Escherichia coli, commonly known as E. coli, is a bacterium widely recognized for its presence in the intestines of humans and other warm-blooded animals. While certain strains of E. coli are notorious for causing severe illnesses, the majority exist harmlessly within the gut, playing a beneficial role in processes like vitamin synthesis and food digestion. This dual nature makes E. coli a fascinating microorganism, with its discovery marking a significant moment in the understanding of the microbial world within us.
The Pioneer Behind the Discovery
The bacterium was first identified by Theodor Escherich, an Austrian pediatrician and bacteriologist (born 1857 in Ansbach, Germany). He qualified as a physician in 1881. His father, a district medical officer, had a keen interest in public health, which likely influenced Theodor’s career path.
Escherich dedicated his research to understanding the bacterial inhabitants of the infant intestinal tract, aiming to define normal bacterial flora and its role in digestion. This focus on infant health and intestinal microbiology provided the context for his investigations.
Unveiling the Bacterium
The discovery of E. coli occurred in 1885 as Escherich investigated the intestinal contents of infants. He examined fecal samples from both healthy and sick babies, employing microscopy and bacterial culturing to isolate and grow bacteria.
Escherich’s studies demonstrated that meconium, the first stool of a newborn, was sterile, and that bacterial colonization of the infant’s intestine began within 3 to 24 hours after birth, originating from the surrounding environment. Using Christian Gram’s staining technique and his own anaerobic culture methods, Escherich isolated and identified 19 different types of bacteria. Among these, he characterized a rod-shaped bacterium he named “Bacterium coli commune,” meaning “common colon bacterium.”
He presented his findings to the Society for Morphology and Physiology on July 14, 1885. The bacterium would later be renamed Escherichia coli in 1919 to honor its discoverer, a designation that received official sanction in 1958.
Immediate Recognition and Importance
Escherich’s discovery and 1886 publication, “The Intestinal Bacteria of the Infant and Their Relation to the Physiology of Digestion,” were recognized as contributions to the nascent field of medical microbiology. This period, often called the “golden age of bacteriology,” saw the increasing acceptance of germ theory, which proposed that specific microorganisms cause diseases.
His work applied Robert Koch’s bacteriological methods to pediatrics, influencing the understanding of infant health and disease. Bacterium coli commune gained prominence as a model organism in scientific research due to its ease of isolation, rapid growth, and adaptability in laboratory settings.
Scientists began to explore its role in both normal physiology and disease states. Escherich himself noted the bacterium’s presence in urine samples from young girls, which highlighted its potential involvement in urinary tract infections. This early recognition established Bacterium coli commune as a subject for investigation into intestinal bacteria and their impact on health.