genes and identified a total of 10 genes related to the adsorption process of phage LP31. After the construction of strain C50041ΔrfaL 58-358, it was found that the knockout strain had a rough phenotype as an O-antigen-deficient strain. Adsorption rate and transmission electron microscopy experiments showed that the receptor for phage LP31 was the O9 antigen of S. Enteritidis. Homology comparison and adsorption experiments confirmed that the tail fiber protein Lp35 of phage LP31 participated in the adsorption process as a receptor-binding protein. IMPORTANCE A full understanding of the interaction between phages and their receptors can help with the development of phage-related products. Phages like LP31 with the tail fiber protein Lp35, or a closely related protein, have been reported to effectively recognize and infect multiple Salmonella serotypes. However, the role of these proteins in phage infection has not been previously described. In this study, we established an efficient screening method to detect phage adsorption to host receptors. We found that phage LP31 can utilize its tail fiber protein Lp35 to adsorb to the O9 antigen of S. Enteritidis, initiating the infection process. This study provides a great model system for further studies of how a phage-encoded receptor-binding protein (RBP) interacts with its host's RBP binding target, and this new model offers opportunities for further theoretical and experimental studies to understand the infection mechanism of phages.

Functionalized coronenes: synthesis, solid structure, and properties.

The construction of coronenes using simple building blocks is a challenging task. In this work, triphenylene was used as a building block to construct functionalized coronenes, and their solid structures and optoelectronic properties were investigated. The single crystal structures showed that coronenes have different packing motifs. Their good solubility and photostability make them potential solution-processable candidates for organic devices.

A phage for the controlling of Salmonella in poultry and reducing biofilms.

As a natural alternative to traditional antimicrobials, phages are being recognised as highly effective control agents for Salmonella and other foodborne bacteria. Due to the high diversity of Salmonella serotypes and the emergence of phage-resistant strains, attempting to isolate more widespread, strictly lytic Salmonella phages is highly warranted. In this study, a lytic phage, LP31, was isolated from poultry faecal samples. Transmission electron microscopy revealed that the phage had a polyhedral head and a retraction-free tail, indicative of the Siphoviridae family. Adsorption rate experiments showed that LP31 required the participation of lipopolysaccharides, but not flagella, during phage adsorption. Host profile identification showed that LP31 could lyse most Salmonella Enteritidis (S. Enteritidis) (96.15%, N = 104) and Salmonella Pullorum (S. Pullorum) (96.67%, N = 60). Initial applications found that LP31 reduced the concentration of static S. Enteritidis on metal surfaces (0.951 log10 cfu/ml) and in the faeces of chicks (2.14 log10 cfu/g). Notably, LP31 could almost completely remove biofilms formed by S. Enteritidis and S. Pullorum in 1 h. These findings suggest that LP31 has a good prevention and control effect against biofilms and planktonic antibiotic-resistant Salmonella, and is therefore a potentially promising biocontrol agent for controlling the spread of Salmonella in the poultry and food processing industries.

Safety of the Salmonella enterica serotype Dublin strain Sdu189-derived live attenuated vaccine-A pilot study.

Salmonella enterica serovar Dublin (S. Dublin) is an important zoonotic pathogen with high invasiveness. In the prevention and control of the Salmonella epidemic, the live attenuated vaccine plays a very important role. To prevent and control the epidemic of S. Dublin in cattle farms, the development of more effective vaccines is necessary. In this study, we constructed two gene deletion mutants, Sdu189ΔspiC and Sdu189ΔspiCΔaroA, with the parental strain S. Dublin Sdu189. The immunogenicity and protective efficacy were evaluated in the mice model. First, both mutant strains were much less virulent than the parental strain, as determined by the 50% lethal dose (LD50) for specific pathogen-free (SPF) 6-week-old female BALB/c mice. Second, the specific IgG antibody level and the expression level of cytokine TNF-α, IFN-γ, IL-4, and IL-18 were increased significantly in the vaccinated mice compared to the control group. In addition, the deletion strains were cleared rapidly from organs of immunized mice within 14 d after immunization, while the parental strain could still be detected in the spleen and liver after 21 d of infection. Compared with the parental strain infected group, no obvious lesions were detected in the liver, spleen, and cecum of the deletion strain vaccinated groups of mice. Immunization with Sdu189ΔspiC and Sdu189ΔspiCΔaroA both provided 100% protection against subsequent challenges with the wild-type Sdu189 strain. These results demonstrated that these two deletion strains showed the potential as live attenuated vaccines against S. Dublin infection. The present study established a foundation for screening a suitable live attenuated Salmonella vaccine.

Application and challenge of bacteriophage in the food protection.

In recent years, foodborne diseases caused by pathogens have been increasing. Therefore, it is essential to control the growth and transmission of pathogens. Bacteriophages (phages) have the potential to play an important role in the biological prevention, control, and treatment of these foodborne diseases due to their favorable advantages. Phages not only effectively inhibit pathogenic bacteria and prolong the shelf life of food, but also possess the advantages of specificity and an absence of chemical residues. Currently, there are many cases of phage applications in agriculture, animal disease prevention and control, food safety, and the treatment of drug-resistant disease. In this review, we summarize the recent research progress on phages against foodborne pathogenic bacteria, including Escherichia coli, Salmonella, Campylobacter, Listeria monocytogenes, Shigella, Vibrio parahaemolyticus, and Staphylococcus aureus. We also discuss the main issues and their corresponding solutions in the application of phages in the food industry. In recent years, although researchers have discovered more phages with potential applications in the food industry, most researchers use these phages based on their host spectrum, and the application environment is mostly in the laboratory. Therefore, the practical application of these phages in different aspects of the food industry may be unsatisfactory and even have some negative effects. Thus, we suggest that before using these phages, it is necessary to identify their specific receptors. Using their specific receptors as the selection basis for their application and combining phages with other phages or phages with traditional antibacterial agents may further improve their safety and application efficiency. Collectively, this review provides a theoretical reference for the basic research and application of phages in the food industry.

Isolation, Characterization, and Application in Poultry Products of a Salmonella-Specific Bacteriophage, S55.

ABSTRACT: Salmonellosis occurs frequently worldwide, causing serious threats to public health. The abuse of antibiotics is increasing antibiotic resistance in bacteria, thereby making the prevention and control of Salmonella more difficult. A phage can help control the spread of bacteria. In this study, the lytic phage S55, whose host bacterium is Salmonella Pullorum, was isolated from fecal samples obtained from poultry farms. This phage belongs to the Siphoviridae and has a polyhedral head and a retraction-free tail. S55 lysed most cells of Salmonella Pullorum (58 of 60 strains, 96.67%) and Salmonella Enteritidis (97 of 104 strains, 93.27%). One-step growth kinetics revealed that the latent period was 10 min, the burst period was 80 min, and the burst size was 40 PFU per cell. The optimal multiplicity of infection was 0.01, and the phage was able to survive at pH values of 4 to 11 and temperatures of 40 to 60°C for 60 min. Complete genome sequence analysis revealed that the S55 genome consists of 42,781 bp (50.28% GC content) and 58 open reading frames, including 25 frames with known or assumed functions without tRNA genes. S55 does not carry genes that encode virulence or resistance factors. At 4 and 25°C, S55 reduced the populations of Salmonella Pullorum and Salmonella Enteritidis on chicken skin surfaces. S55 may be useful as a biological agent for the prevention and control of Salmonella infections.

Epidemic patterns of antimicrobial resistance of Salmonella enterica serovar Gallinarum biovar Pullorum isolates in China during the past half-century.

Pullorum is a chicken-specific systemic disease caused by Salmonella enterica serovar Gallinarum biovar Pullorum (S. Pullorum). This study was carried out to provide basic data for understanding the trends of S. Pullorum. A total of 652 S. Pullorum isolates collected in China during 1962-2019 were examined. Overall, 525 (80.5%) isolates were resistant to at least one antibiotic; 280 (42.9%) isolates resisted 3 or more classes of antibiotics and showed an increasing trend until 2015 and then decreased significantly. The most common multidrug-resistant pattern was ampicillin-tetracycline-nalidixic acid (13.6%). After 2008, 6 classes of antibiotic-resistant strains began to appear, and they have been prevalent ever since. In 2014, a strain resistant to 7 antibiotics (ampicillin-cefazolin-streptomycin-tetracycline-sulphonamides-nalidixic acid-nitrofurantoin) was isolated. The highest antimicrobial resistance was observed for nalidixic acid (71.9%), and the lowest was found for cefotaxime, meropenem, amikacin, gentamicin, fosfomycin, and polymyxin (0%). Our findings monitored the prevalence of the resistance of S. Pullorum during the past half-century in China. Continued surveillance of antimicrobial resistance and the rational use of antimicrobials is necessary and important to control the rapid increase in antimicrobial resistance in S. Pullorum.

The rfbN gene of Salmonella Typhimurium mediates phage adsorption by modulating biosynthesis of lipopolysaccharide.

The study of the interaction mechanism between bacteriophage and host is helpful in promoting development of bacteriophage applications. The mechanism of the interaction with the phage was studied by constructing the rfbN gene deletion and complemented with strains of Salmonella enterica subspecies enterica serovar Typhimurium (Salmonella Typhimurium, S. Typhimurium) D6. The rfbN gene deletion strain could not be lysed by phage S55 and led to a disorder of lipopolysaccharide (LPS) biosynthesis, which changed from the smooth type to rough type. Also, the RfbN protein lacking any of the three-segment amino acid (aa) sequences (90-120 aa, 121-158 aa, and 159-194 aa) produces the same result. Transmission electron microscopy and confocal microscopy assays demonstrated that phage S55 dramatically reduced adsorption to the rfbN deletion strain as compared to the wild strain D6. After co-incubation of the S55 with the purified smooth LPS, D6 could not be lysed, indicating that the smooth LPS binds to the S55 in vitro and then inhibits the cleavage activity of the S55. To sum up, the rfbN gene affects phage adsorption by regulating LPS synthesis. Furthermore, the functioning of the RfbN protein requires the involvement of multiple structures. To the best of our knowledge, this study is the first report of the involvement of the bacterial rfbN gene involved in the phage-adsorption process.

The "fighting wisdom and bravery" of tailed phage and host in the process of adsorption.

In the process of bacteriophage and bacteria struggle, adsorption is the key factor to determine who is the winner. In this paper, the molecular mechanism of tailed bacteriophage recognition and adsorption to host and the strategy of "fighting wisdom and courage" between them are reviewed.

A GntR Family Transcription Factor (VPA1701) for Swarming Motility and Colonization of Vibrio parahaemolyticus.

Motility is important for virulence, biofilm formation, and the environmental adaptation of many bacteria. Vibrio parahaemolyticus (V. parahaemolyticus) contains two flagellar systems that are responsible for motility, and are tightly regulated by transcription regulators and sigma factors. In this study, we identified a novel transcription factor, VPA1701, which regulates the swarming motility of V. parahaemolyticus. The VPA1701 deletion mutant (ΔVPA1701) eliminated the swarming motility on the surface of BHI agar plates and reduced colonization in infant rabbits. RNA-seq assays, confirmed by qRT-PCR, indicated that VPA1701 regulated the expression of lateral flagellar cluster genes. Further analyses revealed that VPA1701 directly binds to the promoter region of the flgBCDEFGHIJKL cluster to regulate the expression of lateral flagellar genes. CalR was originally identified as a repressor for the swarming motility of V. parahaemolyticus, and it was inhibited by calcium. In this study, we found that VPA1701 could inhibit the expression of the calR gene to increase the swarming motility of V. parahaemolyticus. Calcium downregulated the expression of calR, indicating that calcium could increase swarming motility of ΔVPA1701 by inhibiting calR. Thus, this study illustrates how the transcription factor VPA1701 regulates the expression of lateral flagellar genes and calR to control the swarming motility of V. parahaemolyticus.

Role of two-component regulatory systems in the virulence of Streptococcus suis.

Streptococcus suis is an important zoonotic pathogen that causes severe infections and great economic losses worldwide. Understanding how this pathogen senses and responds to environmental signals during the infectious process can offer insight into its pathogenesis and may be helpful in the development of drug targets. Two-component regulatory systems (TCSs) play an essential role in this environmental response. In S. suis, at least 15 groups of TCSs have been predicted. Among them, several have been demonstrated to be involved in virulence and/or stress response. In this review, we discuss the progress in the study of TCSs in S. suis, focusing on the role of these systems in the virulence of this bacterium.