Escherichia coli (E. coli)- An Overview

Habitat of E. coli

Habitat of E. coli E. coli was discovered by Theodor Escherich in 1885 after isolating it from the feces of newborns. E. coli is the normal flora of the human body. The niche of E. coli depends upon the availability of … Read more

Shiga toxin-producing Escherichia coli (STEC)

Shiga toxin-producing Escherichia coli (STEC)

The Shiga toxin-producing E. coli (STEC), is also alternatively referred to as verocytotoxin-producing E. coli (VTEC), and enterohemorrhagic E. coli (EHEC). All members of this group are defined by the presence of Shiga toxin 1 (Stx1) or 2 (Stx2). Some … Read more

Enterotoxigenic E. coli (ETEC)

Enterotoxigenic E. coli (ETEC)

Enterotoxigenic E. coli (ETEC) is defined as containing the E. coli strains that elaborate at least one member of two defined groups of enterotoxins: heat-stable toxin (ST) and heat-stable toxin (LT). Enterotoxigenic Escherichia coli, or ETEC, is thus the name given to a group … Read more

E. coli- Pathogenicity and Clinical Manifestations

E. coli- Pathogenicity and Clinical Manifestations

E. coli is the most common and important member of the genus Escherichia. It is a Gram-negative, facultative anaerobic, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Human Escherichia coli strains are classified as commensal … Read more

Cultural Characteristics of E. coli

Cultural Characteristics of E. coli

Cultural Characteristics of E. coli 1. E. coli is a facultative anaerobes. 2. Its optimum growth temperature is 37°C and ranges from 10°C to 40°C. E. coli on Nutrient Agar (NA) 1. They appear large, circular, low convex, grayish, white, … Read more

Morphology of E. coli

Morphology of E. coli

Morphology of E. coli E. coli is gram-negative (-ve) rod-shaped bacteria. It is 1-3 x 0.4-0.7 µm in size and 0.6 to 0.7 µm in volume. It is arranged singly or in pairs. It is motile due to peritrichous flagella. … Read more

E. coli- Lab Diagnosis, Treatment, Prevention and Control

E. coli- Lab Diagnosis, Treatment, Prevention and Control

Laboratory Diagnosis Urinary Tract Infection Most urine specimens are obtained from adult patients via the clean-catch midstream technique. Bacteriuria can be detected microscopically using Gram staining of uncentrifuged urine specimens, Gram staining of centrifuged specimens, or direct observation of bacteria … Read more

Habitat of E. coli

Habitat of E. coli

Habitat of E. coli Some of the characteristics are: E. coli was discovered by Theodor Escherich in 1885 after isolating it from the feces of newborns. E. coli is the normal flora of the human body. The niche of E. coli … Read more

Enteroinvasive E. coli (EIEC)

Enteroinvasive E. coli (EIEC)

Enteroinvasive E. coli (EIEC) strains are rare in both developed and developing countries. EIEC infections are characterized by a period of watery diarrhea that precedes the onset of scanty dysenteric stools containing blood and mucus. Pathogenic strains are primarily associated … Read more

CHROMagar (Rambach Agar)

CHROMagar (Rambach Agar)

The first chromogenic culture medium for detection of E. coli was invented and patented by Dr. A. Rambach in 1979. This technology is color-based differentiation method. It is based on soluble colorless molecules (called chromogens), composed of a substrate (targeting … Read more

Enteroaggregative E. coli (EAEC)

Stages of pathogenesis of EAEC

Enteroaggregative E.  coli (EAEC) are a heterogeneous collection of strains characterized by their autoagglutination in a “stacked-brick” arrangement over the epithelium of the small intestine and, in some cases, the colon. EAEC strains are currently defined as  E. coli strains that do … Read more

E. coli Pathotypes- ETEC, EPEC, EHEC, EAEC, EIEC, DAEC

E. coli Pathotypes

Escherichia coli (commonly abbreviated E. coli) is a Gram-negative, facultative anaerobic, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Human Escherichia coli strains are classified as commensal microbiota E. coli, enterovirulent E. coli, and extraintestinal pathogenic E. coli (ExPEC) on … Read more

Recombinant DNA Technology- Steps, Applications and Limitations

Recombinant DNA technology

Recombinant DNA technology refers to the joining together of DNA molecules from two different species that are inserted into a host organism to produce new genetic combinations that are of value to science, medicine, agriculture, and industry. Recombinant DNA (rDNA), on the other hand is the … Read more

Rapid Method for Enumeration of E. coli Biotype I

Rapid Method for Enumeration of E. coli Biotype I

This method is modified by Anderson and Parker. Prepare serial tenfold dilutions in peptone water of food. Aseptically transfer sterile cellulose acetate membranes to the surface or dried glutamate agar. Transfer duplicate 1.0 mL aliquots of each dilution to cellulose … Read more

Biochemical Test of Escherichia coli (E. coli)

Biochemical Test of Escherichia coli (E. coli)

Biochemical Test of Escherichia coli (E. coli) Basic Characteristics Properties (E. coli) Capsule Capsulated Catalase Positive (+ve) Citrate Negative (-ve) Coagulase Negative (-ve) Flagella Flagellated Gas Positive (+ve) Gelatin Hydrolysis Negative (-ve) Gram Staining Negative (-ve) Growth in KCN Negative … Read more

E. coli on m-Endo Agar

E. coli growing on m-Endo Agar with golden-green metallic sheen

– E. coli growing on m-Endo Agar with golden-green metallic sheen. – Photo By: Nurul Azira MJ from Penang, Malaysia. – M-Endo Agar is used for enumeration of coliforms in water using a two step membrane filter method. – Red … Read more