ティティアナンパコーン カネート

In response to the escalating antibiotic resistance in multidrug-resistant pathogens, we propose an innovative phagemid-based capsid system to generate CRISPR-Cas13a-loaded antibacterial capsids (AB-capsids) for targeted therapy against multidrug-resistant Staphylococcus aureus. Our optimized phagemid system maximizes AB-capsid yield and purity, showing a positive correlation with phagemid copy number. Notably, an 8.65-fold increase in copy number results in a 2.54-fold rise in AB-capsid generation. Phagemids carrying terL-terS-rinA-rinB (prophage-encoded packaging site genes) consistently exhibit high packaging efficiency, and the generation of AB-capsids using lysogenized hosts with terL-terS deletion resulted in comparatively lower level of wild-type phage contamination, with minimal compromise on AB-capsid yield. These generated AB-capsids selectively eliminate S. aureus strains carrying the target gene while sparing non-target strains. In conclusion, our phagemid-based capsid system stands as a promising avenue for developing sequence-specific bactericidal agents, offering a streamlined approach to combat antibiotic-resistant pathogens within the constraints of efficient production and targeted efficacy.

Phage therapy, the use of bacteriophages (phages) to treat bacterial infections, is regaining momentum as a promising weapon against the rising threat of multidrug-resistant (MDR) bacteria. This comprehensive review explores the historical context, the modern resurgence of phage therapy, and phage-facilitated advancements in medical and technological fields. It details the mechanisms of action and applications of phages in treating MDR bacterial infections, particularly those associated with biofilms and intracellular pathogens. The review further highlights innovative uses of phages in vaccine development, cancer therapy, and as gene delivery vectors. Despite its targeted and efficient approach, phage therapy faces challenges related to phage stability, immune response, and regulatory approval. By examining these areas in detail, this review underscores the immense potential and remaining hurdles in integrating phage-based therapies into modern medical practices.

In response to the escalating global threat of antimicrobial resistance, our laboratory has established a phagemid packaging system for the generation of CRISPR-Cas13a-antimicrobial capsids targeting methicillin-resistant Staphylococcus aureus (MRSA). However, a significant challenge arose during the packaging process: the unintentional production of wild-type phages alongside the antimicrobial capsids. To address this issue, the phagemid packaging system was optimized by strategically incorporated silent mutations. This approach effectively minimized contamination risks without compromising packaging efficiency. The study identified the indispensable role of phage packaging genes, particularly terL-terS, in efficient phagemid packaging. Additionally, the elimination of homologous sequences between the phagemid and wild-type phage genome was crucial in preventing wild-type phage contamination. The optimized phagemid-LSAB(mosaic) demonstrated sequence-specific killing, efficiently eliminating MRSA strains carrying target antibiotic-resistant genes. While acknowledging the need for further exploration across bacterial species and in vivo validation, this refined phagemid packaging system offers a valuable advancement in the development of CRISPR-Cas13a-based antimicrobials, shedding light on potential solutions in the ongoing battle against bacterial infections.

Non-menstrual toxic shock syndrome (non-mTSS) is a life-threatening disease caused by <italic>Staphylococcus aureus</italic> strains producing superantigens, such as staphylococcal enterotoxins A, B, C, and toxic shock syndrome toxin-1 (TSST-1). However, little is known about why the TSS cases are rare, although <italic>S. aureus</italic> strains frequently carry a <italic>tst</italic> gene, which encodes TSST-1. To answer this question, the amount of TSST-1 produced by 541 clinical isolates was measured in both the presence and absence of serum supplementation to growth media. Then a set of <italic>S. aureus</italic> strains with similar genetic backgrounds isolated from patients presenting with non-mTSS and those with clinical manifestations other than non-mTSS was compared for their TSST-1 inducibility by human serum, and their whole-genome sequences were determined. Subsequently, the association of mutations identified in the <italic>tst</italic> promoter of non-mTSS strains with TSST-1 inducibility by human serum was evaluated by constructing promoter replacement mutants and green fluorescent protein (GFP) reporter recombinants. Results showed that 39 out of 541 clinical isolates (7.2%), including strains isolated from non-mTSS patients, had enhanced production of TSST-1 in the presence of serum. TSST-1 inducibility by human serum was more clearly seen in non-mTSS strains of clonal complex (CC)-5. Moreover, the whole-genome sequence analysis identified a set of sequence variations at a putative SarA-binding site of the <italic>tst</italic> promoter. This sequence variation was proven to be partially responsible for the induction of TSST-1 production by human serum. We conclude that the onset of staphylococcal toxic shock syndrome caused by TSST-1-producing CC-5 strains seem at least partially initiated by serum induction of TSST-1, which is regulated by the mutation of putative SarA-binding site at the <italic>tst</italic> promoter.

<title>Abstract</title><italic>Staphylococcus aureus </italic>strains that are susceptible to the β-lactam antibiotic oxacillin despite carrying <italic>mecA </italic>(OS-MRSA) cause serious clinical problems globally because of their ability to easily acquire β-lactam resistance. Understanding the genetic mechanism(s) of acquisition of the resistance is therefore crucial for infection control management. For this purpose, a whole-genome sequencing-based analysis was performed using 43 clinical OS-MRSA strains and 100 mutants with reduced susceptibility to oxacillin (MICs 1.0–256 µg/mL) generated from 26 representative OS-MRSA strains. Genome comparison between the mutants and their respective parent strains identified a total of 141 mutations in 46 genes and 8 intergenic regions. Among them, the mutations are frequently found in genes related to RNA polymerase (<italic>rpoBC</italic>), purine biosynthesis (<italic>guaA, prs, hprT</italic>), (p)ppGpp synthesis (<italic>rel</italic>_{<italic>Sau</italic>}), glycolysis (<italic>pykA, fbaA, fruB</italic>), protein quality control (<italic>clpXP, ftsH</italic>), and tRNA synthase (<italic>lysS, gltX</italic>), whereas no mutations existed in <italic>mec </italic>and <italic>bla </italic>operons. Whole-genome transcriptional profile of the resistant mutants demonstrated that expression of genes associated with purine biosynthesis, protein quality control, and tRNA synthesis were significantly inhibited similar to the massive transcription downregulation seen in <italic>S. aureus </italic>during the stringent response, while the levels of <italic>mecA </italic>expression and PBP2a production were varied. We conclude that a combination effect of <italic>mecA</italic> upregulation and stringent-like response may play an important role in acquisition of β-lactam resistance in OS-MRSA.

The association of Panton-Valentine leukocidin (PVL) toxin with necrotizing soft tissue infection (NSTI) caused by <named-content content-type="genus-species">Staphylococcus aureus</named-content> remains controversial. Here, we report the complete genome sequence of the PVL-negative <named-content content-type="genus-species">S. aureus</named-content> strain JMUB1273, isolated from a patient with pervasive NSTI.