Biology subjects

Schooley, R. T.

Publications and source records attributed to Schooley, R. T..

4 recordsLinked to original sources

bioRxiv2024

In-vitro resensitization of multidrug resistant clinical isolates of Enterococcus faecium and faecalis through phage-antibiotic synergy

Bacteriophages are an increasingly attractive option for the treatment of antibiotic resistant infections, but their efficacy is difficult to discern due to confounding effects of antibiotics. Phages are generally delivered in conjunction with antibiotics, and thus, when patients improve its unclear whether the phages, antibiotics or both are responsible. This question is particularly relevant for enterococcus infections, as limited data suggest phages might restore antibiotic efficacy against resistant strains. Enterococci can develop high-level resistance to vancomycin, a primary treatment. We assessed clinical and laboratory isolates of Enterococcus faecium and Enterococcus faecalis to determine whether we could observe synergistic interactions between phages and antibiotics. We identified synergy between multiple phages and antibiotics including linezolid, ampicillin, and vancomycin. Notably, antibiotic susceptibility did not predict synergistic interactions with phages. Vancomycin resistant isolates (n=6) were eradicated by the vancomycin-phage combination as effectively as vancomycin susceptible isolates (n=2). Transcriptome analysis revealed significant gene expression changes under antibiotic-phage conditions, especially for linezolid and vancomycin, with upregulated genes involved in nucleotide and protein biosynthesis and downregulated stress response and prophage-related genes. While our results do not conclusively determine the etiology of the observed synergistic interactions between antibiotics and phages, they do confirm and build upon previous research that observed these synergistic interactions. Our work highlights how using phages can restore the effectiveness of vancomycin against resistant isolates. This finding provides a promising, although unexpected, strategy for moving forward with phage treatments for Vancomycin Resistant Enterococcus infections.

microbiology↗

bioRxiv2022

Diversified repertoire of phage defenses in Klebsiella pneumoniae: Bi-directional steering effects impacting antibiotic susceptibility

Bacteriophage (phage) therapy is rising as a promising anti-infective option to combat antimicrobial resistance; however, its clinical utilization is severely hindered by the potential emergence of phage resistance. Fortunately, certain phage resistance mechanisms can restore bacterial antibiotic susceptibility, making the combination of phages with antibiotics a potential strategic approach. Here, we demonstrated that phage resistance can also lead to increased antibiotic resistance and provided mechanistic insights into bacterial phage defense mechanisms. We discovered a repertoire of phage resistance mechanisms in Klebsiella pneumoniae, including the disruption of phage binding site (fhuA::Tn and tonB::Tn), extension of phage latent period (mnmE::Tn and rpoN::Tn) and increased mutation frequency (mutS::Tn and mutL::Tn). Different from the prevailing view that phage resistance re-sensitizes antibiotic-resistant bacteria, we revealed a bidirectional steering effect on the bacterial antibiotic susceptibility. Specifically, it was uncovered that, while rpoN::Tn became more susceptible to colistin, mutS::Tn and mutL::Tn caused increased resistance to rifampicin and colistin. Our findings highlight the diversified strategies utilized by K. pneumoniae to overcome phage infection and the parallel effect on the antibiotic susceptibility. Mechanism-guided phage steering represents a rational strategy that should be incorporated into phage therapy to better inform clinical decisions.

microbiology↗

bioRxiv2021

Clinical Phage Microbiology:A suggested framework and recommendations for the in-vitro matching steps ‎of phage therapy

Personalized-phage-therapy is a promising solution for the emerging crisis of bacterial infections that fail to be eradicated by conventional antibiotics. One of the most crucial elements of personalized-phage-therapy is the proper matching of phages and antibiotics to the target bacteria in a given clinical setting. However, to date, there is no consensus guideline for laboratory procedures that enable in vitro evaluation of phages intended for treatment. In this work, we suggest a framework and strategies identify appropriate phages and combine them with antibiotics in clinical microbiology laboratories. This framework, which we term here "Clinical Phage Microbiology" is based on our experience and other previously reported cases of both, successful and failed phage treatments. Additionally, we discuss troubleshooting methodologies for possible pitfalls and special cases that may need to be assessed before treatment including interactions with the host immune system, biofilms, and polymicrobial infections. We believe that the "Clinical Phage Microbiology" pipeline presented here should serve as the basis for standardization of laboratory protocols to match phages for personalized therapy.

microbiology↗

bioRxiv2020

Rethinking Remdesivir: Synthesis of Lipid Prodrugs that Substantially Enhance Anti-Coronavirus Activity

Remdesivir (RDV, GS-5734) is currently the only FDA-approved antiviral drug for the treatment of SARS CoV-2 infection. The drug is approved for use in adults or children 12-years or older who are hospitalized for the treatment of COVID-19 on the basis of an acceleration of clinical recovery for inpatients with this disease. Unfortunately, the drug must be administered intravenously, restricting its use to those requiring hospitalization for relatively advanced disease. RDV is also unstable in plasma and has a complex activation pathway which may contribute to its highly variable antiviral efficacy in SARS-CoV-2 infected cells. Potent orally bioavailable antiviral drugs for early treatment of SARS-CoV-2 infection are urgently needed and several including molnupiravir and PF-07321332 are currently in clinical development. We focused on making simple, orally bioavailable lipid analogs of Remdesivir nucleoside (RVn, GS-441524) that are processed to RVn-monophosphate, the precursor of the active RVn-triphosphate, by a single-step intracellular cleavage. In addition to high oral bioavailability, stability in plasma and simpler metabolic activation, new oral lipid prodrugs of RVn had submicromolar anti-SARS-CoV-2 activity in a variety of cell types including Vero E6, Calu-3, Caco-2, human pluripotent stem cell (PSC)-derived lung cells and Huh7.5 cells. In Syrian hamsters oral treatment with ODBG-P-RVn was well tolerated and achieved therapeutic levels in plasma above the EC90 for SARS-CoV-2. The results suggest further evaluation as an early oral treatment for SARS-CoV-2 infection to minimize severe disease and reduce hospitalizations.

microbiology↗