Pathogenic Escherichia coli: virulence factors, spread, diagnostic problems

Abstract

Escherichia  coli  are  components  of  the noromoflora  of  the  gastrointestinal  tract  of animals  and  humans,  however,  the  E.  coli genome  may  contain  genes  encoding  virulence  factors,  causing  diseases  of  animals and humans with a wide range of pathological changes and clinical manifestations. The presence or absence of virulence factors does not  always  correlate  with  the  serological group,  which  is  not  always  taken  into  account by laboratory specialists and leads to errors in diagnosis. According to the location of  the  pathological  process  caused,  escherichiosis pathogens are divided into diarrheal (DEC)  and  disease-causing  extra-intestinal localization (ExPEC). According to the presence  of  specific  virulence  factors  and  the pathogenesis of the diseases caused, diarrhe-ogenic E. coli are divided into enteropathogenic (HERES), enteroinvasive (EIEC), diffuse-adhesive  (DAEC),  enteroaggregative (EAggEC), enterotoxigenic (ETES) and shigatoxin-producing  or  enterohemorrhagic (ENES or STEC). The last three groups include  E.coli,  which  can  cause  diseases  in productive  animals.  To  E.  The  coli  of  the EXP group  include uropathogenic  (UPEC), which cause neonatal meningitis and sepsis (NMEC,  SEPEC)  and  airborne  pathogenic (ARES),  which  cause  colibacteriosis  in birds.  The  main  factor  in  the  virulence  of ENES is the production of shiga, a toxin that causes  severe  changes  in  the  body.  In  humans,  ENES  cause  hemocolitis,  often  with the  development  of  hemolytic-uremic  syndrome  (HUS),  leading  to  disability  and sometimes death of the patient. Cattle are the reservoir  of  ENES,  clinical  signs  develop only in young animals, adult animals can be carriers of ENES and contaminate milk and meat with strains. These are potential pathogens of Escherichia coli in calves and piglets. The ARES group is represented by E. coli  strains  that  cause  infection  in  poultry, especially broilers, with a variety of pathological  manifestations:  septicemia,  peritonitis, perigepatitis, air bag infections, osteomyelitis.