Shiga toxin-producing Escherichia coli (STEC)

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 but not all EHEC strains are LEE positive and form … Read more Shiga toxin-producing Escherichia coli (STEC)

Enterotoxigenic E. coli (ETEC)

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 of E. coli that produces special toxins that stimulate the lining … Read more Enterotoxigenic E. coli (ETEC)

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 microbiota E. coli, enterovirulent E. coli, and extraintestinal pathogenic E. coli on the basis of their genetic features … Read more E. coli- Pathogenicity and Clinical Manifestations

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, moist, smooth and opaque. 2. They are of 2 forms: Smooth (S) form and Rough … Read more Cultural Characteristics of E. coli

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. Some strains are non-motile. Some strains may be fimbriated. The fimbriae are of type 1 … Read more Morphology of E. coli

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 in urine specimens. On staining, E coli appear as non-spore-forming, Gram-negative rod-shaped bacterium Routine urine … Read more E. coli- Lab Diagnosis, Treatment, Prevention and Control

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 depends upon the availability of the nutrients within the intestine of host organisms. The primary … Read more Habitat of E. coli

Enteroinvasive E. coli (EIEC)

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 with a few restricted O serotypes: O124, O143, and O164. EIEC … Read more Enteroinvasive E. coli (EIEC)

CHROMagar (Rambach Agar)

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 a specific enzymatic activity) and a chromophore. When the target organism’s enzyme … Read more CHROMagar (Rambach Agar)

Enteroaggregative E. coli (EAEC)

Stages of pathogenesis of EAEC

Enteroaggregative E. coli (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 not secrete enterotoxins LT or ST and that adhere to HEp-2 … Read more Enteroaggregative E. coli (EAEC)

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

E. coli Pathotypes

E. coli Pathotypes- ETEC, EPEC, EHEC, EAEC, EIEC, DAEC 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 the basis of their genetic features … Read more E. coli Pathotypes- ETEC, EPEC, EHEC, EAEC, EIEC, DAEC

Recombinant DNA Technology- Steps, Applications and Limitations

Recombinant DNA technology

Recombinant DNA Technology- Steps, Applications and Limitations 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 general name for a piece of DNA that … Read more Recombinant DNA Technology- Steps, Applications and Limitations

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 acetate membranes, using a sterile glass Drigalski spreader, distribute the fluid over the entire membrane … Read more Rapid Method for Enumeration of E. coli Biotype I

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 (-ve) H2S Negative (-ve) Hemolysis Negative (-ve) Indole Positive (+ve) Motility Motile MR (Methyl Red) … Read more Biochemical Test of Escherichia coli (E. coli)