Escherichia coli

Escherichia coli is found in the vast majority of warm-blooded animals. It forms part of the physiological microflora of the colon and the distal part of the ileum. The individual is colonised almost immediately after birth, usually by alimentary route or by transfer from an already colonised individual. In the long term, E. coli is unable to exist outside the host. Therefore, its detection (e.g. in drinking water) is indicative of faecal contamination.

Diseases
Strains of E. coli that are part of the microflora do not cause disease in healthy individuals. It takes one of the following factors to cause a clinically serious infection:
 * disruption of the eumicrobiota, e.g. due to the use of ATBs or immunosuppression, and an overgrowth of E. coli;
 * pathogenic strains' capable of producing various pathogenicity factors (toxins, adhesive pili);
 * Introduction of infection' outside the gut, most commonly into the urinary tract, peritoneal cavity.

Cultivation
Cultivation of E. coli is undemanding. For its isolation and diagnosis, lactose agar is most commonly used. On MacConkey agar' and Endo agar', it grows in colonies surrounded by pink staining indicating lactose fermentation. On blood agar it grows in greyish colonies, some strains (often pathogenic) with complete haemolysis.

Biochemistry
E. coli has very broad enzymatic activity, which is used in its identification. So-called colour series are used, which, by the change in colour after plating and incubation of a colony, allow the species to be classified precisely according to its biochemical properties. This is often used because of the need to distinguish other enterobacteria that participate in the intestinal flora.

Microscopy
In a slide stained with by Gram, E. coli appears as a G-stick with flagella.

Serology
Classical serological procedures are used in more precise determinations. This is mainly used in tracking epidemics and spread of individual strains. The most important is indirect agglutination', which can distinguish individual serotypes of E. coli.

Treatment
Conventional treatment is symptomatic only. Antibiotics are used only in extraintestinal infections and immunosuppressed patients. β-lactam ATBs can be used along with β-lactamase inhibitors. Escherichia coli is sensitive to most antibiotics.

Related articles

 * Infections caused by Escherichia coli

Source

 * ws:Escherichia coli