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Emerging Threat: Insights into Antibiotic-Resistant Infections from Houston Researchers

A troubling rise in severe invasive infections resistant to essential antibiotics has prompted a team of infectious disease specialists at the Houston Methodist Research Institute to investigate a new strain of bacteria known as Streptococcus dysgalactiae subspecies equisimilis (SDSE). This bacterium can infect humans through the skin, throat, gastrointestinal tract, and female genital tract, leading to a spectrum of illnesses that range from strep throat (pharyngitis) to the life-threatening condition of necrotizing fasciitis, commonly referred to as flesh-eating disease.

Although closely related to the well-studied group A streptococcus, or Streptococcus pyogenes, there remains a significant gap in understanding the biology and pathogenic mechanisms of SDSE.

The results of this investigation are detailed in a paper titled “Integrative genomic, virulence, and transcriptomic analysis of emergent Streptococcus dysgalactiae subspecies equisimilis (SDSE) emm type stG62647 isolates causing human infections,” published on October 17 in the journal mBio, which is affiliated with the American Society for Microbiology and the American Academy of Microbiology. The corresponding author for the study is James M. Musser, M.D., Ph.D., who chairs the Department of Pathology and Genomic Medicine at Houston Methodist.

“It is notable that despite the pressing public health implications of SDSE, we have a limited grasp of its molecular pathogenesis,” stated Jesus M. Eraso, Ph.D., the lead author and assistant research professor in pathology and genomic medicine at Houston Methodist.

To elucidate this gap in knowledge, the research team employed a comprehensive integrative strategy to analyze 120 human isolates of a specific SDSE subtype, known as stG62647. Their research included an examination of the genome—where the organism’s DNA information is encoded—its transcriptome—which serves as a snapshot of the gene expression levels at the time of cell collection—and the virulence which indicates the extent of damage inflicted on the host. The peculiar severity of infections associated with the stG62647 strain underscores the importance of this research, as discerning the interactions among these three components enriches the understanding of the disease mechanisms involved.

The findings from this integrative analysis have provided valuable insights into this prominent emerging bacterial threat, offering potential implications for vaccine development. Moreover, the study has given rise to numerous new questions and hypotheses that will guide ongoing research efforts.

In addition to Musser and Eraso, the research team included collaborators Randall J. Olsen, S. Wesley Long, and Ryan Gadd from the Center for Infectious Diseases at the Houston Methodist Research Institute, as well as Sarrah Boukthir, Ahmad Faili, and Samer Kayal from Université Rennes in France.

This research received partial funding from the Fondren Foundation, highlighting the collaborative efforts aimed at addressing the challenges posed by antibiotic-resistant infections.

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