Research by Oscar G. Gomez, MD, PhD, on a specific strain of Shiga-toxin E. coli (STEC) could expand the understanding of STEC infections. 

Gomez Completes Genomic Analysis of Shiga-Toxin E-Coli

Published November 2, 2020

Oscar G. Gomez, MD, PhD, associate professor of pediatrics and chief of the Division of Infectious Diseases, has completed the genomic analysis of a specific strain of Shiga-toxin E. coli (STEC) that can cause severe disease outbreaks and is increasingly common. 

“The findings reveal how this emerging STEC causes severe disease and that it may be as virulent, or even more virulent, than more common STEC strains, leading to severe and even deadly disease in susceptible hosts. ”
Associate professor of pediatrics and chief of the Division of Infectious Diseases
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The research could play a role in expanding the understanding of STEC infections and, potentially, in developing vaccines against them.

265,000 Infections Per Year in US From STEC

Shown is an electron micrograph of E. coli pathogens obtained in the laboratory of Oscar G. Gomez, MD, PhD.

Foodborne pathogens are very common and usually benign, but certain virulent strains of pathogens can result in severe disease and even death. Distinguishing specific strains of pathogens can help scientists better understand them and develop biomarkers to help detect them in patients, expediting diagnosis and treatment.

According to the Centers for Disease Control and Prevention, STEC are estimated to cause more than 265,000 infections per year in the U.S., and are associated with more than 3,600 hospitalizations and approximately 30 deaths.

Paper Describes Severe Illness of Tennessee Child

Published in BMC Genomics, the paper describes the genomic analysis completed on a unique STEC strain isolated from an otherwise healthy 2 ½-year-old child living in Davidson County, Tennessee. 

The pathogen caused severe illness, including hemolytic uremic syndrome, a condition that destroys red blood cells, lowers platelets and blocks blood vessels in kidneys, resulting in anemia and kidney damage.

The child survived, but was hospitalized for a month and sustained severe complications affecting multiple organ systems, including the lungs, heart, kidneys, brain, circulatory system and gastrointestinal tract.

Many Strains Cause Gastrointestinal Disease

The Shiga-toxin producing E. coli the child was infected with is a non-0157 STEC. While the pathogens classified as 0157 STEC infections generally are more common and result in more severe disease, the number of emerging, non-0157 STEC pathogens has been on the increase. Some lead to severe disease, creating a growing public health concern, according to the researchers.

The paper states that there are more than 400 of these non-0157 STEC strains, and more than a quarter are reported to cause gastrointestinal disease, often presenting first as bloody diarrhea with hemolytic uremic syndrome and if untreated, in rare cases, death.

The specific pathogen the child was infected with was STEC 0145:H25. 

“Since genomic studies on emerging non-0157 STEC are limited, our studies are significant because they reveal the genetic makeup of emergent STEC 0145:H25 in comparison with other STEC strains,” says Gomez, corresponding author on the paper.

“The findings reveal how this emerging STEC causes severe disease and that it may be as virulent, or even more virulent, than more common STEC strains, leading to severe and even deadly disease in susceptible hosts,” adds Gomez, who is also a pediatrician with UBMD Pediatrics. “It also provides information on how this potentially preventable infection continues to affect vulnerable individuals.”

Collaborative Effort Between Pediatrics, CBLS

A key finding of the study was that this 0145:H25 serotype leads to particularly severe infection, according to Gomez. Moreover, in addition to carrying virulence genes present in 0157 STEC, it has additional genes and new potential virulence genes as compared to other non-0157 strains that have been studied. 

“These findings deserve further analysis to understand the pathogenesis of these emergent STEC infections,” Gomez says.

The analysis was conducted through a collaboration between the Department of Pediatrics researchers and colleagues at UB’s New York State Center of Excellence in Bioinformatics and Life Sciences (CBLS), whose expertise in bioinformatics and whole genome sequencing analysis allowed the team to uncover the genetic information critical to understanding where these strains are derived from and how they may be traced to unique reservoirs, such as contaminated food products or infected livestock.

Expert in Childhood Gastrointestinal Diseases

Gomez is an expert in childhood infectious gastrointestinal diseases. He established a global health research program, the International Enteric Vaccines Research Program (IEVRP), dedicated to studying the epidemiology, pathogenesis and vaccine development of childhood gastrointestinal infections within the U.S. and abroad. He has also conducted vaccine development research for pediatric infectious diseases.

Julio A. Guerra, MPH, research scientist in the Department of Pediatrics, is a co-author.

Co-authors from the CBLS are:

  • Jonathan E. Bard, associate director of bioinformatics
  • Donald Yergeau, PhD, associate director of genomic technologies

Natasha B. Halasa, MD, MPH; and Chengxian Zhang, PhD, DVM; from Vanderbilt University School of Medicine are other co-authors.