Increased antimicrobial resistance requires effective ways to overcome the global challenge of bacterial infections, including methicillin-resistant Staphylococcus aureus (MRSA). From the emergence of MRSA to its continued evolution, it is important to explore this pathogen from fresh perspectives and develop corresponding coping strategies to counter its growing threat. New coping strategies are continuously emerging, including but not limited to enhancing penetration capabilities or targeting their virulence. This review summarizes the epidemiological characteristics, drug resistance mechanisms, and therapeutic strategies of MRSA that have emerged over the past fifteen years. The focus of this paper is to explore the promising applications and current limitations of novel MRSA control strategies. This review serves as a key resource for treating MRSA infections and discussing novel strategies to overcome bacterial drug resistance.

Although tigecycline is strictly restricted for use in animals, plasmid-mediated tet (X) is increasingly being detected in swine and poultry production, which may be associated with the highly intensive farming model and the use of antibiotics as feed additives. Escherichia coli , as one of the important reservoirs of tet (X), has attracted worldwide attention due to the complex plasmid background and the diversified mobile genetic elements (MGEs). This study isolated nine tet (X)-positive E. coli belonging to a novel sequence type (ST), ST3871, from a commercial swine farm in Hebei, China. Phylogenetic analysis and pulsed-field gel electrophoresis (PFGE) demonstrated that clonal transmission drove the farm-level prevalence of these strains. The ST3871 tet (X)-positive E. coli exhibited resistance to multiple antibiotics and carried various resistance genes. Whole-genome sequencing (WGS) and southern blotting confirmed that these strains carried the plasmid-mediated tet (X4) gene. Conjugation assays revealed that tet (X4)-positive plasmids could be transferred into E. coli and Salmonella . Although the limited sampling range of this study limits further epidemic analysis, the emergence of tet (X)-mediated tigecycline resistance in a novel ST of E. coli undeniably confirms that the tet (X) gene has resided in a wide variety of ST clones, highlighting the significant contribution of E. coli to the dissemination of tet (X). IMPORTANCE: E. coli carrying tet (X) has spread globally, with the most extensive distribution observed in Asia. This study revealed the prevalence of a novel ST3871 E. coli carrying the plasmid-mediated tet (X4) gene on a commercial swine farm in Hebei, China, indicating that the tet (X) gene, particularly plasmid-mediated tet (X), has been distributed across a wide variety of E. coli ST clones. This undoubtedly poses a threat to public health, necessitating comprehensive strategies and continuous monitoring to control it.

Reverse transcription–quantitative real-time polymerase chain reaction (RT-qPCR) is widely used to accurately assess target gene expression. Evaluating gene expression requires the selection of appropriate reference genes. To identify reliable reference genes for Toxoplasma gondii (T. gondii) under varying concentrations of broxaldine (BRO), we employed the ΔCt method, BestKeeper, NormFinder, GeNorm, and the comprehensive web-based platform RefFinder to assess the expression stability of ten candidate reference genes in T. gondii. Herein, our findings reveal that the stability of these candidate reference genes is influenced by different experimental conditions. Under normal conditions, the most stable genes were TGME49_205470 and TGME49_226020. However, the most stable genes differed when BRO concentrations were at 1, 2, and 4 μg/mL. Across all samples, TGME49_247220 and TGME49_235930 were identified as the most stable reference genes. Moreover, we also confirmed the stability of TGME49_247220 and TGME49_235930 as reference genes through RT-qPCR assays. The present study provides a foundation for applying the RT-qPCR method to investigate target gene expression following BRO treatment in T. gondii.

This study developed a novel analytical method integrating liquid-liquid extraction with solid-phase extraction for simultaneous detection of oxyclozanide (OXY) and levamisole hydrochloride (LMS) residues in milk using ultra-high-performance liquid chromatography tandem MS (UPLC-MS/MS). Method validation demonstrated exceptional sensitivity with detection limits of 1.00 ng/mL and quantitation limits of 3.00 ng/mL for both analytes. Low matrix effects (CV <8.00%) and satisfactory recoveries (OXY: 84.00%-108.77%, relative SD [RSD]: 2.20%-8.00%; LMS: 89.50%-119.60%, RSD: 2.10%-8.36%) were achieved across multiple validation parameters, while sample stability remained consistent under varied processing conditions (CV <10.00%). Analysis of 120 commercial milk samples revealed no detectable residues, confirming both the reliability of this monitoring framework and the compliance of Chinese dairy products with international safety standards. As the first reported method enabling concurrent detection of this antiparasitic drug combination, the established protocol provides crucial technical support for veterinary drug residue surveillance, ensuring safer application of compound oxyclozanide suspension in livestock husbandry.

The coexistence of antibiotic resistance genes (ARGs), particularly those conferring resistance to last-resort antibiotics, is increasingly present in lesser-studied bacterial species. Tigecycline is currently one of the last important barriers in the treatment of carbapenem-resistant bacterial infections, whose resistance gene, tet(X), is prevalent across multiple bacterial genera, but the coexistence of tet(X3) and tet(X4) in Acinetobacter sp. is rarely observed. Here, we report a strain co-harboring the chromosomal tet(X3) and plasmid-borne tet(X4) isolated from a commercial beef cattle farm in Henan province, China. The strain exhibited resistance to ampicillin, gentamicin, chloramphenicol, sulfamethoxazole, tetracycline, doxycycline, tigecycline, and omadacycline. Based on whole-genome sequencing (WGS), the strain was identified as A. indicus using Average Nucleotide Identity (ANI) and digital DNA–DNA hybridization (dDDH). Chromosomal tet(X3) was identified in the genetic context, ISVsa3-XerD-tet(X3)-res-ISVsa3. The plasmid-located tet(X4) with the genetic context, ISVsa3-abh-tet(X4)-ISVsa3, and 14 additional resistance genes were located in multiple pdif modules. Two different typing methods, the Rep-based strategy (designed for A. baumanii) and MOB-typer, identified the tet(X4)-positive plasmid as GR31 and rep_cluster_1656, respectively. Conjugation assay failed to observe the transfer of the tet(X4)-positive plasmid into recipients, E. coli J53 and Salmonella LGJ2. The co-occurrence of tet(X3) and tet(X4) in Acinetobacter may suggest a risk of rapid dissemination of tigecycline resistance and the hidden presence of numerous undetected bacteria co-carrying high-risk ARGs in the agroecological system, both of which should cause particular concern.