Escherichia coli (E. coli) is a diverse group of bacteria commonly found in the intestines of humans and warm-blooded animals. Most strains are harmless and are a normal part of a healthy intestinal tract, aiding in digestion and producing vitamin K. However, some strains are pathogenic and can cause a variety of illnesses, including food poisoning, urinary tract infections, and bloodstream infections.
Pathogenic E. coli strains are often categorized by their mechanisms of pathogenicity, with Shiga toxin-producing E. coli (STEC) being a significant concern due to the potent Shiga toxins they produce. STEC infections can result from consuming contaminated food, such as raw or undercooked meat, raw milk, and contaminated produce. Symptoms can range from mild diarrhea to severe bloody diarrhea and abdominal cramps, and in some cases, may lead to hemolytic uremic syndrome (HUS), a life-threatening condition that can cause kidney failure. A recent CDC study indicates that invasive E. coli infections are a growing problem in the United States and are becoming harder to treat. New research also indicates that some E. coli strains can spread as quickly as the swine flu.
E. coli's adaptability and ability to acquire resistance to multiple antibiotics are also areas of ongoing research. Scientists are working to understand how E. coli spreads and adapts in different environments, with recent findings challenging the idea that E. coli survives equally everywhere. Research has shown that E. coli populations carry distinct genomic signatures depending on the host species and ecology from which they are isolated. Moreover, some E. coli strains can form biofilms, dense bacterial clusters that can withstand antibiotics, even if the individual bacteria are not genetically resistant.
