Selective bacteriophages reduce the emergence of resistant bacteria in bacteriophage-antibiotic combination therapy.

Escherichia coli O157:H7 is a globally important foodborne pathogen with implications for food safety. Antibiotic treatment for O157 may potentially contribute to the exacerbation of hemolytic uremic syndrome, and the increasing prevalence of antibiotic-resistant strains necessitates the development of new treatment strategies. In this study, the bactericidal effects and resistance development of antibiotic and bacteriophage monotherapy were compared with those of combination therapy against O157. Experiments involving continuous exposure of O157 to phages and antibiotics, along with genetic deletion studies, revealed that the deletion of glpT and uhpT significantly increased resistance to fosfomycin. Furthermore, we found that OmpC functions as a receptor for the PP01 phage, which infects O157, and FhuA functions as a receptor for the newly isolated SP15 phage, targeting O157. In the glpT and uhpT deletion mutants, additional deletion in ompC, the receptor for the PP01 phage, increased resistance to fosfomycin. These findings suggest that specific phages may contribute to antibiotic resistance by selecting the emergence of gene mutations responsible for both phage and antibiotic resistance. While combination therapy with phages and antibiotics holds promise for the treatment of bacterial infections, careful consideration of phage selection is necessary.IMPORTANCEThe combination treatment of fosfomycin and bacteriophages against Escherichia coli O157 demonstrated superior bactericidal efficacy compared to monotherapy, effectively suppressing the emergence of resistance. However, mutations selected by phage PP01 led to enhanced resistance not only to the phage but also to fosfomycin. These findings underscore the importance of exercising caution in selecting phages for combination therapy, as resistance selected by specific phages may increase the risk of developing antibiotic resistance.

Synthetic phage-based approach for sensitive and specific detection of Escherichia coli O157.

Escherichia coli O157 can cause foodborne outbreaks, with infection leading to severe disease such as hemolytic-uremic syndrome. Although phage-based detection methods for E. coli O157 are being explored, research on their specificity with clinical isolates is lacking. Here, we describe an in vitro assembly-based synthesis of vB_Eco4M-7, an O157 antigen-specific phage with a 68-kb genome, and its use as a proof of concept for E. coli O157 detection. Linking the detection tag to the C-terminus of the tail fiber protein, gp27 produces the greatest detection sensitivity of the 20 insertions sites tested. The constructed phage detects all 53 diverse clinical isolates of E. coli O157, clearly distinguishing them from 35 clinical isolates of non-O157 Shiga toxin-producing E. coli. Our efficient phage synthesis methods can be applied to other pathogenic bacteria for a variety of applications, including phage-based detection and phage therapy.

Harnessing a T1 Phage-Derived Spanin for Developing Phage-Based Antimicrobial Development.

The global increase in the prevalence of drug-resistant bacteria has necessitated the development of alternative treatments that do not rely on conventional antimicrobial agents. Using bacteriophage-derived lytic enzymes in antibacterial therapy shows promise; however, a thorough comparison and evaluation of their bactericidal efficacy are lacking. This study aimed to compare and investigate the bactericidal activity and spectrum of such lytic enzymes, with the goal of harnessing them for antibacterial therapy. First, we examined the bactericidal activity of spanins, endolysins, and holins derived from 2 Escherichia coli model phages, T1 and T7. Among these, T1-spanin exhibited the highest bactericidal activity against E. coli. Subsequently, we expressed T1-spanin within bacterial cells and assessed its bactericidal activity. T1-spanin showed potent bactericidal activity against all clinical isolates tested, including bacterial strains of 111 E. coli, 2 Acinetobacter spp., 3 Klebsiella spp., and 3 Pseudomonas aeruginosa. In contrast, T1 phage-derived endolysin showed bactericidal activity against E. coli and P. aeruginosa, yet its efficacy against other bacteria was inferior to that of T1-spanin. Finally, we developed a phage-based technology to introduce the T1-spanin gene into target bacteria. The synthesized non-proliferative phage exhibited strong antibacterial activity against the targeted bacteria. The potent bactericidal activity exhibited by spanins, combined with the novel phage synthetic technology, holds promise for the development of innovative antimicrobial agents.

The human microbiome and COVID-19: A systematic review.

BACKGROUND: Human microbiotas are communities of microorganisms living in symbiosis with humans. They play an important role in the host immune response to respiratory viral infection. However, evidence on the human microbiome and coronavirus disease (COVID-19) relationship is insufficient. The aim of this systematic literature review was to evaluate existing evidence on the association between the microbiome and COVID-19 in humans and summarize these data in the pandemic era. METHODS: We conducted a systematic literature review on the association between the microbiome and COVID-19 in humans by searching PubMed, Embase, and the Cochrane Library, CINAHL, and Web of Science databases for articles in English published up to October 31, 2020. The results were analyzed qualitatively. This study is registered with PROSPERO (CRD42020195982). RESULTS: Of the 543 articles identified by searching databases, 16 in line with the research objectives were eligible for qualitative review: eight sampled the microbiome using stool, four using nasopharyngeal or throat swab, three using bronchoalveolar lavage fluid, and one using lung tissue. Fecal microbiome dysbiosis and increased opportunistic pathogens were reported in COVID-19 patients. Several studies suggested the dysbiosis in the lung microbiome of COVID-19 patients with an abundance of opportunistic pathogens using lower respiratory tract samples. The association between COVID-19 severity and the human microbiome remains uncertain. CONCLUSION: The human fecal and respiratory tract microbiome changed in COVID-19 patients with opportunistic pathogen abundance. Further research to elucidate the effect of alternation of the human microbiome in disease pathogenesis is warranted.