Abstract. The aim of the work is to study the biological properties of the enteroaggregative Escherichia coli strain isolated from the biopsy material of the colon mucosa of a patient with ulcerative colitis, and to develop a new method for PCR identification of E. coli strains.
Methods: The study involved 46 patients with a verified diagnosis of ulcerative colitis. Isolation of 87 strains of Escherichia coli was carried out from colon biopsy material obtained during a standard endoscopic procedure. The description of the biochemical properties of bacteria was combined with the molecular genetic determination of virulence determinants and the presence of antibiotic resistance mechanisms.
Using the AmpliSense Escherichiose - FL reagent kit, a screening for the presence of diarrheagenic E. coli strains was performed, which revealed the presence of one enteroaggregative strain of E. coli (EAgEC).
The methodological approach to creating a new method for strain identification was based on the search for a unique genetic sequence in the glutamate decarboxylase (gad) gene.
Results: E. coli 18-726 can be described biochemically as typical of its species. The studied strain was characterized by a multiple resistance phenotype (MDR) to antibacterial chemotherapy drugs, as well as a lack of sensitivity to five bacteriophage preparations.
The E. coli 18-726 strain had a unique sequence of the gene encoding the O-antigen, which differed from 188 known O-antigens (ONT) and, by the identity of the nucleotide sequence of the gene encoding the synthesis of the H-antigen, the strain belonged to the H30 serovar. Thus, the antigenic formula of strain EAgEC 18-726 was expressed as ONT:H30.
The E. coli 18-726 strain contained a significant spectrum of genes that implement the properties of virulence (iss, capU, aggA, aggB, aggC, aggD, aap, aar) and resistance to antibacterial drugs (blaCTX-M-15, blaTEM-1B, aadA1, aadA5, mph(A), catB3).
A new method for identifying enteroaggregative E. coli in chronic bowel disease is based on the polymerase chain reaction method using primers for a specific region of the glutamate decarboxylase (gad) gene.
Conclusion:
The biochemical, antigenic and molecular genetic properties of Escherichia coli ONT:H30 18-726 strain (No. B-8857) isolated from a patient with histomorphologically diagnosed ulcerative colitis were analyzed.
2. A method for PCR identification of enteroaggregative strains of Escherichia coli based on the detection of a specific region of the glutamate decarboxylase gene in the genome of strains has been created and patented.