From the Research
Typical E. coli strains are far more prevalent than atypical strains, with typical strains constituting part of the normal gut microbiota and found in approximately 90% of healthy humans. The prevalence of atypical forms, which include pathogenic variants like Shiga toxin-producing E. coli (STEC), enterohemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC), and others, is typically below 5% in developed countries 1. However, their prevalence can vary significantly based on geographic location, sanitation conditions, and exposure to contaminated food or water, with some studies suggesting that atypical EPEC may be associated with prolonged diarrhea 2. In developing regions with limited access to clean water and proper sanitation, the prevalence of pathogenic E. coli strains may reach 20-30% in some populations. The distinction between typical and atypical strains is important clinically, as atypical variants are responsible for various illnesses ranging from mild diarrhea to severe conditions like hemolytic uremic syndrome, while typical strains rarely cause disease unless they reach tissues outside the intestinal tract or affect immunocompromised individuals. Some studies have investigated the prevalence of atypical EPEC and its possible role in causing diarrhea among children, with one study finding that atypical EPEC was diagnosed in 14.7% of patients compared to 10.0% of healthy controls 2. Another study found that atypical EPEC was more closely related to Shiga toxin-producing E. coli (STEC), and like STEC, these strains appear to be emerging pathogens 1. Key factors that influence the prevalence of atypical E. coli strains include:
- Geographic location
- Sanitation conditions
- Exposure to contaminated food or water
- Presence of underlying health conditions
- Age and immune status of the individual It is essential to consider these factors when assessing the risk of atypical E. coli infections and developing strategies for prevention and treatment. Overall, while typical E. coli strains are more prevalent, atypical strains can have significant clinical implications, and their prevalence can vary depending on various factors. The most recent and highest quality study on this topic is from 2022, which found that oral β-lactam antibiotics may be a reasonable step-down treatment option for Enterobacterales bacteremia from a suspected urine source, primarily when alternative options are limited by resistance or adverse effects 3. However, this study did not specifically address the prevalence of atypical E. coli strains. Therefore, the current evidence suggests that typical E. coli strains are more prevalent, but atypical strains can have significant clinical implications, and their prevalence can vary depending on various factors.