From the Guidelines
E. coli is normally present in the human gut as part of the healthy intestinal microbiome, but elevated levels can indicate a pathological condition, such as dysbiosis, intestinal inflammation, or infection, as suggested by the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.
Normal Presence of E. coli
E. coli typically resides in the large intestine and colon where it contributes to normal digestive function and helps prevent colonization by pathogenic bacteria. The guidelines do not specifically address the normal presence of E. coli, but they do provide information on the diagnosis and management of infectious diarrhea, which can be caused by certain strains of E. coli.
Pathological Conditions
High concentrations of E. coli may suggest dysbiosis, intestinal inflammation, or infection. Certain strains of E. coli can become pathogenic, causing conditions like urinary tract infections, diarrhea, or more serious illnesses such as hemorrhagic colitis. The guidelines recommend laboratory diagnostics, including culture for E. coli O157:H7 and Shiga toxin immunoassay or NAAT for Shiga toxin genes, to identify specific pathogenic strains 1.
Diagnosis and Treatment
Diagnosis of problematic E. coli typically involves stool cultures, PCR testing, or other laboratory methods that can identify specific pathogenic strains. Treatment depends on the location and severity of infection, often involving antibiotics, though antibiotic resistance is increasingly common. The guidelines provide information on the diagnosis and management of infectious diarrhea, including the use of nucleic acid amplification tests (NAAT) and specialized stool culture or molecular assays to detect E. coli and other pathogens 1.
Key Points
- E. coli is normally present in the human gut as part of the healthy intestinal microbiome.
- Elevated levels of E. coli can indicate a pathological condition, such as dysbiosis, intestinal inflammation, or infection.
- Certain strains of E. coli can become pathogenic, causing conditions like urinary tract infections, diarrhea, or more serious illnesses such as hemorrhagic colitis.
- Diagnosis of problematic E. coli typically involves stool cultures, PCR testing, or other laboratory methods that can identify specific pathogenic strains.
- Treatment depends on the location and severity of infection, often involving antibiotics, though antibiotic resistance is increasingly common.
From the Research
Presence of E. coli in the GI Tract
- E. coli is a resident of the normal intestinal microbiota [(2,3,4,5,6)].
- It is commonly found in the intestinal flora of humans and animals 3.
Pathological Conditions Associated with E. coli
- Certain strains of E. coli can cause diseases in humans, including intestinal infections (diarrhea, dysentery) and extraintestinal infections (urinary tract infections, respiratory tract infections, meningitis, sepsis) [(2,3,4,5,6)].
- Elevated levels of E. coli can indicate a pathological condition, such as diarrhea, hemorrhagic colitis, dysentery, and hemolytic uremic syndromes [(3,4,5)].
Types of Pathogenic E. coli
- There are several pathogenic groups of E. coli, including enterotoxigenic (ETEC), enterohemorrhagic (EHEC), enteroinvasive (EIEC), enteropathogenic (EPEC), enteroaggregative (EAEC), and diffusely adherent (DAEC) groups [(3,4,5)].
- Each pathotype has distinct virulence-associated characteristics that determine the clinical, pathological, and epidemiological features of the diseases they cause 4.