Kenney, P. | Search bioRxiv

bioRxiv2025

Lytic anti-Staphylococcus aureus phage M963 resensitizes its host to methicillin by a tarS-dependent mechanism

Bacteriophage M963 targeting a clinical strain of methicillin-resistant Staphylococcus aureus (MRSA) was isolated from wastewater. Purification was optimized and the phage was subsequently characterized as a lytic, dsDNA phage within the family Roundtreeviridae and genus Rosenblumvirus. Host range testing against a small library of S. aureus isolates from patients with bacteremia and periprosthetic joint infections showed lytic activity against >60% of tested strains. Evaluation of phage-resistant mutant derivatives of the cognate host showed disruptive mutations within tarS, a gene responsible for modifying wall teichoic acid. tarS products have been proposed as a target of other members of Roundtreeviridae. Synergy testing in MRSA demonstrated phage-antibiotic synergy between M963 and vancomycin, tetracycline, and methicillin. The M963-methicillin synergy prompted testing of the phage-resistant mutant derivatives, showing that phage resistance led to a transient methicillin-susceptible phenotype at clinically relevant minimum inhibitory concentrations in some mutants. Phage M963 is a candidate for compassionate use therapy in appropriate patients. Author SummaryBacteriophages are viruses that kill bacteria. Because of antibiotic resistance, bacteriophages are being used in the treatment of some infections that are resistant to antibiotics or are not improving despite antibiotics. This manuscript describes the discovery of a bacteriophage, named M963, that kills antibiotic resistant Staphylococcus aureus (MRSA). This bacteriophage can kill MRSA from patients with prosthetic joint infections by binding to structures, called wall teichoic acids, on the outside of MRSA. Although the MRSA can evolve to avoid the bacteriophage, this leaves it vulnerable to new antibiotics. By working together with antibiotics, bacteriophage M963 may be a good option for patients with MRSA infections not responding appropriately to standard treatments.

microbiology↗

bioRxiv2019

High accuracy DNA sequencing on a small, scalable platform via electrical detection of single base incorporations

High throughput DNA sequencing technologies have undergone tremendous development over the past decade. Although optical detection-based sequencing has constituted the majority of data output, it requires a large capital investment and aggregation of samples to achieve optimal cost per sample. We have developed a novel electronic detection-based platform capable of accurately detecting single base incorporations. The GenapSys technology with its electronic detection modality allows the system to be compact, accessible, and affordable. We demonstrate the performance of the system by sequencing several different microbial genomes with varying GC content. The platform is capable of generating up to 2 Gb of high-quality nucleic acid sequence in a single run. We routinely generate sequence data that exceeds 99% raw accuracy with read lengths of up to 175 bp. Average quality scores remain above Q30 (99.9% raw sequencing accuracy) beyond 150 bp, with more than 85% of total bases at or above Q30. The utility of the platform is highlighted by targeted sequencing of the human genome. We show high concordance of SNP detection on the human NA12878 HapMap cell line with data generated on the Illumina sequencing platform. In addition, we sequenced a targeted panel of cancer-associated genes in a well characterized reference standard. With multiple library preparation approaches on this sample, we were able to identify low frequency mutations at expected allele frequencies.

genomics↗