Acetate Utilization Test- Principle, Procedure, Results, Uses

What is Acetate Utilization Test? The acetate utilization test is one of the biochemical tests performed for the identification of aerobic organisms by evaluating their ability to utilize acetate present in the growth media. The principle of the acetate utilization test is based on the ability of an organism to utilize acetate as a sole source of carbon. This test …

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Bacterial Conjugation- Definition, Principle, Process, Examples

Bacterial Conjugation Definition Conjugation is the transfer of a plasmid or other self-transmissible DNA element and sometimes chromosomal DNA from a donor cell to a recipient cell via direct contact usually mediated by a conjugation pilus or sex pilus. Recipients of the DNA transferred by conjugation are called transconjugants. The process of conjugation can transfer DNA regions of hundreds to …

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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 A/E cytopathology, resembling EPEC strains. …

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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 of the intestines causing them …

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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 and clinical outcomes. Most infections …

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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 (R) form. 3. Smooth forms …

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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 (hemagglutinating & mannose-sensitive) and are …

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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 cultures should be plated using …

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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 habitat of E. coli is in …

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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 strains are biochemically, genetically, and …

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