In the battle against drug-resistant pathogens, genetic research holds promising answers to our toughest threats. A new study
shows that the best tool for treating Clostridium difficile
infections could be within the genome of the bacteria itself.
Researchers at the University of Texas Health Science Center and the Graduate School of Biomedical Sciences in Houston have uncovered an important new finding to learn just how the C. difficile
bacteria produces toxins, offering some new direction for the development of nonantibiotic drugs to fight dangerous C. difficile
The bacteria are one of the more virulent and widespread drug-resistant pathogens responsible for healthcare associated infections around the world, costing acute care facilities nearly $4.8 billion dollars a year in excess healthcare costs in the United States. CDIs are linked to the use of broad spectrum antibiotics, which when used to treat infections can also suppress the beneficial bacteria that live in our guts and protect us from infections. When that intestinal microflora is compromised, individuals become more susceptible to CDIs when exposed to C. difficile
bacteria on contaminated surfaces or other individuals who are carrying the bacteria.
works by producing two toxins, toxin A and toxin B, that cause life-threatening diarrhea as well as pseudomembranous colitis, toxic megacolon, perforations in the colon, sepsis and rarely death. According to a 2015 study
from the Centers for Disease Control and Prevention (CDC), there are nearly half a million CDIs in the United States each year, and about 15,000 of those cases result in deaths. The CDC considers C. difficile
a public threat needing urgent and aggressive action.
The authors of the new study from the University of Texas have uncovered just how C. difficile
produces the toxins A and B that are responsible for causing disease. They studied several strains of the bacteria and found that some encode two Agr loci in their genomes, designated agr1
. The agr1
locus is present in all of the C. difficile
strains sequenced to date, whereas the agr2
locus is present in a few strains. Until recently, the function of these loci were not known. To understand their roles in toxin regulation and pathogenesis, the researchers used allelic exchange to delete components of agr1
and then examined the mutants for toxin production. In their results, they found that the agr1
mutant cannot produce toxins A and B – in their model the mutant was able to colonize but could not produce disease.