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Infection caused by antibiotic-resistant bacteria is serious threat for public health, and calls for novel antibacterial agents with versatile functions. In particular, nanomaterial is one of promising candidates to fight the increasing antibiotic resistance crisis. Here, we synthesized distinct Fe 3 O 4 @MoS 2 @SDS nanocomposites by ultrasonication assisted SDS coating on the Fe 3 O 4 @MoS 2 . Photothermal investigation indicated that the Fe 3 O 4 @MoS 2 @SDS showed excellent and stable photothermal performance and could be a NIR-induced photothermal reagent. It also displayed superior disinfection ability of Escherichia coli (E. coli), Methicillin-resistant Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa (P. aeruginosa) and in vivo wound healing ability with the help of NIR irradiation. According to the results of electron paramagnetic resonance (EPR) and radical capture tests, plenty of superoxide, hydroxyl radicals, singlet oxygen and living cell reactive oxygen species can be observed under NIR irradiation. Besides, the synergistic effect Fe 3 O 4 @MoS 2 @SDS and NIR irradiation eradicated almost all the biofilms of MRSA, so this kind of function enhanced the disinfection ability of Fe 3 O 4 @MoS 2 @SDS under NIR irradiation. Furthermore, its inhibition effect on antibiotic resistance gene dissemination was also investigated. As expected, the Fe 3 O 4 @MoS 2 @SDS could efficiently and broadly block the horizontal transfer of antibiotic resistance genes which mediated by conjugative plasmids, and its blocking effect was better than that we have reported Fe 3 O 4 @MoS 2 . Overall, our findings revealed that the Fe 3 O 4 @MoS 2 @SDS could be a potential candidate for photothermal-photodynamic therapy and antibiotic resistance gene dissemination inhibition., (Copyright © 2022 Elsevier B.V. All rights reserved.)

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., (Copyright (C), International Association for Food Protection.)

Salmonella Enteritidis (SE) are important zoonotic pathogens, and can be easily transferred to humans by contaminated animal products. Epidemic surveys of SE are necessary in current modern large-scale chicken farms. In this study, Salmonella strains were isolated from possibly infected samples collected at 3 independent farms, and their serotype, drug resistances, virulence genes, and genetic similarity were analyzed by molecular genetic analysis technologies including multilocus sequence typing (MLST), clustered regularly interspaced short palindromic repeats (CRISPR), pulsed-field gel electrophoresis (PFGE), and whole-genome sequencing (WGS). A total of 346 Salmonella strains were isolated from 3,598 samples (9.61%); 329 isolates were identified as SE (95.09%) and 308 isolates were multidrug resistant (93.62%). Virulotyping based on 6 virulence genes showed high similarity in SE isolates of each farm, with the exception of 2 isolates. All SE isolates were found to be the same ST11 type by MLST, and 22 strains of 150 SE isolates selected at random were found to belong to 1 cluster by PFGE and the same SET1 type by CRISPR. WGS results further revealed that these isolates belonged to the same clonal cluster, with high genetic similarity of 99.80 to 100.00%. All these results indicated that these SE isolates were overwhelmingly dominant and demonstrated high genetic similarity, which revealed that the same SE clone might be transmitted in these farms., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

In this study, we found that Fe 3 O 4 promoted horizontal gene transfer (HGT), but when Fe 3 O 4 was composited with MoS 2 , the Fe 3 O 4 @MoS 2 nanocomposite interacting with bacteria significantly blocked the HGT in the conjugation system. qPCR was used to analyze the expression of genes belonging to the chromosome and plasmid in the conjugation system. Results demonstrated that Fe 3 O 4 @MoS 2 inhibited conjugation by promoting the expression of the global regulatory gene (trbA) and inhibiting the expression of conjugative transfer genes involved in mating pair formation (traF, trbB), DNA replication (trfA), and porins (outer membrane protein (omp) A and ompC). All of these genes are related to the permeability of the cell membrane, except for trfA. The results showed that Fe 3 O 4 @MoS 2 interacted with bacteria to decrease their permeability against exogenous DNA. MoS 2 may play an essential role in the HGT-inhibiting activity of Fe 3 O 4 @MoS 2 . This study highlights the diverse biological properties of nano-materials and provides clues for nano-scientists to develop environmentally friendly materials., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Nanomaterials of Al 2 O 3 and TiO 2 have been proved to promote the spread of antibiotic resistance genes (ARGs) by horizontal gene transfer. In this work, we found that Fe 2 O 3 @MoS 2 nanocomposite inhibited the horizontal gene transfer (HGT) by inhibiting the conjugative transfer mediated by RP4-7 plasmid. To discover the mechanism of Fe 2 O 3 @MoS 2 inhibiting HGT, the bacterial cells were collected under the optimal mating conditions. The collected bacterial cells were used for analyzing the expression levels of genes unique to the plasmid and the bacterial chromosome in the conjugation system by qPCR. The results of genes expression demonstrated that the mechanism of Fe 2 O 3 @MoS 2 inhibited conjugation by promoting the expression of global regulatory gene (trbA) and inhibiting the expression of conjugative transfer genes involved in mating pair formation (traF, trbB) and DNA replication (trfA). The risk assessment of Fe 2 O 3 @MoS 2 showed that it had very low toxicity to organisms. The findings of this paper showed that Fe 2 O 3 @MoS 2 , as an inhibitor of horizontal gene transfer, is an environment-friendly material., (Copyright © 2019 Elsevier Inc. All rights reserved.)